Amphibian Diversity Research Articles

Paradigm shift in frog sperm cryopreservation: reduced role for non-penetrating cryoprotectants.

Sperm cryopreservation has been recognised as a tool for preventing loss of genetic diversity in amphibians; however, the combined effect of penetrative and non-penetrative cryoprotectants in cryodiluents is poorly understood. We demonstrate a clear benefit of using low concentrations of non-penetrative cryoprotectants when cryopreserving sperm of Australian tree frogs. Sperm cryopreservation protocols have been developed for an increasing number of amphibian species since the recognition of a global amphibian decline. Yet, the development of these protocols has neglected to elucidate the combined effect of the penetrative(PCP) and non-penetrative cryoprotectant (NPCP) on the recovery of live, motile sperm. The two-factor hypothesis of cryoinjury recognises a trade-off between cooling cells slowly enough to allow osmotic dehydration and therefore avoid intracellular ice formation, but fast enough to minimise effects from increasing extracellular osmolality as the frozen fraction of the media increases during freezing. We tested the effect of two concentrations of a PCP (10 and 15% v/v dimethyl sulfoxide (Me2SO)) and two concentrations of an NPCP (1 and 10% w/v sucrose) in various combinations on the sperm of six pelodryadid frogs. In all species, 15% v/v Me2SO with 1% w/v sucrose provided superior post-thaw recovery with high proportions of forward progressive motility, live cells and intact acrosomes (typically >50% for each). Theoretically, it has been suggested that increased NPCP concentration should improve cell survival by increasing the rate and extent of cell dehydration. We suggest, however, that the elevated osmolality in the unfrozen water fraction when 10% sucrose is used may be causing damage to cells via excessive cell shrinkage and solute effects as proposed in the two-factor hypothesis of cryoinjury. We showed this response in sperm across a range of frog species, providing compelling evidence for this hypothesis. We suggest protocol development using the PCP/NPCP ratios demonstrated in our study will be broadly applicable to many amphibian species.

Pesticides reduce tropical amphibian and reptile diversity in agricultural landscapes in Indonesia.

Pesticide use on tropical crops has increased substantially in recent decades, posing a threat to biodiversity and ecosystem services. Amphibians and reptiles are common in tropical agricultural landscapes, but few field studies measure pesticide impacts on these taxa. Here we combine 1-year of correlative data with an experimental field approach from Indonesia. We show that while pesticide application cannot predict amphibian or reptile diversity patterns in cocoa plantations, our experimental exposure to herbicides and insecticides in vegetable gardens eliminated amphibians, whereas reptiles were less impacted by insecticide and not affected by herbicide exposure. The pesticide-driven loss of a common amphibian species known to be a pest-control agent (mainly invertebrate predation) suggests a strong indirect negative effect of pesticides on this service. We recommend landscape-based Integrated Pest Management and additional ecotoxicological studies on amphibians and reptiles to underpin a regulatory framework and to assure recognition and protection of their ecosystem services.

Molecular characterization of haemosporidian and haemogregarine diversity in southwestern Iberian amphibians and reptiles

The knowledge of the diversity and geographic distribution of parasite species is the first step towards understanding processes of global epidemiology and species conservation. Despite recent increases in research on haemosporidian and haemogregarine parasites of reptiles and amphibians, we still know little about their diversity and parasite-host interactions, especially in the Iberian Peninsula, where a few studies have been conducted. In this study, the haemosporidian and haemogregarine diversity and phylogenetic relationships of the parasites in southwestern Iberian amphibians and reptiles were assessed using PCR approaches on blood samples of 145 individuals from five amphibian and 13 reptile species. The amphibians did not present any of both groups of parasites studied. Regarding reptiles, five Hepatozoon, one Haemogregarina, and one Haemocystidum haplotypes were found infecting four different species, revealing new host records for these parasites. Among them, we found one new Haemocystidium haplotype and three new and a previously reported Hepatozoon haplotype from a north African snake. The latter finding suggests that some Hepatozoon parasites may not be host-specific and have large geographic ranges even crossing geographical barriers. These results increased the knowledge about the geographic distribution and the number of known host species of some reptile apicomplexan parasites, highlighting the great unexplored diversity of them in this region.

