Growing up you believe the world is meant to be the way it is. The older I get the more I realise that this is not the case. The world is full of injustices and atrocities that governments and the voice of faith expect us to accept, though with each passing year they grow fewer and fewer, at least one would hope. I have created this blog as a space for me to rant about all things science, politics, philosophy and religion, before it’s too late and the vessel of new atheism propelled by a growing surge in secularism solves all of the world’s problems for good.

Sunday, 17 July 2011

Genetic diversity losing out to overfishing

Here's an interesting article about a study by Stanford University that looked at the genetic diversity of fish species. It essentially found, with no big surprise, that those species that we currently overfish have had a big decrease in the species' overall genetic diversity (~18%), compared with lightly fished species.

I'm surprised it took us this long to get out there and examine this effect as it seems to be a no brainer. If you kill or remove a substantial portion of a population of individuals it will result in a loss in genetic diversity. At worst, it can lead to a bottleneck where the species loses most of its genetic diversity and will be faced with extinction.

Why is loss in genetic diversity a bad thing you may ask? Well populations that are more diverse stand a much greater chance at adapting or evolving to cope with changes in their environment, whether they're minor or major changes. If a population's genetic diversity is reduced then it's ability to cope with any environmental changes may be hindered at the very least.

For example, Giraffe have a number of different colour morphs that will suit a number of different habitat types. If their preferred habitat type is grassland, the lighter coloured Giraffes will do better than the darker ones, though the darker ones are still present in low numbers. By having this amount of variation the species can adapt when the environment changes. So if the grasslands all died out, or burned in a bushfire, or were cut off to the Giraffes by some event. They'd be forced to move into elsewhere for food. If they moved into woodlands or forests, the darker individuals may have an advantage for camouflaging and hiding from predators, whereas the light coloured ones would stick out like an albino gorilla in a coal mine. Pretty quickly the light coloured morph would lose numbers and the darker morph would become the most common one. The species survives because it is now able to hide well in it's new habitat. However, if the species had had lower genetic diversity, say it had no darker morphs, it may have not been able to adapt to the new environment and be faced with extinction.

When it comes to fish, we've been attacking the most evolutionary robust species in the ocean first. They are the species that are very numerous and found everywhere. Once they're gone though we'll only have the less robust and diverse species to sustain us if we're not careful, and they won't be able to handle anywhere near the same sort of fishing abuse that other species have in the past.

So it's incredibly important we try to conserve as much genetic diversity in all species in the world, not just fish species. Especially in the face of global warming where species will need all the variation they can muster in order to deal with sudden environmental changes world wide.

Go to Overfishing.org for more information.

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