Stream Frog Research Articles

Peptidomic analysis of the host-defense peptides in skin secretions of Rana graeca provides insight into phylogenetic relationships among Eurasian Rana species

Peptidomic analysis of norepinephrine-stimulated skin secretions from the Greek stream frog Rana graeca Boulenger, 1891 led to the identification and structural characterization of a range of host-defense peptides. These comprised brevinin-1GRa, brevinin-1GRb and an N-terminally extended form of brevinin-1GRb, ranatuerin-2GR together with its oxidized form and (11–28) fragment, temporin-GRa, temporin-GRb and its non-amidated form, and a melittin-related peptide, MRP-GR and its (1–18) fragment. The most abundant peptide, MRP-GR significantly (P < 0.001) stimulated insulin release from BRIN-BD11 clonal β-cells at concentrations ≥0.1 nM. Rana graeca (formerly Rana graeca graeca) and the morphologically similar Italian stream frog Rana italica Dubois, 1987 (formerly Rana graeca italica) were originally regarded as sub-species. However, the primary structures of the host defense peptides from both frogs support the claim based upon comparisons of the nucleotide sequences of S1 satellite DNA that R. graeca and R. italica are separate species. Cladistic analyses based upon the primary structures of the brevinin-1 and ranatuerin-2 peptides from Eurasian frogs indicate a close phylogenetic relationship between R. graeca and Rana latastei whereas R. italica is most closely related to Rana dalmatina.

Disentangling causes of seasonal infection prevalence patterns: tropical tadpoles and chytridiomycosis as a model system.

Identifying the factors that affect pathogen prevalence is critical to understanding the effects of wildlife diseases. We aimed to examine drivers of seasonal changes in the prevalence of infection by the amphibian chytrid fungus Batrachochytrium dendrobatidis in tadpoles. Because tadpoles may be important reservoirs for this disease, examining them will aid in understanding how chytridiomycosis affects entire amphibian populations. We hypothesized that temperature is a strong driver of prevalence of Bd in tadpoles, and the accumulation of infection as tadpoles become larger and older also drives prevalence in this system. We studied Litoria rheocola, a tropical rainforest stream frog with seasonal recruitment of annual tadpoles, and surveyed 6 streams in northeastern Queensland, Australia. Comparisons among models relating infection status to stream type, season, their interaction, tadpole age, and water temperature showed that age explained a large portion of the variance in infection status. Across sites and seasons, larger, older tadpoles had increased mean probabilities of infection, indicating that a large component of the variation among individuals was related to age, and thus to cumulative infection risk. Our results indicate that in systems with annual tadpoles, seasonal changes in infection prevalence may be strongly affected by seasonal patterns of tadpole growth and development in addition to stream type, season, and water temperature. These effects may then influence prevalence of infection in terrestrial individuals in species that have relatively frequent contact with water. This reinforces the need to integrate studies of the drivers of pathogen prevalence across all host life history stages.

Is the Italian stream frog (Rana italica Dubois, 1987) an opportunistic exploiter of cave twilight zone?

Studies on frogs exploiting subterranean environments are extremely scarce, as these Amphibians are usually considered accidental in these environments. However, according to recent studies, some anurans actively select subterranean environments on the basis of specific environmental features, and thus are able to inhabit these environments throughout the year. We present the first study on the abundance and spatial use of the Italian stream frog, Ranaitalica, in subterranean environments. We monthly collected data from 66 cave sectors during a whole year (2013), recording &amp;gt; 120 detections of R.italica. Frogs were more frequently found close to the cave entrance, without significant differences between age classes or sexes. Adults generally were observed being higher up along cave walls compared to juveniles. Frogs abundance was higher in areas showing specific environmental features, such as warm temperature, low incident light and the presence of potential prey. Ranaitalica likely occupies subterranean areas characterized by a combination of microclimatic suitability and prey availability.

