Post

We are destroying species' habitats, leading to a mass extinction event. This habitat destruction also reduces the genetic diversity _within_ species. Our latest work develops quantitative models to predict how much genetic diversity has been and _will be_ lost. 🧬🧪🧵 www.pnas.org/doi/10.1073/...

We started with a simple question: What happens to genetic diversity when part of a species' habitat suddenly become uninhabitable?

To answer this, we developed WFmoments, a suite of numerical tools for computing things like π and Fst under arbitrary multi-deme Wright-Fisher models. We complemented this theory with more realistic continuous space SLiM simulations. github.com/moiexpositoalonsolab/wfmoments

What we found surprised us... Species can lose A LOT of habitat without having much effect on genetic diversity. In some scenarios a species can lose 80% of its habitat while retaining 90% of its genetic diversity. But this is just IN THE SHORT TERM.

It can take thousands of generations for the full effects of habitat loss to be felt in terms of genetic diversity. In the long run even small reductions in habitable area can result in large reductions in genetic diversity.

This is BAD. If we monitor the genetic diversity of a species, we might be convinced that it's doing okay, when in fact it may continue to lose genetic diversity for a long time even without losing any more of its habitat!

Everything up to now has assumed that habitat is lost along one edge of the species range (as a rough model for the effects of climate change). If instead we model the kinds of habitat fragmentation that result from land use changes, things get weird.

In these fragmentation scenarios, we actually see genetic diversity _increase_ in the long term. This is super weird! How can destroying habitat result in increased genetic diversity?

What is happening is that locally the species is actually becoming significantly _less_ genetically diverse, but the fragmentation disconnects parts of the species, which slowly diverge from each other. The species-wide diversity masks the plummeting local diversity. Again, this is BAD.

There's a lot more in the paper (along with some fun (at least for me!) population genetics math in the appendix), so please do check it out: www.pnas.org/doi/10.1073/...