Diversification of shrub frogs (Rhacophoridae, Pseudophilautus) in Sri Lanka - Timing and geographic context

US National Science Foundation (DEB 0345885) to CJS and JH; National Geographic Society (7612-04) to CJS; and Society of Systematic Biologists Graduate Student Award for Research to MM. MM was also supported by a Harvard University Center for the Environment (HUCE) Ziff Environmental Postdoctoral Fellowship. (DEB 0345885 - US National Science Foundation; 7612-04 - National Geographic Society; Society of Systematic Biologists Graduate Student Award for Research; Harvard University Center for the Environment (HUCE) Ziff Environmental Postdoctoral Fellowship)Accepted manuscrip

The role of climate and islands in species diversification and reproductive-mode evolution of Old World tree frogs

Large diversifications of species are known to occur unevenly across space and evolutionary lineages, but the relative importance of their driving mechanisms, such as climate, ecological opportunity and key evolutionary innovations (KEI), remains poorly understood. Here, we explore the remarkable diversification of rhacophorid frogs, which represent six percent of global amphibian diversity, utilize four distinct reproductive modes, and span a climatically variable area across mainland Asia, associated continental islands, and Africa. Using a complete species-level phylogeny, we find near-constant diversification rates but a highly uneven distribution of species richness. Montane regions on islands and some mainland regions have higher phylogenetic diversity and unique assemblages of taxa; we identify these as cool-wet refugia. Starting from a centre of origin, rhacophorids reached these distant refugia by adapting to new climatic conditions (‘niche evolution’-dominant), especially following the origin of KEIs such as terrestrial reproduction (in the Late Eocene) or by dispersal during periods of favourable climate (‘niche conservatism’-dominant)

The identity of the Sri Lankan Amblypharyngodon (Teleostei, Cyprinidae)

Morphological and molecular analyses of specimens representative of the geographic range of the cyprinid genus Amblypharyngodon in Sri Lanka suggest the presence of only a single species in the island, for which the name Amblypharyngodongrandisquamis Jordan & Starks, 1917, is available. Amblypharyngodongrandisquamis is a species endemic to Sri Lanka, distributed across the lowlands of both of the island's main climatic zones. It is distinguished from all other species of Amblypharyngodon, including the three species recorded from peninsular India (A.mola, A.microlepis, and A.melettinus), by a suite of characters that includes a body depth of 26.9-31.2% of the standard length (SL), 42-56 scales in the lateral series (of which usually 8-16 are pored), 20-24 circumpeduncular scales, 14-17 scale rows between the origins of the dorsal and pelvic fins, a dorsal-fin height of 21.1-27.6% SL, 18-19 caudal vertebrae and an eye diameter of 22.7-30.5% of the head length. Amblypharyngodongrandisquamis differs from A.melettinus and A.mola by uncorrected pairwise genetic distances of more than 9% and 6%, respectively, for the mitochondrial cytochrome oxidase subunit 1 (COI) gene

The identity of the Sri Lankan Amblypharyngodon (Teleostei, Cyprinidae)

Morphological and molecular analyses of specimens representative of the geographic range of the cyprinid genus Amblypharyngodon in Sri Lanka suggest the presence of only a single species in the island, for which the name Amblypharyngodon grandisquamis Jordan & Starks, 1917, is available. Amblypharyngodon grandisquamis is a species endemic to Sri Lanka, distributed across the lowlands of both of the island’s main climatic zones. It is distinguished from all other species of Amblypharyngodon, including the three species recorded from peninsular India (A. mola, A. microlepis, and A. melettinus), by a suite of characters that includes a body depth of 26.9–31.2% of the standard length (SL), 42–56 scales in the lateral series (of which usually 8–16 are pored), 20–24 circumpeduncular scales, 14–17 scale rows between the origins of the dorsal and pelvic fins, a dorsal-fin height of 21.1–27.6% SL, 18–19 caudal vertebrae and an eye diameter of 22.7–30.5% of the head length. Amblypharyngodon grandisquamis differs from A. melettinus and A. mola by uncorrected pairwise genetic distances of more than 9% and 6%, respectively, for the mitochondrial cytochrome oxidase subunit 1 (COI) gene

