Ants shed light on predicting post-hybridization evolution – ScienceDaily
Researchers at the University of Helsinki found that after multiple hybridization events between two forest ant species, separate hybrid populations evolved independently in the same direction, suggesting that hybridization is predictable.
Understanding the consequences of hybridization, i.e. the mating of two different species and the birth of hybrid offspring, is important because it is a widespread phenomenon in nature. By transferring genetic material between species, it can also help populations adapt to new challenging environments, such as global warming. One key aspect of hybridization is predictability, which is also an important research question: if we could repeat the same hybridization event many times, how often would we get similar results?
Populations develop both quickly and predictably thanks to natural selection
Researchers at the University of Helsinki used separate hybrid populations of wood ants identified in southern Finland to study the predictability of hybridization. They found that after multiple hybridization events between two forest ant species, separate hybrid populations evolved independently in the same direction. They are now very similar in terms of genetic makeup, suggesting that the outcome of hybridization is predictable. The researchers also found that the hybridization occurred less than 50 ant generations ago, about 125 years ago, making it a fairly rapid evolution in nature.
“Since hybridization is also common in many species other than ants, our results can help to understand its consequences more generally. In the long term, our work would help to better understand the effects of hybridization in nature and assess whether it could help species to survive changing environments, says associate professor Jonna Kulmuni from the Faculty of Biology and Environmental Science at the University of Helsinki , who has led ant research at this point for 15 years.
Small step or giant leap in knowledge?
“A little bit of both! Finnish wood ants allow us to observe multiple, very recent hybridization events, and the amount of predictability we found despite this recency is remarkably high, which is quite new. Meanwhile, our study also confirms previous results from a handful of species, including humans, which suggests that the patterns we see in wood ants are quite common,” says researcher Pierre Nouhaud from the University of Helsinki’s Faculty of Biology and Environmental Science.
DNA contains information about the evolutionary history of populations
For this study, the research team collected hybrid individuals from Finnish forests in southern Finland near the Tvärminne zoological station. DNA accumulates mutations as it is passed from parents to offspring, and as such contains information about the evolutionary history of populations. Getting to that history required researchers to reconstruct the first reference genome of red wood ants. The researchers then sequence and analyze the hybrid genomes on the supercomputers of the Science IT Center (CSC). Some analyzes were carried out in collaboration with researchers in Scotland and Portugal.
Reconstruction of past Evolutionary History using computer simulations
“On an evolutionary time scale, we are dealing with recent events, less than 50 ant generations, which had very little time to leave footprints in the DNA sequences. This means that it can be difficult to distinguish between competing hypotheses. In our study, we ran computer simulations We considered different evolutionary scenarios to take this uncertainty into account and to make sure our results are robust,” says Nouhaud.
Next, the ant research team will monitor the genetic makeup of the hybrid populations over several years to find evidence of adaptation and test whether hybrids can combine the temperature ranges of both species, which might help forest ants survive global warming. According to Nouhaud, this can be quite important, because forest ants are key species of boreal forests: they provide food for many species, promote nutrient cycling, hunt e.g. many other insects. Without them, Finnish forests would certainly look completely different!
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Materials provided by university of Helsinki. Note: Content may be edited for style and length.