On page 158, Coyne describes sexual selection. He states that "males compete for females" ,therefore males "should be promiscuous," while females should be coy.
Imagine you are trying to convince someone that sex drives evolution. How would you persuade this person, using society's ideas on what is aesthetically appealing and gender roles?
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In order to persuade someone that sex drives evolution we need to start with the basics of sexual selection. As you've noted, males typically do the competing for females - either physically fighting one another, or putting on elaborate displays to gain the female's favor. Thus, evolutionarily, we can see how the sex drive in males has tangible effects. For instance, Coyne takes the example of the male peacock and its brilliant plumage in comparison to the dull feathers of the female peacock. Clearly, the need of the males to impress the females to engage in reproduction fueled evolutionary traits that help the males to do so. However, at first glance, this sexual dimorphism may seem to violate evolutionary theory, because they "waste time and energy and reduce survival" (146). However, in the long run, we see that its actually selectively advantageous to the species as a whole. Reproduction being one of the key elements of biology (the other being survival), sex is a means by which organisms reproduce. In fact, sex is capable of driving evolution (more so than say, asexual reproduction) because during sex, multiple combinations of genes can result. As we learned in the meiosis unit, during sex, mutations in genes can occur to make the species more selectively advantageous. Thus, as sex happens, as genes mutate, natural selection also happens, and consequently evolution happens. This is clearly related to the theme of evolution - in which organisms influenced by natural selection adapt, migrate, or die - in this case, they adapt.
ReplyDeleteBut looking from a less microscopic perspective and examining society's ideas of aesthetics, we can see that sex drives evolution as well. Coyne brings Darwin's theory: that females choose their mates based on aesthetics. At times in society, this appears to be true. Organisms are always looking towards extending survival. Thus, they look for certain characteristics that symbolize strength, or enhanced survival. For example, in humans, more muscalature seems to denote a greater capability to survive. Thus, the idea of sex evolves from aesthetic appeals as well. Consequently, sex itself drives evolution forward by promoting faster evolution to deal with aspects of the environment that are changing.
Sex undoubtedly drives evolution, as sex allows for two things. The first thing that sex allows is reproduction, which is necessary to create offspring. The second thing that sex drives is, as Ms. I would say, the meiotic shuffle (Ms. I). The meiotic shuffle allows for several different combinations of genes. Recall from the gene unit that alleles for multiple traits can be located on a single chromosome. As the number of alleles increases, the amount of phenotypes and genotypes possible for the offspring increases very rapidly. In this way, and through gene mutations, natural selection ultimately leads to evolution of an organism.
ReplyDeleteThe statement that males have to attract females isn't true for all species, and the main example I have in mind here is humans. Yes, males do go to the gym to pump some iron and get those nice chiseled biceps and abs that the ladies love. However, human females also do their part to appear attractive to males. In fact, it's about as common to see females competing over a male as it is to see males competing over a female. Also, humans are interesting because attraction goes further than just being aesthetically pleasing. An aspect of human compatibility is intellect and personality, which is unique to humans. In light of this, I believe humans are somewhat of an exception to the statement that males must be promiscuous.