How Organisms Adapt to Climate Change

by Zita Sárközi

Our planet’s climate is warming faster than ever before and exceeds known paleoclimate rates of climate change.¹ This rapid shift disrupts the delicate balance that allows plants and animals to thrive. As many as a million species are directly facing the risk of extinction caused by climate-driven environmental changes, with several other species being directly or indirectly affected. But there’s a twist: some organisms might be able to evolve and adapt to survive.² In this blog post, we’ll explore the fascinating world of climate change adaptation on the genomic level, changing organisms’ biology to survive a rapidly warming planet. However, it is important to recognize that while animals may adapt to a changing climate to some extent, their survival is not guaranteed. Therefore, it is crucial that we take responsibility for reducing our contributions to climate change to help safeguard their – and our – future.

Evolutionary Adaptation to Climate Change

Climate change is altering the planet very quickly, which provides an opportunity for scientists to study how it impacts a variety of species. This includes changes in evolutionary selection patterns, allowing species to adapt to climate change.³ While some species can move or adjust their behavior, a vital question emerges: can they evolve genetically in time to survive the altered climate? One area of research focuses on the potential of genetic adaptation as a buffer against climate change’s harshest effects. By inheriting traits that enhance survival in a new environment, populations can potentially avoid going extinct or having to drastically shift where they live. However, the picture is complex. A number of factors influence a species’ ability to adapt genetically, including existing variation, selection pressures, and other ecological processes. By understanding these complexities, we can better predict the fate of species in a changing world.^4,5

An important aspect of understanding genetic adaptation is to determine what traits are directly or indirectly influenced by climate change. Traits directly influenced may include how big the organism can grow, when it reproduces, and how it responds to changing.³ More indirect effects can include things like predator-prey interactions and parasitism³ or acidity and soil type causing a range shift.⁵

One of the most obvious consequences of climate change that affects humans is increasing temperatures. Studies have found that organisms can increase their thermal tolerance. For example, Daphnia magna (a little crustacean) showed increased heat tolerance in an experiment where temperatures were raised over two years. Similarly, Acropora hyacinthus (a species of coral) was able to adapt to increased temperatures and showed reduced levels of bleaching upon heat stress. The molecular mechanisms for this likely include biochemical adaptation of the organisms’ heat shock proteins – proteins that maintain cellular homeostasis and protect from stress – and decreased body size, which gives them a higher surface-to-volume ratio to allow for more efficient cooling.⁵

The ability of a species to adapt to climate change depends on factors such as genetic variation within populations, differences in genetic diversity across regions, and population size. High genetic variation provides more opportunities for beneficial traits to emerge, helping populations survive environmental changes. However, species with low genetic diversity, like certain Drosophila (fruit fly) species in rainforests, face evolutionary inertia. Evolutionary inertia means they struggle to adapt and are more vulnerable to extinction because they do not have many genetic variations to provide the “raw material” for natural selection to act upon. Populations with higher genetic diversity have higher chances of already possessing traits that could help the species survive in a changing environment. Individuals with those traits are more likely to survive and pass on the beneficial gene variations. Without enough variation, populations have fewer chances to evolve in response to climate change. Smaller organisms that have large populations are more likely to show genetic changes in response to climate change. This is because having more individuals and shorter lifespans allows for more genetic differences to appear over time, either by chance (genetic drift) or through new mutations.

However, organisms don’t always need genetic variation to get different results. (Think about how human identical twins always have some small differences even though their genes are the same.) When a single genotype (set of genes) produces more than one outcome (phenotype) in different environments, it is called phenotypic plasticity. Phenotypic plasticity is also an important aspect of species’ responses to climate change. To complicate the matter, phenotypic plasticity itself can also evolve in the context of adaptation to climate change. For example, climate change can alter temperature, pH, and CO₂ concentrations in the environments where organisms live, but those environments are often already inconsistent even without climate change added in. Thus, the evolution of plasticity may play an essential role to maximize organisms’ fitness in heterogenous environments, since the plasticity itself involves different versions of a given gene.⁶ For example, a study on Parus major (great tit birds) showed heritable variation in how individuals adjust their breeding times. This means that individuals inherited the ability to move their breeding time to whenever their caterpillar prey was abundantly available.⁵

Genetic adaptation is only one example of how animals can adapt to climate change. In my next blog post, I’ll approach this problem from a different angle: how animals adapt their migration patterns when the climate changes.

---

References

1. IPCC, 2021: Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change [Masson-Delmotte, V., et al. (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY. doi:10.1017/9781009157896
2. Fabbri, E., & Dinelli, E. (2014). Physiological Responses of Marine Animals Towards Adaptation to Climate Changes. In S. Goffredo & Z. Dubinsky (Eds.), The Mediterranean Sea (pp. 401–417). Springer Netherlands. doi: 10.1007/978-94-007-6704-1_23
3. Franks, S. J., & Hoffmann, A. A. (2012). Genetics of Climate Change Adaptation. Annual Review of Genetics, 46(1), 185–208. doi: 10.1146/annurev-genet-110711-155511
4. Edelsparre, A. H., Fitzpatrick, M. J., Saastamoinen, M., & Teplitsky, C. (2024). Evolutionary adaptation to climate change. Evolution Letters, 8(1), 1–7. doi: 10.1093/evlett/qrad070
5. Meester, L. D., Stoks, R., & Brans, K. I. (2018). Genetic adaptation as a biological buffer against climate change: Potential and limitations. Integrative Zoology, 13(4), 372–391. doi: 10.1111/1749-4877.12298
6. Kelly, M. (2019). Adaptation to climate change through genetic accommodation and assimilation of plastic phenotypes. Philosophical Transactions of the Royal Society B: Biological Sciences, 374(1768), 20180176. doi: 10.1098/rstb.2018.0176