Class Notes (835,574)
United States (324,189)
ANT 2301 (23)

Sexual Selection

5 Pages
Unlock Document

ANT 2301
Geoffrey Thomas

ANT 2301 NOTES 09-03 Topic 2 SEXUAL SELECTION  INTRA VS INTER SELECTION  Darwin o Descent of man and selection in relation to sex (1871) o Males fight with antlers for access to females  Intra sexual selection –“male-male competition”  Females wait for victor or choose the most beautiful  Strategies o Maximize reproductive success o Males- mate w. every available female w/out getting hurt from other males o Females- choose the “most fit” mate  Sexual selection theory o Special form of nat. selection o The struggle by one sex for mating w/ other sex o Two forms:  Intrasexual selection: male-male competition for access to females  Intersexual selection: female mate choice  Happens to correlate with good genes  Greater decorations in males with polygyny  Females more decorated with monogamy  Female choice favors 3 kinds of male traits o 1) That directly increase fitness of female  Defend good territory, protect, provision o 2) Indicate good genes, offspring fitness  Peacock eyespots = >offspring survivorship o 3) nonadaptive but conscious  Frog mate call that is easiest to hear  Runaway sexual selection o Female mutant appears among pop. Of non-choosy females… o Male w. random preferred trait gets equal chance w. non-choosy +> odds w/ choosy female, so he has >RS o He passes on preferred random trait + the preference to daughters o Trait and preference spread (self-fulfilling)  Female Mate Choice o Females invest more in offspring so they have more to lose by making a bad mate choice so you expect them to be more choosy  Mate Choice Mechanisms in Primates o Active solicitation  Females in estrus will follow males around, making distinct vocalizations and facial expressions o Refusals to mate  Refuse to mate and will show aggression against courting males o Subtle signals  Sometime a female will persistently approach other males, often of a lower rank that her current partner  What traits might a female select for in a mate o Dominance rank o Unfamiliarity  Avoid harmful effects of inbreeding  Prevent infanticide o “Good genes” o Variety of mates  Group care of offspring  Difference between choice and preference o Preference is desires or propensities that an individuals possesses  Does not always result in choice o Female mate choice is an action that can be observed and measure- what the female does  May be affected by male behavior  Male behavior constrain female choice o Male-male competition  Lower males might not be allowed to get near females o Male coercion of females  Males will often use aggression to initiate and maintain coercions o Dominance and reproduction  Isn’t always what it seems- coercion (rape)  Female mate choice in chimpanzees o Females exhibit preferences for particular males o Males may affect female options o Therefore, females must try to control whether sexual interactions occur and the outcome of these interactions o Study measured whether females were effective at implementing their mate preferences  Expectations and results o Females expected to be more choosy and males more competitive during fertile periods than non fertile periods o Female success should be positively correlated with females factors such as rank and rage and negatively correlated w/ measures male rank and age o Although males were generally dominant to females the females could effectively resist male solicitations  Intrasexual selection o Commonly believed that male mating competition results in increased sexual dimorphism  Ass. w/ mating systems  Polygynous systems have unimale/multifemale groups where the male can defend the small group of females  Bigger= easier to defend females  OPERATIONAL SEX RATIO o Gros-Louis and Richards 1996: sexual dimorphism, the OSR and the intensity of male competition in polygynous primates  Consider adult sex
More Less

Related notes for ANT 2301

Log In


Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.