Metapolystoma ohlerianum n. sp. (Monogenea: Polystomatidae) from Aglyptodactylus madagascariensis (Anura: Mantellidae)

PurposeDespite Madagascar’s high amphibian diversity of more than 400 species, only a few polystome species are known from the island. The dissection of frogs from museum collections, together with amphibian and parasite surveys conducted in Madagascar led to the discovery of an undescribed polystome infecting Aglyptodactylus madagascariensis. The purpose of this study is to formally describe this species.MethodsPolystomes recovered from A. madagascariensis were stained (Acetocarmine) and mounted (Canada balsam) to facilitate morphometrics and taxonomic drawings. Some specimens were fixed in absolute alcohol, a Bayesian tree inferred from the analysis of concatenated 18S, 28S and COI gene sequences was constructed and pairwise distances were calculated. Parasites collected from archived hosts in museums were used for histology and scanning electron microscopy (SEM).ResultsPolystomes recovered from A. madagascariensis display characteristics of the genus Metapolystoma and morphologically differed from all other known metapolystomes. The Bayesian phylogeny shows that Metapolystoma n. sp. ex. A. madagascariensis and M. falcatum are sister species with high Bayesian posterior probability. Histological and SEM investigations contributed to morphological descriptions.ConclusionsMorphological examination supported by phylogenetic analysis and genetic divergences revealed distinct differences from all known metapolystome species, supporting the description of a new species. Differences between the life cycles of Metapolystoma and Polystoma provided additional evidence for the validity of that genus as taxon. Whereas Polystoma may display ovoviviparity on rare occasions after incomplete egg expulsion towards the end of the breeding season, Metapolystoma displays true ovoviviparity. We emphasize the need for parasite surveys in Madagascar and recommended for museum material to be examined for polystomes to provide supplementary material and localities for further field investigation.Graphical

Spatial Patterns of Species Diversity of Amphibians in a Nature Reserve in Eastern China

Elevational gradients provide an excellent opportunity to assess biodiversity patterns and community structure. Previous studies mainly focus on higher elevations or are limited to small areas in mountainous regions. Little information can be found on amphibian biodiversity in middle- and low-elevational areas, hence our study was devoted to filling up the current gaps in these research areas. To understand the variability of biodiversity of amphibian species in the Fujian Junzifeng National Nature Reserve in eastern China, our study included taxonomic and phylogenetic components to describe the various patterns of regional and elevational distribution. The results showed that (1) most of the taxonomic and phylogenetic diversity metrics were correlated; with regard to the surveyed area, Faith's phylogenetic diversity index (PD) and net relatedness index (NRI) were positively correlated with the Shannon-Wiener index (H'), Margalef index (DMG), and species richness (S), while negatively with the Pielou index; whereas for elevation, only the Pielou index was positively correlated with the nearest taxon index (NTI), but negatively with other indices; (2) taxonomic and phylogenetic diversities did not differ among the three survey locations but differed significantly along the elevational gradient; Simpson index, H', S, and DMG had a hump-shaped relationship with elevations, and PD decreased gradually with the increase in elevation, whereas NRI and NTI sharply increased at the elevation above 900 m; (3) the species range size and the corresponding midpoint of amphibians were affected by a strong phylogenetic signal, which supports the elevational Rapoport's rule upon removal of Pachytriton brevipes and Boulenophrys sanmingensis from the study.

RANGE EXPANSION OF GREEN TREEFROGS (HYLA CINEREA) IN SOUTHERN ILLINOIS: NO EVIDENCE OF PARASITE RELEASE.

