Climate change is becoming an increasingly critical concern, endangering the survival of various plant and animal species worldwide as temperatures continue to rise and ecosystems undergo transformations.
Certain species have managed to respond to this challenge through rapid evolutionary adaptation and other behavioral or physiological changes. For instance, dark-colored dragonflies are gradually becoming lighter in color to reduce their heat absorption from the sun. Mustard plants are adjusting their flowering times to align with earlier snowmelts. Lizards are developing increased cold tolerance to cope with the unpredictable fluctuations in our changing climate.
However, scientific studies indicate that the pace of climate change is far outstripping the ability of most species to adapt effectively.
What is Evolutionary Adaptation? In the realm of biology, “adaptation” holds a precise meaning. It refers to genetic alterations that are inherited across generations, enhancing a species’ capacity to thrive in its environment. These genetic modifications differentiate evolutionary adaptation from “acclimation” or “acclimatization,” which encompass advantages that are not inherited by offspring. For example, individuals relocating to high-altitude cities may temporarily produce more red blood cells to acclimate to lower oxygen levels.
Throughout the world, numerous plant and animal species have successfully adapted to diverse warm and arid environments, leading scientists to ponder whether these species might adapt to our rapidly changing climate. However, current evidence suggests that most species are struggling to achieve such adaptations.
Evolving: Fast and Slow Recent research focused on the populations of 19 bird and mammal species, including owls and deer, highlights a potential obstacle to adaptation. Species with lengthy maturation periods find themselves in a predicament – by the time their offspring are born, the climate has already shifted. Genes that conferred advantages to the parents, such as precise hatching times or optimal growth, may no longer benefit the offspring. While these slow-maturing animals are adapting to climate change, the rate of adaptation in each generation falls short of ensuring their survival, leading to an estimation that nearly 70% of the studied local populations are vulnerable to climate-driven extinction in the coming decades.
In contrast, small-bodied animals like many fish, insects, and plankton typically mature quickly. Nonetheless, recent research on these fast-maturing species, such as copepods and small fish, reveals another hurdle for rapid genetic adaptation to climate change. Many of these species possess genes enabling them to endure environments that are 1 to 2 degrees Celsius warmer than current conditions. However, if temperatures rise by 4 to 5 degrees Celsius, new genetic mutations become necessary for survival. To assess species’ resilience, scientists exposed these populations to gradual warming over multiple generations. They found that while these species adapted to the initial temperature increase, they eventually faced extinction as genetic mutations allowing them to thrive in hotter conditions occurred at a slower rate than temperature changes.
Cold-blooded species like lizards, frogs, and fish, which cannot regulate their body temperatures effectively, are especially vulnerable to climate change. Although they have the potential to evolve in response to changing conditions, rapid adaptation often leads to smaller populations due to the deaths of individuals that cannot tolerate higher temperatures. Even if these species evolve, they may still face extinction due to issues like inbreeding, harmful mutations, or disease epidemics. For instance, research in Mexico revealed that a high mortality rate among heat-sensitive lizards caused 12% of all lizard populations to go extinct between 1975 and 2009. Despite some heat-tolerant individuals surviving in each population, climate change was predicted to cause a 54% extinction rate by 2080.
Evolutionary Adaptation Isn’t the Sole Solution Species employ various strategies to cope with rising temperatures. One alternative is acclimation, often referred to as “phenotypic plasticity.” For instance, in the U.K., great tits – small birds commonly found in yards and forests – adjust their egg-laying times to hatch nestlings just as winter conditions abate, irrespective of the specific timing.
Nonetheless, a recent analysis of over 100 insect species worldwide, including beetles and grasshoppers, casts doubt on the effectiveness of acclimation. These species exhibited only a marginal increase in heat tolerance (0.1°C) on average when acclimating to a 1°C rise in air temperatures during their development. This suggests that the rate of global warming surpasses species’ capacity for acclimation.
Plants and animals also have the option to escape the consequences of global warming by migrating to cooler habitats. Global analysis of more than 12,000 plant and animal species has indicated that many are moving towards higher latitudes and elevations to keep pace with rising temperatures. However, migration is not always a viable solution, as some species face geographical limitations. For instance, tropical birds residing at high mountain altitudes have no room for further upward migration. Consequently, tropical species may be on an “escalator to extinction.”
High-latitude and high-elevation habitats present additional challenges for species, including oxygen scarcity, further complicating migration strategies.
Conclusion While evolutionary adaptation may alleviate some of the impacts of global warming, existing evidence suggests that it may not be sufficient to counter the current rates of climate change. Acclimation and migration provide more immediate solutions, but research indicates that these strategies may also fall short. Although some species are gradually adapting to different environments, including those shaped by human activities such as urbanization, the accelerated pace of global warming places them under immediate threat. Protecting these species will require humanity to curtail activities contributing to climate change.
[Note: This article is republished from The Conversation, a nonprofit, independent news organization that provides factual and reliable analysis to help navigate our complex world.]