Population structure of the Pacific angel shark (Squatina californica) along the northwestern coast of Mexico based on the mitochondrial DNA control region

Abstract

Population structure has direct consequences on species evolution, local adaptation, and the capacity of a metapopulation to adapt to climate change. In this study we assess the genetic structure and demographic history of the Pacific angel shark, Squatina californica, along the northwestern coast of Mexico using the mitochondrial control region. Results showed high levels of genetic diversity and reveal genetic differentiation between the samples from the Pacific coast of the Baja California Peninsula and those from the Gulf of California. These genetic differences are consistent with ontogenetic differences previously reported for S. californica off the northwestern coast of Mexico. Our findings can be explained by the low dispersal ability and habitat preference of the angel shark and by the complex geomorphology off the northwestern coast of Mexico. Contrasting historical demographic patterns were observed: population expansion in the gulf and population stability, with a declining trend, in the Pacific; however, more studies are required to corroborate demographic patterns in both populations. Our results point to 2 distinct management units of the Pacific angel shark in the study area, and this may have direct implications for the management and conservation of this species in Mexico.