With temperatures climbing, precipitation patterns changing, and the weather becoming less predictable and more intense, a 2016 study decided that climate change is already considerably interrupting organisms and ecosystems on land and in water. Animals are not only altering their range and altering the timing of crucial life span — they are also exhibiting differences in their gender boosters, tolerance to heat, and within their bodies. Some of these changes may enable a species to adapt, while others could speed its demise.
Move, Adapt or Die
Animals can respond to climate change in only three ways: They could move, adapt or perish.
Many creatures are moving to high elevations and latitudes to escape warming temperatures, but climate change may be occurring too fast for many species to outrun it. In any case, moving isn’t necessarily an easy solution–entering new land could signify limiting more competition for food, or even interacting with unfamiliar species. Some animals, such as the hamster-like American pika, are at the extent of their range. Pikas need the cool moist conditions of the alpine Sierra Nevadas and Western Rockies, but the rugged habitat they need is becoming hotter, drier, and less snowy. Since they already live so high in the mountains, there is nowhere left to go if their terrain becomes inhabitable. Other animals attempting to proceed to cooler climes may be hemmed in by highways or other manmade structures.
Additionally, some consequences of rising temperatures can not be outrun. Lately, the butterflies’ southern migration was delayed by up to six months because warmer than normal temperatures don’t cue them to fly south.
As temperatures warm, their migrations could fall out of sync with the bloom time of the nectar-producing crops that they rely on for food. Logging where they overwinter in Mexico along with the dwindling of the milkweed habitat, in which they breed and their larvae feed, due to drought, heat, and herbicides are added aspects in the monarch’s reduction. Its numbers have decreased by 95% in the previous two decades.
As temperatures rise in the Arctic and sea ice melts, polar bears will also be losing their food source; they’re often not able to find the sea ice they use to search seals out of and rest and breed on. Puffins in the Gulf of Maine normally consume white hake and herring, but as oceans warm, these fish are moving farther north. The puffins are attempting to feed their young on butterfish rather, but baby puffins are not able to swallow the bigger fish, so many are starving to death.
Many Species are Adapting
As spring arrives earlier, insects emerge sooner. Some migrating birds are laying their eggs before match insect availability so their young will have meals. Within the last 65 years, the date when female butterflies in southern Australia emerge from their cocoons has shifted 1.6 days earlier per decade since temperatures there have heated 0.14˚C a decade.
Coral reefs, which are actually colonies of human animals called polyps, have experienced extensive bleaching as the oceans warm–when overheated, they expel the vibrant symbiotic algae that live inside them. Scientists studying corals about American Samoa discovered that lots of corals in pools of water had not been breached.
When they exposed these corals to higher temperatures at the lab, they discovered that only 20 percent of these expelled their algae, whereas 55 percent of corals from saltwater pools additionally exposed to the heat expelled theirs. When corals from a cool pool were moved into a hot pool for a year, their warmth tolerance improved–just 32.5 percent currently reverted their algae. They adapted with no genetic change.
This coral study illustrates the distinction between evolution through natural selection within the course of several generations, and adaptation through phenotypic plasticity–the ability of an organism to change its developmental, behavioral, and physical features during its life in response to changes in the environment. (“Plasticity” here means flexible or malleable. It has nothing to do with the hydrocarbon-based products that are clogging our seas and ponds.) The corals living in the hot pools had evolved over many generations as natural selection favored the survival of their most heat-tolerant corals and allowed them to replicate. But the corals from the cool pool subjected to the warmer water were also able to accommodate because they’d phenotypic plasticity.