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LEQ: How do new species develop?

LEQ: How do new species develop?. http://www.pbs.org/wgbh/evolution/library/11/2/quicktime/e_s_4.html. Perpetuation of genes defines evolutionary fitness. Struggle for Existence & Survival of the fittest

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LEQ: How do new species develop?

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  1. LEQ: How do new species develop? http://www.pbs.org/wgbh/evolution/library/11/2/quicktime/e_s_4.html

  2. Perpetuation of genes defines evolutionary fitness • Struggle for Existence & Survival of the fittest • Because there are limiting resources (food, shelter, competition, predation, etc…) organisms struggle to survive. • Organisms that are best suited for their environment will have a better chance to survive allowing them to reproduce and pass on their traits that made them better suited for survival.

  3. Perpetuation of genes defines evolutionary fitness… • Fitness • The contribution an individual makes to the gene pool of the next generation, relative to the contribution of other individuals in the population • Those with higher fitness will make a greater contribution to the gene pool; those with lower fitness may not contribute to the gene pool at all

  4. Natural Selection can alter variation in a population… • Type of natural selection that favors intermediate variants by acting against extreme population • Human birth weight is usually in the range of 6.5lbs to 9lbs. Smaller babies have increased health risks. Larger babies lead to health risks for the mother. Stabilizing Selection Example

  5. Natural Selection can alter variation… • Type of natural selection that acts against the relatively rare individuals at one end of the phenotype range. • Pesticide resistance in insects. Directional Selection Example

  6. Natural Selection can alter variation… • Type of natural selection that favors extremes over intermediate phenotypes • Coloration of African Swallowtail – extremes mimic unpalatable species; most common / non-mimic becomes easy prey Disruptive Selection Example

  7. Sexual Selection • Sexual selection is natural selection for mating success • It can result in sexual dimorphism, marked differences between the sexes in secondary sexual characteristics

  8. Intrasexual selection is competition among individuals of one sex (often males) for mates of the opposite sex • http://youtu.be/Ez7RUSCUhzk

  9. Intersexual selection, often called mate choice,occurs when individuals of one sex (usually females) are choosy in selecting their mates • Male showiness due to mate choice can increase a male’s chances of attracting a female, while decreasing his chances of survival • http://youtu.be/W7QZnwKqopo

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