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Eavesdropper INFO INFO Recipient - Eavesdropper PART II SOCIAL EAVESDROPPER INFO Signaler Receiver (‘intended’) (sender) (recipient) INTERCEPTIVE
Krebs’ Experiment (1977) • Remove males • Monitor settlement • Yasukawa’s experiment (1981) • Mute males via removing • a portion of the hypoglossal • nerve
Songs to advertise territory ownership and aggression to other males – 3 examples • Muted males creates more territory intrusions • Experimental playbacks delays territorial settlement in the • absence of males • There is a level of sophistication males recognize neighbors • from strangers in the Dear-Enemy Effect
#1 Song (Type) Matching Counter singing Marsh Wrens Track 38 (Kroodsma)
Repertoire Matching Beecher’s Studies on the song sparrow Bird 3 W V U Bird 2 X Bird 1 O P B I C A F E D T N H J S L K R Q G Bird 4
(1) Match song exactly Type Matching (2) Match with another shared song Repertoire Matching (3) Sing a unshared song
Neighbors tend to repertoire match • more than expected by chance • Neighbors type-match early and • repertoire match later in the season Song functions to communicate to territory ownership in very sophisticated ways Type Match Repertoire Match Unshared
SOCIAL EAVESDROPPER INFO (C) (A) (B) INFO Signaler Receiver (‘intended’) (sender) (recipient)
Non-overlapping Low aggression Overlapper = aggressive Overlapping High aggression Overlapped = passive
♂ ♂ ♂ ♂ McGregor et al. 1997 aggressive passive ♂ exposed to aggressive male playback kept its distance; ♂exposed to passive male playback approached quickly
♂ Peake et al. 2001 • Varied intruder’s aggressiveness by the amount of song overlap producing: • Overlappers • Alternators • Random (inconsistent) • Overlapped
Otter et al. 1999 ♂ ♂ ♂ ♂ EPCs in 2 of 20 aggressive owner’s nests i.e., low cuckolding In Otter et al’s work on tits there was no reproductive effect, But on Mennill et al’s work on red-winged blackbirds there was ♀ Aggressive owner ♀ Passive owner EPCs in 12 of 23 passive owner’s nests i.e., high cuckolding
SOCIAL EAVESDROPPER INFO (C) Clearly Social Eavesdropping occurs by both sexes (A) (B) INFO Signaler Receiver (‘intended’) (sender) (recipient)
Eavesdropping on decisions of others Do conspecific choices reveal information?? Mate copying & the evolution of cultural
The Choice Test Paradigm Male 2 Male 1
? ? Results of Copying Experiment Time near as a proxy for mate choice Male 1 Male 2 In 85% of trials, females preferred males that were near model female (G = 10.8, P < 0.005) Model female was near this male
Control 3 (viewed from above) Male 2 Male 1 Focal female Female Female
Results of Control 3 Male with visible model Male Focal female In 85% of trials, females preferred males that were near the visible model female (G = 10.8, P < 0.005)
Results (No Model Present) In 85% of trials, females preferred more colorful male (G = 10.6, P < 0.005)
Males Differ by 12% - Model Near Less Colorful Male
Results: Males Differ by 12% - Model Near Less Colorful Male In 85% of trials females prefer less colorful male. A complete reversal.
1 0.8 0.6 Proportion choosing more orange male 0.4 0.2 Treatment Control 0 0.04 (I) 0.12 (II) 0.24 (III) 0.40 (IV) Mean difference in orange body color Mate-copying overrides differences in mate cues Treatment and control are significantly different for I, II and III, but not IV
From date copying in guppies to date copying in humans?
Survey (for females) Chris was interviewed independently by five women. Each interview lasted 20 minutes and the interviewer was allowed to ask anything she wanted. The five women then rated Chris on several characteristics. These ratings were made using 10-point scales, where the higher the number, the more positive the rating. In terms of physical attractiveness, Chris’ average rating was 3 out of 10 (where 1 = extremely unattractive and 10 = extremely attractive).... In addition, the five women were asked to indicate how interested they would be in dating Chris. 4 of the 5 women indicated an interest in dating Chris.
2- 4 allow us to study attributes associated with copying Questionnaire 1. How interested would you be in dating Chris? Not at all Very 1 2 3 4 5 6 7 2. How good do you think Chris’ social skills are? Not good at all Very good 1 2 3 4 5 6 7 3. How good do you think Chris’ sense of humor is? Not good at all Very good 1 2 3 4 5 6 7 4. How wealthy do you think Chris is? Not wealthy at all Very wealthy 1 2 3 4 5 6 7
Results • Physical attraction targets eliciting a greater response • than low physical attraction targets (P < 0.005 for both sexes). • BUT effect of peer attention highly significant (p < 0.0001) • & Females were more affected by differential peer attention than were • males (p < 0.01).
Results - Attributes • Both males and females thought high peer attention individuals had • bettersocialskills (p <0.01) • better sense of humor (p < 0.01) • Morewealth (p<0.01 There was, however, a significant peer attention x gender interaction, with females perceiving greater differences in male wealth as a function of peer attention.
Summary • Both males and females are affected by physical attraction. • Both males and females engage in “date copying”. • Females weigh the decisions of others more strongly than males. • Both sexes attribute social skills, a sense of humor and wealth to • those individuals preferred by others. • Females associate peer attention and wealth more strongly than • males.