Sunday, March 28, 2010
Race to Evolve
As we all know, and as Coyne pointed out, "[natural] selection [is] extremely slow, altering populations over thousands or millions of years" (2009, p. 116). But, often times, populations are faced with great, immediate danger. For example, the European honey bees introduced to Japan are faced with attacks by the formidable Asian giant hornets (Coyne, 2009, p. 111). While Japanese honey bees, having coexisted for a long time with Asian giant hornets, are able to fend off Asian giant hornets, European honey bees, being an introduced species to Japan, are not. It is possible that adaptations protecting European honey bees against Asian giant hornets can arise within European honey bee populations and proliferate via natural selection. For European honey bees, the rise of such adaptations is a race against time, for Asian giant hornets can very easily wipe out the European honey bee population of Japan before such adaptations appear within the European honey bee population. To win this race, a population must be able to adapt and evolve quickly. What are some examples of species engaged in a race to evolve before they are obliterated? What are some examples of adaptations that speed up genetic drift?
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Though natural selection usually does take several thousands to millions of years, let's not forget that this is because the generation gaps/intervals are larger for some species such as mammals compared to bacteria that can reproduce 20 minutes. I don't think that there are any specific adaptation that can accelerate adaptation and evolution which is primarily why it takes several thousand to million of years for natural selection to create an adaptation. However, I suppose that if a species can accelerate its own reproduction such as bacteria or some genetically modified trees/plants, the chance of a random mutation over a certain time might be higher. In the situation of the Asian giant hornets and the European honey bee, I believe the reason that the native Japanese honey bees can defend themselves against the Asian giant hornet because of the idea of coevolution, which is a species' change in genetic composition because of another species' change in genetic composition. To suddenly introduce the European honey bees to Japan will not give European honey bees enough time to adapt, while the Japanese Giant Hornet and the Japanese Honeybee had spent thousands of years combating each other to survive and reproduce. This reminds me of that video we watched on viruses in which a hospital had a certain bacteria that had to compete with the virus to survive.
ReplyDeleteAdaptations that would speed up evolution would be accelerated reproduction and producing larger amounts offspring. Accelerated reproduction and producing larger amounts of offspring would speed up evolution because the each offspring has a chance of having a helpful mutation, which would then spread throughout the population and aid the species evolve. However, reproduction requires massive amounts of energy, so the development of accelerated reproductive rates would have to coincide with changes in environmental factors that would either increase the amount of energy sources available to the organism or that lower amount of energy the organism must expend in other activities. This relates to the theme of interdependence in nature as increased reproductive rates are dependent on environmental conditions in order to be made viable.
ReplyDeleteHoneybees appear to be in a singularly unpleasant position for adapting quickly. Honeybee hives have a single reproducing female: the queen. The rest of the females are workers and cannot reproduce. This eliminates much of the gene pool that could possibly contribute to developing an adaptation. Though in theory the need for adaptation could trigger a behavioral change in honeybees that result in more royal jelly being fed to larvae to produce more queens and therefore increase the number of reproducing individuals in the community. Increased drone (male honeybee) production could also aid in speeding the adaptation of honeybees as queens copulate with multiple drones, and each drone provides an opportunity for genetic variation. This adaptation may already be in effect, as queens that copulate with more drones tend to be more attractive to worker bees, a behavior that may have grounds in genetics. Queens that mate with multiple drones produce more genetically variant offspring, and it is beneficial for a queen that produces varied offspring to have more workers that aid the queen and larvae in staying alive. (http://www.sciencedaily.com/releases/2007/10/071008183309.htm)