Mountain Survey of Amphibians and Reptiles and their Conservation Status in Manaslu Conservation Area, Gorkha District, Western Nepal

Aim The Manaslu Conservation Area (MCA), a geographically diverse protected area, is known for high diversity of flowering plants and endemism. However, information about status of herpetofauna is limited. This study aims to fill this gap by updating diversity and distribution of herpetofauna of the MCA.&#x0D; Location Sirdibas, Bihi and Prok Village Development Committees (VDCs), Gorkha district, Manaslu Conservation Area (MCA).&#x0D; Materials and methods We used a multi-prolonged strategy combining visual encounter survey (VES) along six transects (500m each) in Sirdibas, Bihi and Prok VDCs, patch sampling (PS) in two sites in Ghap and Prok VDCs and opportunistic observations (OO) along trekking trails from Sirdibas to Prok to document the presence of herpetofauna. We conducted questionnaire survey using photo-elicitation technique (PET) (n=30) to collect ethnoherpetological data.&#x0D; Key Findings We prepared a checklist of 22 species of amphibian and reptile by verification of data from VES, PS, OO and literature review. The Himalayan rock lizard, Laudakia tuberculata was common in all the study sites. The Hodgson’s racer - Elaphe hodgsonii was first described in the study area. The abundance of herpetofauna species decreased with increasing elevation (r = -0.53, P &lt; 0.01). There was a positive association between species abundances and temperature (r = 0.49, P &lt; 0.01). The ethnoherpetological survey revealed that the stream frogs locally called ‘Paha’ (genus ‘Amolops’, ‘Chaparana’ and ‘Paa’) were commonly consumed for food and presumed health benefits. This may impose a serious threat. We recommend similar systematic study to document and describe herpetofauna in the region.

Taxonomic Reappraisal of the Northeast Mindanao Stream Frog, Sanguirana albotuberculata(Inger 1954), Validation ofRana mearnsi, Stejneger 1905, and Description of a New Species from the Central Philippines

Abstract: With a published multilocus phylogenetic analysis as our guide, we use new data from the external phenotype and genetically defined distributions of evolutionary lineages to resolve species boundaries associated with the southwest Mindanao Stream Frogs, Sanguirana everetti (Boulenger 1882), its junior synonym, Rana mearnsi, Stejneger 1905, and the northeast Mindanao Stream Frogs, Sanguirana albotuberculata (Inger 1954). Consideration of relationships, distributions, type localities, phenotypic data, and type specimens clearly indicates that the names R. mearnsi and S. albotuberculata refer to the same lineage, and we recognize the oldest available name (Sanguirana mearnsi) for this species. We also define the central Philippine lineage (from Negros, Masbate, and Panay islands) as a distinct new species. Long confused with S. everetti, the new taxon is readily diagnosed and biogeographically restricted to the West Visayan faunal region. The new multilocus estimate of phylogeny and our multivaria...

Cytotoxic peptides with insulin-releasing activities from skin secretions of the Italian stream frog Rana italica (Ranidae).

Peptidomic analysis of norepinephrine-stimulated skin secretions from Italian stream frog Rana italica led to the purification and characterization of two host-defense peptides differing by a single amino acid residue belonging to the brevinin-1 family (brevinin-1ITa and -1ITb), a peptide belonging to the temporin family (temporin-ITa) and a component identified as prokineticin Bv8. The secretions contained relatively high concentrations of the methionine-sulphoxide forms of brevinin-1ITa and -1ITb suggesting that these peptides may have a role as antioxidants in the skin of this montane frog. Brevinin-1ITa (IVPFLLGMVPKLVCLITKKC) displayed potent cytotoxicity against non-small cell lung adenocarcinoma A549 cells (LC50 =18μM), breast adenocarcinoma MDA-MB-231 cells (LC50 =8μM) and colorectal adenocarcinoma HT-29 cells (LC50 =18μM), but the peptide was also strongly hemolytic against mouse erythrocytes (LC50 =7μM). Temporin-ITa (VFLGAIAQALTSLLGKL.NH2 ) was between three and fivefold less potent against these cells. Brevinin-1ITa inhibited growth of both Gram-positive Staphylococcus epidermidis and Gram-negative Escherichia coli as well as a strain of the opportunist yeast pathogen Candida parapsilosis, whereas temporin-ITa was active only against S. epidermidis and C. parapsilosis. Both peptides stimulated the release of insulin from BRIN-BD11 clonal β-cells at concentrations ≥1nM, but brevinin-1ITa was cytotoxic to the cells at concentrations ≥3μM. Copyright © 2017 European Peptide Society and John Wiley & Sons, Ltd.

