Chapter 11.5 Flashcards Preview

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Flashcards in Chapter 11.5 Deck (9)
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1

SEXUAL DIMORPHISM

The difference in appearance between males and females

2

SEXUAL SELECTION

Is a type of natural selection resulting from variation in the ability to obtain mates

it increases the chance of reproduction by increasing there desirablity 

3

2 forms of SEXUAL SELECTION

1. INTRASEXUAL SELECTION

2. INTERSEXUAL SELECTION

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INTRASEXUAL SELECTION

memebers of one sex compete among themselves for access to the opposite sex ( mate choice plays no part in deciding the winner)

The strongest fighters are more likely to past on their alleles

5

INTERSEXUAL SELECTION

members of one sex choose their mates from among multiple members of the opposite sex

6

Why do males usually show the greatest effects of selection

In most but not all animal species, females spend more energy rearing offspring than do males because of this investment females tend to be more selective

7

How does sexual selection promote traits that would seem to decrease fitness

Sexual selection selects for extreme phenotypes in one sex, and those extreme variations often place the individual at a disadvantage for survival (e.g., a peacock’s longer tail will make him more visible to predators and slower in escaping).  However, since these traits increase fitness by increasing mating success, sexual selection remains an active force in the population.

8

What is the difference between intrasexual selection and intersexual selection

Intrasexual selection occurs when members of the same sex compete for mating opportunities with the opposite sex.  Intersexual selection occurs between males and females of the same species: one sex chooses a mate of the other sex based on the presence of a characteristic.

 

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