Insights into genetic variation and demographic history of sharpnose rays: examinations of three species of Telatrygon (Elasmobranchii, Dasyatidae) from the Indo‐West Pacific

Abstract

Coastal and demersal chondrichthyans (sharks, rays, and skates) are expected to exhibit high levels of genetic differentiation in areas of complex geomorphology. Population genetic studies investigating the extent to which demographic history shapes the genetic structure of these fishes are rare. Here, we combined mitochondrial DNA (Cytb and ND2) and 8 nuclear microsatellite loci from 244 individuals to examine the population genetic structure and demographic history of the 3 Indo-West Pacific species of sharpnose rays (Telatrygon zugei, Telatrygon biasa, and Trygon crozieri). High levels of genetic variation both within and between species were identified. Phylogenetic analysis partitioned haplotypes into 2 lineages supporting divergence of T. zugei from T. crozieri and T. biasa during the Pleistocene. Furthermore, microsatellite-based clustering analyses identified 4 genetic groups (i.e. T. zugei from Japan, T. zugei from coastal China, T. biasa from Gulf of Thailand, and T. crozieri from the Andaman Sea). Measurements of genetic differentiation also support these 4 groups. Additionally, Pleistocene demographic expansions were examined in all genetic groups. The climate oscillations and current hydrologic cycles in the Indo-West Pacific appear to coincide with the hypothesis regarding speciation and the observed demographic history trends of the sharpnose rays. Considering the species group has, until recently, been thought to be one species, these results are critical for defining management units and guiding conservation efforts to preserve stingray biodiversity.

The Genetic Diversity of White-Backed Planthoppers (Sogatella furcifera) between Myanmar and Yunnan Province of China

“…Mitochondrial genes are extremely suitable for tracing the history of populations, estimation of migration, and gene flow [44,45]. Since the mitochondria of most insects are haploid and inherited maternally, the mitochondrial genome is transmitted clonally [46].…”

Amphibious mudskipper populations are genetically connected along coastlines, but differentiated across water

“…In some amphidromous species (those that are primarily freshwater occupants with a short marine larval dispersal phase), there may be no genetic structure within islands, but high levels of endemism resulting from restricted movement across areas of open water (Liao et al, 2021). Conversely, many completely marine organisms show biogeographical patterns associated with the marginal seas of the region (Liu et al, 2007; Qi et al, in press; Zhong et al, 2020), no detectable structure at all (Liu et al, 2006), or patterns based on regional currents (Gallagher et al, 2015). Many marine species with larger distributions show no population structure within small regions, but instead across large geographical areas, such as the North vs. South Pacific (Vaux et al, 2021).…”