PhD defense of Wei Cheng Tan

PhD defense of Wei Cheng Tan

Wei Cheng Tan has just very successfully defended his PhD thesis!

Effects of habitat fragmentation on herpetofauna in Southeast Asia: From broad-scale responses to fine-scale responses in an ever-changing anthropogenic landscape

Watch the public defense of the thesis on YouTube


Habitat loss and fragmentation are undoubtedly significant drivers of biodiversity loss worldwide, with Southeast Asia being a hotspot of biodiversity and facing numerous anthropogenic pressures. However, the impacts of habitat fragmentation on biodiversity are still not fully understood, and further research is required to determine the responses of different taxa to this threat. Reptiles and amphibians (herpetofauna), in particular, are among the most threatened groups globally, with Southeast Asia being home to a high diversity of species and facing imminent threats from habitat loss and fragmentation. By combining bibliographic analyses and macroecological methods, this thesis aims to contribute to the knowledge on the current global state of habitat fragmentation research in herpetofauna and the broad and fine-scale responses of Southeast Asian reptiles to various forms of habitat fragmentation.

Chapter 1: This chapter introduces the concepts of habitat fragmentation and its effects on biodiversity. It accentuates the importance of Southeast Asia for habitat fragmentation research due to its complex geological history, high species richness, and rapid habitat loss. It also describes the plight of the Southeast Asian herpetofauna, focusing on their vulnerability to habitat loss and fragmentation in freshwater environments. Lastly, the chapter gives a brief overview of the methodologies and approaches used throughout this thesis.

Chapter 2: Recent decades have seen a surge of funding, published papers, and citations in the field as threats to biodiversity continue to rise. However, how research directions and agendas are evolving in this field remains poorly understood. This chapter presents a global review of past and current state of research on habitat fragmentation for reptiles and amphibians. Here, I systematically reviewed published literatures on habitat fragmentation effects on reptiles and amphibians from 1990 to 2020, with the aim of identifying geographical and taxonomical trends on the various forms of habitat fragmentation, and the sampling methods and response variables commonly employed to identify them. The study reveals several patterns and biases in research efforts, such as the concentration of studies in wealthy and English-speaking countries, and the under-representation of certain regions (e.g. Africa and Southeast Asia) and taxa (e.g. caecilians, fossorial reptiles). It specifically calls for increased attention to these taxa in Southeast Asia, which have received less scientific scrutiny compared to other regions of the world. Moreover, there is a shift in research agendas toward studies utilizing technological advancements including genetic and spatial data analyses. These findings suggest important associations between sampling methods and prevalent response variables but not with the forms of habitat fragmentation. This review suggests the need for more studies on genetic and spatial patterns, with emphasis on underrepresented reptile and amphibian taxa. This chapter sets the context for the subsequent chapters by highlighting the existing gaps in the field.

Chapter 3: This chapter uses species distribution models to investigate the broad-scale responses of threatened semi-aquatic or freshwater reptiles to current and future climatic and anthropogenic conditions. More specifically, it examines the habitat suitability of endangered freshwater crocodiles and turtles and assesses the effectiveness of existing protected areas in conserving these species across Southeast and South Asia (in the Indomalayan realm). Species distribution models are highly successful in predicting potentially suitable habitats of a species based on their environmental niche and presence records. The results suggest that protected areas may be insufficient in the face of current anthropogenic pressures and future climate change. The chapter emphasizes the importance of considering both climatic and non-climatic factors in species distribution models. The results of this chapter are essential for conservation planning and management, as they provide insights into important areas and reserves that should be prioritized.

Chapter 4: This chapter zooms in from a broad-scale to fine-scale view of species response to habitat change, focusing on the effect of logging, which affects more than half of the remaining tropical forests in Southeast Asia. Logging has direct and indirect impacts on freshwater turtle habitats, such as altering stream hydrology and increasing sedimentation. In this chapter, I examine the fine-scale responses of two freshwater turtle species to Reduced Impact Logging, a sustainable forestry method, in Deramakot reserve in Sabah, Malaysian Borneo. I use occupancy models to estimate the probability of species detectability and habitat associations across a post-harvest recovery gradient (1 –21 years since logging), using presence and absence data. Results for the non-threatened soft-shelled turtle, Dogania subplana are inconclusive. However, the study reveals a significant negative association between monthly rainfall and the detection of the threatened hard-shelled turtle, Notochelys platynota. The occupancy probability of N. platynota is positively associated with greater distance from logging roads. Nevertheless, both species appear to be relatively common throughout the reserve. The chapter suggests that forests managed sustainably, i.e. using Reduced Impact Logging could serve as conservation areas for imperiled freshwater turtle species in the region.

Lastly, chapter 5 summarizes the results of this thesis and its implications and contributions to the field. It also considers the limitations of the approaches and methodologies used. Overall, this thesis emphasizes the urgent need for more research on the effects of habitat fragmentation on herpetofauna in Southeast Asia and the importance of incorporating both broad and fine-scale data. This work is a significant step towards providing easily reproducible studies to be used as a baseline to ensure the long-term survival of these vulnerable species in Southeast Asia.

These papers are already published and included in the thesis:

Harrer, S., P. Ginal, W. C. Tan, J. W. Binaday, A. C. Diesmos, R. Manalo, T. Ziegler, and D. Rödder. 2024. Disappearing archosaurs – an assessment of established protected areas in the Philippines to save the Critically Endangered, endemic Philippine Crocodile (Crocodylus mindorensis). Salamandra 60: 29-41. (PDF)

Mobaraki, A., M. Erfani, E. Abtin, J. C. BritoW. C. Tan, T. Ziegler, and D. Rödder. 2023. Last chance to see? Iran and India as strongholds for the Marsh crocodile (Crocodylus palustris). Salamandra 59: 327–335. (PDF)

Tan, W. C., A. Herrel, and D. Rödder. 2023. A global analysis of habitat fragmentation research in reptiles and amphibians: What have we done so far? Biodiversity and Conservation 32: 439–468. (PDF)

Tan, W. C., P. Ginal, A. G. J. Rhodin, J. B. Iverson, and D. Rödder. 2022. A present and future assessment of the effectiveness of existing reserves in preserving three critically endangered freshwater turtles in Southeast Asia and South Asia. Frontiers of Biogeography 2021, 14.1, e50928. (PDF)

Breeding programs initiated in Vietnam to help turtle species threatened by extinction

Conservationists have initiated breeding programs in Vietnam to recover spotted softshell turtle populations threatened by overconsumption and habitat loss. Based on a literature study, field surveys across Vietnam, and genetic screenings of collected samples, researchers estimated the range and conservation status of Pelodiscus variegatus, the spotted softshell turtle. The data were then used to model the species’ potential range in Vietnam.

Release of offspring of the spotted softshell Phot. C. T. Pham

Conservation breeding programs are intended to support the protection of the endangered spotted softshell turtle. In order to find out more about their occurrence on the Indochinese mainland, researchers have now published a study on habitat suitability and distribution patterns in the journal Nature Conservation. The study combines molecular analyses and species distribution modeling to identify priority conservation areas.

The study was published with the participation of the Vietnam Academy of Science and Technology (VAST), the Vietnam National University Hanoi and the Asian Turtle Program (Vietnam), as well as the Cologne Zoo and the Leibniz Institute for the Analysis of Biodiversity Change (LIB).

The spotted softshell turtle (Pelodiscus variegatus) has been known from Vietnam and Hainan Island, China, since 2019. It is considered a delicacy in these countries. In China alone, hundreds of millions of turtles are traded every year, making them the most consumed turtles in the world. Habitat loss and degradation, competition with non-native turtle species and habitat pollution are further reasons for the species’ decline.

Although several protected areas in Vietnam appear to offer suitable habitats for this turtle species, the researchers were unable to detect populations in any of the areas studied. “We therefore assume that the spotted softshell turtle is particularly threatened with extinction,” emphasizes PD Dr. Dennis Rödder, Curator of Herpetology at the Museum Koenig Bonn of the LIB.

