Today’s Boston Globe carried an interesting article about how climate change has caused and will continue to cause species to evolve as they adapt to new conditions. It seems that scientists have identified five species that have already evolved due to climate change: the pitcher plant mosquito; Canadian red squirrels; the European blackcap (a bird); the fruit fly; and the European great tits (yes that’s really its name, and it’s a bird).
At left is a photo of the purple pitcher plant, Sarracenia purpurea, home to the pitcher plant mosquito, Wyeomyia smithii. (Photo courtesy of Janet Novak and the Connecticut Botanical Society.) The mosquito lives exclusively in bogs where the purple pitcher plant grows. Purple pitcher plants can live up to 100 years, eating insects that drown in its pitcher-shaped, water-filled leaves. This particular mosquito has a symbiotic relationship with the pitcher plant, because it doesn’t die in the leaves and actually feeds on decaying insects that have drowned.
Researchers are trying to predict how species will adapt to a 3 – 7 degree climate change by the end of the century. They’ve found that in Maine, these mosquitos are entering hibernation 1 week earlier than they did 30 years ago, in response to the later arrival of New England winters.
Scientists say that the a species that have shorter life cycles are better equipped to quickly adapt to environmental changes:
The unobtrusive mosquito’s story illustrates a sobering consequence of climate change: The species best suited to adapting may not be the ones people want to survive. Scientists say species with short life cycles — Wyeomyia smithii lives about eight weeks — can evolve quickly and keep up with changing environmental conditions as a result. Rodents, insects, and birds, some carrying diseases deadly to humans, are genetically programmed to win. Polar bears and whales, which take years to reproduce, are not.
“Rapid climate change is actually now driving the evolution of animals — that is a dramatic event,” said Christina M. Holzapfel, who, with her husband, William E. Bradshaw, has documented genetic changes in hundreds of thousands of mosquitoes at their University of Oregon lab in Eugene.
This could lead to obvious consequences like the introduction of new animal- and insect-borne diseases.
“The world is going to be a very different-looking place,” said Loren Rieseberg, an evolutionary biologist at the University of British Columbia in Vancouver. He has done rough calculations suggesting that species that take longer than two years to reproduce will not be able to keep up with the current pace of climate change. Some of the laggards will probably become extinct, he said, while others will migrate to new places. “We are going to have very different sets of organisms living together,” he said.
How might climate change affect human evolution?
Most species, including humans, have a built-in flexibility — scientists call it phenotypic plasticity — that allows them to adjust to temporary environmental conditions. It is partly why we can withstand Boston’s frigid winters and steamy summers.
But when the changes are all in the same direction and continue for a long time — such as the warming taking place in New England — Charles Darwin’s natural selection can take over: Individuals with certain characteristics better suited to the changed environment survive in greater numbers than others in the population. Those individuals then pass on those favorable genetic characteristics to their offspring, eventually leading to evolutionary change in the entire population.
Scientists have only identified 5 species whose habits have adapted to climate change, but that’s not to say that other species haven’t adapted–they just haven’t been documented yet. They don’t know enough yet to make any specific predictions, even though they know that short-lived species tend to evolve more easily than long-lived ones:
Some long-lived species may be able to adjust without genetic changes; humans, for example, can move from flood-prone areas as sea levels rise. Some short-lived species may die because their environment changes too greatly for them to survive.
Darn! I was kind of hoping that climate change pooh-poohers might not make the cut. But unfortunately, most of them will move inland.
“The moral of the story is that things are going to be different,” said Kevin Emerson, a graduate student in the Bradshaw-Holzapfel lab. “Whether we know exactly what is going to be different . . . I don’t think we can say. But people have to accept that things are changing.”