University:
Amherst College
Course:
BIOL 281 | Animal Behavior with Lab
Academic year:

2011
Views:

431

Pages:

4
Author:

Rhys Delgado

Mate choice Mate choice sage grouse Males less so Boa spp. Females generally more discriminating Rana spp. sockeye salmon On what basis are mates chosen? Direct benefits Indirect benefits Direct benefits: protection Direct benefits: food Newly protected female moth being rejected by spider rattlebox moth hanging-fly Increase duration of courtship Rattlebox moth feeding off rattlebox plant, obtaining alkaloids Direct benefits: food Chimpanzees sometimes hunt for meat “Meat for sex” hypothesis Female dance flies trick males into giving up nuptial gifts Male moth transfers alkaloids to female Direct benefits: spermatophores Mormon cricket tiger salamander Some attached to females scorpion Some deposited on substrate 1 Direct benefits: spermatophores Direct benefits: sexual cannibalism praying mantis Why do they do this? redback spider spermatophylax sperm Mycoplasma conjunctivitis Direct and indirect benefits: parasites avoidance Hamilton and Zuk: females should mate with males with traits that predict parasite/pathogen resistance Satin bowerbird coloration is honest indicator of parasite load Marlene Zuk Bill Hamilton Plumage redness is inversely related Mycoplasma bacterial infection in house finches Direct and indirect benefits: parasites avoidance Females prefer caring males 10 9 8 7 Nest area (ln) • Males sometimes responsible for nest construction, parental care • Female choice based on benefits to offspring 6 5 4 Sand goby Betta splendens 3 2 1 0 0 50 100 150 200 250 300 350 Duration of male displays toward female sedge warbler 16 of 22 females chose “low oxygen” male 2 Preference for extreme traits widowbirds peacocks Control Elongated Control Shortened Preference exists even if trait is novel Number of matings Change in number of matings Preference for extreme traits black-throated and zebra finches Experimental Fluctuating asymmetry = chance differences in paired structures scissor-tailed flycatcher stalk-eyed fly Preference for symmetrical traits S-L S-S S-L S-S S-L A-L A-L A-S A-S A-L S-S A-S Female preference Preference for symmetrical traits length symmetry three-spined stickleback Conclusion? Symmetry more important than size Indirect benefits: good genes Indirect benefits: Fisherian (“runaway”) selection Why choose extreme or symmetrical traits? Good genes hypothesis ♂ ♀ Trait unrelated to male quality Trait passed to sons, preference for daughters R.A. Fisher Related idea: “sexy son” hypothesis 3 Good genes vs. Fisherian selection Good genes vs. Fisherian selection Hypotheses not mutually exclusive Good genes (and Fisherian selection?) in population of peacocks Hamilton-Zuk hypothesis Females prefer males resistant to parasite A aa Aa AA If preferred trait is genetic, runs quickly to fixation How do you explain natural variation in trait? Hamilton-Zuk hypothesis Population vulnerable to invasion by parasite B Females now prefer males resistant to B 4

Primary and Secondary Sexual Traits Part 2

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