The results of the ecological modeling show that Pelodiscus variegatus may also occur in Laos. “However, on the border between Vietnam and Laos and in wetlands, we were only able to find patchy evidence of it,” says Rödder, describing the modeling.

Vietnamese conservationists, in collaboration with Prof. Dr. Thomas Ziegler from Cologne Zoo, have launched conservation breeding programs in Vietnam to save populations of the spotted softshell turtle that are threatened by overconsumption, habitat loss and mixing with invasive species.

The researchers calculated the distribution range and conservation status of the spotted softshell turtle based on a literature review, field studies across Vietnam and genetic studies of collected samples. The data was used to model the potential range of the species in Vietnam.

To restore the species’ natural populations, the Institute of Ecology and Biological Resources (IEBR, VAST) in Vietnam and Cologne Zoo have launched an in-country conservation breeding program. By the end of 2023, 50 young and healthy turtles had already been released into the wild in a location with a suitable climate and habitat in northern Vietnam.

Based on the results of the study, it is hoped that further individuals can be reintroduced into protected areas in north-central Vietnam, the distribution center of the spotted softshell turtle. In this way, the consortium hopes to stem the decline of the species and make a further contribution to the global “Reverse the Red” movement – by applying the IUCN’s “One Plan Approach to Conservation”, in which all available expertise works together to optimize species protection.

Soft-shelled turtles of the genus Pelodiscus are widespread from south-eastern Siberia to China and Vietnam. However, human transportation and breeding activities have extended their range to Indonesia, northern Australia, western Europe, North America, Hawaii and Mauritius.

Traditionally, this genus was considered monotypic, i.e. with only one recognized species, the Chinese softshell turtle (Pelodiscus sinensis). However, recent research has shown that the genus is much more diverse and at least seven species are known to science, which consequently have smaller distributions and are more threatened.

“Due to their morphological similarity, expanding settlements and agricultural activities, overexploitation and aquatic lifestyle, it is often difficult to study them in their natural habitat to better understand their distribution as well as their population and conservation status,” says Rödder. “Unfortunately, only part of the species’ potential range is protected so far and there is no known evidence from protected areas, which underlines the need for extended or even new protected areas.”

Original study:

Le MD, Rödder D, Nguyen TT, The Pham C, Nguyen TQ, Ong AV, McCormack TEM, Nguyen TT, Le MH, Ngo HT, Ziegler T (2024) Climatic niche modelling and genetic analyses highlight conservation priorities for the Spotted Softshell Turtle (Pelodiscus variegatus). Nature Conservation 55: 67-82. (PDF)

PhD defense of Philipp Ginal

Philipp Ginal has just very successfully defended his PhD thesis!

Invasion biology of amphibians and reptiles: From observations to predictive spatial models

His thesis entitled “Invasion biology of amphibians and reptiles: From observations to predictive spatial models” comprises six publications. Overall, his thesis is broadly folded, and comprises several target species across different taxonomic groups (i.e., anurans, urodeles, squamates), scales (i.e., local, regional, macro-ecological landscapes), and methodological approaches (i.e., population size estimation, connectivity modeling, correlative and mechanistic species distribution modeling, mechanistic quantification of activity time budgets). The focus of my thesis relies on the methodological approaches and therefore, the red line here starts with relatively simple models and ends with a novel, complex mechanistic approach.

Furthermore, three publications consider the African Clawed Frog, Xenopus laevis (Daudin, 1802), which is among the most invasive amphibian species in the world.

Two further publications focus on the Oriental Garden Lizard, Calotes versicolor (Daudin, 1802) complex, a wide-spread but neglected invader with potential negative impacts, and the Italian Cave Salamander, Speleomantes italicus (Dunn, 1923), which is non-native but locally very restricted with no known negative impacts yet. Another publication considers the invasive fungal disease Batrachochytrium salamandrivorans Martel et al. 2013 (Bsal), which has substantial negative impacts on macro-ecological scales, and one of its host species, the European Fire Salamander, Salamandra salamandra (Linnaeus, 1758).

These papers are already published and included in the thesis:

Ginal, P., N. Kruger, C. Wagener, L. Araspin, M. Mokhatla, J. Secondi, A. Herrel, J. Measey, and D. Rödder. 2023. More time for aliens? Performance shifts lead to increased activity time budgets propelling invasion success. Biological Invasions 25: 267–283. (PDF)

Ginal, P., W. C. Tan, and D. Rödder. 2022. Invasive risk assessment and expansion of the realized niche of the Calotes versicolor species complex (Daudin, 1802). Frontiers of Biogeography 14.3, e54299. (PDF)

Ginal, P., M. Mokhatla, N. Kruger, J. Secondi, A. Herrel, J. Measey, and D. Rödder. 2021. Ecophysiological models for global invaders: Is Europe a big playground for the African clawed frog? Journal of Experimental Zoology – Part A: Ecological and Integrative Physiology 2020: 158-172. (PDF)

Ginal, P. C.-H. Loske, T. Hörren and D. Rödder. 2021. Cave salamanders (Speleomantes spp.) in Germany: tentative species identification, estimation of population size and first insights into an introduced salamander. Herpetology Notes 14: 815-822. (PDF)

Ginal, P., F. D. Moreira, R. Marques, R. Rebelo, and D. Rödder. 2021. Predicting terrestrial dispersal corridors of the invasive African clawed frog Xenopus laevis in Portugal. NeoBiota 64: 103–118. (PDF)

André Vincente Liz: PhD defense

Comparative phylogeograpy of the Sahara – Sahel: a spatiotemporal approach to biodiversity dynamics in the largest warm desert on erth

Our PhD Student André Vincente Liz just successfully defended his PhD thesis, congratulations! A full recording of the defense is provided by the University of Porto.


The Sahara-Sahel environments are home to rather endemic desert biotas highly adapted to the region’s aridity constraints and the dry/humid climatic cycles that took place throughout the Plio-Pleistocene. Species’ contemporary patterns harbour a crucial potential to understand the impacts of these steep fluctuations on the desert’s landscape, as well as to develop integrative conservation agendas that help preserving a highly vulnerable local wildlife. Yet, this baseline biological knowledge has been traditionally lacking for the region. With the advent of molecular phylogeography at the end of the 20th century, biodiversity studies in the Sahara-Sahel have started unravelling novel aspects of its intricate natural history, primarily how palaeoclimatic and subsequent land-cover shifts have shaped the distribution and genetic structure and diversity of local species by triggering different eco-evolutionary processes. Core biogeographic and evolutionary hypotheses have been posed, including population divergence in allopatry, which often led to speciation, dispersal and colonisation of new environments, including trans-Saharan migrations across the desert, or events of secondary contact. Notwithstanding the remarkable recent advances in regional research, biodiversity patterns in some of the most unique features within the region’s eco-physiographic diversity remain virtually unknown. Besides, the phylogeographic scenarios that have been proposed lack corroboration under a common framework.

Aiming to provide the first comprehensive picture of biodiversity patterns in the Sahara-Sahel, this thesis builds upon a comparative phylogeography framework that seeks to verify and expand the major biogeographic and evolutionary questions posed for the region. For this purpose, I assessed all publicly available DNA data for Sahara-Sahel vertebrates (i.e., >1,000 species) and selected the most relevant taxa based on data availability and species’ distribution within the study area. I tested phylogeographic scenarios through the integration of different molecular and eco-geographic analyses, including phylogenetics, phylogeography, population genetics, species distribution modelling (SDM), and geostatistics. These analyses allowed inferring the location of ecological refugia, dispersal corridors, and hotspots of intra-specific diversity for regional species according to their habitat requirements, i.e. those more- (xeric) or less (mesic) adapted taxa to the desert’s extreme aridity. Considering that the advent of arid conditions in North Africa triggered the diversification of the most xeric taxa, examining the phylogenetic ages of these species allowed estimating the chronology of the Sahara for the first time from a biological point of view. During the development of this thesis, I also generated new biodiversity data that allowed examining phylogeographic hypotheses in poorly known regions of the Sahara-Sahel, which yet constitute key elements to understand the region’s natural history. Specifically, I (1) addressed the role of Central Sahara highlands in historical biodiversity dynamics, and (2) examined biodiversity patterns throughout the hyper-arid Sahara.

