Topic+7+Spacing,+Mating+Ecology

2 tasmanian hen a rail simultaneous polyandry slide

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2. Tasmanian hen (a rail) simultaneous polyandry. Slide Class: What do you think about the males? The answer will be revealed only in lecture. IV. Monogamy is not always perfect. Genetic advances allow ascertaining parents, and when that was done, a big surprise in birds: extra-pair paternity . In this case, the female was always known to be the mother, but the father was not always the father: varies from zero to near 80% among species, with average about 15% of offspring that don’t have the true father a member of the pair. So males are feeding other than their own offspring often. A given clutch of young can have several fathers, one mother of course. Why? Thought to be mostly a matter of female choice. Field study by Kempenaers et al on Blue Tit Slide. Males that lose paternity survive less well, are smaller, and raise fewer young.
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V. Alternative sexual strategies A. The female “infidelity” is an alternative strategy for them. B. For males, alternative strategies can be much more severe, taking on different morphs even – especially likely in polygynous systems: 1. Ruff (like a snipe) Slide has lek. Two types of males: lek and satellite (sneak copulations). In part genetic. 2. Fish also, topminnow 2 slides studied by Constantz. Territorial vs non-territorial – the latter look like females, which are smaller and different colors. Mating is external and they will get in to the territory and leave their sperm (unknown if the coloration is genetic). VI. Ultimate mating strategy: change sex A. Hoffmann studied hogfishes. Slide Males have harems. Females in dominance hierarchy. If male removed, top female changes into male in 7-10 days. Hoffmann also looked at time-energy strategy for this fish. Can look at the same individual when male and when female (so control for individual identity). Switched immediately to one with flexible energy requirements rather than fixed. Short time spent feeding as male to variable and usually longer when female. B. The opposite: males change to females in Crepidula mollusks, called limpets. Slide They live in a stack, where bottom individuals are largest and oldest and are females. No polygyny, so no relation for males between their body size and mating frequency. Rather, the larger females produce more eggs, so better to be female when large.
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  • Fall '08
  • Strong,D
  • Reproduction, Polygyny, males, Polyandry, Mating system

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