Ecology Lecture 6

Important Upcoming Dates

• BIOL 1011 Final Exam: Thursday, April 10, at 8:30 a.m., Dalplex
  • Exam duration: 2.5 hours
  • Format: 70 multiple-choice questions (35 on Ecology & 35 on Animal Biology)
• Accommodations: Submit exam booking to Accommodate by Friday, March 14 (important for accommodation verification)
• Registration for 2025/2026 courses: Opens Wednesday, March 19 (check Dal Online for specific registration times)

Intro Bio Workshop

• When: Most Fridays, 1:35-2:25, LSC 244
  • Next Topic: Community Structure + Concrete Examples (March 7)
  • Registration: Not required, all welcome; check Brightspace for details.

Academic Programs and Advising Fair

• Event Date: Friday, March 7, 11:30 am to 1:30 pm, McInnes Room, SUB
  • Purpose: Opportunity to talk to faculty advisors in Science and other programs, ask about majors, minors, honors, and certificates.
  • Participants: Representatives from various fields including Biology, Chemistry, Psychology, Marine Biology, and more.

Exam Preparation Notes

• Ecological Concepts: Understand general ecological concepts rather than memorizing specific dates or names.
• Interpreting Equations: Equations will be provided if required; focus on understanding how to interpret them.

Behavioral Ecology

• Natural Selection and Behavior: The relationship between behavior and natural selection focusing on:
  • Survival and Reproduction:
  • Individuals with favorable behaviors have better chances of survival and reproduction.
  • Behavioral effects on individual fitness:
    • Benefit: Increases fitness
    • Cost: Decreases fitness.

Key Terms in Behavioral Ecology

• Fitness: Refers to evolutionary fitness; likelihood of passing on genes.
• Actor: The animal performing the behavior.
• Recipient: The other animals involved.

Key Concepts in Social Behavior

1. Altruism: Actions that benefit others at a cost to oneself.
2. Group Living and Social Organization: Benefits vs. costs of living in groups.
3. Types of Mating Systems: Monogamous, polygamous, and promiscuous.

Social Behavior Costs vs. Benefits

Summary Table

Inclusive Fitness

• Definition: Total impact on gene passing through
  1. Producing offspring
  2. Helping relatives produce more.

Kin Selection

• Concept: Acts that promote reproductive success of relatives, sharing a proportion of genes.
• Hamilton’s Rule: Natural selection favors acts if C < r imes B
  • C = Cost to altruist
  • r = Relatedness (shared genes)
  • B = Benefits to recipient (increased reproduction)

Relatedness Examples

• Parent-Child: r = 1/2
• Grandmother-Granddaughter: r = 1/4 (can be derived by calculating shared alleles).

Scenarios in Kin Selection & Fitness

1. Scenario 1: Saving a sibling may decrease inclusive fitness (Calculating costs and benefits based on future offspring).
2. Scenario 2: Risk of dying to save a sibling can increase inclusive fitness if costs are outweighed by benefits (cost of future reproduction).

Social Organizations and Group Living

• Benefits: Cooperative feeding, defense, etc.
• Costs: Disease, restricted reproduction.
• Conditions for Evolution of Group Living: Overall benefits must outweigh costs.

Types of Social Structures

1. Cooperative Breeding: Example with wolves and scrub jays.

2. Eusocial Societies: Complex social structure often seen in insects (e.g. ants, bees).

• Role of queen and workers in colony.

Benefits of Kin Selection**

• Sibling Survival: Improved chances due to protection and group living.
• Individual Fitness through Helpers: Gain experience and strength by staying with the group.

Notable Examples

• Naked Mole Rats: Eusocial behavior in defenders and workers; harsh habitat influences group dynamics.

Mating Systems Overview

1. Monogamous: One pair bond.
2. Polygamous: Individuals mate with multiple partners.
3. Promiscuous: Looser bond structures (e.g., Prairie vole).

Environmental Influence on Behavior

• Behaviors are shaped by selection; successful behavior offers a benefit-to-cost ratio that favors survival and reproduction (inclusive fitness and kin selection).