Evidence of positive selection in the COI mitochondrial gene in the blue crab Callinectes sapidus (Decapoda: Portunidae)

The Blue Crab (Callinectes sapidus Rathbun, 1896) is a decapod crustacean native to the Western Atlantic coast that has become a highly invasive presence in Mediterranean waters since the 1950s. This species incarnates multiple characteristics that render it a successful invader: large size, high reproductive output, a generalist diet, euryhalinity, and eurythermal physiology. This study aims to investigate the evolutionary implications of the colonization of Mediterranean ecosystems by looking at the evolution of the mitochondrial gene COI in invasive C. sapidus. After assessing phylogenetic relationships of native and invasive populations, signs of selection analyses were carried out, revealing a multitude of sites under positive selection in invasive populations. Our results might point toward an ongoing trend of adaptive evolution triggered by the selective pressure that a new environment exerts upon this invasive species in Mediterranean ecosystems.