Two evolutionary units on the South American razor clam Ensis macha (Bivalvia: Pharidae): genetic and morphometric evidence

MÁRQUEZ, FEDERICO; TROVANT, BERENICE; VAN DER MOLEN, SILVINA; SEPÚLVEDA, ROGER D.; DOÑA, JORGE; JOHNSON, KEVIN P.; VIERNA, JOAQUÍN

ORGANISMS DIVERSITY & EVOLUTION

SPRINGER HEIDELBERG

Lugar: HEIDELBERG; Año: 2020

1439-6092

The patterns of genetic and phenotypic diversity in marine life are the result of different geological and ecological processes. Weanalyzed the pattern of genetic and morphometric variation of the razor clam Ensis macha along its entire geographic distribution.This species is one of the most important shellfish resources of South America. To uncover the genetic variation across this species,we used sequences of the COI mitochondrial gene and of 856 nuclear orthologs. To describe morphological variation in the shape ofthe shell, we used elliptic Fourier analysis followed by multivariate statistics. Two main genetic lineages were found, designated asNorthern and Southern clades. This genetic distinction is concordant with a biogeographic transition along the Pacific coast ofSouthern South America, which is also known for other taxa. Based on the genetic distance between the two lineages, each lineagecan be considered an incipient species. Morphological approaches revealed similar results, though therewas no strict concordancebetween the morphometric and the genetic results. Geological history and ecological processes could both be responsible for thevariation across the range of E. macha. In particular, fragmentation and isolation between populations may have favored geneticdiversification, while the environment may havemolded the variation shell shape. Lastly, our results have important implications forfisheries management, to preserve biological diversity of the world?s southernmost razor clam species.