Evolution of Sexual Reproduction
Sexual reproduction is somewhat of an enigma. Based solely on the idea that the goal of reproducing is to pass on ones genes, it seems almost disadvantageous. Why pass on half of your DNA when you have the opportunity to pass it all on? The idea must be then, that instead of increasing reproductive success directly by spreading more of an organisms genes, sexual reproduction does so by increasing the offspring's ability to survive. The two most accepted theories on the emergence of sexual reproduction are consistent with this idea. They hypothesize that sexual reproduction first increases the spread and creation of advantageous traits and second functions as an efficient method by which to remove disadvantageous traits from the gene pool (1).
The Host-Parasite Arms Race
The co-evolution of host and parasite seems the perfect situation to spur huge changes. In a relatively stable environment, there is little selective pressure to push for evolutionary revolutions, but as parasites evolve with their hosts in a so-called evolutionary arms race, there is constant incentive to improve. The parasite model is one hypothesis for the origin of sexual reproduction. Based on it, the selective pressure of co-evolving parasites drove early eukaryotes to seek sexual selection as a means of creating and spreading positive traits while removing negative ones (1). This coincides with what is known as the red queen hypothesis, which states that organism must be constantly evolving in order to survive when pitted against other evolving organisms (2).
Consequences of Sexual Reproduction
The evolution of sexual reproduction had many consequences. The result of greatest interest to this topic was the development of multiple genders. In many situations, having two entities with separate reproductive roles was advantageous. Thus, after many generations, genders began to differentiate, leading to the sexual dimorphism we see today.
Works Cited
1. Hurst, LD, and JR Peck. "Recent Advances in Understanding of the Evolution and Maintenance of Sex." Trends Ecol Evol. 11.2 (1996): 46-52. Web.
2. "Red Queen Hypothesis." Wikipedia 2015. Web. 27 Apr 2015.
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1. http://pawcurious.com/topic/blog/daily-life/cancer-sucks/
2. "Red Queen Hypothesis." Wikipedia 2015. Web. 27 Apr 2015.
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1. http://pawcurious.com/topic/blog/daily-life/cancer-sucks/