Undocumented translocations spawn taxonomic inflation in Sri Lankan fire rasboras (Actinopterygii, Cyprinidae)

A recent (2013) taxonomic review of the freshwater-fish genus Rasboroides, which is endemic to Sri Lanka, showed it to comprise four species: R. vaterifloris, R. nigromarginatus, R. pallidus and R. rohani. Here, using an integrative-taxonomic analysis of morphometry, meristics and mitochondrial DNA sequences of cytochrome b (cytb) and cytochrome oxidase subunit 1 (coi), we show that R. nigromarginatus is a synonym of R. vaterifloris, and that R. rohani is a synonym of R. pallidus. The creation and recognition of unnecessary taxa (‘taxonomic inflation’) was in this case a result of selective sampling confounded by a disregard of allometry. The population referred to R. rohani in the Walawe river basin represents an undocumented trans-basin translocation of R. pallidus, and a translocation into the Mahaweli river of R. vaterifloris, documented to have occurred ca 1980, in fact involves R. pallidus. A shared haplotype suggests the latter introduction was likely made from the Bentara river basin and not from the Kelani, as claimed. To stabilize the taxonomy of these fishes, the two valid species, R. vaterifloris and R. pallidus, are diagnosed and redescribed, and their distributions delineated. We draw attention to the wasteful diversion of conservation resources to populations resulting from undocumented translocations and to taxa resulting from taxonomic inflation. We argue against translocations except where mandated by a conservation emergency, and even then, only when supported by accurate documentation

Molecular phylogeny and phylogeography of ricefishes (Teleostei: Adrianichthyidae: Oryzias ) in Sri Lanka

Ricefishes of the genus Oryzias occur commonly in the fresh and brackish waters in coastal lowlands ranging from India across Southeast Asia and on to Japan. Among the three species of Oryzias recorded from peninsular India, two widespread species, O. carnaticus and O. dancena, have previously been reported from Sri Lanka based on museum specimens derived from a few scattered localities. However, members of the genus are widespread in the coastal lowlands of Sri Lanka, a continental island separated from India by the shallow Palk Strait. Although recent molecular phylogenies of Adrianichthyidae represent near-complete taxon representation, they lack samples from Sri Lanka. Here, based on sampling at 13 locations representative of the entire geographic and climatic regions of the island's coastal lowlands, we investigate for the first time the molecular phylogenetic relationships and phylogeography of Sri Lankan Oryzias based on one nuclear and two mitochondrial markers. Sri Lankan Oryzias comprise two distinct non-sister lineages within the javanicus species group. One of these is represented by samples exclusively from the northern parts of the island; it is recognized as O. dancena. This lineage is recovered as the sister group to the remaining species in the javanicus group. The second lineage represents a species that is widespread across the island's coastal lowlands. It is recovered as the sister group of O. javanicus and is identified as O. cf. carnaticus. Ancestral-range estimates suggest two independent colonizations of Indian subcontinent and Sri Lanka by widespread ancestral species of Oryzias during two discrete temporal windows: late Miocene and Plio-Pleistocene. No phylogeographic structure is apparent in Sri Lankan Oryzias, suggesting that there are no strong barriers to gene flow and dispersal along the coastal floodplains, as is the case also for other generalist freshwater fishes in the island

Unearthing the Fossorial Tadpoles of the Indian Dancing Frog Family Micrixalidae

Tadpoles of the monotypic Indian dancing frog family Micrixalidae have remained obscure for over 125 years. Here we report the discovery of the elusive tadpoles of Micrixalus herrei from the sand beds of a forested stream in southern Western Ghats, and confirm their identity through DNA barcoding. These actively burrowing tadpoles lead an entirely fossorial life from eggs to late metamorphic stages. We describe their internal and external morphological characters while highlighting the following features: eel-like appearance, extensively muscularized body and tail, reduced tail fins, skin-covered eyes, delayed development of eye pigmentation in early pre-metamorphic stages (Gosner stages 25–29), prominent tubular sinistral spiracle, large transverse processes on vertebrae II and III, ankylosed ribs on transverse processes of vertebra II, notochord terminating before the atlantal cotyle-occipital condyle junction, absence of keratodonts, serrated well-formed jaw sheaths, and extensive calcified endolymphatic sacs reaching sacrum posteriorly. The tadpole gut contains mostly fine sediments and sand. We discuss the eel-like morphology and feeding habits of M. herrei in the context of convergence with other well-known fossorial tadpoles. This discovery builds the knowledge base for further comparative analyses and conservation of Micrixalus, an ancient and endemic lineage of Indian frogs