For several decades, green treefrogs (Hyla cinerea) have been undergoing rapid range expansion northward and eastward in Illinois, Indiana, and Kentucky. While range expansion of green treefrogs in these states may be linked to climate change, a recent study suggested this expansion could be facilitated by parasites, given that expanded range populations of green treefrogs from Kentucky and Indiana exhibited significant decreases in helminth species diversity compared to those examined from historical locations of Kentucky. Because rapid range expansion may lead to hosts escaping their parasites (= parasite release), a reprieve from parasitic infection could allocate additional resources to growth and reproduction and thus facilitate the expansion. The present study compares patterns of helminth diversity for green treefrogs from historical and 2 types (early and late expansion) of expanded range locations of southern Illinois to test whether these range-expansion populations are also experiencing a reduction in parasitism due to parasite release. The results of this study did not find significant differences in helminth diversity when helminth communities of green treefrogs from their historical and expanded ranges were compared. These results appear to downplay the putative role of parasite release in the northward range expansion of H. cinerea in Illinois. Studies are underway to determine whether local factors, including abiotic conditions and amphibian host diversity, play a more prominent role in influencing helminth diversity of green treefrogs.

Digest: Salamanders reveal novel trajectories of amphibian MHC evolution.

How does amphibian MHC diversity fit in the landscape of vertebrate evolution? Mimnias et al. (2022) address this gap in the field of MHC evolution by focusing on the lesser described MHC class I in salamanders. These findings contribute to understanding MHC diversity and the susceptibility of amphibians to pathogens, which could lead to future research on a major threat to amphibian biodiversity, chytrid fungi.

Amphibian decline in a Central European forest and the importance of woody debris for population persistence

Achieving an understanding of species’ temporal and spatial abundance patterns is a prerequisite for proper conservation and management decisions. Little is known of the ecological indicators of census size or biomass of terrestrial amphibian communities and historical estimates of population size are rare. Here we took advantage of abundance and biomass data collected in 1967/1968 for a leaf-litter amphibian community in Niepołomice Forest (NF) in south-central Poland. Using the same technique (removal sampling), we censused the amphibian community of this forest 50 years later (2016/2017), spatially matching a subset of current plots with the historical sampling sites. Averaged over all plots, we revealed at least a fourfold decline in amphibian abundance from 2817 ± 776 individuals/ha in 1967 to 674 ± 508 individuals/ha currently, paralleled by a decline in biomass from roughly 15.5 ± 1.7 to 3.8 ± 3.1 kg/ha. The decline was more striking (over 15-fold) for current plots placed in the same forest division as the historical plots (mean counts of 157 ± 103 individuals/ha corresponding in biomass to 1.0 ± 0.5 kg/ha). We also recorded a change in species composition between surveys, and propose that conversion of aquatic habitat and forest succession have decreased amphibian diversity and abundance in NF. Further, we estimated densities of anuran amphibians in forest plots differing in management regime and local habitat characteristics for contemporary plots (all historical plots were placed in managed forest). We found that unmanaged, old growth forest plots with coarse woody debris on the forest floor held on average twice as many anurans compared to plots in managed stands. Average body condition of the most common species, Rana temporaria, measured as a scaled mass index, was enhanced in plots situated in old growth forest. Our findings suggest that the preservation of old growth forests containing coarse woody debris may boost anuran abundance, biomass and body condition, and has the potential to buffer against long-term demographic decline. Moreover, the retention of deadwood could be a means of increasing the conservation potential of managed forests for terrestrial amphibian communities.

Amphibian diversity of wetlands of Rewa district of Madhya Pradesh with a note on the morphometric characters of Duttaphrynus melanostictus

Rewa district is gifted with lot of wetlands significantly Bichhiya, Bihar and Tamas wetland is home of 12 amphibian species under 5 family. Of which 1 species belonged to family Bufonid, 2 species to family microhylid, 1 species to family Rhacophorid, 6 species to family Dicroglossidae and 2 species to Ranidae. Morphometric study was carried out for Duttaphrynus melanotic. Significant variation was observed in the morphometric characteristics of D. melanotic with its Lectotype. Supratympanic fold was found to be present and parietal ridge is absent in case of specimens of Rewa, while vice versa in Lectotype. Webbing formula found to be I0-1II0-1½III1-3½IV3½-1½ in case of lectotype, where as in the specimens from Rewa it is I1-1½ II1½-2½ III1½-3½ IV3½-1½.

