Lavc f10 lecture 11 primate reproductive strategies

Anthro 101: Human Biological Evolution Lecture 11: Primate Reproductive Strategies Office Drop-in Hours AHS 308 Tutoring Lab Hours AHS 232 T 5:30 - 6:30 M & T 1 - 4 Th 11:15 - 12:15, 1:15 - 3:15 Student ID required F 12 - 1:30 by appointment

Attendance survey ,[object Object],[object Object]

Studying Primate Behavior ,[object Object],[object Object],[object Object],[object Object],[object Object]

Behaviors are adaptations to particular social environments ,[object Object],[object Object],[object Object],[object Object],[object Object]

Mammalian females are committed to invest in offspring ,[object Object],[object Object],[object Object],[object Object]

Costs of Maternal Care ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Primate females invest heavily in each infant and produce few total offspring ,[object Object],[object Object],[object Object],[object Object],[object Object],Golden monkey

What strategies do females use to enhance reproductive success? 1. Care 2. Competition 3. Cooperation

1. Female primates provide many types of care for their offspring ,[object Object],[object Object],[object Object],[object Object],[object Object]

How much care should females give offspring? ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Golden monkey

2. Female reproduction is limited by access to food: ,[object Object],[object Object],[object Object],Silver leaf monkey

3. Competition sometimes favors cooperation among females ,[object Object],[object Object],[object Object],[object Object]

3. Competition sometimes favors cooperation among females ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Cooperation: In marmosets and tamarins, female RS depends on helpers

Selection shapes male reproductive strategies of males, too ,[object Object],[object Object],[object Object],[object Object],[object Object]

1. Males can increase RS by investing in offspring ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

2. Males can increase RS by competing ,[object Object],[object Object],[object Object],[object Object],[object Object]

Intra-sexual selection in primate males ,[object Object],[object Object],[object Object],[object Object]

Inter-sexual selection in primate males ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],mandrill tamarin

Pair-bonded species: Marmosets & Tamarins ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Dusky titi monkeys

Pair-bonede species: Gibbons and siamangs Males are attentive to mates Sing duets in territorial displays Females have priority of access Males help care for infants

Competitive males & distant fathers: multi-male groups ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Multi-male groups ,[object Object],[object Object],[object Object], The Bone Room 2010

More intense male-male competition leads to greater sexual dimorphism

Baboon males are twice as big as females

Males are well-armed for conflict

Males fight over access to receptive females

These fights can be very costly to males

High rank enhances male reproductive success Baboons

Intense male-male competition can also lead to sperm competition….and larger testes…in species where females mate promiscuously Monogamous 1- ♂, Multi-♀ Multi- ♂, Multi-♀ Observed/Expected Size 0.5 1.0 1.5 2.0

In multi-male groups, some males provide low cost care ,[object Object],[object Object],[object Object]

One-male groups: Competition to gain access to females is intensified ,[object Object],[object Object],[object Object]

Infanticide is a sexually-selected male reproductive strategy ,[object Object],[object Object],[object Object],[object Object],[object Object]

If infanticide is a sexually-selected male reproductive strategy, we predict: ,[object Object],[object Object],[object Object],[object Object],[object Object]

1. Infanticide is associated with changes in male status: Males don’t kill unless they GAIN reproductive access they did not have before

1. Males begin to kill infants soon after they join group Hanuman langurs, Borries & Koenig 2000

2. Males kill unweaned infants Probability of surviving presence of infanticidal male Langurs Howlers 0-3 3-6 6-9 > 9 Age (mos)

3. Males don’t kill own infants

4. Infanticidal males gain reproductive benefits ,[object Object],[object Object]

Infanticide is a major cause of mortality % deaths due to infanticide

Counterstrategies to thwart infanticide ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

In baboons, male-female ties may be response to infanticide ,[object Object],[object Object],[object Object],[object Object]

Sexually-selected infanticide has now been documented in a number of taxa ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Many still think its pathological and not adaptive

Controversy persists because people confuse “is” and “ought” ,[object Object],[object Object],[object Object],[object Object],[object Object]

In-Class Activity #5 ,[object Object],[object Object],[object Object],[object Object]

Lavc f10 lecture 11 primate reproductive strategies

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