Wall‐following – Phylogenetic context of an enhanced behaviour in stygomorphic Sinocyclocheilus (Cypriniformes: Cyprinidae) cavefishes

With 75 known species, the freshwater fish genus Sinocyclocheilus is the largest cavefish radiation in the world and shows multiple adaptations for cave‐dwelling (stygomorphic adaptations), which include a range of traits such as eye degeneration (normal‐eyed, micro‐eyed and eyeless), depigmentation of skin, and in some species, the presence of “horns”. Their behavioural adaptations to subterranean environments, however, are poorly understood. Wall‐following (WF) behaviour, where an organism remains in close contact with the boundary demarcating its habitat when in the dark, is a peculiar behaviour observed in a wide range of animals and is enhanced in cave dwellers. Hence, we hypothesise that wall‐following is also present in Sinocyclocheilus, possibly enhanced in eyeless species compared to eye bearing (normal‐/micro‐eyed species). Using 13 species representative of Sinocyclocheilus radiation and eye morphs, we designed a series of assays, based on pre‐existing methods for Astyanax mexicanus behavioural experiments, to examine wall‐following behaviour under three conditions. Our results indicate that eyeless species exhibit significantly enhanced intensities of WF compared to normal‐eyed species, with micro‐eyed forms demonstrating intermediate intensities in the WF distance. Using a mtDNA based dated phylogeny (chronogram with four clades A–D), we traced the degree of WF of these forms to outline common patterns. We show that the intensity of WF behaviour is higher in the subterranean clades compared to clades dominated by normal‐eyed free‐living species. We also found that eyeless species are highly sensitive to vibrations, whereas normal‐eyed species are the least sensitive. Since WF behaviour is presented to some degree in all Sinocyclocheilus species, and given that these fishes evolved in the late Miocene, we identify this behaviour as being ancestral with WF enhancement related to cave occupation. Results from this diversification‐scale study of cavefish behaviour suggest that enhanced wall‐following behaviour may be a convergent trait across all stygomorphic lineages

Is Chytridiomycosis an Emerging Infectious Disease in Asia?

The disease chytridiomycosis, caused by the fungus Batrachochytrium dendrobatidis (Bd), has caused dramatic amphibian population declines and extinctions in Australia, Central and North America, and Europe. Bd is associated with >200 species extinctions of amphibians, but not all species that become infected are susceptible to the disease. Specifically, Bd has rapidly emerged in some areas of the world, such as in Australia, USA, and throughout Central and South America, causing population and species collapse. The mechanism behind the rapid global emergence of the disease is poorly understood, in part due to an incomplete picture of the global distribution of Bd. At present, there is a considerable amount of geographic bias in survey effort for Bd, with Asia being the most neglected continent. To date, Bd surveys have been published for few Asian countries, and infected amphibians have been reported only from Indonesia, South Korea, China and Japan. Thus far, there have been no substantiated reports of enigmatic or suspected disease-caused population declines of the kind that has been attributed to Bd in other areas. In order to gain a more detailed picture of the distribution of Bd in Asia, we undertook a widespread, opportunistic survey of over 3,000 amphibians for Bd throughout Asia and adjoining Papua New Guinea. Survey sites spanned 15 countries, approximately 36° latitude, 111° longitude, and over 2000 m in elevation. Bd prevalence was very low throughout our survey area (2.35% overall) and infected animals were not clumped as would be expected in epizootic events. This suggests that Bd is either newly emerging in Asia, endemic at low prevalence, or that some other ecological factor is preventing Bd from fully invading Asian amphibians. The current observed pattern in Asia differs from that in many other parts of the world

Photography

Image 1: FUTA rally at Hyde Park, Colombo