Elevated alpha diversity in disturbed sites obscures regional decline and homogenization of amphibian taxonomic, functional and phylogenetic diversity

Loss of natural habitat due to land-use change is one of the major threats to biodiversity worldwide. It not only affects the diversity of local species communities (alpha diversity) but can also lead to large-scale homogenization of community composition (reduced beta diversity) and loss of regional diversity (gamma diversity), but these effects are still rarely investigated. We assessed the impact of land-use change on taxonomic, functional and phylogenetic diversity of amphibians in Rwanda, both on the local (community-level) and regional scale (country-wide). Alpha diversity in local communities was higher in farmland than in natural habitats; however, species turnover among farmland sites was much lower than among natural sites, resulting in highly homogenized communities and reduced taxonomic, functional and phylogenetic gamma diversity in farmland across Rwanda. Amphibians found in farmland were mostly disturbance-tolerant species that are widespread in eastern Africa and beyond. In contrast, most of the regionally endemic frog species that make this region a continent-wide hotspot of amphibian diversity were found only in the natural habitats. Ongoing habitat conversion might result in further homogenization of amphibian communities across sub-Saharan Africa and the loss of regional endemism, unique evolutionary lineages, and multifunctionality.

Effect of water physicochemistry on amphibian abundance in Sub-tropical Kupinde Lake of the Nepal Himalaya

Abstract. Sunar CB, Pandey N, Chand B, Upadhyaya LP, Thapa B, Pant RR, Khanal L. 2022. Effect of water physicochemistry on amphibian abundance in Sub-tropical Kupinde Lake of the Nepal Himalaya. Intl J Bonorowo Wetlands 12: 92-99. Amphibians are the key bioindicators of ecosystem health. Their diversity and abundance are affected by the physicochemical factors of the environment. Wetland ecosystems of the Himalaya are under the threat of human activities and current climate change. However, hydrochemical status and faunal diversity are poorly documented in the wetlands of western Nepal. This study characterized the physicochemical parameters of water in Kupinde Lake in the Salyan District of Karnali Province, Nepal, and established the association between amphibian abundance and those parameters. A total of 24 samples of surface water were collected at the lake's edge during October 2021, and 18 physical and chemical parameters were analyzed. Visual encounter surveys were conducted at each water sampling site to count amphibians within a circle of two meters in diameter. The lake water was slightly alkaline (mean pH = 8.16±0.29), and the major dominating cation and anion were Ca2+ and HCO3-, respectively. Amphibian abundance was positively correlated with pH, HCO3-, and NH4+ and negatively correlated with EC, TDS, CO2, Cl-, and Na+. The polynomial regression analysis revealed amphibian abundance has a consistent positive association with water pH (r2 = 0.497, p < 0.05) and unimodal relation with the temperature (r2 = 0.188, p < 0.05). Low amphibian diversity and dominance of a single amphibian species, the Indian skipper frog (Euphlyctis cyanophlyctis Schneider, 1799), indicate poor ecosystem health of the lake. The findings of this study provide baseline information for monitoring and managing the Kupinde Lake.

Diversity of amphibians and reptiles in Yunnan region of the Yunling Mountains

Diversity of amphibians and reptiles in Yunnan region of the Yunling Mountains

Environmental and topographic drivers of amphibian phylogenetic diversity and endemism in the Iberian Peninsula.