Notably, the phylogenetic insights brought by xeric taxa suggest that the onset of aridification in North Africa occurred in the Mid Miocene, contrasting remarkably with geological and climatological findings. The age of the Sahara is still a controversial topic; evidence for this is that new studies keep reporting contrasting estimates: from 7 up to 11 Myr. This thesis provides the first comprehensive chronology for the impact of regional aridification on Saharan wildlife. Beyond vertebrates, this work also looked at the age of the remaining taxonomic groups for which molecular data was available (i.e., scorpions), given the low number of species that occupy the desert’s extreme environments. This analysis highlighted the need for systematic assessments on Saharan xeric arthropods, such as beetles, spiders or grasshoppers, which present profound knowledge shortfalls despite being major elements within the region’s biological diversity.

Concerning the lack of phylogeographic knowledge for some of the least known regions of the Sahara-Sahel, two studies were conducted. In the first one, I assessed whether the mountains of Central Sahara acted as historical ecological refugia and diversification hotspots for mesic taxa, while also aided in trans-Saharan faunal translocations during humid desert stages. Insights come from the phylogeographic assessment of Acanthodactylus boskianus, a species complex inhabiting mesic environments and distributed at both sides of the desert and in scattered populations throughout the Central Sahara highlands. Results revealed that mountains in Southern Algeria (i.e., Tassili N’Ajjer, Ahaggar), South-western Libya (i.e., Fezzan, Akakus), Niger (i.e., Aïr), and Northern Chad (i.e. Tibesti) harbour historical climatic stability that favoured the local persistence of A. boskianus. Besides, the few genetic samples available from the region recovered high local lineage diversity, with reports of old and mountain endemic clades. Lack of genetic differentiation between some Mediterranean, Central Saharan, and Sahelian populations suggest the existence of recent gene flow between both sides of the desert, which could be explained through the intermittent ecological suitability here observed across interconnected Central Sahara mountainous refugia. In the second study, I analysed the genetic structure and diversity of species inhabiting the most arid environments of the Sahara, where knowledge on biodiversity patterns was almost inexistent. For this purpose, I conducted a phylogeographic assessment of the Acanthodactylus scutellatus complex, which embeds six currently recognised species that possibly comprise the most widespread vertebrates across hyper-arid Saharan habitats. Results recovered surprisingly high levels of intra-specific diversity, including several previously unknown sympatric or parapatric lineages that exhibit both nuclear and mitochondrial differentiation, suggesting species status. These findings evidence that biodiversity estimates for xeric Saharan habitats are likely neglecting a notable amount of undescribed diversity, which seemingly originated in allopatry due to the steep habitat fluctuations that took place throughout the Plio-Pleistocene. Interestingly, the origin of some of these lineages dates back to the Miocene, coinciding with the onset of dry/humid fluctuations in North Africa. Some environments of the northern Sahara, such as the Algerian ergs (i.e., sand-dune fields), were found to be particularly rich in terms of intra-specific diversity. A contrasting pattern was found across southern Sahara latitudes and the Sahel, where the lack of genetic differentiation between distant populations suggested that population dispersal at this latitude was common. The assessment of individual lineage genetic imprints allowed delimiting potential areas of refugia within these desert corridors, however, fine-scale research is needed to clarify whether they correspond to specific landscape features such as palaeolakes, ergs or mountain outskirts.

The primary component of this thesis was the comparative phylogeography assessment, which I conducted after setting the biological chronology of the desert, generating additional data, and refining key phylogeographic hypotheses. This meta-analysis was conducted through the integration of molecular and ecological components for 107 selected desert taxa, including reptiles, mammals, amphibians, and scorpions. During this process, roughly 8,500 DNA sequences were analysed, most of them corresponding to published data retrieved from GenBank and some newly produced to fill key taxonomic and geographic gaps. The analyses of DNA information allowed estimating areas of high genetic diversity and connectivity for each individual species, as well as for the mesic and xeric communities. The molecular component was integrated with an SDM approach, which expanded the methodological framework traditionally applied to biodiversity assessments in the deserts of North Africa. As such, I incorporated for the first time historical hydrological and vegetation data into the SDM pipeline, thus considering previously overlooked ecological dimensions which likely played a major role in historical species responses to dry/wet fluctuations. The historical shifts in species’ range were modelled for the selected 107 taxa using over 28,000 observation records. Results allowed verifying the major biogeographic and evolutionary questions previously proposed for the region. Patterns of intra-specific diversity confirm that the isolated mountains of Central Sahara are important centres of diversity, several of which still lack baseline biodiversity knowledge, with clear examples in Chad (i.e., Tibesti, Ennedi) and Sudan (i.e., Jabal Marrah). High diversity was also found across the northern Sahara for xeric taxa, suggesting that this region harbours a crucial role in the evolution and persistence of truly-desert species, despite local biodiversity patterns being also poorly known. Refugia inferences corroborate the importance of the Atlantic region for most of the species, as well as northern Sahara areas for xeric taxa and mountains for mesic taxa. Additionally, patterns of genetic and ecological connectivity confirm that corridors across Central Sahara highlands played a major role in trans-Saharan dispersals, which can be comparable to that of the Nile Valley and the Atlantic Coast.

This thesis provides integrative knowledge that can be immediately applied to biodiversity conservation agendas in the deserts of North Africa, as well as to the study of biodiversity in deserts and arid regions. In addition, insights on species’ genome and habitat imprints expand our understanding of the natural history of the region, with implications for the evolution and migration of both the desert’s endemic biotas and the early humans that peopled the Sahara and dispersed out of Africa at the end of the Quaternary. Besides, this thesis opened new biogeographic and evolutionary questions that would require additional research efforts, as well as pinpointed areas of dramatic biodiversity shortfalls that should be targeted in future studies.

Parts of his thesis are already published:

Liz, A. V., D. Rödder, D. V. Gonçalves, G. Velo-Antón, M. M. Fonseca, P. Geniez, P.-A. Crochet, and J. C. Brito. 2023. Overlooked species diversity in the hyper-arid Sahara Desert unveiled by dryland-adapted lizards. Journal of Biogeography 50: 101–115. (PDF)

Liz, A. V., D. V. Gonçalves, G. Velo-Antón, J. C. Brito, P.-A. Crochet and Rödder, D. 2022. Adapt biodiversity targets to climate change. Science 376: 589-590. (PDF)

Liz, A. V., D. Rödder, D. V. Gonçalves, G. Velo-Antón, M. M. Fonseca, P. Geniez, P.-A. Crochet, and J. C. Brito. 2021. The role of Sahara highlands in the diversification and desert colonisation of the Bosc’s fringe-toed lizard. Journal of Biogeography 48: 2891–2906.

Assessment of the threat status of reptile species from Vietnam – Implementation of the One Plan Approach to Conservation

Just published:

Stenger, L., A. Große Hovest, T. Q. Nguyen, C. T. Pham, A. Rauhaus, M. D. Le, D. Rödder, and T. Ziegler. 2023. Assessment of the threat status of reptile species from Vietnam – Implementation of the One Plan Approach to Conservation. Nature Conservation 53: 183–221.

Subsequent to a recently published study in Nature Conservation highlighting the gaps in the protection of Vietnam´s amphibians, Thomas Ziegler and his international cooperation team now present another threat analysis, this time dealing with a detailed assessment of Vietnam’s reptile fauna to uncover gaps in conservation.

