Sexual Dimorphism

Topics: Sex, Male, Female Pages: 4 (1197 words) Published: September 23, 2013
Introduction:
In Charles Darwin’s theory of evolution, it states that individuals will experience mutations when their hereditary information is transcribed and copied, known as DNA. These mutations in the DNA could give the organism an advantage in its ecosystem, helping it to survive and giving it an increased chance to reproduce, where the mutation will be passed to its offspring. This creates variation in species where individuals in a population will have an evolution advantages over others of its species due to its fitness, which is its ability to function in its environment. (Hedrick and Temeles, 1989) These changes, if favorable to the organism will become more common in the species due to the ones that have this trait it can breed more, increasing the amount of individuals with this trait through their offspring, slowly changing the species.

These traits that give advantages can be anything that gives one an advantage, such as better eyesight to see predators, or larger claws to defend its young. In many species, different sexes will develop different traits to better suit to their needs to survive, known as sexual dimorphism. If a male or female develops a mutation that helps it in its ecological niche or to survive allowing it to outcompete others of its gender in caring for its young, or fighting for better mates, it will be able to pass this on due to it being more fit, causing a difference in between the two sexes. (Hedrick and Temeles, 1989) It can also occur if there is a need to compete for food in between sexes. This occurs due to the evolutionary advantage that the individual has, and is extremely common in nature, such as male deer having a large set of antlers to fight with other males for chances to male, which passes on this trait, making it more common. The male deer with the larger set of points will be able to fight better and mate more, giving his male offspring larger antlers, furthering the difference between male and females in...

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Physiological Reviews 78: 1-33
Hedrick, A. V. and E. J. Temeles. 1989. The evolution of sexual dimorphism in animals:
hypotheses and tests. Trends in Ecology and Evolution 4:136-138.
Ralls, K. 1977. Sexual dimorphism in Mammals: Avian Models and Unanswered Questions
The American Society of Naturalists. 111:917-938
Temeles, E. J., Pan, I.L., Brennan, J. L., and J. N Horwitt. 2000. Evidence for ecological
causation of sexual dimorphism in a hummingbird. Science 289:441-443
Wolfenbarger, L. L. 1997. Red coloration of male northern cardinals correlates with mate quality
and territory quality. Behavioral Ecology 10:80-90
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