Sink or swim? Potential for high faunal turnover in Australian rivers under climate change

AbstractAimClimate change threatens biodiversity in all ecosystems, and major shifts in species distributions are expected. Freshwater ecosystems are considered particularly vulnerable due to the ectothermic physiology of most freshwater species and their limited habitat extent and capacity to track climate trends. In this study, we examined what broad patterns in freshwater riverine species turnover might be expected under climate change across continental Australia and what are the implications of these patterns for aquatic species and the low aquatic biodiversity of some bioregions?LocationContinental Australia.MethodsWe built statistical relationships between bioclimatic environments and the occurrence of species of four freshwater taxa (freshwater fish, crayfish, turtles and frogs) and examined trends in projected species turnover for a ‘business as usual’ climate scenario. We used Maxent to model species distributions and present the median projection across 18 global climate models. A recently derived national stream network was used to generate estimates of mean annual river flow and to produce realistic species distributions and migration options by restricting dispersal and migration opportunities usually available to riverine fauna.ResultsHigh species turnover was driven overwhelmingly by potential local extinctions particularly for stream frogs and crayfish where their current biodiversity is largely confined to higher elevation headwater streams. We predicted high turnover for inland regions of Australia, which are arid and generally support fewer freshwater species.Main conclusionsOur analysis indicates that under the most severe emissions pathway, projected climate change is likely to cause substantial changes to the composition of faunal assemblages in Australian rivers well before the end of this century. While freshwater systems globally are subject to immediate and pressing threats from anthropogenic land and water use, management interventions addressing these pressures need to be considered within the context of climate change.

Effects of Logging and Oil Palm Expansion on Stream Frog Communities on Borneo, Southeast Asia

AbstractThe conversion of tropical rain forests to oil palm plantations is a major threat to Southeast Asia's rich biodiversity. Fostering forest species communities in secondary forests, agroforestry systems, and plantations is therefore increasingly becoming a conservation focus. This study uses standardized transect‐based sampling to compare species richness, density and community composition of stream anuran assemblages among primary forests, repeatedly logged forests and oil palm plantations in northern Borneo. In primary forest streams, we recorded an average of 19 frog species, compared to 15 species in logged forests and 11 species in oil palm plantation streams. However, the high percentage of canopy cover above the plantation streams mitigated this loss to some extent. This study corroborates numerous studies that oil palm plantations have mainly negative effects on the region's biodiversity. However, our results also demonstrate the high conservation value of logged forests for Bornean stream‐dependent anurans. We conclude that palm plantations have a largely unused potential to promote regional anuran biodiversity.

A New Species of Stream Frog of the Genus Hylarana from the Mountains of Southern Mindanao Island, Philippines

Abstract: I describe a new species of frog of the Hylarana signata species complex from Mt. Busa, Sarangani and South Cotobato provinces, southern Mindanao Island, Philippines. The new species is distinguished from all other members of the H. signata complex by a unique combination of characters of external morphology, biochemical allelic variation, and the species’ position in phylogeny, estimated by analysis of multilocus DNA sequence data. Justification for recognition of the new species is further supported by marked sequence divergence in mitochondrial and nuclear genes. The new species has been collected only once in >20 yr despite targeted survey efforts on Mindanao, and multiple possible explanations are available to explain its extreme rarity. The recognition of this species, on the basis of a single previously misidentified specimen, accentuates the importance of collecting large sample sizes of specimens during faunistic surveys. Recognition of a new species from a locality that has now been h...

