IB144Lecture Mating Systems Outline Fall 09 12_4

IB144Lecture Mating Systems Outline Fall 09 12_4 - IB C144,...

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IB C144, Fall, 2009 December 4, 2009 Mating Systems Outline This will be a quick review of mating systems. We will not be so concerned with mate choice, but rather with how many mates an animal takes. I. Simple classification scheme: A. MONOGAMY: An individual male or female mates with only one partner per breeding season or episode of breeding. B. POLYGAMY: An individual male or female mates with more than one partner per breeding season or episode. 1. Polygyny: one male, more than one female 2. Polyandry: one female, more than one male 3. Polygynandry: two or more females and two or more males. This is different from general promiscuity because the members live in a stable unit. II. It was long held that mating systems were determined largely by differences in parental investment. In a classic paper in 1977, Emlen and Oring argued that mating systems were determined not only by differences in parental investment, but also by several possible ecological factors including: A. Strength of predation B. Distribution of food, nest sites, or other critical resources C. Duration, timing and synchrony of breeding season D. Requirements of young E. Population density, age structure and other demographic characteristics
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These variables place constraints on the ability of females to choose among potential partners and in the ability of males to monopolize females. The result is a wide variety of mating systems. III. Monogamy. 1 male; 1 female per breeding episode A. Sexual selection theory predicts that this should be rare since males should try to mate with as many females as possible. However, in some environments receptive females are scare and/or the cost of finding them is high. It may be better to guard a potential mate and insure your paternity rather than keep looking. 1. In the snapping shrimp, Alpheus armatus , pairs live commensally with sea anemones. IV.
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IB144Lecture Mating Systems Outline Fall 09 12_4 - IB C144,...

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