Clam fishing along 1300 km Chilean coastline: A morphometric and genetic survey of Mulinia edulis King, 1832

Abstract

Mulinia edulis, also known as Taquilla clam, is a fishery resource, and one of the 6 species of clams commercially exploited in Chile. Valuable advances have been made for its culture, but there is still uncertainty regarding the species associated with the main commercial banks. The hypothesis was that, if the different harvested banks of M. edulis correspond to a single species along the Chilean coast, when comparing individuals from the north, central and south, they should not present significant morphological differences in their valves. The aim of this paper is to analyze and compare the morphology of M. edulis valves using geometric morphology and genetic comparison by sequencing the mitochondrial gene Cytochrome oxidase I and 16S RNA gene. Samples were obtained in three main fishery grounds, Tongoy Bay (northern), Arauco Gulf (central) and Ancud Bay (southern). In the inner side of the right valve 28 morphological landmarks were set, using TPS Util and R package geomorph, landmarks settings were overlaid through the generalized Procrustes analysis. Principal Components Analysis (PCA), using residuals were conducted among locations and sex. The results show no in-fluence of size or sex on shape of the valves. Through PCA analysis banks were differentiated by their shape. Abductor muscle and pallial sinus show the most relevant differences, especially when comparing northern and southern clams, where Arauco Gulf shows an intermediate morph. The three localities show low genetic diversity and little differentiation between them. This finding suggests that the fishery of taquilla clam is sustained only by M. edulis.