RachelM

http://myxo.css.msu.edu/~dule/pdf/Misevic2009.pdf

Researchers in New Zealand investigate the evolution of sex based on different fitness habitats.  The relationship between genotype and fitness is known as the fitness landscape. 

These researchers investigated three types of fitness landscapes, smooth random, and NK (rugged landscape).  Using computer simulations, they found that the evolution of sex is different for different landscapes.  They also describe the difficulty of predicting the evolution of sex experimentally which leads to a vast number of theories as to “why sex?”  The authors state that there is a two-fold cost to sex and their models attempt to predict when sex will be beneificial and when it will not be. 

Several theories come into play; The Red Queen Hypothesis, Fisher Muller, Hill Robertson (identically to Fisher Muller), and Mutational Deterministic Hypothesis.  Fisher-Muller states that sex is advantageous because “it allows for beneficial mutations that arise in different lineages to recombine, thereby reducing clonal interferences and speeding up adaptation (Cooper 2007).”  The Red Queen Hypothesis however describes an arms race between individuals. The latter hypothesis assumes that the deleterious genes are only slightly deleterious and adding a mutation has a great effect.  This is known as synergistic epistatis.

For the record, the Red Queen’s Race actually took place in Lewis Carroll’s book “Through the Looking Glass” not Alice in Wonderland.  These two books are known collectively as the Annotated Alice despite what Hollywood and Tim Burton might believe. 

With all these theories in mind, it seems almost impossible to test theoretically or experimentally.  I am curious to know whether there is a true theory to back up the mystery of sexual evolution.  Could it be at all these theories can come into play?  Are some organisms driven by one theory, such as the Red Queen Hypothesis, while other organisms conform to the Mutualistic determinism theory, or is there one simple overall “answer” that describes why sex evolved countless times in very different organisms.  Or can all these theories play a small role in sex evolution?