Globally, reptiles are considered a group of special conservation con­cern, as they play an important role in almost all ecosystems and often have relatively small distri­bution ranges, making them especially vulnerable to anthropogenic threats.

As Vietnam’s herpetofauna is among the richest in the world and particularly threatened due to habitat loss and overharvesting for traditional medicine, pet trade, and food, it is critical to assess their conservation status.

The publication was based on the bachelor thesis of Lilli Stenger conducted at the University of Cologne, Germany. “Being able to focus my bachelor thesis on the threat status of the reptiles extant in Vietnam was a great opportunity and I am proud of this contribution,” says Lilli Stenger about her thesis project performed in Ziegler’s lab at the Cologne Zoo, Germany. 

The scientists identified 484 reptile species known from Vietnam, noting that the number is likely to go up, as the country is regarded as a top biodiversity hotspot, and the rate of new reptile species discoveries remains high. As many as 159 (33%) reptile species are endemic to the country, with more than half of them (55%) reported exclusively from only a single locality, making them especially vulnerable to extinction. 

“With 131 subregional endemic species and 88 of them restricted to their type locality, the country needs to establish additional local conservation areas to safeguard the microendemic species.” explains one of the authors of the present study, Prof. Dr. Truong Quang Nguyen of the Institute of Ecology and Biological Resources (IEBR), Hanoi.

According to the IUCN Red List of threatened species, 74 of the 484 species recorded from Vietnam are classified as threatened with extinction, including 34 endemic species. Most of threatened reptiles are lizards, followed by snakes and turtles, with 100% of the species in Vietnam listed as Vulnerable or higher. For more than half of Vietnam’s endemic reptiles (85 out of 159), the IUCN Red List status is either missing or outdated and further research is imperative for these species, the researchers say.

According to species richness maps, the Central Annamites region in central Vietnam harbors the highest endemic species diversity (32 species) as well as highest subregional endemic species diversity (21 species), which highlights it as a site of particular importance for reptile conservation.

“Integrating microhabitat level species richness maps and spatial patterns of local endemism rates is essential to identify priority areas for further conservation measures as habitat loss and increased anthropogenic pressures in these areas would adversely affect a higher number of species than it would in other areas” explains Associate Professor Dr. Dennis Rödder, curator of herpetology of the Leibniz Institute for the Analysis of Biodiversity Change, Museum Koenig in Bonn, Germany.

Alarmingly, a protected area analysis showed that 53 of the 159 endemic species (33.2%) including 17 threatened species, have been recorded exclusively from unprotected areas, such as the Critically Endangered Gia Lai Bent-toed Gecko or Endangered Peter’s Butterfly Lizard and Psychedelic Rock Gecko.

 “For these species as well as for the 28 species considered Data Deficient (DD) or those whose conservation statuses have not been evaluated (NE), population assessments should be undertaken as quickly as possible to design appropriate conservation measures in due time,” says co-author Dr. Cuong The Pham from IEBR. 

Successful protection must also include the listing of the most threatened endemic species in national and international legislations to provide them with additional support, as many threatened and/or endemic species are still missing from those legislations. The Vietnamese-German team already could achieve first promising results such as the inclusion of some threatened Vietnamese lizard species in the appendices of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), but more of such advances are still needed.

According to data from Species360’s Zoological Information Management System (ZIMS), 109 (22.5%) of the total 484 species reported to occur in Vietnam are represented in global zoos, with the highest diversity concentrated in facilities in Europe and North America. However, only 6.3% (10 out of 159) of the Vietnamese endemic species are maintained ex situ, thus it is crucial that zoos consider shifting their focus to commit more resources to threatened endemic species.

In order to successfully protect threatened species and meet the objectives of the One Plan Approach of IUCN’s Conservation Planning Specialist Group (CPSG), which refers to the interaction of “in situ” (on site) and “ex situ” (in zoos and stations) measures involving various expertise and thus enabling optimized, contemporary species conservation, ex situ populations must be included in global conservation planning. “This is intended to support the in situ conservation efforts and to buy time as well as to save species from going extinct, as ex situ populations still are available for reintroductions” says co-author Anna Rauhaus, section keeper in Cologne Zoo’s Terrarium division, where 36 species of herpetofauna from Vietnam are held, 19 of them threatened and 25 species of them successfully bred, and most of them connected with in situ conservation measures in Vietnam. .

“Two most endangered turtle species in Vietnam and in the world, the Vietnamese pond turtle (Mauremys annamensis) and the Yangtze giant softshell turtle (Rafetus swinhoei), illustrate the significance of ex situ conservation measures. Both of the species are also not known from any protected area. While Mauremys annamensis is likely to be extinct in the wild, Rafetus swinhoei is on the brink of extinction. Whereas ex situ conservation programs have been implemented in time for Mauremys annamensis with a high number of individuals being kept and bred in zoos and stations, unfortunately, no such initiative has been established for Rafetus swinhoei”, Prof. Dr. Minh Le from the Hanoi National University emphasizes.

“In this regard, modern zoos, as well as local facilities, can play a crucial role in not only conducting or financially supporting in situ conservation projects, but also by protecting species from extinction through maintaining ex situ assurance colonies to reinforce in situ conservation programs, once needed. The Cologne Zoo in Germany and its partner, the Melinh Biodiversity Station in Vietnam, have already successfully implemented a number of conservation breeding initiatives for highly threatened species such as Vietnamese crocodile lizards or Tiger geckos “ explains Prof. Dr. Thomas Ziegler, Vietnam conservation team member and coordinator from Cologne Zoo, Germany.

The present study aims to provide a baseline to authorities, conservationists, rescue centers, and zoos, so that they can follow up with appropriate conservation measures for endangered Vietnamese reptiles. 

A global analysis of habitat fragmentation research in reptiles and amphibians: what have we done so far?

Our new review on habitat fragmentation research in amphibians and reptiles is just published in Biodiversity and Conservation early online! My PhD student Nicholas Tan did a great job analysing the global patterns of research agendas based on more than 1400 papers, comparing methodological and taxonomic biases across geographical regions. The full text is available here:

Tan, W. C., A. Herrel, and D. Rödder. A global analysis of habitat fragmentation research in reptiles and amphibians: What have we done so far? Biodiversity and Conservation.

Habitat change and fragmentation are the primary causes of biodiversity loss worldwide. Recent decades have seen a surge of funding, published papers and citations in the field as these threats to biodiversity continue to rise. However, how research directions and agenda are evolving in this field remains poorly understood. In this study, we examined the current state of research on habitat fragmentation (due to agriculture, logging, fragmentation, urbanisation and roads) pertaining to two of the most threatened vertebrate groups, reptiles and amphibians. We did so by conducting a global scale review of geographical and taxonomical trends on the habitat fragmentation types, associated sampling methods and response variables. Our analyses revealed a number of biases with existing research efforts being focused on three continents (e.g., North America, Europe and Australia) and a surplus of studies measuring species richness and abundance. However, we saw a shift in research agenda towards studies utilising technological advancements including genetic and spatial data analyses. Our findings suggest important associations between sampling methods and prevalent response variables but not with the types of habitat fragmentation. These research agendas are found homogeneously distributed across all continents. Increased research investment with appropriate sampling techniques is crucial in biodiversity hotpots such as the tropics where unprecedented threats to herpetofauna exist.

