mating and courtship

Sexual Selection

Selection for traits that increase mating success rather than surviva

sexual dimorphism

Males and females are physically different

Fitness

ability to have grandchildren

Anisogamy

◦ Leads to unequal investment

◦ The female invests more

Mutual mate choice

Both sexes are selective

◦ Occurs when costs are borne equally by both sexes

Courtship Rituals

The process that results in two adult animals becoming a couple for the

purpose of mating and producing offspring

Mechanisms of Courtship: Physical Characteristics

Morphological features that assist in obtaining mates

Types of physical characteristics

Body size

◦ Larger animals have advantage in competition

◦ Larger animals can produce more gametes

◦ Weaponry

◦ Horns, antlers, claws

◦ Provide an advantage in competition

◦ Coloration

◦ Vivid color patterns attract attention

◦ Energetically expensive – proof of health

◦ Signals readiness

Mechanisms of Courtship: Behaviors

Patterns of response to environmental signals that assist in obtaining mates

Types of Courtship Behaviors

◦ Vocalizations

◦ Attract attention

◦ Allow individual identification

◦ Expensive – proof of health

◦ Dances and gestures

◦ Attract attention

◦ Pheromone production

◦ Attracts attention

◦ Signals readiness

Arthropods

Weaponry (horns, etc.)

◦ Used in physical combat

◦ Pheromones

◦ Dances

Cephalopods

Body Size

◦ Color displays

◦ “Dances

Fish

◦ Body Size, dances, coloration displays

Amphibians

Body Size, vocalizations

Reptiles

Pheromones (snakes)

◦ Vocalizations (alligators)

◦ Dances (turtles – head bobbing, shell ramming)

Birds

Vocalization (song)

◦ Dances and Gestures

◦ Color displays (bright feathers)

Mammals

Body size

◦ Weaponry (horns, antlers, claws)

◦ Vocalizations

◦ Dances and Gestures

◦ Pheromones

Courtship Patterns in Humans

Humans have little natural ability compared to other animals

◦ Can’t change color, shape, size

◦ Poor sense of smell

◦ Poor sense of hearing

◦ No real weaponry

◦ So: We use tools in courtship

◦ Only animal to do so

Human Courtship and Tools

Visual Displays

◦ Dye, paint, make-up

◦ Clothing

◦ Hairstyle

◦ Expensive products (car, jewelry, etc.)

Vocalizations

◦ Love letters, texting, phone calls

◦ Musical instruments, recordings

Pheromones

◦ Perfume, cologne

Human mate choice is very complicated

Mate selection depends on

◦ Physical appearance/stature

◦ Individual behavior

◦ Courtship tools

◦ Social status/cultural rules

◦ Economics

◦ Legislation

Not all factors count equally

◦ Depends on culture and the individual