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Mitochondrial genetic divergence of Chiton articulatus (Polyplacophora: Chitonida) in the Mexican Tropical Pacific

Thelma A Aguilar-Rendon, Omar Hernando Avila-Poveda , Nancy C Saavedra-Sotelo

Abstract

Context: Chiton articulatus is a gonochoric, free-spawning mollusk with short-lived trochophore larvae inhabiting rocky shores along the fragmented and heterogeneous Mexican Tropical Pacific (MTP). Its limited dispersal in this patchy environment may lead to genetic divergence among populations. Aims: Our objective was to characterize the genetic diversity and population structure of C. articulatus based on mitochondrial DNA. Methods: We conducted a phylogeographic analysis using the Cytochrome c oxidase subunit I (COI) gene of mitochondrial DNA collected from 100 C. articulatus organisms located across its geographic distribution. Key Result: The findings revealed high levels of genetic diversity and a high number of private haplotypes. The structure analysis indicated six genetically distinct clusters with low connectivity. Divergence between the northern and southern populations was evident, with central mixing suggesting that gene flow adhered to the stepping-stone model. The historical demography indicated that the populations experienced sudden expansions during the late Pleistocene and early Holocene. Conclusions: The northernmost and southernmost C. articulatus populations exhibit significant genetic divergence, suggesting the presence of distinct stocks in the MTP. Nevertheless, we recommend prioritizing the conservation of central populations, as they serve as essential genetic reservoirs for all populations.

MF24172  Accepted 22 March 2025

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