Comparative population structure of two dominant species, Shinkaia crosnieri (Munidopsidae: Shinkaia) and Bathymodiolus platifrons (Mytilidae: Bathymodiolus), inhabiting both deep‐sea vent and cold seep inferred from mitochondrial multi‐genes

Abstract

Deep‐sea hydrothermal vents and cold seeps, limited environments without sunlight, are two types of extreme habitat for marine organisms. The differences between vents and cold seeps may facilitate genetic isolation and produce population heterogeneity. However, information on such chemosynthetic fauna taxa is rare, especially regarding the population diversity of species inhabiting both vents and cold seeps. In this study, three mitochondrial DNA fragments (the cytochrome c oxidase submit I (COI), cytochrome b gene (Cytb), and 16S) were concatenated as a mitochondrial concatenated dataset (MCD) to examine the genetic diversity, population structure, and demographic history of Shinkaia crosnieri and Bathymodiolus platifrons. The genetic diversity differences between vent and seep populations were statistically significant for S. crosnieri but not for B. platifrons. S. crosnieri showed less gene flow and higher levels of genetic differentiation between the vent and seep populations than B. platifrons. In addition, the results suggest that all the B. platifrons populations, but only the S. crosnieri vent populations, passed through a recent expansion or bottleneck. Therefore, different population distribution patterns for the two dominant species were detected; a pattern of population differentiation for S. crosnieri and a homogeneity pattern for B. platifrons. These different population distribution patterns were related to both extrinsic restrictive factors and intrinsic factors. Based on the fact that the two species were collected in almost identical or adjacent sampling sites, we speculated that the primary factors underlying the differences in the population distribution patterns were intrinsic. The historical demographics, dispersal ability, and the tolerance level of environmental heterogeneity are most likely responsible for the different distribution patterns.

Population genetic structure of the deep‐sea mussel Bathymodiolus platifrons (Bivalvia: Mytilidae) in the Northwest Pacific

“…Meanwhile, the haplotype network constructed based on each mitochondrial gene also revealed no obvious genetic structure. These results were consistent with previous studies based on mitochondrial markers, indicating a high dispersal capability and a lack of population differentiation of B. platifrons in the Northwest Pacific (Kyuno et al., ; Miyazaki et al., ; Shen et al., ).…”

“…Meanwhile, the haplotype network constructed based on each mitochondrial gene also revealed no obvious genetic structure. These results were consistent with previous studies based on mitochondrial markers, indicating a high dispersal capability and a lack of population differentiation of B. platifrons in the Northwest Pacific (Kyuno et al, 2009;Miyazaki et al, 2013;Shen et al, 2016). The discrepancy between results obtained from analyzing mitochondrial genes and SNPs was considered to be due to the different number and types of genetic markers used, resulting in different resolution.…”

“…Previous studies based on one or several mitochondrial genes revealed a lack of genetic differentiation among vent and seep populations of B. platifrons (Kyuno et al, 2009;Miyazaki et al, 2013;Shen et al, 2016). Nevertheless, our recent study based on 9,307 genomewide single nucleotide polymorphisms (SNPs) generated by the type IIB restriction site-associated DNA (2b-RAD) approach detected a clear genetic divergence between individuals of B. platifrons from a vent field in the Okinawa Trough (OT) and a methane seep in the South China Sea (SCS) .…”

Exploring the Ecology of Deep-Sea Hydrothermal Vents in a Metacommunity Framework

“…For example, Calyptogena clams and Shinkaia squat lobsters show significant genetic structuring between methane seep and hydrothermal vent field populations, whereas no structuring has been observed in Lamellibrachia tubeworm and Bathymodiolus mussel populations (Watanabe et al, 2010;Shen et al, 2016;Yang et al, 2016). Recent genome-wide analyses of B. platifrons revealed differentiation between methane seep populations the in South China Sea and hydrothermal vent populations in the Okinawa Trough (Xu et al, 2017).…”

Taxonomic research on deep‐sea macrofauna in the South China Sea using the Chinese deep‐sea submersible Jiaolong

“…Because the 2 species were collected in almost identical or adjacent sampling sites, we speculated that the primary factors underlying the differences in the population distribution patterns were intrinsic. The historical demographics, dispersal ability, and tolerance level to environmental heterogeneity are most likely responsible for the different distribution patterns (Shen et al 2016).…”