Animal Behavior: Signals, Emotions, and Sexual Selection

Signals

Evolved displays modifying receiver behavior for sender's benefit.

Cues

Incidental information transfer without sender's benefit.

Ovulation in Chimps

Example of a signal indicating reproductive status.

Ovulation in Humans

Example of a cue, not directly beneficial.

Unforced Honesty

Honesty where sender and receiver's interests align.

Forced Honesty

Honesty despite conflicting interests of sender and receiver.

Bears Marking Trees

Example of enforced honesty in animal behavior.

Primary Emotions

Basic, inborn emotions like fear and fight response.

Secondary Emotions

Complex emotions evaluated and reflected upon cognitively.

Private Mind Problem

Inaccessibility of others' thoughts and feelings.

Adaptive Value of Jealousy

Facilitates prey-guarding and mate-guarding behaviors.

Adaptive Value of Joy

Encourages play through dopamine release in the brain.

Adaptive Value of Grief

Non-adaptive byproduct of love, learning danger.

Adaptive Value of Love

Enhances mating success and offspring care.

Adaptive Value of Embarrassment

Promotes adherence to social norms and reciprocity.

Mirror Neurons

Neurons firing during both action and observation.

Mechanists Analysis

Focus on hormonal spikes related to emotions.

Fitness Analysis

Evaluates how emotions enhance survival and reproduction.

Honest Visual Signals

Displays of size and strength, like deer antlers.

Handicap Signals

Costly signals indicating fitness, like widowbird tails.

Optimal Signal Point

Greatest distance between benefit and cost lines.

Social Costs of Cheating

Aggressive punishment for dishonest signaling in groups.

Deception

Common across species, not within species.

Receiver Benefit

Attention to signals benefits the receiver.

Sexual Selection

Selection for traits enhancing mating success. focuses on traits that enhance an individual's ability to acquire mates

Natural Selection

Survival of the fittest; includes sexual selection.

Secondary Sex Characteristics

Traits like antlers or plumage for mating.

Sexual Dimorphism

Differences in appearance between sexes.

Monogamy

One male and one female mate exclusively.

Polygyny

One male mates with multiple females.

Polyandry

One female mates with multiple males.

Polygynandry/promiscuity

Multiple males and females form mating groups.

Mate Preference

One sex chooses mates based on traits.

Gamete Investment

Energy spent on gamete production varies by sex.

Eggs

Large, immobile, food-rich female gametes.

Sperm

Small, mobile male gametes.

Parental Investment

Energy devoted to offspring care varies by sex.

Reproductive Success (RS)

Females limited by egg production resources.

Genetic Diversity

Offspring benefit from varied genetic backgrounds.

Allele Sterility

Same allele in honey bees leads to sterile males.

Non-monogamous species

Species where individuals mate with multiple partners.

Sperm competition

Competition among sperm from different males.

Elaborate penises

Traits evolved in species with multiple female partners.

Monogamy

Mating exclusively with one partner.

True monogamy

Rare form of monogamy with exclusive mating.

Social monogamy

Living in pairs without sexual exclusivity.

Goodwife hypothesis

Females need male help to raise offspring.

Danger hypothesis

Risk of males leaving to find mates.

Pop 'Em out hypothesis

Short brood intervals discourage mate searching.

Sociopath hypothesis

Aggressive individuals have more surviving offspring.

Mutually assured destruction

Cheating leads to reproductive failure for both partners.

Biodiversity decline

Global reduction in species variety.

Dilution effect

Loss of diversity reduces disease transmission risk.

Asexual reproduction

Reproduction without gamete exchange.

Sexual reproduction

Reproduction involving gamete exchange.

Gamete size difference

Females produce fewer, larger gametes.

Sex ratio

Proportion of males to females in a population.

Operational sex ratio

Ratio of males to females actively seeking mates.

Male-biased

More males available in the mating pool.

Female-biased

More females available in the mating pool.

Sexual dimorphism

Systematic differences between sexes in a species.

Resource Defense Polygyny

Males control resources to attract females.

Female Defense Polygyny

Males defend resources to access females directly.

Leks

Mating arenas where males display for females.

Scramble Competition Polygyny

Males race to find widely dispersed females.

ESS

Stable strategy maintained by natural selection.

Hawks vs Doves

Two strategies in frequency-dependent selection.

Positive Frequency Dependent Selection

Majority phenotype has fitness advantage.

Negative Frequency Dependent Selection

Minority phenotype gains fitness advantage.

Fitness

Reproductive success of an individual.

Same-Sex Behavior

Non-adaptive behavior due to mistaken identity.

Reciprocity

Exchange of fitness benefits between individuals.

Instant Reciprocity

Immediate exchange of benefits, e.g., egg trading.

Delayed Reciprocity

Future benefits exchanged after recognizing cheats.

Female Dispersion

Influences the mating system and competition.

Mating Success Variation

Large differences in male mating success observed.

No Male Parental Care

Males do not provide care for offspring.

Traditional Display Sites

Locations where males aggregate to attract females.

High Fitness Male

Male with superior traits preferred by females.

Mating Season

Time frame when females are receptive to mates.

Epigenetics

Gene regulation influenced by environmental factors.

Birth Order Effect

Older brothers increase likelihood of male homosexuality.

Cumulative Fitness Gain

Overall fitness increase from reciprocal interactions.

Hypotheses for same sex mating behavior

- Same-sex behavior might occur because of weak sex discrimination

- Same-sex sexual behavior arises as a byproduct when selection acts on a separate trait, such as high sexual responsiveness

- Social bonds

- practice

- raising offspring

In general, females prefer traits that deviate from the population mean, in the direction of _______ __________

Greater Quantity

Why is choosiness costly?

- increased predation risk on the female

- increased predation risk on nest & offspring

- loss of time and energy

- investment required into cognitive adaptations

- male harassment

- females who are too choosy may never mate

Quality

Overall phenotypic and genetic constitution; high quality individuals 'better' than low quality individuals

Altruism

An altruistic behavior is one that benefits another individual at some cost to the altruist

Natural selection favors altruism toward kin because helping relatives, even at a cost to oneself, can increase the propagation of shared genes.

Kin Selection

Genetic contribution to next generation influenced by:

- Direct fitness

- Indirect fitness

Inclusive fitness = Direct + Indirect fitness

The coefficient of relatedness

the probability that the alleles in one individual are identical copies, due to common ancestry, of alleles in another individual

Calculate r : raise ½ to a power equal to the number of links in a pedigree separating two relatives and then sum independent paths involving each common ancestor

parent-offspring conflict

the evolutionary conflict arising from differences in the optimal amount of parental investment from the perspective of the parent and the offspring.

Siblicide

killing your siblings so you don't have to compete with them

sexual conflict

the evolution of phenotypic characteristics that confer a fitness benefit to one sex but a fitness cost to the other

sneakers

animals that steal from others

Monogamy Hypotheses

Lekking mating system

males gather in groups called leks and display their mating displays for potential mates

Direct fitness

refers to an individual's own reproductive success, meaning the number of offspring they produce and raise successfully.

Indirect fitness

the fitness that an individual gains by helping relatives pass on copies of their genes

Inclusive fitness

sum of an individual's direct and indirect fitness.

Parental favoritism

when one or both parents allocate an unfair amount of valuable resources to one child over others