A new study has found genomic evidence of hybridization between two species of sea stars that live on the rocky coasts of Europe and North America. The species are Asterias rubens, known as the common sea star, and Asterias forbesi, also known as the Forbes sea star.
According to the analyzed genomic data, it has been proven that these species interbred in the cold waters of the North Atlantic, giving rise to hybrid starfish that live and thrive from the coasts of New England to the marine areas of Canada.
This study, which provides the first evidence of extensive genome-wide hybridization in an ecologically important coastal species, suggests that sea stars have distinct environmental preferences. The species A. forbesi has a limited geographical range and limited adaptation to local environments, while A. rubens occurs in Western Europe. These preferences are also reflected in their genomes.
The study’s species distribution models predict the emergence of hybrid zones where the ranges of both species overlap, suggesting that environmental selection has played an important role in maintaining these zones. Additionally, A. forbesi has been observed to have greater tolerance to warm temperatures, while A. rubens prefers colder habitats, and hybrids occur in areas with tolerable temperatures for both species.
These starfish are considered “keystone species” with significant impacts on surrounding marine communities. When they are removed from their intertidal communities, the impacts are devastating and the diversity of the ecosystems involved collapses. Therefore, it is crucial to study these species to protect the marine environment as they have knock-on effects on the rest of the community.
This research, funded by the National Science Foundation and published in the journal Molecular Ecology, raises new questions about how hybrid movement and climate change might affect the distribution of these starfish in the future.
