Climate change isn’t just killing off species — it’s changing them

U of T researchers find certain genetic variations are linked to environmental factors

Melting ice caps and nuclear proliferation have seen a surge in popularity within apocalyptic fiction — notably, the idea that anthropogenic climate change has given rise to outlandish beasts like the killer sharks of Sharknado or the invading ‘Kaiju’ of Pacific Rim.

While Earth is nowhere near that point yet, U of T researchers have taken a step back from the fantastical, weighing in instead on the link between climate change and genetic changes.

One notable study published in Science earlier this month examined the evolutionary responses of yellow warblers to climate change. Yellow warblers are migratory birds that inhabit a wide geographical distribution in North America and dwell in a variety of habitats. The birds were chosen for further study as declines in some populations indicated that they may have been subject to negative effects of climate change.

The study obtained data by collecting DNA samples from 229 birds from across the yellow warblers’ area of habitation. 100,000 single-nucleotide polymorphisms a distinction apparent in a single base pair of a DNA sequence were analyzed in relation to 25 environmental variables.

These variables included precipitation, temperature, or elevation. They found that certain polymorphisms were strongly associated with environmental factors, lending credence to postulations that populations of yellow warblers are dying out due to changing environmental conditions.

According to Dr. Arthur E. Weis, a professor of Ecology and Evolutionary Biology at U of T, yellow warblers are not the only species who exhibit evolutionary responses to climate change. He noted that anthropogenic changes to the environment have already spurred genetic changes in various species depending on the length of their life cycles.

“Species with very rapid life cycles will generally evolve faster,” said Weis. “Fruit flies, for instance, can go through many generations per year, and so are likely to have rapid evolutionary shifts.” In contrast, forest trees have longer life cycles and respond relatively more slowly to natural selection.

Other examples include mustard weed, which have survived recent California droughts by naturally selecting plants that flower quicker. Fruit fly populations at higher latitudes have also started to show genetic changes that reflect adaptations to warmer temperatures.

Regardless of the magnitude of the effects seen today, many agree that this is an important phenomenon to study.

“Conservation planners can make better decisions if they can take evolutionary potential into account,” said Weis. “Species likely to adapt quickly may need less attention that slow ones.”

According to the study and based on current changes in climate, the impact and strain of anthropogenic sources of global warming on biodiversity will only continue to intensify.

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