Notes on Social Behaviour and Cooperation in Animals

Beyond BIO: Optional Activities for BIO220 Students
  • Purpose: Fun and informative events for BIO220 students.
  • Location for More Info: Quercus under Modules → Beyond BIO.
Upcoming Events:

  • High Park Nature Walk

    • Date: Saturday, March 8th
    • Sign-up: Available via link on Quercus.
    • Description: Explore wildlife in one of Toronto’s largest natural parks (e.g. songbirds, mammals, turtles).

  • BIO220 Talks: Research and Grad School

    • Date: Wednesday, March 12th, 11:10 am – 12:00 pm
    • Location: Room SS 1084, Sidney Smith Hall (100 St. George)
    • Topics: Research at U of T and experiences with grad school by TAs.
    • Refreshments: Free coffee and snacks provided.
Topics to be Discussed at the Talk:
  • Climate Change
  • Population Dynamics
  • Conservation Policy
  • Temperature-dependent Sex Determination
  • Geographical Trends
  • Behavioural & Sensory Ecology
  • Macroevolution
  • Reproductive Isolation
  • Speciation
  • Genetics
  • Freshwater Ecology
  • Urban Waterways
  • Ecotoxicology
  • Microplastics
  • Extinction Risk Assessment
  • Applying for Grad School
  • Day-to-Day Grad School Life
Lecture 16: Social Behaviour: Cooperation & Altruism
  • Outline:
    1. Definitions of cooperation and altruism
    2. Shared direct benefits
    3. Reciprocity
    4. Kin selection
Key Definitions:
  • Altruism: Behaviour increasing another individual's fitness at a cost to one's own fitness.
  • Cooperation: Behaviour benefiting both individuals when adopted by two or more individuals.
Social Behaviour Implications
  • Challenges traditional evolutionary theory by natural selection.
  • Darwin's Quote (1859): Expressed difficulty in explaining why individuals increase fitness of others at the cost of their own.
Shared Direct Benefits
  • Key Concepts:
    • Cooperation can yield immediate benefits.
    • Example: Cooperative breeding where offspring survival increases through shared parenting efforts.
Game Theory Introduction
  • Components:
    • Players, Strategies, Pay-off schedule.
  • Hawk-Dove Game:
    • Contest for resources between aggressive (Hawk) and peaceful (Dove) strategies.
    • Payoff matrix showing outcomes based on strategies adopted.
Payoff Matrix Analysis
  • Strategy Outcomes: Dependent on rewards and cost of fighting.
  • Example with Payoffs: If reward ($R$) > $2 imes$ cost ($C$), prefer Hawk strategy.
Reciprocity
  • Concept: In repeated interactions, cooperation might be beneficial compared to selfishness.
  • Iterated Prisoner's Dilemma: Examines how cooperative strategies evolve.
Prisoner’s Dilemma Basics
  • Two players choose to cooperate or defect; outcomes vary based on choices made.
  • Best Strategy: "Tit for Tat" - starts cooperative and follows partner's last move.
Evolution of Reciprocity in Species
  • Apply iterated prisoner’s dilemma to animal behaviour during predator inspections.
Kin Selection
  • Definition: Selection based on genetic relatedness impacts altruism.
  • Hamilton’s Rule:
    • c=extCostofaltruismtoactorc = ext{Cost of altruism to actor}
    • b=extBenefitofaltruismtorecipientb = ext{Benefit of altruism to recipient}
    • Condition: b imes r > c
Altruism in Social Amoebae
  • Example: Dictyostelium discoideum
    • Behaviour: Forms stalk to allow spores to disperse under resource scarcity.
    • Shows kin discrimination in aggregating behaviour.
Summary of Evolution by Natural Selection & Cooperation
  • Natural selection increases frequency of alleles based on reproductive success but cannot favor self-sacrificial genes.
  • Self-sacrificial behaviour can propagate if relatedness facilitates the reproduction of those genes.
  • Cooperation can evolve through shared benefits, reciprocity, and kin selection.