Researchers verified a large gene flow of this species, despite the distance, current and biogeographical breaks in its distribution.
The so-called rock crab (Metacarcinus edwardsii) is most captured crab species by the fishing industry in Chile. With a convex shell, serrated edges and a reddish purple color, it is considered of vital importance for artisanal fishing in the central area of our country.
Research on its taxonomy in 1957 defined its distribution from Ecuador to the Strait of Magellan. However, specimens were only found in Chile from the Valparaíso Region to the south. This led a group of scientists to carry out a massive sequencing of the rock crab through DNA samples, collecting individuals in the areas of Valparaíso, Dichato, Tomé, Tumbes, Valdivia, Ancud, Quellón and Aysén, between 2013-2014 and 2020-2021.
The research, published in Scientific Reports, and led by Dr. David Véliz, from the Department of Ecological Sciences of the Faculty of Sciences of the University of Chile and the Center for Ecology and Sustainable Management (ESMOI) confirmed that, despite the distance of more than 1,700 kilometers and the geographical differences that exist along the Chilean coast, there is great genetic diversity, which is favorable for the species.
“We confirm that there is a clear pattern of high gene flow between the crab populations, which are genetically stabilized at a temporal level throughout the distribution studied, since when examining the DNA of samples taken in both periods, no major differences between them were detected,” explained Dr. Véliz.
The hypothesis was that due to a biogeographic break in latitude 42°S (parallel to the island of Chiloé) and the duration of the larval stage of the crabs, the species could be affected by this break, but this was not the case. “If there is gene flow, this will maintain populations that are separated by great distances as a species,” he explained.
The investigation also determined that there is a large open population of this resource, even with the presence of environmental variations such as the Humboldt Current, which runs from south to north.
Dr. Luis Miguel Pardo, director of the Graduate School of the Faculty of Sciences of the Austral University of Chile (UACh) and researcher at the Center for Dynamic Research of High Latitude Marine Ecosystems (IDEAL) and co-author of the study, highlighted the importance of local coastal circulation in the dispersal of rock crab larvae. “The conservation of these resources could occur with the protection of marine areas at multiple points of their biogeographic range, since the larvae released at these points will not have a defined direction in larval transport,” he added.
The researchers emphasize that this study will make it possible to advance in the fishing management of M. edwardsii, given that artisanal fishing depends in part on this species in the south-central zone of Chile.
Read the study here.