One of Humanity’s most important problems at the moment is global warming; this is said to be mainly caused by the increase in carbon dioxide in the Earth’s atmosphere resulting from the burning of fossil fuels. Given how serious the consequences of global warming can be, its possible effects and the responses from human beings are being extensively analyzed.
Genetic studies are being used to analyze these effects, and maybe even predict them and find solutions and mitigating measures. Specifically, it is interesting to wonder whether the effects of climate change have reached deep into the organisms, i.e. their genes.
Genetics against extinction
Extinction rates are currently increasing in speed. However, this phenomenon is not only due to climate change; there are factors such as elimination, reduction and/or change of habitats, overfishing, etc.
New genetic techniques can be very useful. They can be used to attempt to “revive or resuscitate” extinct or endangered species (cloning from well-preserved biological material, e.g. mammoths), and to analyze the critical survival factor of genetic variability within a species.
For instance, it was possible to determine that out of the more than 64,000 vertebrate species studied by UICN in 2012, more than 10% are endangered due to the aforementioned factors. Also, most of this group shows a major reduction in its genetic variability. We need to implement measures to stop this genetic decline. To this end, it may be useful to apply different tools of conservation genetics: in vitro reproduction of endangered species, freezing of embryos and eggs, adding a breeding member to dwindling populations, DNA databases, etc.
Learning from other migrations
Fortunately, in addition to genetic intervention, living beings offer options for resisting climate change without risk of extinction. Here we have three types of responses.
First, migration from areas with increasing temperature levels to colder areas in terms of latitude or altitude. When we analyze several genetic markers (DNA segments with an identifiable physical location), we can see which colonization movements took place after the last glacial period (12,500 years ago), such as in the case of many sea and land organisms.
It has also been possible to track the migrations after the Little Ice Age, (Middle Ages to mid-1800s). This was the case, for instance, of foxes on the islands in Northern Europe. And more recently, genetic studies of the skin of cod fished during the 19th century have helped to analyze the migration processes in the Greenland sea.
These studies generate ideas that can be applied to the preservation and recovery of species that migrate due to global warming.
Climate change: acclimatization, yes; adaption, maybe
Organisms respond in two other ways to global warming: acclimatization and adaption.
The techniques of the “omics” derived from genetics (genomics, transcriptomics, proteomics, etc.) are starting to divide phenotypic changes (morphology, physiology, behavior, etc.) derived from climate change into acclimatization (differences only in the number of certain RNAs and/or proteins) and adaptation (there are also DNA differences, and new types of RNAs and proteins may appear). At the moment, most research shows that possible changes in organisms due to climate changes represent acclimatization; there is little evidence of true adaptation.
Based on these provisional findings, some authors defend that there is not enough genetic information to support the existence of clear and sustained global warming over time. In other words, they argue that global warming is still not a strong enough factor to be able to select certain genetic variations and produce real adaptation. Until now, climate change would have determined how certain genes work, i.e. species acclimatization to the new climate.
Nevertheless and in opposition to the idea that acclimatization is a short-term response that cannot be inherited, there is the possibility that some types of acclimatization (those derived from epigenetic changes in DNA such as methylation) can be inherited and “used” to resist climate change, at least for several generations. Meanwhile, will real adaptation “arrive”?
More on DNA and global warming
We should not forget the specific effect of climate change on human health and illnesses. In addition to the its direct effects on human beings (such as breathing and allergic disorders), global warming can influence the dissemination of vectors of epidemic diseases such as the flu, plague or malaria. For example, birds, rodents or mosquitos. Genetics warns that in the case of the flu, for instance, some outbreaks (such as the “Spanish flu” in the early 19th century) may be related to a decrease in population size and genetic variability of the virus vector(s) such as ducks, geese and other wild birds.
Furthermore, genetic studies may contribute to two other major aspects of climate change. Firstly, with regard to clarifying the response of many bacteria and microorganisms to climate change. For example, picoplankton: its metabolism was unknown until now, since the cultivation of picoplankton was not possible. Now, the “omics” make it possible to characterize its metabolism and its potential role in the response to climate change without requiring cultivation.
Finally, genetically modified organisms (mostly bacteria and vegetables) can be used to fight against the effects of climate change such as drought or increased carbon dioxide in the Earth’s atmosphere, and even to recover deteriorated or altered ecosystems.
Manuel Ruiz Rejón
Granada University, Autónoma de Madrid University.