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Lecture 17

BIO SCI 94 Lecture Notes - Lecture 17: Anisogamy, Gamete, Disruptive Selection

Biological Sciences
Course Code
Nancy Burley

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Parental Investment (PI)
Any investment in individual offspring that increases chance that offspring will
survive/ reproduce, while decreasing parent’s ability to invest in additional
Time, resources, nutrition
Consequence: population sex ratios tend toward 1:1 (due to balancing selection)
The sex with greater PI is a limiting resource for the sex with lower PI
Greater male-male competition
Higher PI
Lower PI
Low potential reproductive rate
High potential reproductive rate
Exercise choice of mates
Compete for mates
Improve fitness by quality of mates
Improve fitness by quantity of mates
Species with male control of resources
Lack of female control over male choice
Intense male to male competition
Intraspecific arms race between males and females
Ex. lions
Species with greater male PI
Greater male mate choice and competition among females
These species tend to be polyandry
Rare in animals, but taxonomically diverse
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