Evolution

Question 1

Adaptations

Answer 1

Biological traits that make an individual better suited to survive and reproduce in its habitat

Question 2

4 Basic Mechanisms of Evolution

Answer 2

• Mutation
• Genetic drift
• Migration
• Natural selection

Question 3

Natural Selection

3 factors for it.

Answer 3

Mechanism of evolution; Differential survival and reproduction of organisms as a result of heritable differences between them.

3 Factors of Natural Selection:

• Variability
• Differential reproduction
• Heritability

Question 4

Selective Transmission

Answer 4

Traits best for survival and reproduction will be reproduced at higher rates

Question 5

Stabilizing Selection

Answer 5

• Selection AGAINST departure from species typical adaptive design
• Bell curve shaped
• Keeps traits stable over generations

Question 6

Darwin’s Finches Example in Natural Selection

Answer 6

• Drought caused elimination of small seeds, leaving only large seeds
• Only birds with big beaks able to eat hard seeds
• Small beaked birds died off
• Offspring in next generation had bigger beaks

N.S conditions met: Big beaks are a heritable trait, beak size varied in the population, those with big beaks had better reproductive success.

Question 7

Darwinian Fitness

Answer 7

The reproductive success of an individual: How well an organism survives and produces viable offspring relative to others in the population

• Average reproductive success of a genotype relative to alternative genotype
• Natural selection aims to maximize fitness of individuals

Question 8

Evolution

Answer 8

Change in gene frequencies over generations

• Due to intro of new gene variants via mutations

Question 9

Sexual Selection

Answer 9

• The component of natural selection that acts on traits that influence an organism’s ability to obtain a mate
• Results in differential reproductive success
• Includes intersexual and intrasexual selection

Question 10

Intersexual Selection

Answer 10

• Interactions between different sex that determine sexual success
• Females choose their mates

Question 11

Intrasexual Selection

Answer 11

• Interactions with the same sex that determines sexual success
• Males compete with eachother for mates

Question 12

Trade-Offs in Sexual Selection

Answer 12

• Traits that are advantageous in sexual success may hinder physical survival
• Increases fitness nonetheless due to passing down traits –mating
• Survival promoted through evolution of mating traits being seasonal (Elk antlers, etc.)

Question 13

Species Characteristic Behaviours

+ Sand Pipers

Answer 13

• Evolved behaviours specific to a species that increase fitness
• Topography, habitat, group size, social systems…
• Example: Difference in foraging strategies across sandpiper species

Question 14

4 Types of Social Behaviour (actor/recipient)

Answer 14

1. Cooperation (+/+)
   * Reaps more benefits than selfishness
2. Selfish (+/-)
3. Altruism (-/+)
4. Spite (-/-)

Question 15

Foraging in Groups

Answer 15

• Increases success for finding food
• Individuals spend less time vigilantly scanning
• More individuals can forage, while others scan for predators

Question 16

“Good of the Group” Myth

Answer 16

• Natural selection cares about the gene, not the group
• Altruism cannot be explained by a gene
• Those with altruism gene will have decreased fitness and go extinct
• Altruism exists due to indirect fitness

Question 17

Direct Fitness

Answer 17

Fitness from personal reproduction

Question 18

Indirect Fitness

Answer 18

Fitness from the reproduction of close genetic relatives

• Can be increased by helping kin to successfully raise offspring
• Explains altruistic behaviours

Question 18

Inclusive Fitness

Answer 18

• Combined fitness of one’s own offspring and the offspring of their relatives
• Direct + Indirect Fitness

Question 19

Hamilton’s Rule

Answer 19

Altruistic behaviour will occur if:
rB > C
* r: Degree of relatedness of the two individuals
* C: Reproductive cost to actor
* B: Reproductive benefit to recipient

Question 20

Determining Relatedness

Answer 20

Relatedness is the probability that the actor and recipient share the gene in question.
* Depends on inheritence and family tree… parents and siblings share 50%, aunts and grandparents share 25% (.50x.50)

Question 21

Eusocial Hymenoptera

Answer 21

• Level of social organization where individuals spent lives serving colony without reproducing
• Occurs due to relatedness and Hamilton’s rule
  * Members of colony support the reproductive success of few individuals that will pass down their traits
• Altruistic behaviour
• Example: Honey bees!

