BYU22203 6 Kin selection 2023

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Course Information

Lecture Title

• BYU222-3 Organisms to Ecosystems

• Lecture 14: Cooperation Part 1

Introduction to Kin Selection

• Natural selection appears straightforward but has complexities

Darwin's Concerns

• Sexual Selection: How can maladaptive traits persist?

• Altruism: Why do animals cooperate when selfish behavior could be advantageous?

Altruistic Behaviors in Nature

• Altruistic behaviors counter the selfish model of natural selection.

• Examples of cooperation:

  • Parent spiders caring for young

  • Wild dogs sharing kills

  • Unrelated meerkats babysitting

  • Human blood donations

Understanding Altruism

• Definition: Altruism decreases the actor's fitness while increasing others'. (Skelton 1993)

• Examples include behaviors that incur costs to an individual for the benefit of others.

Existence of Altruism

• Possible reasons for the existence of altruism:

  1. Groups with altruists persist better than selfish groups.

  2. Altruists may ultimately gain benefits.

  3. True altruism exists only in humans.

  4. Other theoretical frameworks exist without conclusive answers.

Evolution of Altruism

• Group selection is widely misunderstood; altruism does not benefit the species directly.

Example Scenario: Group Composition

• Sharing Group: Produces 1 baby per year, survives famine

• Selfish Group: Produces 2 babies, may die from famine

  • Sharing seems beneficial until selfish individuals infiltrate.

• Result: Increase in selfish monkeys undermines sharing behavior.

Consequences of Altruism

• Evolution favors traits that maximize individual reproductive success.

• Traits that are not susceptible to invasion by alternative strategies are termed Evolutionarily Stable Strategies (ESS) (Maynard Smith 1972).

Reasons for Cooperation

• Five main reasons:

  1. Unique nature of humans

  2. Reciprocal altruism

  3. Kin selection

  4. Forced cooperation

  5. Mutualism

• The sequence of discussion may vary.

Human Uniqueness

• Human acts include rescues, adoption, blood donation despite potential fitness costs.

• This may arise from past instincts tied to kin-related interactions.

Game Theory and Cooperation

Example: Game of Chicken

• Scenario of collision risk:

  • Outcomes: Depends on each driver’s willingness to swerve.

• Introducing clear non-swerve signals can alter expected outcomes towards cooperation.

Forced Cooperation in Animals

Example: Shelduck Creche

• Shelducks create a creche for chicks, risking feeding time for vigilance against predators.

• Cooperation may provide indirect benefits for the individual’s offspring.

Cuckoo Parasitism Case

• Reed Warbler feeds cuckoo chicks, even at a fitness cost, due to cognitive resource constraints.

• Simplistic rules help reduce cognitive load, even if they sometimes result in costly mistakes.

Rules of Thumb in Animal Behavior

• Animals use simple cues or 'releasers' to trigger behaviors, leading to refined, efficient responses in situations of uncertainty.

Cooperation and Intelligence

• Poll question regarding expectations for cooperation across different intelligence levels:

  1. More intelligent = More cooperative

  2. Less intelligent = Less cooperative

Relationship Between Intelligence and Cooperation

• The relationship shows:

  • Kin selection more beneficial at lower IQ levels.

  • Reciprocal altruism mainly observed at higher IQ levels.

  • Limited cooperation found in the intermediate intelligence range.

Kin Selection Examples

Parental Care

• Behaviors like shielding offspring from predators serve both direct and indirect fitness advantages.

• Birds may feign injury to protect nests.

Altruism Towards Unrelated Children

• Poll question on motivations to assist unrelated crying children:

  1. Emotional response

  2. Active dislike

  3. Fitness benefits

  4. Evolutionary predisposition

Parental Care Dynamics

• Costs are weighed against future benefits.

• Coefficient of Relatedness (r): A measure of genetic relatedness influencing cooperative behavior, described by Sewall Wright.

Calculating Coefficient of Relatedness

Basic Examples

• Parent-Offspring: r = 0.5

• Siblings: r = 0.5

• Grandparents and Grandchildren: r = 0.25

Coefficient of Relatedness in Aunts and Nephews

Calculation Method

• Employs multiple routes (n) and generational links (L) to determine relationships.

Hamilton's Rule Explained

• Acts are beneficial if the cost (C) to the actor is lower than the benefit (B) to the recipient times the coefficient of relatedness (r).

• Formulation: C < rB

Kin Selection Examples in Aphids

• Aphids alarm others with pheromones, at a cost, to save kin, demonstrating kin selection strategies.

Belding’s Ground Squirrel Behavior

Alarm Calling

• Young males rarely call due to dispersal, while others call based on relatedness.

• Alarm calls are directly related to the cost incurred against their degree of kinship.

Mechanisms of Kin Recognition

• Different criteria such as scent and appearance play roles in recognition, especially in larger groups.

Eusociality in Hymenoptera

Genetic Relationships

• Explained by haplodiploidy; however, relatedness to sisters promotes cooperative breeding over direct offspring production.

Eusociality in Naked Mole Rats

• Social structures benefit raised siblings over direct descendants due to high kinship coefficients within inbred populations.

Conclusion on Kin Selection vs Unrelated Altruism

• Upcoming discussions will cover altruism between unrelated individuals.

Suggested Readings

• Davies, Krebs, and West: Behavioral Ecology

• Alcock: Animal Behavior 10th Ed.

Additional Resources

• Research articles on cooperative and kin selection behavior.

• Online resources and videos for further exploration.