Phylogeographic Analysis Suggests a Recent Population Bottleneck in the Rare Red Sea Tridacna squamosina

Abstract

Giant clams are an important ecological component of coral reefs in the Red Sea, as they enhance the reef’s productivity and provide habitat that can increase diversity. Three species of giant clams, namely Tridacna maxima, T. squamosa, and T. squamosina have been described within the Red Sea. However, due to its scarcity, information about the distribution and ecology of T. squamosina in the Saudi Arabian Red Sea is still lacking. This study used DNA barcoding to confirm the identity of the rare T. squamosina in the Farasan Banks. Six mtCOI fragments (500 bp) of T. squamosina were successfully amplified using the SQUA-primers for the first time. We used our data along with 18 reference sequences (16S) from the online database to assess the genetic diversity and population structure of T. squamosina. Low genetic diversity among the T. squamosina populations inferred from the 16S sequences implies a recent bottleneck for this species, which is supported by their historically higher diversity based on the coalescent-based estimator. Given the small population abundance and limited genetic variation of T. squamosina, it may warrant immediate local protections such as biobanking and fertility preservation programs as well as effective integrated coastal zone management plans.

Charting a course for genetic diversity in the UN Decade of Ocean Science

“…In the marine environment, anthropogenic impacts have affected genetic diversity in wild populations in numerous ways (Figure 1). Fishing pressures and the selection of certain phenotypes have led to fisheries‐induced evolutionary effects such as reduced body size and maturation at smaller body sizes, as well as reductions in genetic diversity through population declines and overharvesting (Heino et al, 2015; Lim et al, 2021; Pinsky & Palumbi, 2014; Price et al, 2019). Evidence of genetic bottlenecks and reductions in effective population size have been identified in Atlantic cod populations ( Gadus morhua ) from the North‐West Atlantic, in Pacific Salmon from British Columbia, as well as in populations of New Zealand snapper ( Pagrus auratus ) following overexploitation from industrial fishing practices (Hauser et al, 2002; Kess et al, 2019; Price et al, 2019).…”