Posted: Jul 27, 2010 1:17 pm
Aiming to select for land traversal ability in a fish that doesn't yet have this is a bit ambitious to put it mildly, but there are other traits you can select for in an appropriate environment. Here's one idea you can run with that would probably yield measurable results in something like 50 generations or so, and all you'd need is sufficient space and funds to run the setup!
Set up an aquatic environment that's very long. At each end, create some rockwork for some Cynotilapia afra or other Mbuna type fish to set up territories upon. At one end, you arrange for the rocks to be light coloured (e.g., limestone), and at the other end, you arrange for dark rocks to be used. Introduce a population of Cynotilapia afra to each end of the pond.
Now the reason you choose these fish, and this setup, is because Cynotilapia afra and other Mbuna-type Cichlids are strongly territorial, and do not stray very far from rock screes. So if you have your rock screes separated by a large open gap, they won't cross it. Consequently, you'll have two isolated populations, which will duly set about breeding. Of course, you'll have to keep the light coloured rocks scrubbed of algae so that they stay light, but this shouldn't be a problem if you set things up appropriately. Now, give these fishes 50 generations or so, and you should start to see the fishes that live around the light coloured rocks becoming progressively lighter in colour with each new generation, whilst those that live over the dark rocks gravitate toward a dark colour scheme. Similar experiments have been performed with guppies, but Mbuna have behavioural characteristics that make them a much more interesting model organism.
Keep those populations isolated for long enough, and you could end up with a situation in which your two populations are no longer interfertile with each other, in which case you've got yourself a speciation event in your pond, and you have the material for a Nature paper!
Set up an aquatic environment that's very long. At each end, create some rockwork for some Cynotilapia afra or other Mbuna type fish to set up territories upon. At one end, you arrange for the rocks to be light coloured (e.g., limestone), and at the other end, you arrange for dark rocks to be used. Introduce a population of Cynotilapia afra to each end of the pond.
Now the reason you choose these fish, and this setup, is because Cynotilapia afra and other Mbuna-type Cichlids are strongly territorial, and do not stray very far from rock screes. So if you have your rock screes separated by a large open gap, they won't cross it. Consequently, you'll have two isolated populations, which will duly set about breeding. Of course, you'll have to keep the light coloured rocks scrubbed of algae so that they stay light, but this shouldn't be a problem if you set things up appropriately. Now, give these fishes 50 generations or so, and you should start to see the fishes that live around the light coloured rocks becoming progressively lighter in colour with each new generation, whilst those that live over the dark rocks gravitate toward a dark colour scheme. Similar experiments have been performed with guppies, but Mbuna have behavioural characteristics that make them a much more interesting model organism.
Keep those populations isolated for long enough, and you could end up with a situation in which your two populations are no longer interfertile with each other, in which case you've got yourself a speciation event in your pond, and you have the material for a Nature paper!