Map of study locations for a amphibians and b reptiles with each circle representing the study location of papers included in the review. The colour scale of the continents ranging from 0 – 0.9 indicates the proportions of amphibian and reptile species represented in the reviewed papers when compared to known species in the world (obtained from AmphibiaWeb and ReptileDatabase): a Europe (0.73), Africa (0.23), North America (0.23), South America (0.18), Oceania (0.07) and Asia (0.06) and b Europe (0.27), Oceania (0.18), Africa (0.12), North America (0.11), South America (0.09) and Asia (0.02)
Co-authorship map of countries involved in habitat fragmentation research in a amphibians and b reptiles. The colours represent the continents countries belong to. Each circle represents an author’s country and the size represents the collaboration frequency with other countries. The lines between the nodes represent the collaboration networks between the countries while the thickness of the lines indicates the collaboration intensities between them. Category co-occurrence network maps for c amphibians and d reptiles. The colour represents the different cluster groups each category belongs to. Abbreviations for the categories in forms of habitat change: fragmentation (FGM), agriculture (AGR), Logging (LOG), Mining (MIN), Urbanisation (URB), road (RD), other habitat fragmentation (OHC); sampling methods: genetics (GEN), direct tracking method (DTM), aerial photographs (APT), GIS/ Satellite images (GIS), experimental (EXP), prediction/ simulation models (PSM) and response variables: species richness/ diversity (SPR), functional richness/ species guild (FCR), presence/ absence (PAS), population (POP), abundance (ABD), dispersal (DSP), breeding sites (BRD), fitness measure (FIT), interspecific interaction (INT), extinction/ colonisation rate (ECR), microhabitat preference (MHP), comparison between generalist and specialist (CGS), other response variables (ORV) (see also Online Appendix 1). Maps are created in VOSviewer
Species coverage for each taxonomic family in selected papers of amphibians. The numbers on each row indicate the total number of species known in its respective family (obtained from AmphibiaWeb 2021)
Species coverage for each taxonomic family in selected papers of reptiles. The numbers on each row indicate the total number of species known in its respective family (obtained from ReptileDatabase)

21st European Conference of Herpetology in Belgrad, Serbia

Our group joined the 21st European Conference of Herpetology in Belgrad, Serbia, where our Herpetologists from the LIB, Musem Koenig were very active. We presented five talks and posters! The conference was awesome and the organizers did a very good job. Thank you very much! Here are some impressions and the abstracts.

Oral presentation
More time for aliens? Performance shifts lead to increased activity time budgets propelling invasion success
Ginal P.1,*, Kruger N.2,3, Wagener C.2,4, Araspin L.2,5, Mokhatla M.2,6, Secondi J.3,7,
Herrel A.8, Measey J.2, Rödder, D.1
1Zoologisches Forschungsmuseum Alexander Koenig (LIB), Bonn, Germany
2Centre for Invasion Biology, Department of Botany and Zoology, Stellenbosch University, Stellenbosch, South Africa
3Univ. Lyon, Université Claude Bernard Lyon 1, CNRS, ENTPE, UMR 5023 LEHNA, Villeurbanne, France
4Department of Zoology, University of Oxford, UK
5UMR 7179 C.N.RS/M.N.H.N., Département Adaptations du Vivant, Bâtiment d’Anatomie Comparée, Paris, France
6Department of Zoology and Entomology, University of Pretoria, Private Bag x20, Pretoria, Rondevlei Scientific Services, Garden Route National Park, South African National Parks, Sedgefield, South Africa
7Faculté des Sciences, Université d’’Angers, Angers, France
8UMR 7179 C.N.R.S/M.N.H.N., Département Adaptations du Vivant, Bâtim’ent d’Anatomie Comparée, Paris, France
*Corresponding author (e-mail): Philipp Ginal (
In the Grinnellian niche concept, the realized niche and potential distribution is characterized as an interplay among the fundamental niche, biotic interactions and geographic accessibility. Climate is one of the main drivers for this concept and is essential to predict a taxon’s distribution. Mechanistic approaches can be useful tools, which use fitness-related aspects like locomotor performance and critical thermal limits to predict the potential distribution of an organism. These mechanistic approaches allow the inclusion key ecological processes like local adaptation and can account for thermal performance traits of different life-history stages. The African Clawed Frog, Xenopus laevis, is a highly invasive species occurring on five continents. The French population is of special interest due to an ongoing expansion for 40 years and a broad base of knowledge. We hypothesize that the French population exhibit increased in activity time in the invasive European range that could be devoted to fitness-relevant activity and (2) tadpoles may have less activity time available than adult frogs from the same range. We investigate how thermal performance traits translate into activity time budgets and how local adaptation and differences in the thermal responses of life-history stages may boost the European Xenopus invasion. We use a mechanistic approach based on generalized additive mixed models (GAMMs), where thermal performance curves were used to predict the hours of activity and to compare the potential activity time budgets for two life-history stages of native and invasive populations. Our results show that adult French frogs have more activity time available in Europe than those in South African frogs, which might be an advantage in searching for prey or escaping from predators. However, French tadpoles do not have more activity time in Europe compared to the native South African populations indicating that tadpoles do not suffer the same strong selective pressure as adult frogs.   

Oral presentation
Ecomorphology of the locomotor apparatus of the genus Cyrtodactylus (Gekkota, Squamata)
Riedel J.1,2,*, Higham T.3, Grismer L.4, Russell A.5, Reinhold K.2, Rödder D.1
1Museum Koenig Bonn – Leibniz Institute for the Analysis of Biodiversity Change, Bonn, Germany
2Department of Evolutionary Biology, Bielefeld University, Bielefeld, Germany
3Department of Evolution, Ecology, and Organismal Biology, University of California, Riverside, CA, USA
4Department of Biology, La Sierra University, Riverside, CA, USA
5Department of Biological Science, University of Calgary, Calgary, Alberta, Canada
*Corresponding author (e-mail): Jendrian Riedel (
Adaptive radiations, clades of closely related species diversified along one or more morphological and/or ecological niche axes, garner considerable interest from evolutionary biologists. Lizard radiations diversifying along spatial niche space are hypothesised to exhibit distinct changes in body length and relative limb dimensions. One hypothesis predicts that cursorial species have relatively longer hind limbs associated with faster running speeds and relatively shorter forelimbs preventing the latter from interfering with hind limb stride frequency. Accordingly, scansorial species are expected to have relatively shorter limbs, with the fore and hind extremities of more equal length, to promote the maintenance of their center of gravity closer to the substratum. Alternatively, terrestrial species in closed habitats could benefit from relatively shorter limbs because these may reduce their entanglement with more frequently encountered obstacles, whereas scansorial species could benefit from longer limbs which would result in greater limb spans and static stability. Cyrtodactylus is a speciose and ecologically diverse gekkonid genus. From generalist ancestors this clade has repeatedly produced specialists with narrow spatial niches, such as the occupancy of karst formations, caves, granite boulders, and different strata within the arboreal niche. For cave specialists, distinct morphological changes are associated with niche occupancy. The degree of morphological diversification exhibited by the other habitat specialists remains unknown, however. We investigated whether associations exist between limb dimensions and microhabitat use in this genus, to test if either of the opposing hypotheses can be confirmed for this successful radiation. To do so we measured body length and relative limb dimensions in a large sample, including all major lineages, reconstructed the phylomorphospace occupied by the species and tested for associations between spatial niche and limb morphology. We found strong separation between spatial niche groups, although overlap exists particularly among functionally related niches such as those of granite and karst specialists.     

