Molecular evolution and convergence of the rhodopsin gene in Gymnogobius, a goby group having diverged into coastal to freshwater habitats

Abstract

The visual system in animals serves a key role in adaptation to a new environment, sexual selection and speciation due to its deep links to fitness through food search, predation avoidance and mate recognition. Therefore, evolutionary patterns of change in the visual system is a crucial topic for understanding evolutionary responses to natural and sexual selection (Seehausen et al., 2008). Opsin genes are often focused on as vision-related genes in studies of adaptive evolution (Lin et al., 2017). Structural changes in the proteins encoded by opsin genes are directly related to changes in visual function (Bowmaker, 2008); hence, opsin genes enable examination of the relationship between amino acid (AA) substitutions and visual adaptation. Furthermore, phylogenetic patterns of structural and functional changes in opsin genes can provide deep insights into evolutionary relationships between ecological changes and the visual system-especially in groups that have undergone adaptive radiation. Such phylogenetic patterns can be influenced by new

The complete mitochondrial genome of a Biwa goby, Gymnogobius isaza (Tanaka, 1916)

“…Furthermore, in the phylogenetic analyses based on 3,209 bp sequences combining mitochondrial Cytb and three nuclear markers not used in previous studies, both of the above tree topologies were yielded depending on the differences in the ML and BI analytical methods (Ito et al. 2021 ). The inconsistency in the phylogenetic relationships among these Gymnogobius species may be due to interspecific hybridization or incomplete lineage sorting as suggested for other Japanese gobiid species (Yamasaki et al.…”

“… 2019 ), but the genetic information for G. isaza is limited to partial sequences of several mitochondrial and nuclear markers (Tabata and Watanabe 2013 ; Ito et al. 2021 ), and there are no available primer sets specifically designated for this species. In this study, we sequenced the whole mitochondrial DNA of G. isaza with the aim of designing specific primers for future eDNA surveys.…”

Does larval ability to modulate body buoyancy explain successful colonization of freshwater environments by diadromous gobies?

“…This study targeted three amphidromous Gymnogobius species, G. petschiliensis, G. opperiens, and G. urotaenia, which are distributed across the Japanese Archipelago, Korean Peninsula, and Yellow Sea coast (Stevenson, 2002;Ishino, 2005;Ito et al, 2022). All three species usually spawn in freshwater stream areas, migrate downstream to the sea immediately after birth, drift along the coast for 2-3 months during the larval stage, and return to streams when juveniles, forming large schools (Dotu, 1955;Harada, 2002).…”

“…The genus Gymnogobius (Gobiidae), a marine-originated goby group, includes diadromous species both with and without FWR populations, in addition to marine, brackish water, and strictly freshwater species (Stevenson, 2002). A clade in Gymnogobius includes three amphidromous (G. petschiliensis, G. opperiens, and G. urotaenia) and one strictly freshwater species (G. isaza) (Aizawa et al, 1994;Harada et al, 2002;Ito et al, 2022).…”

A key evolution in gene expression plasticity for freshwater colonisation in early life stage of fish

“…Among teleosts, the goby family Gobiidae includes more than a hundred amphidromous species (Augspurger et al, 2017;Delgado and Ruzzante, 2020). The marine-originated goby genus Gymnogobius , distributed in East Asia, includes at least three amphidromous, five freshwater species and eight marine and estuarine species (Ellingson et al, 2014;Chiba et al, 2020;Ito et al, 2022). The diversity in the life history and habitats makes this an attractive group to study the processes of freshwater colonisation (Fig.…”