Scientists have managed to set up an experiment in which pushed two powerful evolutionary forces - natural selection and founder effect.
When animals or plants to colonize new territories, some individuals away from the native population and founds his own. It is clear that the pioneers could not take all the genetic diversity of the original population - they are only those genes that have them. Therefore, the new small population to survive the depletion of the gene pool variability in it falls, and all individuals tend to any one parameter specified by the founders. This evolutionary-genetic effect is called - founder effect. It is opposed by natural selection: in order to survive in the new environment, the population must act by trial and error, that is, her hand should be a lot of options, some of which are so useful. That is, genetic diversity should be high.

Of course, nobody explicitly not observed. Scientists have found new populations of certain species, differing from each other, and began to theorize: is the current shape of animals due to natural selection or random effect due to the founder. Researchers from the University of Rhode Island (USA) decided to determine the mutual influence of these factors, based on the evolutionary experiment. They settled a few pairs of lizards, Anoles on several islands of the Bahamian archipelago, where they still did not have these lizards. Conditions favorable to the experimentalists: the initial population was living in a wooded area, whereas the other islands in the vicinity of the “pilot” the same lizard lived in the bush more open spaces. In forest lizards longer hind legs, with which they are best crawls through the thin branches and leaves. In shrub Anoles hind legs is shorter, they are comfortable balancing, traveling on the open-thick trunks and rocks.

Lizards resettled in 2005 and a year later, scientists have seen clear signs of the founder effect: genetic diversity of lizards in each of the seven inhabited islands has fallen sharply, and all populations showed a significant variation in the length of the hind legs. The effect of the founder did not pay attention to environmental conditions: the advantage of the option feature was that by chance was at the first “colonizers.” Therefore, all the populations were different from each other and from the parent population. The next few years were marked by natural selection, which is made to shorten the rear legs of lizards - the animals have started to adapt to environmental conditions. However, traces of the original founder effect remained: those of lizards, which were after the settlement of the longest legs and remained in that sense, champions and more, although the length of the hind limbs, and diminished.

3 February 2012 | , effect, experiment, force, part, plant, population, selection, territory

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