Oral presentation
Bite or run? Ecomorphological relationship in African agamas
Tan N.W.C.1,*, Measey J.2, Vanhooydonck B.3, Herrel A.4
1Herpetology Section, LIB, Museum Koenig, Bonn, Germany
2Centre for Invasion Biology, Department of Botany and Zoology, Stellenbosch University, Stellenbosch, South Africa
3Department of Biology, University of Antwerp, Antwerpen, Belgium
4Département Adaptations du Vivant, UMR 7179 C.N.R.S/M.N.H.N., Bâtiment d’Anatomie Comparée, Paris, France
*Corresponding author (e-mail): Nicholas Wei Cheng Tan (
Understanding the relationships between form and function can help us to understand the evolution of phenotypic diversity in different ecological contexts. Many animals display morphological and behavioural adaptations to the habitats in which they live and the resources they exploit. Whole-organism performance traits such as bite force and locomotion are ecologically relevant as they reflect the ability of an organism to include a wider diversity, different or differently sized prey, to escape from predators, or to defend territories. Here, we investigate ecomorphological relationships between diet, morphology, bite force and locomotor performance (sprint speed and endurance) in six species of South African agamids from three habitat types (ground-dwelling, rock-dwelling, and arboreal). Diet analyses showed that ants are a major food source, alongside with active prey such as beetles, wasps and flies. Body and head size are not directly related to diet, although greater in-levers for jaw closing (positively related to bite force) are associated to an increase of hard prey in the diet. Rock-dwelling species have a relatively flatter head than other species, possibly as an adaptation for crevice use. However, even when correcting for jaw length and jaw out-lever length, rock-dwelling species bite harder than ground-dwelling species. Further, endurance capacity of these lizards is correlated with hind limb and toe lengths. Interestingly, however, we demonstrate trade-offs in performance where specialisation towards speed comes at the detriment of endurance. Arboreal species have longer hind limbs, and higher exertion capacity and mean speed. However, for a given hind limb length, they appear to be slower than the other habitat specialists. In sum, our study illustrates the role of morphology in driving functional changes and how habitat use impacts morphology and locomotor performance but not bite force.

Oral presentation
Spatiotemporal patterns of habitat use by the sand lizard (Lacerta agilis Linnaeus, 1758): Effects of climatic seasonality?
Schmitz L.M.1, Clement V.F.1, Edanackaparampil J.1, Ginal P.1, Schluckebier R.1,
Rödder D.1,*
1LIB, Museum Koenig Bonn, Leibniz Institute for the Analysis of Biodiversity Change, Bonn, Germany
*Corresponding author (e-mail): Dennis Rödder (
The distribution and occurrence of a species in its habitat is inevitably linked with its ecology. To successfully monitor and protect species, it is important to investigate which species-specific factors influence its interactions with the environment. In this study, we focus on patterns in habitat use of the sand lizard (Lacerta agilis). Seasonal as well as sex and age dependent habitat use differences were reported from the species’ range edges. To verify such trends in the core area of its distribution, we analyzed the habitat factors weather, microclimate, microhabitat structures and time dependence, which may have an impact on the behavior of the sand lizard. Using generalized linear models, hypervolumes, density estimations and Chi-squared tests, we found that the movement patterns of the individuals can neither be described by time differences, climatic conditions, or habitat composition, nor do they show habitat or weather-related differences of movement among sexes or age. Here we show that in the case of a population from the core distribution area at the Dellbrücker Heide (Germany), habitat use solely is influenced to a low degree by differences related to ontogeny of the sand lizards and does not depend on any of the other evaluated factors. These results from the core distribution area of the sand lizard show an enormous contrast to findings of populations from peripheral distribution areas, i.e. the United Kingdom, Latvia, Romania, Bulgaria, and the Pyrenees. This implies that seasonal habitats shifts are more extreme at the range edges of L. agilis to compensate deteriorating habitat conditions than in the periphery.

Plenary lecture
History of herpetological research on the Balkan Peninsula
Böhme W.1,*
1Leibniz Institute for the analysis of biodiversity change (LIB) – Museum Koenig, Adenauerallee, Bonn, Germany
*Corresponding author (e-mail): Wolfgang Böhme (
Southern Europe consists mainly of three large and separate peninsulas shaping the northern coastline of the Mediterranean Sea. Of these, the Iberian peninsula in the west harbours two countries, viz. Portugal and Spain, while the central Apenninian peninsula is made up by just one country, viz. Italy. The Balkan peninsula, in contrast, consists of significantly more countries, including independent states established upon the breakup of former Yugoslavia, then Albania, Bulgaria and Greece. Geographically, as defined by the famous Serbian geographer Jovan Cvijić, also the south of Romania and the European part of Turkey („Turkish Thrace“) have to be added. This historically induced multinational cultural diversity had also great influence on the history of science, including herpetology. The global birthplace and also the name-provider of the term herpetology was Greece and its language, where for instance Aristotle (384-322 BC) wrote an astonishingly exact description of the chameleon while the role of snakes was more a mythological one, nonetheless influential for the entire realm of the Greek-Roman antiquity. But since the origin of modern herpetology by the fundamental work of Carolus Linnaeus, mostly researchers from more northern parts of Europe started to study Balkan herpetology. The lecture will review the main contributors to the herpetology of the Balkan peninsula. They will be discussed countrywise, according to the contemporary geographic delimitations. A focus is laid on the remarkable shift from initially mostly foreign researchers towards autochthonous herpetologists taking care by themselves for the exploration of their respective countries. An overview of the zoogeographical importance of Balkan amphibians and reptiles is given, followed by a summary of important endemic species living in this herpetological diversity hotspot.

Poster presentation
Microhabitat specific performance of the chytrid fungus Batrachochytrium salamandrivorans and its impact on Salamandra salamandra (Linnaeus, 1758) in western Germany
Deiß F.1,*, Ginal P.1, Rödder D.1
1LIB, Museum Koenig Bonn, Leibniz Institute for the Analysis of Biodiversity Change, Bonn, Germany
*Corresponding author (e-mail): Felix Deiβ (
Nowadays, chytridiomycosis is one of the greatest threats to the diversity of amphibians worldwide. Caused by both, the well-known chytrid fungus Batrachochytrium dendrobatidis (Bd) and the chytrid fungus Batrachochytrium salamandrivorans (Bsal), it plays a decisive role in amphibian declines. The pathogen Bsal, which originally was introduced from Southeast Asia, was discovered in Europe for the first time in 2013. It is particularly harmful to caudate species, as it causes epidermal ulcerations, anorexia and ataxia, which ultimately lead to death in infected animals. As a result it has locally eradicated the formerly common fire salamander Salamandra salamandra in some regions of north-western Europe. In the Netherlands, for example, the fire salamander population has shrunk by 96%. Currently, Germany is the most affected area, with two hotspots: the Ruhr region and the southern Eifel. To simulate the performance of Bsal in its main invasive distribution area, we computed microclimatic surfaces, as temperature has shown to be the most important parameter affecting Bsal. These were simulated based on different habitat types, derived from the most recent Corine Land Cover 2018 maps. Although almost the entire study area would support the growth of Bsal, there are clear differences in the likely performance between different, small-scale environments. Based on these findings, possible Bsal hotspots are identified and recommendations for conservation activities are given     

Poster presentation
Last chance to see? Iran and India as strongholds for the Marsh crocodile (Crocodylus palustris)
Mobaraki A.1, Erfani M.2, Abtin E.3, Brito J.C.4,5,6, Tan W.C.7,*, Ziegler T.8, Rödder D.7
1Natural Environment Deputy, Wildlife conservation and management Bureau, Department of Environment, Tehran, Iran
2Department of Environmental Sciences, Faculty of Natural Resources, University of Zabol, Iran
3Natural Environment Division, Department of Environment Office in Sistsan and Baluchestan Province, Zahedan, Iran
4CIBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, InBIO Laboratório Associado, Campus de Vairão, Universidade do Porto, Portugal
5Departamento de Biologia, Faculdade de Ciências, Universidade do Porto, Portugal
6BIOPOLIS Program in Genomics, Biodiversity and Land Planning, CIBIO, Vairão, Portugal
7Zoologisches Forschungsmuseum Alexander Koenig, Bonn, Germany
8AG Zoologischer Garten Köln, Germany
*Corresponding author (e-mail): Nicholas Wei Cheng Tan (
Predictions of future change in species distributions are necessary for defining adequate conservation planning actions over space and time. The Marsh crocodile (Crocodylus palustris) is native to the freshwater habitats of the Indian subcontinent and in south-eastern Iran. Habitat loss is currently the most important factor threatening crocodile dispersal and persistence, and climate change will likely place increasing pressure on populations. This study used ecological niche modelling (Maximum entropy) to predict the current distribution of the species and to project it to future climate conditions. For this purpose, 380 occurrence records were used for model computation and environmental data were obtained from Worldclim 2.0. Averages of eight global circulation model outputs assuming four IPCC6 per story lines in 2081-2100 were used as future ensembles. Furthermore, future possible anthropogenic pressure was quantified using economic growth models. Temperature Annual Range was the climatic variable with highest contribution in the modelling. Presently, the most potential suitable habitats are located in Sri Lanka, south-eastern peninsular of India, tropical moist forest along the west coast of India, border between Nepal and India, and the south coast of Iran and Pakistan. In the future, these suitable habitats are predicted to be further fragmented and to move further inland. Additional threats may arise due to increased human conflicts due to human population growth. Conservation actions should therefore focus on those areas which remain climatically comparatively stable with a low potential of human conflicts. Key areas are located in the northern parts of India and at the westernmost range edge of the species in Iran.    

