Researchers Uncover Proof of Hybridization Among Sea Star Species

Researchers have recently uncovered compelling genomic data revealing the crossbreeding of two North Atlantic sea star species, commonly known as starfish. For years, scientists had suspected that these species, found along the rocky coastlines of Europe and North America, were interbreeding in the chilly waters of the North Atlantic Ocean. Now, an analysis of this genetic information confirms the existence of thriving hybrid starfish populations stretching from New England to the Canadian Maritimes.

Published in the journal Molecular Ecology, a study provides genome-wide evidence of hybridization between two closely related sea star species: Asterias rubens, the common starfish, and Asterias forbesi, known as Forbes’ sea star. Melina Giakoumis, a Ph.D. candidate in the Graduate Center’s Biology program and associate director of the Institute for Comparative Genomics at the American Museum of Natural History, who is the corresponding author, described it as the “first genome-wide evidence of extensive hybridization in an ecologically important coastal species.”

The research aimed to determine whether these sea stars were indeed interbreeding in their natural habitats and to identify the environmental factors influencing this phenomenon. DNA samples were collected from both species at 33 locations in the North Atlantic, and comprehensive DNA sequencing was conducted, including samples from Asterias amurensis, the Northern Pacific sea star, which served as a control group.

Through the genomic data analysis, scientists confirmed that widespread hybridization had taken place between the two sea star species, spanning from Cape Cod to Nova Scotia. These sea stars were found to have distinct environmental preferences: A. forbesi was adapted to local environments within a limited geographic range, while A. rubens had a broader distribution extending to western Europe. These preferences were reflected in their genomes.

Species distribution models accurately predicted hybrid zones where the ranges of these sea stars overlapped, with the Gulf of Maine at the epicenter of hybridization. This suggested that environmental selection played a significant role in maintaining these hybrid zones. Furthermore, the results indicated that A. forbesi exhibited greater tolerance for warmer temperatures, whereas A. rubens preferred colder habitats, and hybrids were found in areas with temperatures suitable for both species.

The study underscores the ecological importance of these sea stars, recognized as “keystone species” with substantial impacts on the marine communities surrounding them. Removal of these sea stars from intertidal communities has been shown to lead to a collapse in diversity within these ecosystems.

The research raises two critical questions: Will the hybrid sea stars migrate in response to changes in sea surface temperatures to the extent that one species replaces the other? Or will they enhance the resilience of both species by providing a source of genetic diversity that allows them to better adapt to climate-related changes?

Sea stars play a stabilizing role in ecosystems because they primarily consume dominant competitors. Therefore, understanding these species is crucial for marine conservation efforts, as their presence has far-reaching effects on the broader community.

Notably, the Gulf of Maine is warming at a rate faster than 99% of the global ocean, underscoring the importance of considering environmental influences on the distribution of genomic variation in North Atlantic sea stars as the climate continues to change.

Hybridization is a common phenomenon in nature and has become more apparent as genomic data expands. This study, as the first to provide genome-wide evidence of hybridization in these sea star species, supports the work of evolutionary biologists and other scientists studying intertidal ecology. It also has potential implications for wildlife management and the protection of intertidal zones in the North Atlantic.

– “Scientists find evidence of sea star species hybridization” (2023, September 11). Retrieved from

Source: Graduate Center, CUNY

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