Question 22

Cues of Kinship

Significance?

Answer 22

Significant for altruism, social behaviours, and preventing inbreeding (decreased fitness)
1. Those who live close to you / neighbours
2. Mother’s association
* (Caring for you since birth, recognizing her very early on)
3. Co-residence with other children (Siblings)
4. Phenotype Matching: Evalation of relatedness based on assessment of phenotypic similarity

Question 23

Phenotype Matching Influence on Humans

Answer 23

Debruine’s Investment Game Studies show that individuals trust and share more often with those who resemble them.

• P1 has $4: could untrust P2 and divide money equally OR trust P2 and potentially earn more money
• P2 has control over more money: could share equally w P1 or $1 to P1 (selfish)
• P1 can make the most money by trusting P2 to share equally
• P2 can make the most money by betraying P1
• P1 would be more trusting of a P2 that looks like them – cue of relatedness

Question 24

Reciprocity ## Footnote Direct and Indirect

Answer 24

Explains why we still help those who don't look like us / do not indicate **relatedness.** * **Indirect reciprocity:** People help others that have helped others * Establishes a good reputation * **Direct reciprocity:** Individuals help each other and both benefit

Question 25

Squirrels and Altruism

Answer 25

* Alarm calls by squirrels are an altruistic warning of approaching predators * Eliciting a call increases individual's own risk * Females give calls more often as they live near kin their whole lifetime * Cost to themselves offset by **indirect fitness** * Males give less calls as they disperse * Only few of surrounding squirrels share his genes, so benefit to indirect fitness is much smaller

Question 26

Applications of Relatedness in Humans

Answer 26

* 6% of homicide cases comitted by genetic relatives (much lower when including in-laws and relationships, in which it is 25%) * **Cinderella Effect:** Higher rates of child abuse amongst stepchildren than biological children

Question 27

Parent-Offspring Conflict

Answer 27

The conflict that arises from differences in optimal parental investment form the viewpoints of the parents and offspring * What maximizes parental fitness differs from what maximizes offspring fitness * You are twice as valuable as your sibling since your child will have twice as many of your genes * Parents think you are equally valuable, so resources divided equally * Offspring must fight for resources

Question 28

Cues to Fertility and Quality

Answer 28

Traits that will contribute to healthy offspring. * **Fluctuating Asymmetry:** Measure of bilateral traits that are symmetrical over the population * Optimal body can indicate health * How masculine/feminine an individual appears * Appropriate levels of hormones * **Waist to hip ratio:** Low in women, high in men

Question 29

Expense of Gametes

Answer 29

Eggs are more expensive than sperm. Influences how males and females increase reproductive success: * Females invest more into offspring (compared to males) * Males invest less into offspring, more into re-entering gene pool more often (having more mates)

Question 30

Paternal Uncertainty ## Footnote Different jealousies

Answer 30

Men are not certain of their paternity the same way women are. * Males evolved to avoid **cuckoldry** – Investing less in offspring in case it is not their genetic offspring * Results in more **sexual jealousy** where woman has sex with others * Women more prone to **romantic jealousy** where a man leaves relationship to form a new one

Question 31

Outcome Variance in Reproductive Success | What does this signify?

Answer 31

* Men have a higher variance in reproductive success than women * Loosely gathered around mean – wider range of outcomes Significance: * Explains risk-taking behaviour: If you’re already likely to get nothing, taking risks can be “worth it.” * Connection between homeless men and homicide (a risk!) * Aggression and homicide * Stronger sexual selection