Social Behavior Hermits must have lower fitness than social individuals Use of Space Clumped, random, or dispersed (variance/mean ratio) mobility = motility = vagility (sedentary sessile organisms) Philopatry Fluid versus Viscous Populations Coarse-grained versus fine-grained utilization Individual Distance, Daily Movements Home Range Territoriality (economic defendability) Resource in short supply Feeding Territories Nesting Territories Mating Territories

Sexual Reproduction Monoecious versus Diecious Evolution of Sex —> Anisogamy Diploidy as a “fail-safe” mechanism Costs of Sexual Reproduction (halves heritability!) Facultative Sexuality (Ursula LeGuin -- Left Hand of Darkness) Protandry -- Protogyny (Social control) Parthenogenesis (unisexual species) Possible advantages of sexual reproduction include: two parents can raise twice as many progeny mix genes with desirable genes (enhances fitness) reduced sibling competition heterozygosity biparental origin of many unisexual species Protandry —> Protogyny —>

Sexual Selection Mating Preferences Sex that invests the most is the most choosy about mates Competition for the best mates of the opposite sex Jealousy, Desertion, Cuckoldry Certainty of Maternity, Uncertainty of Paternity Epigamic selection (intersexual, between the sexes) “ Battle of the sexes ” Natural selection produces a correlation between male genetic quality and female preference “ Sexy son ” phenomenon (females cannot afford to mate with males that are not attractive to other females)

Intrasexual vs. intersexual (epigamic) sexual selection Mating preferences in Drosophila and pigeons Certainty of Maternity, Uncertainty of Paternity “Battle of the sexes” Cuckoldry —> jealousy Desertion —> Mating Rituals, Complex Courtship Sex that invests most in most choosy about mates Natural selection produces a correlation between male genetic quality and female preference “Sexy son” phenomenon (females cannot afford to mate with males that are not attractive to other females) Mating systems, monogamy, polygamy, polygyny threshold Marsh nesting (wrens, blackbirds, jacanas) Pinniped harems and sexual size dimorphisms Floating populations of non-breeding males

Mate Choice Experiments Drosophila subobscura Side-step courtship dance Females mated to inbred males: 264 fertile eggs, 50% mated Females mated to outbred males: 1134 fertile eggs, 90% mated

Nancy Burley ’ s Mate Choice Experiments Nancy Burley Nancy Moran

Mate Choice Experiments

Mating Systems Promiscuity Monogamy Polygamy Polygyny Polyandry Polygyny threshold: minimal difference in male territory quality that is sufficient to favor bigamous matings by females Long-billed Marsh Wren Jared Verner

Quetzal

etzel puted to be morphic

Leks Runaway Sexual Selection (Fisher) Handicap Hypothesis (Zahavi) Sensory Exploitation Hypothesis (Ryan) Alternative mating tactics Internal versus External Fertilization Satellite males Ecological Sexual Dimorphisms Bower birds Ratites Bushland tinamou

Male Atwater Prairie Chicken

Dinosaur fossils suggest that male parental care could be ancestral in birds If so, ratites could have retained the ancestral state And, if so, then female care and biparental care would be derived conditions A male of the medium-sized predatory dinosaur Troodon (North America late Cretaceous) brooding a clutch of eggs. Female archosaurs extract substantial amounts of calcium and phosphorus from their skeletal tissues during egg formation. Histologic examination of cross sections of bones (femur, tibia, and a metatarsal bone) from an adult Troodon found in direct contact with an egg clutch revealed little evidence of bone remodeling or bone resorption, suggesting that the bones were those of a male. Fossilized remains of Troodon and two other types of dinosaurs found with large clutches of eggs suggest that males, and not females, protected and incubated eggs laid by perhaps several females (Credit: Bill Parsons)