Second Exam: Thursday 29 OctoberCovers Chapters 5, 8, 9, and 10Lectures 10 to 19 plus Agriculture Global Warming The Vanishing Book of Life on Earth Plastics Intelligent Design?The Weakest Link TechnologyEconomics

Lecture # 1722 October 2015

Sexual Selection

Mating Preferences

Certainty of Maternity, uncertainty of paternity Competition for the best mates of the opposite sex Sex that invests the most is the most choosy about mates Jealousy, Desertion, Cuckoldry

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 matewith males that are not attractive to other females)

Sexual Selection Mating Preferences

Drosophila subobscura

Inbred versus outbred male flies differed in viable sperm counts.Females mated to inbred males laid an average of only 264 eggs,whereas females mated to outbred males laid 1134 fertile eggs.

Within an hour, virgin females exposed to outbred males mated 90%of the time but only 50% of those exposed to inbred males matedduring the first hour. Female side-step dance courtship display.

Sexual SelectionMating Preferences Mate Choice Experiments

Nancy Burley Nancy Moran

BlueCheck

Blue Bar

Ash Red

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Columba livia

Sexual Selection

Mating PreferencesSex that invests the most is the most choosy about matesCompetition for the best mates of the opposite sexJealousy, Desertion, CuckoldryCertainty of Maternity, Uncertainty of PaternityEpigamic 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)

Sexual Selection

Mating PreferencesSex that invests the most is the most choosy about matesCompetition for the best mates of the opposite sexJealousy, Desertion, CuckoldryCertainty of Maternity, Uncertainty of PaternityEpigamic 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)

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

Jacana, Lily Pad Walker -- Polyandry

Polygyny threshold: minimal difference in male territory quality that

is sufficient to favor bigamous matings by females

b = Polygyny threshold

etzelputed to bemorphic

Male Peacock, a victim of female mating preference

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

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 large 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)

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Red-eyed Vireo