Over the past few years, the need to act against climate change has become apparent. From the recent Australian bushfires to the burning of the Amazon rainforest, the impending devastation caused by climate change has emphasised the critical need for leaders to implement strategies in order to take action against the dangers of climate change.
Climate change is rapidly changing global temperatures and causing extreme fluctuations in precipitation. These changes have and are continuing to force organisms to adapt and evolve to avoid extinction. How organisms respond to changes in their environment is partly dependent on their genetics. For genetic adaptation to occur, populations need to have variation within their genes. In this blog, we will explore the role of genomics in studying climate change.
Climate change adaptation
In the current climate, the future persistence of species relies on their ability to adapt to changing conditions. According to a recent report, 5% of all species are at risk of extinction from 2°C global warming alone. Analysing genomic variation and the environment of a given species can provide insight and predict species’ responses to the rapid climatic shifts. Below we provide two examples of genomic analyses related to species’ adaptation to climate change.
Corals
Coral reefs support the most diverse marine ecosystems on the planet. Recent evidence has found that warmer ocean temperatures driven by climate change have caused Australia’s Great Barrier Reef to lose over half of its corals since 1995. The study noted that the potential recovery of older corals is uncertain due to the increasing frequency and intensity of disturbance events. Over the past two decades, coral bleaching has become more severe and frequent, with future predictions indicating this trend will continue. Loss of coral reefs destroys habitats of diverse marine species, making their loss one of the most pressing environmental issues of our time.
Nonetheless, not all corals are impacted equally. The genus Acropora is an important reef taxon globally. It has a high growth rate and contributes significantly to reef growth, island formation, coastal protection and also supports fisheries. In addition, the complex 3D structures of Acropora corals provide habitats for more than a million species of marine organisms. Unfortunately, Acropora species are highly susceptible to coral bleaching caused by increased seawater temperatures. Therefore, experts expect them to decline in the near future.
In a recent study, published in Molecular Biology and Evolution, researchers examined genomic novelties of all 15 Acropora species and three species of coral outside this genus to shed light on their evolutionary success. The team found that the Acropora ancestor diverged from other corals around 120 million years ago. Importantly, the diversification of Acropora corals occurred 25-60 million years ago. This finding is important as it suggests that Acropora diversified when the world’s oceans were much warmer than they are today. This indicates that their genetics may enable them to adapt to vast changes in temperature.
The team also found three notable genetic additions from before this coral genus diversified. Researchers have previously identified two of these, which associate with response to environmental stress, typically heat. However, the third gene which encodes DMSP lyase is the first reported finding of its existence in Acropora corals. This gene allows corals to produce dimethyl sulphide, which when transferred into the air aids in formation of clouds. This implies that when temperatures get too high, the corals are able to create small clouds which can protect them by providing shade and filtering out the light. Nonetheless, the authors warned that the speed of modern climate change may exceed the corals’ ability to adapt, particularly when faced with other stressors such as coastal pollution.
Yellow Warblers
Integrating genomic analyses is important to determine potentially ‘genetically vulnerable’ populations. While migratory birds are highly sensitive to climate change, little is known about how populations differ in adaptive capacity. Yellow warblers (Setophaga petechia) are migratory birds with a wide distribution across North America. They occupy a rich set of habitats from marshes and forests to urbanised areas. Recent decline of some populations has raised concerns that they may be negatively impacted by climate change.
A study a few years ago, published in Science, integrated population genomics and environmental data to examine the genomic basis of climate change adaptation in yellow warblers. Yellow warblers are broadly distributed. This makes them an ideal system for investigating variation in local climate adaptation. The team pieced together genomic regions that responded to climate-related changes and searched for traces of selection in those regions. From this, the team were able to determine which populations had the greatest mismatch with their environment. In other words, which populations were most genetically vulnerable.
They found that the more vulnerable populations resided along the Rocky Mountains, a region often affected by droughts. The authors noted that these findings coincided with population declines reported in the literature. This strong link suggests that genomic vulnerability may accurately forecast populations that may be at risk of declining. This could enable experts to implement appropriate conservation efforts within identified areas and populations.
Moving forward
Global climate change threatens biodiversity. A major problem is the fact that many species are challenged by the pace of climate change and therefore may not be able to respond fast enough to adapt. Populations that persist can tolerate these changes through phenotypic plasticity or genetic adaptation. Those that cannot will experience demographic collapses and may go extinct.
Currently, most models to predict species’ responses to climate change use ecological and evolutionary information. Genomic data is becoming increasingly important within healthcare and personalised medicine, and its value here is also apparent. Genomic data could help researchers understand species’ evolutionary potential and use this to improve prediction models. Today, several models incorporate genetic or evolutionary information. For example, genomic hybrid species distribution models use geographical covariation of SNP frequencies with environmental variation. This essentially subdivides species’ distribution into genetic clusters associated with climatic conditions. Nevertheless, the development of such accurate models requires extensive amounts of data, particularly genomic data. It is critical that both science and society work together to meet the urgent need of action in the face of accelerating global climate change.
“We are at a unique stage in our history. Never before have we had such an awareness of what we are doing to the planet, and never before have we had the power to do something about that.
Surely we all have a responsibility to care for our Blue Planet. The future of humanity and indeed, all life on earth, now depends on us.” – Sir David Attenborough, broadcaster and natural historian.
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