COSTS OF REPRODUCTION

COSTS FOR FEMALES A. Gestational Costs –

COSTS FOR FEMALES B. Lactational Costs – Compared with pregnancy costs 80% 200+%

COSTS FOR FEMALES B. Lactational Costs – Effect of litter size 2x

COSTS FOR FEMALES C. Variation Due to Sex of Offspring – Polygyny and sexual dimorphism

COSTS FOR FEMALES

C. Variation Due to Sex of Offspring

COSTS FOR FEMALES C. Variation Due to Sex of Offspring – Bighorn sheep:

COSTS FOR FEMALES C. Variation Due to Sex of Offspring – Bighorn sheep:

COSTS FOR MALES A. Behavioral – Increased movements during breeding season

COSTS FOR MALES A. Behavioral – Increased scent marking during breeding season

COSTS FOR MALES A. Behavioral – Costs of fighting red deer – 13-29% of mortality mule deer – 19% injury

COSTS FOR MALES B. Morphological – antler growth

COSTS FOR MALES C. Physiological – Example: Brown antechinus

COSTS FOR MALES C. Physiological – Brown antechinus males

COSTS FOR MALES C. Physiological – Example: Brown antechinus

COSTS COMMON TO BOTH SEXES The cost of poor mate choice l inbreeding l immunodeficiencies l lowered reproductive success

CUTTING REPRODUCTIVE COSTS: SEX RATIO VARIATION A. Theories for Adjusting Sex Ratios at Birth – Variation in reproductive success of males and females (Trivers-Willard hypothesis)

CUTTING REPRODUCTIVE COSTS: SEX RATIO VARIATION A. Theories for Adjusting Sex Ratios at Birth Predictions of Trivers-Willard for polygynous species:

CUTTING REPRODUCTIVE COSTS: SEX RATIO VARIATION A. Theories for Adjusting Sex Ratios at Birth – Local resource competition In primates: – inheritance of female dominance, so …

…male reproductive success is not closely tied to maternal investment Mandrill Japanese macaques Proboscis monkeys

CUTTING REPRODUCTIVE COSTS: SEX RATIO VARIATION A. Theories for Adjusting Sex Ratios at Birth – Local resource competition Predictions: – produce philopatric sex if resources plentiful – only dominant females produce philopatric sex if food scarce

CUTTING REPRODUCTIVE COSTS: SEX RATIO VARIATION B. Potential Causes – Timing of insemination

CUTTING REPRODUCTIVE COSTS: SEX RATIO VARIATION B. Potential Causes – Sperm selection in females Production of leukocytes

CUTTING REPRODUCTIVE COSTS: SEX RATIO VARIATION B. Potential Causes – Sperm selection in males

CUTTING COSTS: COOPERATIVE BREEDING A. Carnivores biparental or communal care higher milk production increased postnatal growth rates

CUTTING COSTS: COOPERATIVE BREEDING B. Primates (marmosets) elevated growth rates reduced intervals between births

CUTTING COSTS: COOPERATIVE BREEDING C. Rodents (prairie voles) older juvenile helpers increased weight at weaning shorter time to eye opening

CUTTING COSTS: INFANTICIDE AS A REPRODUCTIVE STRATEGY A. An Evolutionary Perspective – Males safeguard paternity – Males increase offspring sired – Females reduce losses Hanuman langurs

CUTTING COSTS: INFANTICIDE AS A REPRODUCTIVE STRATEGY B. Removing the Log from Our Own Eye – Darwin on infanticide in humans – Infanticide in societies hunter-gatherers ancient Greece 18th century Europe and bed deaths girls in colonial America girls in India, China