3-4-08 - Psyc-131 March 4, 2008 Do females prefer males...

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Psyc-131 March 4, 2008 - Do females prefer males with extreme versions of the trait? o Males often have what appear to be maladaptive ornaments (especially polygamous species) o Widowbird – males do provide resources to female in the form of territory males have a tail (which is costly) which they have (and then lose) during mating session hard to maneuver with tails and they are costly bc of the energy required grow them Males arrive to territory before females and then attract the females by singing Captured these birds for experiment: 4 treatments – shortened (cut tails off), elongated (pasted the cut tails that he had just cut off others), and 2 controls (one left them alone, and one cut and then glued so have normal sized tail) Males that had tails elongated attracted significantly more females to territory They are artificially long, and yet females are still attracted to them this experiment just shows that females DO prefer males with longer tails; not why or what attracts them though o Barn swallows – socially monogamous, males come to territories before females do and then compete for territories Again, shortened, elongated, and 2 controls increase in number of days for pairing if tails were shortened; males that have elongated mates found mates the quickest o House finch – males are slightly redder than females; males that are redder than others are in better condition redness is acquired through diet (signal of ability to acquire food) Experiment – responses of female house finches to males of different plumage color Shows that females prefer red males but doesn’t say why o Song sparrow – female song sparrows’ responses to male songs 2 samples: males whose songs showed a high proportion of copying, and males whose songs showed a low proportion of copying HPC showed more displays Look at how faithfully they’ve copied their tutors songs question of whether you’re a good mimic o Chickadees Stimulated contests among male chickadees and showed them to the females – males show their dominance by interrupting other males’ songs Females hear: o Aggressive playback: intruder dominates mate, then neighbor dominates intruder Neighbor is dominant 1
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Psyc-131 March 4, 2008 o Subordinate playback: mate dominates intruder, then intruder dominates neighbor Some females have mates that have been dominant to their neighbor Some females have mates that have been subordinate to their neighbor High ranking males test: aggressive playback has higher % of nests containing extra-pair young o Test for paternity o Find that these females are very sensitive to the dominant status of their mate some females behave in a very sneaky fashion o Even really artificial traits can be attractive to females bands are put on the ankles of the bluethroat birds
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This note was uploaded on 04/17/2008 for the course PSYC 131 taught by Professor Seyfarth/cheney during the Spring '08 term at UPenn.

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3-4-08 - Psyc-131 March 4, 2008 Do females prefer males...

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