Understanding the ecological and evolutionary processes driving biodiversity patterns and allowing their persistence is of utmost importance. Many hypotheses have been proposed to explain spatial diversity patterns, including water-energy availability, habitat heterogeneity, and historical climatic refugia. The main goal of this study is to identify if general spatial drivers of species diversity patterns of phylogenetic diversity (PD) and phylogenetic endemism (PE) at the global scale are also predictive of PD and PE at regional scales, using Iberian amphibians as a case study. Our main hypothesis assumes that topography along with contemporary and historical climate are drivers of phylogenetic diversity and endemism, but that the strength of these predictors may be weaker at the regional scale than it tends to be at the global scale. We mapped spatial patterns of Iberian amphibians' phylogenetic diversity and endemism, using previously published phylogenetic and distribution data. Furthermore, we compiled spatial data on topographic and climatic variables related to the water-energy availability, topography, and historical climatic instability hypotheses. To test our hypotheses, we used Spatial Autoregressive Models and selected the best model to explain diversity patterns based on Akaike Information Criterion. Our results show that, out of the variables tested in our study, water-energy availability and historical climate instability are the most important drivers of amphibian diversity in Iberia. However, as predicted, the strength of these predictors in our case study is weaker than it tends to be at global scales. Thus, additional drivers should also be investigated and we suggest caution when interpreting these predictors as surrogates for different components of diversity.

Critical review of the phytohemagglutinin assay for assessing amphibian immunity.

Infectious diseases are a major driver of the global amphibian decline. In addition, many factors, including genetics, stress, pollution, and climate change can influence the response to pathogens. Therefore, it is important to be able to evaluate amphibian immunity in the laboratory and in the field. The phytohemagglutinin (PHA) assay is an inexpensive and relatively non-invasive tool that has been used extensively to assess immunocompetence, especially in birds, and more recently in amphibians. However, there is substantial variation in experimental methodology among amphibian PHA studies in terms of species and life stages, PHA doses and injection sites, and use of experimental controls. Here, we compile and compare all known PHA studies in amphibians to identify knowledge gaps and develop best practices for future work. We found that research has only been conducted on a limited number of species, which may not reflect the diversity of amphibians. There is also a lack of validation studies in most species, so that doses and timing of PHA injection and subsequent swelling measurements may not effectively evaluate immunocompetence. Based on these and other findings, we put forward a set of recommendations to make future PHA studies more consistent and improve the ability to utilize this assay in wild populations, where immune surveillance is greatly needed.

Species Diversity of Amphibians along Altitude Gradient at Hala – Bala Wildlife Sanctuary, Narathiwat Province

Species Diversity of Amphibians along Altitude Gradient at Hala – Bala Wildlife Sanctuary, Narathiwat Province

Gathering morphological and molecular data for identifying two species of trematodes from the neotropical Vaillant's frog, Lithobates vaillanti (Amphibia: Ranidae) in the highlands of Chiapas, south-eastern Mexico.

Mexico possesses a large diversity of amphibians partly due to its complex topography and transitional position between the Nearctic and Neotropical biogeographical regions. However, its helminth parasite fauna has been relatively poorly studied. Specimens of the Vaillant's frog, Lithobates vaillanti (Brocchi) were sampled in the tropical rain forest of Nahá, in the Chiapas Highlands, and examined for parasites. Two trematode species were collected from their hosts; morphologically, specimens were allocated to the genera Langeronia Caballero and Bravo-Hollis, 1949 and Haematoloechus Looss, 1899, respectively. Individuals were sequenced for two molecular markers (the mitochondrial cytochrome c oxidase gene, and the ribosomal gene 28S), and processed for morphological analyses, including scanning electron microscopy. The new evidence was not enough to accomplish the identification at species level of Langeronia sp. due to the lack of sequence data from the type localities of Langeronia parva Christian, 1970 and Langeronia macrocirra Caballero and Bravo-Hollis, 1949. Likewise, the newly generated data were useful to properly identify the adult specimens of lung flukes as Haematoloechus complexus Seely, 1906.

