Animals and plants may not be able to keep pace with climate change by evolving, a UC Davis study suggests.
Multi-generational studies of higher organisms would have been, well, a bit too long-term, so the scientists worked with a tide pool copepod called Tigriopus californicus.
But, while it’s found from Alaska to Baja California, it showed little ability to evolve heat tolerance.
the team grew the short-lived creatures in the lab for 10 generations, subjecting them to increased heat stress in order to select for more heat-tolerant animals.
At the start, because of the copepods’ wide geographic range, they showed a great deal of variability in heat tolerance.
But within those populations, the team was able to coax only about a degree Fahrenheit of increased heat tolerance over 10 generations. In most groups, they say, the increase in heat tolerance hit a plateau before that point.
Although the copepods are widespread geographically, individual populations are very isolated, confined to a single rocky outcrop where wave splash can carry them between pools. That means there’s very little flow of new genes across the population as a whole.
“It’s been assumed that widespread species have a lot of genetic capacity to work with, but this study shows that may not be so,” says co-author Rick Grosberg, professor of evolution and ecology at UC Davis.
“The critical point is that many organisms are already at their environmental limits, and natural selection won’t necessarily rescue them.”
