International Journal of Marine Science, 2025, Vol.15, No.1, 1-14 http://www.aquapublisher.com/index.php/ijms 4 constructed a phylogenetic tree using the maximum likelihood method. The results support that Abalone species can be divided into several major branches (clades) (Nam et al., 2017; Botwright et al., 2019; Guo et al., 2019). For example, the analysis showed that H. discus and H. discus were clustered first, and the two formed the North Pacific abalone branch; while the Australian green abalone (H. laevigata) and the South African abalone (H. midae) formed the Southern Hemisphere abalone branch. The American species such as red abalone (H. rufescens), black abalone (H. cracherodii) and pink abalone and white abalone form the American abalone branch, which is distantly related to the Asian-Oceanian abalone. The whole genome phylogenetic tree is generally consistent with the traditional classification results based on mitochondrial DNA, but some details have been revised. For example, this study supports the view that the disc abalone group along the coast of Japan is a geographical population of the wrinkled disc abalone, rather than an independent species. For another example, the nine-hole abalone (H. diversicolor) and its subspecies form an independent small branch, suggesting that its relationship with the wrinkled disc abalone is more distant than previously thought. This suggests that the nine-hole abalone may be classified as a different subgenera within the genus. It is worth mentioning that the support rate of each major branch in the phylogenetic tree of this study is very high, thanks to the reliable signals provided by the massive sites of the whole genome. In contrast, previous trees based on single genes or mitochondrial genomes may have insufficient support for some nodes due to systematic uncertainty. The camel-eared abalone (H. asinina) was clearly placed at the base of the abalone phylogenetic tree and separated from other temperate abalone branches early. This is consistent with the geographical distribution, that is, tropical abalone may represent an ancient evolutionary lineage of the genus Abalone (Barkan et al., 2024). Phylogenetic reconstruction based on whole genome data provides a clearer picture of the species relationship of the genus Abalone and provides a new basis for taxonomy and evolutionary biology research. Figure 1 (a) Orthologous gene-based phylogenetic relationship in select abalone species, showing the close-relatedness among H. midae, H. rubra and H. laevigata and bootstrap values based on 100 pseudo-replicates given at the branching node. (b) Phylogeographic distribution of abalone species, based on whole genome SNP phylogenomic relationships (bootstrap values calculated on 100 pseudo-replicates given at the branching node), in relation to their optimum mean temperatures. The genome-wide SNP phylogeny places the South African abalone close to other southern abalones. Species occurrence information are from the Global Biodiversity Information Facility (GBIF) and optimal temperature values were retrieved from SeaLifeBase (https://www.sealifebase.se). (c) Positively selected genes (PSGs) identified with genes involved in immune defence, sensory response, and reproduction in selected abalone species) (Adopted from Tshilate et al., 2023)
RkJQdWJsaXNoZXIy MjQ4ODYzNA==