The current biodiversity crisis may be larger than previously thought. Researchers from Singapore have discovered the genetic diversity of a common fruit bat species has shrunk 30-fold over the last 90 years despite the species being widely regarded as unaffected by urbanisation.

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There are some realisations you come across during an education in Genetics, that never really get talked about publicly *or privately*. I’m sure many of you can think of touchy subjects in Genomics. But *this* particular issue is the tip of an Iceberg we don’t typically talk about *ever*, and there’s a lot under there if you take the plunge. Essentially, the argument is that you can mess up the genetic health of a species without that species going extinct – “silent genocide”. The number of total extinctions as a result of man is large and for the most part well understood. The rate of “technical genocide” however, is very difficult to measure (without cheap sequencing) and all peaks into what might be there suggest we fucked up really hard. You might have heard of the peppered moth (*Biston betularia*) that was once white and became black during the industrial revolution in the UK. That’s not true. Nothing changed colour. There was a freak family of peppered moths that were black, and would ultimately “survive” the industrial revolution by being camouflaged. The genetic diversity in a single family, even a large extended family, is not sufficient to ensure the survival of a species. I’ll say that again because it’s non-intuitive. If everyone on the planet died except your family, you will all die out due to inbreeding in 5 generations. (The only exception is if you are already highly inbred to begin with and selected to survive like that, like a European King or Queen, or a well controlled backcrossed mouse model strain). So while the public might think the moths changed colour as the black gene is passed around, reality is more like there was a moth genocide, and only the few lucky white moths that mated with a black moth before getting eaten contributed to the bulk of the genetic diversity seen in peppered moths today. Even though the moths are now back to being white, **things haven’t returned to normal.** When coal stopped being burned and the black moths went back to being easy food for the birds, there would have been another significant human selection on peppered moths. However, as the de-smogging of cities occurred across the UK gradually – far slower than the adoption of steam engines that turned everything black – more genomic fugitives from black moths could make it into their white descendants and on to now. The speed/size of the selective pressure is the key to the reduction in diversity it will result in. But the reason we don’t talk about genetics like this in public is because of WWI and WWII. The implications there are bad. But it’s just as true for humans as it is for all the other species on the planets: we are all under human selection now; whether the other humans realise it or not.


I think climate change has already had its fingers in this scenario already.


Maybe this has to do with higher natural selection in urban environments?


Is this not the logical result of natural selection, in any population? I mean, even Darwin’s finches were not genetically diverse within their local populations.