One important component of parental investment is the

One important component of parental investment is the -...

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One important component of parental investment is the investment in gametes . This serves as one means of distinguishing the sexes. Females are the sex with a large parental investment per gamete . Example are eggs which have the nutrients to promote the development once fertilization occurs. Males have a smaller parental investment per gamete ; generally carries only genetic information. Some birds: each egg = 15-20% of a females body weight. In males, millions of sperm produced each ejaculation; total output per reproductive season < 5% of body weight. (The difference is less pronounced, but still significant, in mammals). This difference in investment in gametes has important consequences for how these resources are invested and hence how selection might act differently in the two sexes. In general, females should commit their eggs for reproduction prudently ; males need not be so cautious in their commitment of sperm. Put in evolutionary
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Unformatted text preview: terms, the reduction in fitness of a female that squanders an egg will be greater than the reduction in fitness of a male that squanders a sperm (give or take a million). Another important component of parental investment is parental care , care of the zygote after fertilization. The amount of parental care is also frequently quite different in males and females. In species with internal fertilization the female is &quot;stuck&quot; with the egg after fertilization. In many species the female also cares for the young after they hatch. Males are not anatomically tied to the egg and hence are sometimes &quot;freed&quot; from this additional parental care. Moreover, in species where multiple matings occur, a male cannot be certain that a females offspring were fathered by him . Benefit of caring for unrelated offspring is low , a male can increase fitness by avoiding parental care....
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This note was uploaded on 11/05/2011 for the course BIOLOGY MCB2010 taught by Professor Jessicadigirolamo during the Fall '10 term at Broward College.

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