Adapting to Novel Environments Together: Evolutionary and Ecological Correlates of the Bacterial Microbiome of the World’s Largest Cavefish Diversification (Cyprinidae, Sinocyclocheilus)
The symbiosis between a host and its microbiome is essential for host fitness, and this association is a consequence of the host’s physiology and habitat. Sinocyclocheilus, the largest cavefish diversification of the world, an emerging multi-species model system for evolutionary novelty, provides an excellent opportunity for examining correlates of host evolutionary history, habitat, and gut-microbial community diversity. From the diversification-scale patterns of habitat occupation, major phylogenetic clades (A–D), geographic distribution, and knowledge from captive-maintained Sinocyclocheilus populations, we hypothesize habitat to be the major determinant of microbiome diversity, with phylogeny playing a lesser role. For this, we subject environmental water samples and fecal samples (representative of gut-microbiome) from 24 Sinocyclocheilus species, both from the wild and after being in captivity for 6 months, to bacterial 16S rRNA gene profiling using Illumina sequencing. We see significant differences in the gut microbiota structure of Sinocyclocheilus, reflective of the three habitat types; gut microbiomes too, were influenced by host-related factors. There is no significant association between the gut microbiomes and host phylogeny. However, there is some microbiome related structure at the clade level, with the most geographically distant clades (A and D) being the most distinct, and the two overlapping clades (B and C) showing similarities. Microbes inhabiting water were not a cause for significant differences in fish-gut microbiota, but water quality parameters were. Transferring from wild to captivity, the fish microbiomes changed significantly and became homogenized, signifying plastic changes and highlighting the importance of environmental factors (habitat) in microbiome community assembly. The core microbiome of this group, at higher taxonomic scale, resembled that of other teleost fishes. Our results suggest that divergent natural environments giving rise to evolutionary novelties underlying host adaptations, also includes the microbiome of these fishes.
Citation: Sudasinghe H, Pethiyagoda R, Maduwage K, Meegaskumbura M (2019) The identity of the Sri LankanAmblypharyngodon (Teleostei, Cyprinidae). ZooKeys 820: 25–49. https://doi.org/10.3897/zookeys.820.29632
Using an integrative taxonomic approach, using samples from throughout their geographic range, we show that there is only a single Amblypharyngodon species in Sri Lanka- Amblypharyngodon grandisquamis Jordan & Starks, 1917. It 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)
Citation - Sudasinghe H, Herath J, Pethiyagoda R, Meegaskumbura M. 2018. Undocumented translocations spawn taxonomic inflation in Sri Lankan fire rasboras (Actinopterygii, Cyprinidae) PeerJ 6:e6084 https://doi.org/10.7717/peerj.6084
Fire Rasboras of Sri Lanka was thought to comprise of four species: R. vaterifloris, R. nigromarginatus, R. pallidus and R. rohani. Here, using an integrative-taxonomic analysis of morphometry, meristics and mitochondrial DNA sequences 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. vateriflorisand 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. peerj.com/articles/6084/?td=bl
Systematic revision of Microhyla (Microhylidae) frogsof South Asia: a molecular, morphological, and acoustic assessment
This study presents a systematic revision of South Asian members of the taxonomically challenging genus Microhyla Tschudi, 1838. Species relationships and diagnostic characters are determined by integrating molecular, morphological, and acoustic approaches, through which we also recognize six groups of closely related species. In addition, a new species from the southern Western Ghats of India is formally described as Microhyla darreli sp. nov. Species accounts of all the 16 recognized members from South Asia include current taxonomic status, metric and meristic characters, divergence in mitochondrial DNA, phylogenetic relationships, acoustic characters, re- vised geographical distributions, and natural history notes. Molecular and morphological relationships of three poorly known members — M. chakrapanii, M. karunaratnei, and M. zeylanica M. berdmorei and another potential new species close to M. heymonsi in India corrected. For comparative purposes, molecular, morphological, and acoustic relationships are also discussed for eight closely related East and Southeast Asian species. Consequently, insights from this study will facilitate a much-needed comprehensive revision of the Pan-Asian frog genus Microhyla.
Diversification of shrub frogs (Rhacophoridae, Pseudophilautus) in Sri Lanka – Timing and geographic context
This paper is about the diversification of shrub frogs on the hills on the island of Sri Lanka - origins, patterns and rates. Hope this will help future research on this remarkable group
•Pseudophilautus diversification, begins during Oligocene (31 MYA)
•A stately pace of lineage accumulation despite orogeny and climate change.
•Assemblages in most regions comprise of species arising from diverse clades.
•MRCA of a back-migrating clade to India (8.8 MYA), reconstructs as a lowland form.
•Island’s mountains serve as species pumps and refuges for Pseudophilautus evolution.
Three new students joined our lab group this semester: Mr. Gajaba Ellepola, a lecturer from the University of Peradeniya, Sri Lanka, who is pursuing his Ph.D. work, Miss Sun Dan, a Ph.D. student from Ji Lin Province in China and Mr. Mao Ting Ru, a masters student from Nanning, China.
We review and clear the taxonomy of the members of the genus Labeo of Sri Lanka. We used an integrative taxonomic analysis using morphology, morphometry, DNA and ecology. We see that the three Labeos of Sri Lanka do not form a monophyletic clade. This is indicative of multiple dispersal events from India to Sri Lanka. We describe and rename the species that was previously recognized as Labeo dussumieri of Sri Lanka as a new species. The newly described species is Labeo heladiva - heladiva is an ancient name for Sri Lanka. At lease two of the three Labeo species of the island need immediate conservation intervention. The work was inspired and supported by Rohan Pethiyagoda and led by Hiranya Sudasinghe. Full Text is available on Research Gate.
About seven years ago, when we were beginning to take a closer look at the vocalizations of frogs, from within the dark forested streams of the highest peaks of the Knuckles mountains, we came across a booming call that we had never hear before. We thought that it was a new species. One of my friends also brought this species to the notice soon afterwards. So we got together and started documenting the distribution, morphology, genetic characteristics and the bone structures of the Lankanectes populations across Sri Lanka. In almost all aspects we considered, the population that we heard was different from the rest of the Lankanectes of the island. So we described it as a new species - Lankanectes pera. We named the frog after the University of Peradeniya, the premier research and teaching university in Sri Lanka, which was celebrating her 75th anniversary last year. The alumni of this great university refer to her affectionately as "Pera". The frog is highly specialized for life in clear, cold, forest covered streams of the mountains, and together with a very sparse distribution, the future of the frog is uncertain. Hence we highlighted this frog to be critically endangered. We hope that identifying this frog will help direct conservation attention to both the habitat of this frog and the frog itself. The authors of the paper are Gayani Senevirathne, Pradeep Samarawickrama, Nayana Wijayathilaka, Kelum Manamendra-Arachchi, D. Samarawickrama and myself. The work was done at Pera. By Madhava Meegaskumbura