Specious Speciation in Sea Stars
According to a news release from UC Davis, sea stars have undergone “superfast evolution” as a new species has emerged in merely in the past 6,000 to 22,000 years. As we discussed in our series on “specious speciation” earlier this year, it’s not uncommon for claims of new “species” to entail what turns out to be trivial evolutionary change. That seems to be the case here, as the press release admits:
Grosberg and colleagues studied two closely related “cushion stars,” Cryptasterina pentagona and C. hystera, living on the Australian coast. The animals are identical in appearance but live in different regions: Hystera occurs on a few beaches and islands at the far southern end of the range of pentagona.
Apparently these “identical in appearance” sea stars differ in their modes of reproduction — though both modes are common in sea stars. Thus, a caption that goes with the story says:
The sea stars Cryptasterina hystera and C. pentagona are close relatives with very different ways of reproducing but difficult to tell apart. A new study shows the species separated just a few thousand years ago.
Given the prevalence of diverse modes of reproduction in sea stars, an ID perspective might suggest this group as a whole is pre-programmed with the capacity to reproduce in different ways, and that’s what the researchers have observed.
Image credit: Jon Puritz/University of Hawaii at Manoa.