Study analyzes how ecological specialization occurs in marine species

In contrast to terrestrial biota, aquatic species with planktonic larvae can sustain massive population sizes, and due to the lack of geographic barriers in the vastness of the oceans, they often exhibit high-level gene flow.

The closely linked aquatic ecosystems have fostered a plethora of biodiversity. As a result, aquatic species pose a threat to traditional theories of local speciation and adaptation, called the “marine speciation paradox.”

Lately, researchers led by Prof. Qiang Lin from the South China Sea Institute of Oceanology (SCSIO) of the Chinese Academy of Sciences reported how ecological specialization occurs in widely dispersed marine organisms using an integrated study of genetic, ecological, and morphological information.

Their results were recently published in Diversity and Distributions. The researchers studied the cranial morphology, ecological niche, and genetic structure of S. schlegeli along Chinese seashores to uncover phylogeographical trends.

Ecological niche characterization using hypervolumes revealed that the three clades (East China Sea clade, Yellow Sea clade, and South China Sea clade) diverged in recognized niches throughout their distribution range, and genetic findings confirmed three distinct clusters representing three geographical lineages.

At the last glacial maximum, habitat suitability estimates for this species revealed a strong geographical split between north and south populations, which may have resulted in a genetic separation between South China Sea (SCS) and East China Sea-Yellow Sea (ECS-YS) lineages.

Furthermore, identifying genes under natural selection is critical for determining the genetic basis of local adaptation influencing fitness trait development and population divergence, and several primary genes are involved in cold adaptation (csde1), growth (pax7), and eye development (eys, rx3).

This research would contribute to a deeper understanding of the differentiation of marine fish populations, as well as new insights into the studies of marine species dispersal, speciation, and distribution.