Social interactions in a neotropical stream frog reveal a complex repertoire of visual signals and the use of multimodal communication

Visual communication has evolved independently in several families of frogs and is complex in diurnal stream frogs. In addition to isolated visual and acoustic signals, some species may emit multimodal displays characterized by the association of these signals. Through the analysis of focal recordings obtained in situ in southern Brazil, we investigated the visual and multimodal communication in the diurnal stream frog Crossodactylus schmidti. We found a complex visual repertoire of nine signals used in intraspecific communication, of which the signal Both legs kicking was described for the first time. Males, females and juveniles emitted visual signals, but males had a larger repertoire and used most signals in agonistic interactions. The four most common visual signals, Toe flagging, Limb lifting, Body jerking and Running-jumping, were emitted predominantly upon rocks in the stream bed. The emission of isolated visual and acoustic signals, as well as audiovisual displays with simultaneous or temporally coupled components, demonstrates that the communication in C. schmidti is complex and that the multimodal displays may have different functions. We discuss the historical, behavioural, ecological factors which may have influenced the evolution of the visual repertoire of C. schmidti, and how the ritualization of derived activities similar to visual signals may have led to the evolution of part of the repertoire. This study provides novel results on visual and multimodal communication for the genus Crossodactylus and demonstrates that C. schmidti represents an appropriate model for studies of complex displays.

Erratum to: Social interactions in a neotropical stream frog reveal a complex repertoire of visual signals and the use of multimodal communication (Behaviour 151 (2014) 719–739, DOI:)

In the above-mentioned article, the following corrections should have been made: On page 732, line 32: Physalaemus pustulosus should read: Engystomops pustulosus On page 734: line 1: . . . frog-biting midges attacked a calling male. The interaction with midges. . . should read: . . . parasitic flies attacked a calling male. The interaction with the flies. . . On page 734, line 10: P. pustulosus should read: E. pustulosus On page 734, line 17: Corethrella should read: parasitic flies On page 734, lines 20–21: . . . may have reduced calling activity and increased the use of visual signals to avoid attacks of midges should read: may have reduced calling activity to avoid being parasitized On page 734, line 23: frog-biting midges should read: parasitic flies On page 734, line 27: to repel attacks of eavesdroppers like frog-biting midges should read: to repel attacks of eavesdroppers On page 735, lines 6, 16 and 26: in all cases, frog-biting midges should read: parasitic flies On page 736, line 10: Corethrella should read: Corethrella

Geographic distribution of the chytrid pathogen Batrachochytrium dendrobatidis among mountain amphibians along the Italian peninsula

The amphibian chytrid pathogen Batrachochytrium dendrobatidis (Bd) is considered a major cause of amphibian population declines, particularly in montane areas. Here, we investigated the presence and distribution of Bd among populations of 3 mid- to high-altitude species spanning the entire Italian peninsula (486 individuals from 39 sites overall): the stream frog Rana italica, the fire salamander Salamandra salamandra gigliolii, and the alpine newt Mesotriton alpestris apuanus. We found Bd in all of the analyzed species. Despite the widespread distribution of the pathogen, its overall prevalence (6, 9 and 19%, respectively) was lower than previously reported for the endangered Apennine yellow-bellied toad Bombina pachypus (62.5%). Moreover, several populations of the species studied here were not infected, even at sites where Bd has been detected in other host species. When coupled with the lack of evidence for Bd-related mortalities in these species in peninsular Italy, these results suggest that mechanisms of resistance and/or tolerance are protecting populations of these species from the pathogenic activity of Bd. Nevertheless, in light of the dynamic pattern of Bd-host interactions reported in other studies, of Bd-related mortalities in at least 1 study species (S. s. salamandra) in other areas, and the ongoing climate changes in montane environments, we suggest that the occurrence of Bd should be considered a potential threat to the long-term persistence of these species, and urge the implementation of monitoring and conservation plans.