Marche ou Morra: herpetofauna atropelada ao longo da rodovia BR-040, uma antiga estrada na Mata Atlântica do Sudeste do Brasil

Abstract The construction of highways is responsible for access to previously protected areas, resulting in changes in landscape and dynamics of the animal populations that live in these areas. These enterprises are the major responsible for the mortality of wild animals, surpassing hunting and even the trafficking of animals. The objective of this study was to make a list that reflects the diversity of amphibians and reptile’s road-killed along the BR-040, a highway that crosses the threaten lowland Atlantic Forest in Southeastern region of Brazil, including the use of microhabitats, lifestyle, activity pattern, reproductive cycles, and possible rare or endangered species. The study area consists of 180,4 km of highways. Monitoring began in 2006 and continues to the present day. A total of 1,410 individuals from 60 species were recorded in this study. The reptiles were more frequent in number of individuals and species. The commonest species recorded were Crotalus durissus and Dipsas mikanii. We have registered a single endangered species: Ranacephala hogei. The highest rates of road-kill were recorded during the wet season. Road-kills of fauna is a major threat to species, studies are of great importance to define plans that seek to mitigate the effects generated by these enterprises.

Functional and phylogenetic metrics to evaluate the potential of flagship species: the case of the salamander Ambystoma ordinarium

Abstract Flagship species are those chosen to raise support for broader conservation marketing campaigns and can be used as symbols of the ecosystem services and evolutionary history of particular areas. Thus, flagship species can be employed for the protection of endangered species and threatened ecosystems. Northeastern Michoacán, Mexico, is an important region for amphibian diversity but approximately 40% of its mature forest has been removed. Among northeastern Michoacán amphibians, the use of Ambystoma ordinarium as a flagship species is supported by its co-occurrence with other threatened amphibians along riparian zones. To support this proposal, however, it is important to assess the functional traits and evolutionary history of amphibian species sharing their habitat with A. ordinarium. To evaluate the potential of A. ordinarium as a flagship species, we estimated the functional and phylogenetic diversity of amphibian assemblages in 60 riparian zones. The results showed that amphibian assemblages sharing habitat with A. ordinarium presented higher functional and phylogenetic diversity than those in which this species was absent. These results highlight the potential of A. ordinarium as a flagship species for the protection of associated amphibian species, their functions, and evolutionary history.

Spatial and seasonal dynamics of amphibians from shallows and forests in urban and Peri-urban areas of Daloa (Ivory Coast, West Africa)

The disappearance of forests and biodiversity in Côte d'Ivoire is also due to the expansion of urban areas. This expansion was carried out without any concern for the preservation or restoration of the natural resources. The Daloa area, in addition to the forest relics, contains shallows, important for agriculture. These shallows were mostly landing sites for drainage water from various horizons. To assess the conservation status of these environments, amphibians, due to their high sensitivity to changes in environmental conditions, were used to assess the biotic integrity of the ecosystems. Thus, daytime and night-time sampling were carried out in urban, peri-urban shallows and peri-urban forests. These acoustic, visual and capture samplings lasted 12 months and revealed the presence of 20 amphibian species. Nineteen species were found in urban shallows, peri-urban forests and 17 species in peri-urban shallows respectively. There was no significant difference between the species richness of the different habitats (Kruskal-Wallis test, p > 0.05). Furthermore, in the rainy season, amphibian diversity was higher in peri-urban forests than in shallows. In addition, over the whole study area, Amphibian abundance was higher in the rainy season than in the dry season. Also, the most frequent species in this area was Ptychadena mascareniensis. Finally, in the rainy season, the distribution of Amphibians in peri-urban forests was more equitable than that of dry season and in other sites.

More accurate, consistent, and reliable data for amphibian species are needed from China's nature reserves

AbstractDetailed, accurate, and reliable data regarding the occurrence of amphibian species in nature reserves (NRs) are important to facilitate effective conservation and management programs. We evaluated the current situation and research gaps in amphibian species inventories of NRs in mainland China by conducting a systematic review of papers on amphibian diversity research in NRs from 1956 to 2021. Generally, there was a gradual increase in amphibian survey intensity and standards, however, as some important parameters were lacking, such as species abundance and threats to amphibians. The standardization of amphibian surveys in NRs needs to urgently be strengthened and effectively implemented. We hope that highlighting these biases and gaps could provide actionable information for decision‐makers and improve conservation practices affecting amphibians in China and other native fauna elsewhere.