Nadia Singh, University of Oregon – How Organisms Cope with Environment Change

Can environment play a role in the diversity of offspring?

Nadia Singh, associate professor of biology at the University of Oregon, looks to fruit flies to find out.

Research topics: Evolutionary genetics, population genetics, population genomics. Causes and consequences of recombination rate variation and mutation rate variation.

How Organisms Cope with Environment Change

That sexual reproduction is ubiquitous in nature is a massive evolutionary puzzle. Sex is hugely costly! There is the cost of producing males, there is the dilution of genetic material, and there’s the cost of finding a mate. How is that more than 99% of multicellular organisms reproduce sexually? Not only that, but many of these species have evolved incredibly elaborate ways in which to do so! Think about a peacock’s plumage, or the courtship dance of fruit flies.

Clearly, there must be benefits to sex that outweigh these costs. One benefit is recombination, which refers to the reciprocal exchange of genetic material between chromosomes. Recombination takes place during the specialized type of cell division that gives rise to gametes, which is a key component of sexual reproduction. As a consequence of this genetic exchange, each gamete that is produced is distinct from every other gamete, and it’s also genetically distinct from the organism that created it.

In my lab, we use fruit flies as a model system to study recombination. One interesting thing is that how many recombination events there are is actually sensitive to the environment. This was first documented in fruit flies over 100 years ago! We and others have shown that stressful conditions actually lead to organisms to produce more recombinant offspring than expected. More recombinant offspring means that your offspring are more genetically diverse. From an evolutionary perspective, this is really interesting because it seems like it could be a bet-hedging strategy. That is, under challenging conditions, organisms produce a genetically diverse pool of offspring, increasing the chances that at least some will survive. We’ve shown it in flies, others have shown it in other species including mosquitoes, plants, yeast, and mice. Given how pervasive it is across species, it’s certainly worth thinking about whether something similar could be operating in our own species.