Spotted stream frog diversification at the Australasian faunal zone interface, mainland versus island comparisons, and a test of the Philippine ‘dual‐umbilicus’ hypothesis

AbstractAimTo utilize comprehensive geographical sampling and a new, multilocus dataset to re‐examine the biogeography of spotted stream frogs (Hylarana signata complex) throughout Southeast Asia. To compare patterns of diversification among stream frog populations on land‐bridge islands and oceanic islands and to re‐evaluate a previous ‘dual‐invasion’ hypothesis for the origins of endemic Philippine taxa.LocationSoutheast Asia, Sundaland, and the Philippines.MethodsWe sequenced two mitochondrial and two nuclear gene regions for members of the Hylarana signata complex. We used summary statistics and phylogenetic networks to characterize genetic variation; phylogenetic relationships and ancestral ranges were estimated using Bayesian and likelihood methods. We used the preferred topology and Bayesian methods to evaluate a previous biogeographical ‘dual‐invasion’ hypothesis.ResultsIn contrast to expectations, we found highly divergent, demographically stable and geographically regionalized lineages on the mainland and on land‐bridge islands, but minimally divergent, widespread and clinally distributed populations, with evidence of recent demographic expansion, in adjacent oceanic island populations. Novel phylogenetic relationships depart from previous studies and our data strongly reject the previously published ‘dual‐invasion’ hypothesis.Main conclusionsOur results join new literature demonstrating that species on mainland and continental shelf islands may harbour high levels of unrecognized diversity, whereas adjacent oceanic island archipelagos can and do support naturally occurring widespread species. Although our data indicate that the individual identities of species previously hypothesized to be involved in the ‘dual‐invasion’ scenario may have been incorrect, this mechanism for faunal exchange between the archipelago and adjacent mainland undoubtedly has contributed substantially to the accumulation of endemic vertebrate diversity in the Philippines.

Presence of the chytrid fungus Batrachochytrium dendrobatidis in a Vulnerable frog in Trinidad, West Indies

ESR Endangered Species Research Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials ESR 20:131-136 (2013) - DOI: https://doi.org/10.3354/esr00485 Presence of the chytrid fungus Batrachochytrium dendrobatidis in a Vulnerable frog in Trinidad, West Indies Jahson B. Alemu I1, Michelle N. E. Cazabon-Mannette1, Andrew A. Cunningham2, Lena Dempewolf1, Adrian Hailey3,*, Ryan P. Mannette1, Kerrie T. Naranjit1, Matthew W. Perkins2, Alicia C. J. Schmidt-Roach1 1Project L.E.A.P., c/o Department of Life Sciences, The University of the West Indies, St. Augustine, Trinidad and Tobago 2Institute of Zoology, Zoological Society of London, Regent?s Park, London NW1 4RY, UK 3Department of Life Sciences, The University of the West Indies, St. Augustine, Trinidad and Tobago *Corresponding author. Email: adrian.hailey@sta.uwi.edu ABSTRACT: Amphibian chytridiomycosis occurs on a small proportion of West Indian islands, but the entire Caribbean region, including Trinidad, offers a suitable environment for the infection. We report the presence of the causative agent Batrachochytrium dendrobatidis (Bd) in 2 out of 12 populations sampled of the Vulnerable Trinidad stream frog, Mannophryne trinitatis. We analyzed 184 skin swabs collected from wild frogs using real-time PCR analysis. Follow-up sampling determined a prevalence of Bd infection of 3 and 23% in these 2 populations. We did not find any evidence of associated clinical disease. Bd-positive populations were located at the highest elevations studied (425 to 450 m). These 2 populations had more juveniles than other populations, and juveniles were more likely to be infected than adults. Our results suggest that sampling juveniles may provide the greatest sensitivity for any future monitoring for the presence of Bd in M. trinitatis populations in Trinidad. KEY WORDS: Mannophryne trinitatis · Aromobatidae · Juveniles · Amphibian chytrid · Caribbean Full text in pdf format PreviousNextCite this article as: Alemu JB I, Cazabon-Mannette MNE, Cunningham AA, Dempewolf L and others (2013) Presence of the chytrid fungus Batrachochytrium dendrobatidis in a Vulnerable frog in Trinidad, West Indies. Endang Species Res 20:131-136. https://doi.org/10.3354/esr00485 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in ESR Vol. 20, No. 2. Online publication date: April 02, 2013 Print ISSN: 1863-5407; Online ISSN: 1613-4796 Copyright © 2013 Inter-Research.

