genetic diversity

Founder's Effect and Genetic Diversity

  • Founder's Effect: When a new population is established by a small number of individuals from a larger population, limiting the genetic diversity of the new population.

    • Initial birds that migrated brought a subset of the total genetic pool.

    • Overcoming inbreeding was crucial for their survival.

    • Success influenced by luck and environmental conditions.

Impact of Environmental Events

  • Environmental Challenges: Severe weather events (e.g., heat waves, temperature spikes) can significantly affect species survival.

    • Example: A prior winter's 90-degree weather led to a lack of seeds for growing season, impacting food availability.

    • Genetic diversity aided in adapting to these environmental changes.

Conservation and Relocation Efforts

  • Human Intervention: Relocation of species to preserve them from environmental threats.

    • Example: Swarm petrels from Turn Islands were moved due to rising sea levels—artificial nesting sites built for them.

    • Species like these are endemic and do not exist elsewhere.

    • Range expansion initiated by human action to enhance population viability.

Bottleneck Effects in Populations

  • Bottleneck Events: Events that drastically reduce population size, leading to loss of genetic diversity.

    • Wildfire Events: Can lead to population bottlenecks, similar to natural events that drastically reduce numbers.

    • Sea Otters: Once removed from their habitat, the population was bottlenecked.

      • Reintroduction led to positive ecological effects (e.g., healthier seagrass, increased algae diversity).

    • Elephant Seals: Historical hunting for blubber led to dramatic population reductions, now slowly rebounding but still facing genetic challenges.

Genetic Diversity and Recovery Challenges

  • Genetic Diversity Loss: Once lost, recovery can be difficult without gene flow from neighboring populations.

    • Bottleneck situations may restrict genetic diversity, complicating adaptation and recovery.

Migration and Gene Flow

  • Key Definitions:

    • Migration: Movement of individuals into a new population; can lead to increased genetic diversity.

    • Gene Flow: Exchange of genetic material between different populations, enhancing genetic diversity.

      • Distinguished from interbreeding within a single population.

      • Important for maintaining population similarity and resilience.

Example Discussions

  • Discussions in class about factors affecting population dynamics, including the relationship between migration and population size.