Evolution Blog

 One type of male-male competition is sperm to sperm competition. An example of this is displayed in dragonflies. Male dragonflies use their own genitalia to physically remove the sperm of another male from the female they're trying to mate with. Once they do that, they will then mate with the female using their own sperm. A second type of male-male competition is combat competition. Male deer grow antlers mainly during breeding seasons. These antlers are used when fighting another male for mating rights with a female. Not only do these fights have a substantial consequences, but growing the antlers in the first place requires a lot of energy.  These two forms of male to male competition are similar in that the overall goal for them is to survive and reproduce offspring with the female they choose. The difference is that with sperm to sperm, they may have already got the female they wanted. Whereas with combat competition, neither male has rights to that female yet.

I understand what sexual selection is and how it works, but one thing that confused me was how can some species sexually select for such unique traits when they were not previously selected for in previous generations? Obviously traits being selected for can change over time due to natural selection, but it would be interesting to know how those features contribute/benefit that species. Once concept discussed that I personally found interesting, was that scientists do not have a pin-pointed reason for why females prefer a specific trait of males over another. I learned in physiology that pheromones play a big part in human's sexual selection, but otherwise this topic is still being debated. Scientists do know, however, that a female's preference leads to direct or indirect benefits from the male to her.

  Something that makes me happy is cuddling with this little guy! His name is Sosa and he's only eight months old! He already weighs 85 pounds but he is a big teddy bear!

 3 Questions I have: 1. How are subspecies categorized and determined? 2. How long does speciation typically take? 3. Have individuals ever been categorized as the wrong species? If so, what was the characteristic(s) missed that actually set them apart?

Genetic drift is RANDOM. Examples of genetic drift include the Founder Effect and the Bottleneck effect.   Natural selection is NOT an example of genetic drift because it is not random. 

 Phenotypic plasticity is the ability of an organism to alter its phenotype in response to the environment without altering its genotype. In "The Genetic Basis of Adaptation following Plastic Changes in Coloration in a Novel Environment," a study was done on lizards that live on lava rocks. When on these lava rocks, the lizards expressed a dark color that was similar to that of the lava rock. However, researchers found that when taken off the lava rocks and put into sand, the lizard's expressed a lighter color in response to the change of substrate.  Additionally, the researchers compared the lava rock lizards to lizards not living on the lava rocks. They found that both groups of lizards expressed dark phenotypes when on the rocks. However, the lizards that already lived on those rocks had a darker phenotype than those who did not. When placed on the sand, researchers found that both groups of lizards expressed the same color of lightness.  Phenotypic plasticity is what ...