Strict consistency between genetic and topographic landscapes of the brown tree frog (Buergeria robusta) in Taiwan

Taiwan presents an excellent opportunity to build a phylogeographic paradigm for fine-scaled differentiation occurring within short distances on an single island. Due to the limitation of habitat availability on the island, demographic histories of species in Taiwan were strongly influenced by glacial–interglacial cycles. Nevertheless, there are relatively few studies demonstrating such phylogeographic patterns for islands, especially in subtropical Asia. In this study, we aim to construct the genetic landscape of a philopatric stream frog Buergeria robusta by an intense and fine-scaled collection throughout the island. The deduced genetic landscape of B. robusta presented extremely high congruence with the actual topography of Taiwan. Two major lineages were found on the eastern and the western sides of Taiwan with a non-overlapping distribution, indicating the importance of the Central Mountain Range as the major biogeographic barrier. Both clades showed a strong and congruent tendency of demographic or distributional expansion in recent history based on different analyses. Population expansion of such a subtropical lowland species might be a result from a release of available habitat in post-glacial periods.

A New Species of Stream Frog (Sanguirana) from the Mountains of Luzon Island, Philippines

We describe a distinctively patterned new species of cascade stream frog from the mountains of Nueva Vizcaya and Aurora provinces, Luzon Island. The new species belongs to the genus Sanguirana, the definition of which we expand to include all Philippine species previously referred to the Rana (Hylarana) everetti complex. The new species is distinguished from other members of the genus by its possession of a bright yellow-green dorsum with conspicuous orange flower-shaped spots in females, bright white, postaxial dermal flanges on the limbs, green-to-purple flank transition, and a highly tuberculate, white venter, in addition to the absence of a dark canthal stripe. The new species is known only from high-gradient, cascading mountain streams between elevations of 750 and 1450 m in mature secondary forest and minimally disturbed primary forests. The discovery of such a distinctive new species emphasizes the relatively high degree to which endemic anuran diversity in the Philippines is still underestimated and underappreciated.

Variability in escape trajectory in the Trinidadian stream frog and two treefrogs at different life-history stages

Most studies investigating anuran jumping behaviour have examined the relationship between body size and parameters such as jump distance, velocity, and force; however, few have investigated jump trajectory. We constructed an arena to determine escape trajectories in relation to the direction of an artificial stimulus in the aromobatid Mannophryne trinitatis (Garman, 1888) and two treefrogs, Trachycephalus venulosus (Laurenti, 1768) and Hypsiboas geographicus (Spix, 1824). Three categories of M. trinitatis (i.e., tadpole-transporting males, nontransporting males, and females) and three ontogenetic stages of the treefrogs were compared. Mannophryne trinitatis escaped in a broadly predictable trajectory away from the stimulus, although jump trajectories were highly variable, suggesting a degree of unpredictability. No systematic differences were found between categories of M. trinitatis, adding to the findings of previous studies that larval transport incurs no measurable locomotor costs on antipredatory jumping behaviour with regards to jump angle and distance. The treefrogs showed similar patterns of escape trajectory and unpredictability. There were no consistent differences between life-history stages and no relationship between distance jumped and angular deviation. In M. trinitatis and H. geographicus, there was some evidence of bimodality in escape trajectory. The results are discussed in the context of other work on escape trajectories and the concept of “protean” defence strategies.

