Endemicity and radiation in waterfalls of the Western Ghats: The genus Cremnoconchus (Gastropoda: Littorinidae).

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Publisher: Elsevier B.V.
Document Type: Report
Length: 437 words

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Keywords Divergence; Endemic; Freshwater; Gastropod; Periwinkle; Waterfalls Highlights * We used two mitochondrial and one nuclear marker to construct phylogeny of the Genus Cremnoconchus, an endemic genus restricted to waterfalls of the Western Ghats. * The Genus Cremnoconchus, a marine relative in the freshwater is monophyletic and has nine described and 12 undescribed lineages. * There are two distinct clades (Central and Northern), corresponding to the two different regions of the Western Ghats. * Genus Cremnoconchus evolved from marine ancestors around 90.40 mya. * Results help in conservation of this charismatic species in the freshwater habitats which are under severe threat. Abstract Snails of the genus Cremnoconchus -- the only freshwater members of the gastropod family Littorinidae -- are endemic to the spray zones of numerous waterfalls in the Western Ghats of India. Cremnoconchus consists of nine described and possibly numerous undescribed species as many of these appear to be restricted to specific waterfalls. This is the first attempt at resolving the relationships between the various species in this genus and establishing its monophyly in the family. Further, we also undertake species delimitation analysis to characterize cryptic diversity in this group. Phylogenetic analyses based on nuclear and mitochondrial genes support the monophyly of Cremnoconchus within the family. A fossil-calibrated Bayesian time tree suggests that this freshwater lineage diverged from its marine counterparts around 90.40 million years ago. The separation of Cremnoconchus from its marine ancestors might have been facilitated by the break-up of Gondwana or fluctuating sea levels during this period. Species delimitation analysis retrieved 12 potentially undescribed species in this group. These species formed two distinct clades in the phylogeny, one largely confined to the northern Western Ghats and the other to the central Western Ghats. Species belonging to the northern and central Western Ghats seem to have separated around 56.11 mya, i.e. after the northern Western Ghats were formed. Additionally, spatial isolation due to the patchiness of suitable habitats (waterfalls) and low mobility might have facilitated their diversification. Author Affiliation: (a) SMS Foundation Centre for Biodiversity and Conservation, Ashoka Trust for Research in Ecology and the Environment (ATREE), Royal Enclave, Srirampura, Jakkur PO, Bangalore 560064, India (b) Institute of Paleobiology, Polska Akademia Nauk, Twarda 51/55, Warszawa 00-818, Poland (c) Centre for Ecological Sciences, Indian Institute of Sciences, Malleshwaram, Bangalore 560012, India (d) Yenepoya Research Centre, Yenepoya (Deemed to be University), University Road, Derlakatte, Mangalore 575018, India * Corresponding author. Article History: Received 8 August 2020; Revised 30 May 2022; Accepted 2 June 2022 (footnote)1 Authors contributed equally. Byline: Anwesha Saha (a,b,1), Sudeshna Chakraborty (a,1), G. Ravikanth (a), K. Praveen Karanth (c), N.A. Aravind [aravind@atree.org] (a,d,*)

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Gale Document Number: GALE|A708782311