Evidence of hybridization between starfish species

2023-09-11 16:44:09

Using genomic data, researchers have discovered that two species of North Atlantic starfish are interbreeding – MELINA GIAKOUMIS

MADRID, 11 Sep. (EUROPA PRESS) –

A genomic analysis has confirmed suspicions that two species of North Atlantic starfish hybridize and thrive from the coasts of New England to Canada.

A study, published in the journal Molecular Ecologypresents genomic evidence of hybridization between two closely related species of starfish: Asterias rubens, the common starfish, and Asterias forbesi, known as the Forbes starfish.

“It is the first evidence of extensive genome-wide hybridization in an ecologically important coastal species.“said corresponding author Melina Giakoumis, associate director of the Comparative Genomics Institute at the American Natural History Museum.

The biologists set out to find out whether starfish interbred in nature and, if so, what environmental factors influenced their appearance. The researchers took DNA samples from both species at 33 sites in the North Atlantic and then performed DNA sequencing that included samples of Asterias amurensis, the North Pacific starfish, used as a control group.

Through genomic data, scientists discovered that widespread hybridization had occurred between the two species of starfish from Cape Cod to Nova Scotia.

Sea stars were shown to have different environmental preferences: A. forbesi has a limited geographic range with adaptation to local environments, and A. rubens has a broader range extending to western Europe. These preferences are also evident in their genomesthe researchers said.

The study’s species distribution models accurately predicted the emergence of hybrid zones where these ranges overlapped (the Gulf of Maine was at the center of hybridization), suggesting that environmental selection played an important role in the preservation of hybrid zones. Furthermore, the results indicate that A. forbesi has a greater tolerance to warmer temperatures, while A. rubens prefers colder habitats and the hybrids are found in areas with tolerable temperatures for both species.

The study highlights the ecological importance of both starfish, considered “keystone species” with significant impacts on surrounding marine communities. When removed from their intertidal communities (the coastal areas between high and low tide), diversity among those entire ecosystems has been shown to collapsesaid Giakoumis.

“Two questions arise from this study,” said Michael Hickerson, a biology professor at the City College of New York and Giakoumis’s advisor. “Will the movement of hybrids accelerate to follow changes in sea surface temperatures to the point that one species replaces the other? Or will they rescue the two species by being a source of gene combinations that allow greater resilience to climate changes due to a greater capacity to adapt?”

“Since starfish preferentially eat dominant competitors, they provide stability to the ecosystem“explained the biologist. “Therefore, it is crucial to study these species for marine conservation, as they have knock-on effects on the rest of the community.”

Giakoumis points out that the Gulf of Maine is warming faster than 99% of the global ocean. “Our results imply that the distribution of genomic variation in North Atlantic sea stars is influenced by the environment, which will be crucial to take into account as the climate changes,” he adds.

Hybridization is thought to be common in nature, Giakoumis notes, and has been observed more frequently as genomic data expands. As the first study to provide evidence for genome-wide hybridization in these starfish species, the research supports the work of evolutionary biologists and other scientists studying intertidal ecology, the authors said, with possible implications for wildlife management and the protection of intertidal zones in the North Atlantic.