Poster presentation
Captive breeding, embryonic and larval development of the Zimmermann’s poison-frog Ranitomeya variabilis (Zimmermann and Zimmermann, 1988), (Anura: Dendrobatidae)
Regnet R.A.1,2,*, Rech I.1, Rödder D.1,2, Solé M.1,2
1LIB, Museum Koenig Bonn, Leibniz Institute for the Analysis of Biodiversity Change,
Bonn, Germany
2Programa de Pós Graduação em Zoologia, Universidade Estadual de Santa Cruz – (UESC), Salobrinho, Ilhéus, Bahia, Brazil
*Corresponding author (e-mail): Ruth Anastasia Regnet (
Following recent taxonomic changes in Ranitomeya variabilis (Zimmermann and Zimmermann, 1988), we provide herein, for captive bred specimens from French Guiana a description of husbandry in captivity; image-based measurements of total length (TOL) and surface area of individuals throughout embryonic to larval development using the SAISAQ (Semi-Automatic Image based Surface Area Quantification) tool. Furthermore, we provide a detailed larval staging from early staged embryo to metamorph. Clutches of R. variabilis were composed of four to six dark grey eggs, deposited in a mass and wrapped in a colorless gelatinous capsule. Deposition occurs mainly on the largest and basal axils of phytotelma, and less often in photographic film containers, offered as artificial phytotelma. The obtained growth data by SAISAQ showed in comparison with SAISAQ data of other Ranitomeya species a similar growth pattern. However, we noted a remarkable TOL difference between R. variabilis and other Ranitomeya tadpoles, which was also traceable in the ontogenetic data. The developmental stages largely corroborate with the generalized Gosner’s staging system for anuran embryos and larvae. Development from stage eight of Gosner through metamorphosis took 80 to 91 days, with a survival rate of 54%. Differences were observed mainly on the labia and teeth differentiation, which occurred a stage later than expected in the general staging system. As well as, the atrophy of the oral apparatus, which started one stage earlier than expected in two tadpoles. The provided data brings new knowledge about the reproductive biology of this species and supports in situ breeding programs for conservation purposes. We are confident that these data can support the identification of R. variabilis tadpoles in natural environment and the differentiation of tadpoles from the sister species R. amazonica. As well as, providing new data, that can help to clarify the biogeographic distribution and taxonomic arrangement of the species.

Poster presentation
Niche differentiation in the relict, endemic spiny frogs Allopaa hazarensis and Chrysopaa sternosignata
Hofmann S.1,*, Masroor R.2, Litvintchuk S.3, Vershinin V.4, Jablonski D.5
1Museum Koenig Bonn, LIB – Leibniz Institute for the Analysis of Biodiversity Change, Bonn, Germany
2Pakistan Museum of Natural History, Garden Avenue, Shakarparian, Islamabad, Pakistan
3Institute of Cytology, Russian Academy of Sciences, St. Petersburg, Russia
4Institute of Plant and Animal Ecology, Russian Academy of Sciences, Ekaterinburg, Russia
5Comenius University in Bratislava, Bratislava, Slovakia
*Corresponding author (e-mail): Sylvia Hofmann (
The relict, endemic taxa Allopaa and Chrysopaa are key elements of the Hindu Kush-Himalayan amphibian fauna and share an early-Miocene evolution, making them important proxies for the reconstruction of the Paleogene history of the Tibetan Plateau and the evaluation of respective modern scenarios of the development of the HTO. However, there is no much information on the distribution of these taxa. We here provide species distribution models for both taxa and test the hypotheses of niche differentiation. The average performance of our MaxEnt models was considered significantly better than random. They show, that both taxa are geographically separated with an allopatric distribution pattern, and that BIO8 (mean temperature of wettest quarter) was most important to the models. Further, our findings provide strong support for distinct niche divergence among C. sternosignata and A. hazarensis. The study contributes to the knowledge about the distribution of these species and provide basic information for guiding future management of them.   

Poster presentation
Disappearing archosaurs – an assessment of established protected areas in the Philippines to save the Critically Endangered and endemic philippine crocodile Crocodylus mindorensis
Harrer S.1, Tan W.C.1, Ginal P.1,*, Binaday J.1, Diesmos A.1, Manalo R.1, Ziegler T.2,3,
Rödder D.1
1LIB, Museum Koenig Bonn, Bonn, Germany
2AG Zoologischer Garten Köln, Köln, Germany
3Institut für Zoologie, Universität zu Köln, Köln, Germany
*Corresponding author (e-mail): Philipp Ginal (
Once distributed all over the Philippines, the endemic Philippine Crocodile Crocodylus mindorensis is threatened with extinction. Less than 140 mature individuals live in the wild. Human activities like fishing and illegal poaching, as well as land-use change and habitat conversion cause a continuing threat for the remaining populations. Therefore, designated protected areas were evaluated with species distribution models (SDMs) for improved future conservation efforts. For this purpose, the existing IUCN-reserves were analysed for climatical suitability (combining bioclimatic and remote sensing variables), wetland occurrences and the human footprint index by using MaxEnt and QGIS. Based on topical species records, our final SDM-model showed high performance and revealed the climatically most suitable areas on Luzon and Mindanao. However, only small parts of the climatically optimal area and suitable wetlands are currently covered by reserves. Case in addition, none of the species’ records is located within a protected area. The anthropogenic pressures in the reserves were diverse and varied between a low and moderate level. Most of the records are found in areas with a moderate to medium human footprint. Considering the three criteria, only ‘Northern Sierra Natural Park’, ‘Agusan Marsh Wildlife Sanctuary’ and ‘Upper Agno River Basin Resource Reserve’ revealed to be suitable conservation areas for C. mindorensis. The other reserves seemed to be unsuitable, whereas suitable areas outside protected areas are highly recommended for further surveys. Therefore, the current network of existing protected areas needs significant improvement to provide well-suited and long-term protection for C. mindorensis. More surveys are also necessary to find hidden, so far overlooked populations and verify C. mindorensis tolerance level for human footprint.   

First in-person conference 2022

We are back on stage! Joining the 10th Biennial Conference of the International Biogeography Society in Vancouver, Canada, my PhD students and I had finally the opportunity to present our research. As a hybrid conference, all talks are available online.

IBS 2022 Vancouver: Nicholas Wei Cheng Tan: A global analysis of habitat change research in reptiles and amphibians

Habitat change and fragmentation is the primary cause of biodiversity loss worldwide. Recent decades have seen a surge of funding, published papers, and citations in the field as current threats to biodiversity continue to rise. However, how research directions and agendas are evolving in this field is still poorly understood. In this study, we examined the current state of research on the most threatened groups of vertebrates, reptiles, and amphibians. We did so by conducting a global scale review of geographical and taxonomical trends regarding habitat change (agriculture, logging, fragmentation, urbanization, and roads) and the associated sampling methods and response variables. We reveal a number of biases, in particular, that existing research efforts are characterized by distinct continents (e.g. North America, Europe, and Australia) and study groups (e.g. amphibians) and a surplus of studies measuring species richness and abundance with seemingly contradictory results. However, we found a recent shift in the research agenda towards studies utilizing technological advancements including genetic and spatial data analyses. Our results suggest important associations between sampling methods and the response variables measured which are commonly used in explaining the effects of different types of habitat change. Increased research investment with appropriate sampling techniques is crucial in biodiversity hotspots such as the tropics where unprecedented threats to herpetofauna exist.