Phylogeography of the Clicking Stream Frog Strongylopus grayii (Anura, Pyxicephalidae) reveals cryptic divergence across climatic zones in an abundant and widespread taxon

The Clicking Stream Frog (Strongylopus grayii) occurs throughout southern and eastern South Africa across summer, aseasonal and winter rainfall areas. Because of its contiguous distribution and extended breeding season this species might be expected to show a phylogeographic pattern of isolation by distance rather than divergent geographical lineages. To investigate population structure and make inferences about physical processes that have influenced gene flow in this species, two mitochondrial genes (ND2 and 16S) were sequenced for 64 frogs from across the distribution of the species. Phylogenetic analyses (parsimony and Bayesian) revealed two well-supported clades partitioning the range of this taxon, with one clade restricted to the northeast (summer rainfall) and the other restricted to the south (winter and aseasonal rainfall). The magnitude of sequence divergence between these clades is higher than expected, and is typical of levels of sequence divergence found among closely related species of pyxicephalid frogs. Phylogeographic analyses of sequence networks and spatial analysis of molecular variance (SAMOVA) revealed additional geographical structure within each of these lineages. This study demonstrates the effectiveness of climatic transitions as barriers to gene flow and as potential agents for vicariant speciation.

Rivers as barriers for high elevation amphibians: a phylogeographic analysis of the alpine stream frog of the Hengduan Mountains

AbstractAt high altitude, rivers may function as barriers for amphibians. We examined 21 populations of Scutiger boulengeri from the Hengduan Mountains with 1038 base pairs of mitochondrial cytochrome b gene sequences. The haplotypes of S. boulengeri formed three clades on the gene tree, and each clade was restricted to one mountain ridge separated by two major river systems, the Yalong River and the Dadu River. The vicariant pattern of the gene tree suggests that these rivers functioned as effective barriers during population differentiation. On the other hand, mountain ridges may have facilitated amphibian movement. Populations within the uninterrupted mountain ranges of clades II and III, revealed little genetic structure. The northern clade I, harboured a substantial amount of genetic variation, which might be the consequence of the rugged terrain and heterogeneous habitat of this area. Furthermore, one outgroup species, Scutiger glandulatus, formed the fourth clade and nested within S. boulengeri, suggesting that S. boulengeri is likely a paraphyletic species or a species complex.

The importance of environmental heterogeneity for species diversity and assemblage structure in Bornean stream frogs

1. Several hypotheses have been proposed to explain the structure of multi-species assemblages. Among these, abiotic environmental factors and biotic processes are often favoured. Several recent studies examining anuran communities identified environmental factors to be only of minor importance in the composition of leaf-litter and canopy assemblages in pristine forests. Instead, spatial effects and spatially structured environments were considered more important. 2. In this study, we investigated whether these findings could also be confirmed for very heterogeneous stream habitats in the primary rainforest of the Ulu Temburong National Park, Brunei Darussalam. We thus investigated anuran assemblage compositions on 50 stream sites with regard to environmental and spatial influences. 3. Cross-product correlations indicated that both factors (spatial and environmental parameters) determined assemblage composition of anurans. Environment itself may be spatially structured, yet this interrelation did not contribute to the explainable variation of frog community compositions within the study area. 4. Detailed analyses of the environmental parameters with nonmetric multidimensional scaling revealed that community structure was mostly affected by three major environmental characters: stream turbidity, river size and the density of understorey vegetation. Based on these habitat characteristics, we assigned species to three distinct habitat guilds. 5. The results underline the importance of riparian habitat heterogeneity in pristine forests in structuring anuran assemblages. We conclude that different anuran assemblages, that is, leaf litter, canopy and stream communities, follow different assemblage rules and thus are not directly comparable.