Transgenerational effects can favor the natural selection of fitter individuals and, thus, facilitate evolution. There are risks, especially for humans.
Climate change may be accelerating the evolution of some species, especially those with short life cycles.
The conclusion is from research conducted by scientists at the University of Liverpool and Molecular Biology and Evolution. The study indicates that extreme heat does not only affect exposed organisms: it can also leave biological marks that pass on to subsequent generations.
The work analyzed fruit fly populations (Drosophila melanogaster) collected in regions with different climatic conditions: Spain and Finland. The results show that a single heat wave can alter the expression of 23 geneswith effects detectable up to the fourth generation.
These changes, according to , do not result from mutations in DNA, but from epigenetic mechanisms, that is, processes that quickly activate or deactivate genes in response to the environment.
The researchers concluded that flies from warmer areas, such as Manzanares, responded better to heat stress. Their descendants accelerated development, reaching maturity earlier and thus increasing their chances of survival in a context of extreme heat. Already the populations of Finland, less accustomed to high temperatures, showed a more disorganized and less effective adaptation.
The team led by Ewan Harney argues that these transgenerational effects can favor the natural selection of fitter individuals and, therefore, facilitate evolution. Instead of a slow process, evolution may be being pushed to faster rates by the pressure imposed by global warming.
Still, the authors warn of the risks. One artificial acceleration of evolution can increase differences between populations of the same speciesto the point of compromising reproductive compatibility between groups living in different environments. This could worsen biological fragmentation and threaten the stability of ecosystems.
The study also suggests that species with short lives are in a better position to keep up with the rapidity of climate change, as they reproduce faster and accumulate adaptations in less time. On the contrary, organisms with long life cycles, such as humans, will have less room to respond biologically to this pressure.
Understanding which species and populations are able to adapt, and which are left behind, will be decisive in guiding conservation strategies in the European Union and in other international contexts, at a time when the climate is transforming not only habitats, but also the mechanisms of evolution themselves.