IBS 2022 Vancouver: Philipp Ginal: Mechanistic SDMs and connectivity models

One main threat promoting the worldwide amphibian decline is the introduction of non-indigenous amphibians, like the African Clawed Frog Xenopus laevis, which is now one of the widest distributed amphibian occurring on five continents with ongoing expansion including large parts of Europe. Different types of statistical models can be useful tools in invasion biology. Species Distribution Models (SDMs) and the concept of ecological niche are essential to predict the invasive risk of those species, while connectivity models can be used to reconstruct past dispersal routes or to highlight areas of risk for future invasion. On a macroecological scale, we used mechanistic SDMs to predict the potential distribution for X. laevis across Europe. Based on physiological performance trials we calculated size and temperature depending response surfaces, which were scaled to the species’ range matching the critical thermal limits. Theseecophysiological performance layers were used in a standard correlative SDM framework to predict the potential distribution in South Africa and Europe. We found thermal performance differed significantly among native and invasive populations indicating some degree of fundamental niche change, which lead to different potential distribution patterns for the native and invasive populations in the respective ranges. Furthermore, on a local scale, we used connectivity models based on remote-sensing derived resistance kernels to reconstruct the X. laevis invasion for Portugal and identified several areas, which might be corridors for future invasion risk.

IBS 2022 Vancouver: André Vincente Liz: Diversification cradles in the Sahara-Sahel: contrasting evolutionary histories in functional groups urges a reassessment of priority conservation zones

The Sahara-Sahel Desert presents distinct bioclimatic and phytogeographical regions, where desert communities aggregate in localized biodiversity hotspots that arose from historical eco-evolutionary processes. These hotspots may differ across functional groups, due to the variable biogeographical affinities of desert taxa. The current characterization of hotspots is based on assessments at the species level (e.g., endemism richness) and lacks information on intra-specific genetic variability, despite its crucial importance for species persistence. Herein, we infer diversification cradles across the Sahara-Sahel taking into account differences in species habitat requirements. Phylogenetic diversity was mapped for well-sampled representatives of mesic and xeric desert taxa across the study area. Main diversification cradles were located in mountain areas and low sand-dune fields for mesic and xeric taxa, respectively. Mountain cradles match with the main potential mesic refugia for the ongoing climate crisis. Further studies on the barely-known Central Sahara highlands are needed to understand the magnitude of their regional diversity, even if they are already included in conservation strategies. On the contrary, xeric cradles remain ignored in conservation planning, due to the presumed low ecological diversity of sand-dune ecosystems. Xeric cradles may be particularly threatened by global warming, as species occur close to their physiological limits, and human pressures, including the expansion of extractive activities, green energy and agro-forestry. Thereby, we call for an urgent need to consider xeric diversification cradles in conservation planning. The location of diversification cradles in the Sahara-Sahel largely overlaps with inaccessible areas subjected to long-lasting conflicts, which greatly constrains research and conservation efforts.

IBS 2022 Vancouver: Dennis Rödder: Climate change drives mountain butterflies towards the summits

Climate change impacts biodiversity and is driving range shifts of species and populations across the globe. To understand the effects of climate warming on biota, long-term observations of the occurrence of species and detailed knowledge of their ecology and life-history is crucial. Mountain species particularly suffer under climate warming and often respond to environmental changes by altitudinal range shifts. We assessed long-term distribution trends of mountain butterflies across the eastern Alps and calculated species’ specific annual range shifts based on field observations and species distribution models, counterbalancing the potential drawbacks of both approaches. We also compiled details on the ecology, behavior and life history, and the climate niche of each species assessed. We found that the highest altitudinal maxima were observed recently in the majority of cases, while the lowest altitudes of observations were recorded before 1980. Mobile and generalist species with a broad ecological amplitude tended to move uphill more than specialist and sedentary species. As main drivers, we identified climatic conditions and topographic variables, such as insolation and solar irradiation. This study provides important evidence for the responses of high mountain taxa to rapid climate change. Our study underlines the advantage of combining historical surveys and museum collection data with cutting-edge analyses.

High from the air, drones help survey sand lizard habitat

Understanding the space use and habitat needs of animals is essential for effective species conservation. Small animals use small structures that are difficult to monitor. LIB researchers have now used drones in a study to depict these small structures in high-resolution habitat maps. The research team was able to show how important low blackberry bushes are for sand lizards in the Dellbrücker Heide in Cologne. The drone method can find application in nature conservation and landscape planning.

“What is their neighborhood or quarter for people is their home range for wild animals,” explains Dr. Dennis Rödder, curator of Herpetology section at the Leibniz Institute for the Analysis of Biodiversity Change (LIB) in Bonn. This area is familiar to them, it’s where they move around and it fulfills their ecological needs in their daily lives, from food to shelter. After exploring the surrounding area, the animals usually return to this area. Therefore, mapping the habitat in the home range can provide valuable insights into the spatial and structural needs of wildlife. Understanding these requirements is becoming increasingly important as human impacts alter landscapes. “We hope that our work will not only remain theoretical but will also find application in conservation and landscape planning,” explains Vic Clement, PhD student at the LIB.

Sand lizards and their home range are small, as are the structures in their habitat. High-resolution maps depicting individual bushes, grass, sand or trees are therefore required for monitoring. Drones provide a remedy here: from a low altitude, they take high-resolution images of the area so that individual structures can be easily distinguished. The LIB researchers now merged the observed home ranges of the animals studied with the detailed map and were thus able to examine the structure of the habitat within the boundaries of the home range and compare it with the surrounding area. Clement, Schluckebier, and Rödder demonstrated that sand lizards in the Dellbrücker Heide favor low brambles, while avoiding open sandy areas and high vegetation. Preferences for grass and other low bushes, on the other hand, vary from animal to animal.

“The sand lizard as a cultural successor is often a victim of disturbance, destruction, or fragmentation of its habitats by human activities. Compensatory and protective management could now be better formulated with our data,” also hopes Rieke Schluckebier, Master’s candidate in the Herpetology section of the LIB. In recent years, drones have increasingly proven to be a useful tool for answering ecological questions. This time-efficient method of surveying habitat structures can be of great benefit in the management of protected areas.


Clement, V.F., R. Schluckebier, & D. Rödder (2022). About lizards and unmanned aerial vehicles: assessing home range and habitat selection in Lacerta agilis. Salamandra, 58: 24–42.

On niches and ranges – how do animals respond to climate change?

…unfortunately only in german:

AUS UNSERER VORTRAGSREIHE DES KÖLNER ZOOS- gemütlich auf der heimischen Couch genießen: Di., 08.02.2022, 19:30 Uhr: „Von Nischen und Arealen – Wie reagieren Tiere auf den Klimawandel?“ Dr. Dennis Rödder, Forschungs-Museum Koenig – Offizielle Seite

Der menschengemachte Klimawandel hat bereits heute einen weltweit messbaren Einfluss auf die Biodiversität. Mögliche Effekte zeigen sich auf allen Ebenen, von zeitlichen Verschiebungen in der Phänologie der Arten bis hin zu Veränderungen in ihren Verbreitungsgebieten. Der Vortrag gibt einen Überblick darüber, was wir bislang beobachten konnten und was wir in Zukunft erwarten.



Museum Koenig

Leibniz Institute for the Analysis of Biodiversity Change (LIB)

Adenauerallee 127

53113 Bonn


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