Evolving Doors

By JW Dowey - 10 Apr 2013 14:38:39 GMT
Evolving Doors

Wikimedia photograph, illustrating one of the many species for which this research is critically important for survival. It's a young cod or codling from Belgian waters; Credit: © Hans Hillewaert

While environmental change still seems to bamboozle us as if we couldn't possibly be responsible, we now seem able to grasp that evolution is actually happening around us. The need is to predict how well species adapt to global warming. Their ecological and evolutionary timescales must be compared.

Many studies have been carried out on how an animal matures. How long does a domestic animal take to reach a size at which it can be marketed? The more modern approaches are no different. Population ecologists at Leeds University are claiming that ecology and evolution are acting hand-in-hand. Tim Benton explains, "The implicit assumption has always been, from Darwin onwards, that evolution works on long timescale and ecology works on short timescales. The thinking was that if you squash a population or you change the environment then nothing will happen from an evolutionary point-of-view for generations and generations, for centuries."

To investigate how the cod, Gadus morhua, had reduced in size by genetic means over time, the paper here investigated how a lab. animal reacted to similar harvesting. The obvious need would be for the animals to mature more quickly so that they could breed. The soil mites used were harvested as either juveniles or adults or simply left alone. Their genetics, life history and populations were then assessed to see what differences emerged. A large fish would have similar responses, but it would be impossible to observe such large samples in test tubes as was done here!

The change was rapid, evolutionary and remarkable. Over 20 generations, the age of maturity doubled, coupled with higher fecundity. That is equivalent to a human becoming mature at 27 instead of 14 years. For a cod, the difference could mean changing from a rapid, 2-year maturation to the longest known, which is 7 years. In the mites, the appearance, especially size, changed clearly over the period too, especially under "low-food conditions." Age at maturity showed the most significant change however, with a general loss of genetic diversity among the populations used. The new environment and selection affected the mites in the same way as was found in wild guppies. These Asian fish were subject to adult and juvenile predation in a similar study.

Evolutionary factors can quickly join the ecological factors that currently obsess conservationists. Siting of reserves was Professor Benton's example: "Do you put the nature reserves just 10 miles apart because that is how far the animals travel now, but in 50 years time, they might disperse five miles."(because of evolutionary change). But any reversal of evolutionary change is much more difficult than the simpler change we make in environments. There is no reverse gear for evolution, it seems, although stranger events have happened. The good news for fishermen, although not for the endangered Atlantic cod at the moment, is that populations in the experiment showed an increase in yield of 13% in the harvests of adults

Tom C. Cameron, Daniel O'Sullivan, Alan Reynolds, Stuart B. Piertney and Tim G. Benton published their research in the journal, Ecology Letters.

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Topics: Fish / Evolution