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Similar to Magpali et al (2020) Adaptive evolution of hearing genes in echolocating dolphins (1)
Similar to Magpali et al (2020) Adaptive evolution of hearing genes in echolocating dolphins (1) (20)
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Magpali et al (2020) Adaptive evolution of hearing genes in echolocating dolphins (1)
- 1. Adaptive evolution of hearing genes in echolocating dolphins Magpali, L.1 ; Freitas, L.1 ; Ramos, E. K. S.1 ; de Souza, E. M. S.1 ; Nery, M. F1 . 1. University of Campinas / Biology Institute, Brazil Correspondence email: leticiamagpali@gmail.com Twitter: @leticiamagpali I Meeting of Systematics, Biogeography and Evolution (SBE)
- 2. Introduction Cetaceans share a unique evolutionary history, marked by the transition from land to the ocean Followed by a rapid diversification through multiple habitats: polar waters, estuaries, coastal waters, rivers, deep ocean was essential to the evolution of echolocation and is mediated by the activity of hearing genes mostly inside inner and outer hair cells of the cochlea Inia geoffrensis, Amazon river dolphin Sotalia guianensis, Guiana dolphin. Estuaries and coastal waters Orcinus orca, Killer Whale. Such radical environmental changes likely posed strong constraints on their echolocation systems through the evolution of different acoustic patterns (Jensen et al. 2018) and cochlear morphologies (Costeur et al. 2019) in echolocating dolphins BACKGROUND GOAL Study the molecular evolution of hearing genes among dolphins from different habitats, looking for patterns of adaptive convergence and positive selection HYPOTHESIS Dolphins from riverine, oceanic and coastal habitats have evolved under different selective regimes on hearing genes HIGH FREQUENCY HEARING Cochlear hair cell
- 3. Material and methods Selected GENES CLDN141 (adhesion protein; ion flow) TMC11 (development) SLC26A52 (motor protein) CDH231,2 (adhesion protein; ion flow) SMPX1 (stereocilia movement regulation) Branch-model analyses performed on PAML → two model x one model Directly required for hair cell function and development Previously reported under: 1- positive selection in odontocetes (Davies et al. 2011, McGowen et al. 2014, Foote et al. 2015). 2- molecular convergence between dolphins and bats (Liu et al. 2010, Shen et al. 2012, Xu et al. 2013, Liu et al. 2014) 5 nucleotide gene trees 5 protein gene trees Sequence extraction with BLAST + python script Coding sequences only
- 4. Results Minkewhale Baiji dolphin Beluga NarwhalNarrow ridged finless porpoise Orca Pacific White-Sided Dolphin Long-finned pilot whale Guiana dolphin Tucuxi river dolphin Common bottlenose dolphin Sperm whale Echolocating dolphins TMC1 protein gene tree recovered possible bat-dolphin convergence, showing echolocating dolphins and bats as sister groups. Echolocating bats Branches under positive selection recovered by aBSREL (highlighted). Contrast-FEL sites with different overall dN/dS among river and marine dolphins in TMC1 (1) and CDH23 (36)aBSREL branches under positive selection: TMC1 and CDH23 alignments CDH23 species tree with branch under selection highlighted MEME sites under positive selection in dolphin branches: CDH23 (8), SLC26A5 (1), TMC1 (3) Whale No tree supported dolphin-dolphin convergence SUMMARY
- 5. Discussion and conclusion Preliminary selection analysis on codeml indicates altered selective regimes in at least one branch (among cetaceans and reference species) for all genes TMC1 and CDH23 possible targets to investigate adaptive convergence/differential selection between river and marine dolphins? Contrast-FEL results suggest that some sites within these genes have evolved differently between freshwater and marine dolphins BUSTED + aBSREL results indicate gene-wide episodic diversifying selection among dolphin branches Codeml: two model and branch-site models to locate branches and sites positively selected More accurate convergence tests will allow examine convergence within dolphins from different habitats Locate and characterize sites under selection dolphins showed proportionally less selected sites compared to reference species *reference tree= dolphins + whales + other species *dolphin tree = only dolphins Future directions SLC26A5, TMC1, CDH23 under positive selection in some, but not all, dolphin lineages S.guianensis has recently split from sister species and P. catodon has sonar adaptations to deep diving HOWEVER... no support for molecular adaptive convergence so far 1 2