Natural Selection is defined as a selection where only the organisms best able to adapt in their environment tend to survive and transmit their genetic characteristics in grater numbers to following generations while those less adapted tend to be eliminated all together. Sexual Selection is considered by some, to be a type of natural selection, that affects traits that influence an individuals ability to choose or get a sexual partner, rather than traits that effect a beings ability to survive. Sexual Selection is thought to be responsible for the evolution of many extravagant physical features, such as long plumes in birds, bright colors in many animals, and complex display behaviors to attract a mate.
Darwin defined sexual selection as the effects of the "struggle between the individuals of one sex, generally the males, for the possession of the other sex". In sexual selection, a male individual may have better traits for fighting other males so that he may be selected for by a female, or may just have ornamental traits that may catch the eye of a potential mate and increase mating success. Darwin states that, "The sexual struggle is of two kinds: in the one it is between the individuals of the same sex, generally the males, in order to drive away or kill their rivals, the females remaining passive; while in the other, the struggle is likewise between the individuals of the same sex, in order to excite or charm those of the opposite sex, generally the females, which no longer remain passive, but select the more agreeable partners." This is where sexual dimorphism comes into play and why many males and females differ in size, color, and other physical differences.
Dawkins talks more about why natural selection does not favor a shifted sex ratio and why it is that so many males exist when there need not be so many. He states that Darwin did not solve this, but Fisher did. Dawkins takes the stand stated in the first paragraph that sexual selection is a type of natural selection. The selfish gene must be passed forward so you must find a suitable mate to help that occur.
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when you mentioned about the physical features from sexual selection, such as the long plumes in birds,it makes me think about how sometimes sexual and natural selection can be at odds with one another since like the example of the long plumes in birds, that trait may attract mates but it may also decrease that individual's chance for survival since the long plumes would make the bird more visible to predators. this is just a thought I had. I love how you frased your last sentence, I was thinking the same thing when I wrote my post and I completely agree. good post!
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