Lecture Notes on Local Adaptation

Lecture 4 - Local Adaptation

Introduction

  • Speaker: Tom Reed from the School of BEES, UCC.

  • The lecture centers on local adaptation and variation within and among species.

Variation at Different Levels

Across Species Variation

  • Examples of finch species:

    • Cactus Finch

    • Sharp-beaked Ground Finch

    • Cocos Island Finch

    • Large Ground Finch

    • Medium Ground Finch

    • Small Ground Finch

    • Warbler Finch

    • Mangrove Finch

    • Woodpecker Finch

    • Small Tree Finch

    • Vegetarian Finch

    • Medium Tree Finch

    • Large Tree Finch

Within-Species Variation

  • Discussion of variation within the same population during different seasons.

  • Refers to seasonal changes affecting identical species.

Within Population Variation

  • Different morphs exist in the same location at the same time.

Geographic Variation

  • Provides examples using various tiger subspecies:

    • Malayan Tiger

    • South China Tiger

    • Bengal Tiger

    • Siberian Tiger

    • Sumatran Tiger

    • Indochinese Tiger

  • Emphasizes a continuum of spatial variation within species.

Fine-Scale Population Differences in Blue Tits

  • Laying dates referenced with proportionate clutch sizes across different populations.

  • Comparative analysis between populations in Corsica and Mainland.

    • Study sites noted: Montpellier and Calvi in Corsica.

Adaptive (Phenotypic) Differentiation

  • Cites Coates et al. (2018) regarding classifications:

    • Subspecies, Varieties, Races

    • Named species, Cryptic species, Confirmed candidate species

    • Phrase named species

    • Discusses different forms of Evolutionarily Significant Units (ESUs):

    • Waples ESU

    • Crandell et al. ESU

    • Fraser, Bernatchez ESU

    • Ryder ESU

    • Mee et al. DU

    • Moritz ESU

    • Moritz MU

    • Avise ESU

  • Historical isolation and genomic divergence are referenced.

Local Adaptation Example: The Spider, Agelenopsis aperta

Case Study 1

  • Spider's feeding preferences are examined across populations:

    • Hedrick, Ann V., and Susan E. Riechert (1989): Found genetic variation in foraging behavior.

  • Arizona spiders attack less vigorously than those in New Mexico (Criterion 1 met).

Testing Genetic Differences: Common Garden Experiment

  • Comparison of behavioral differences across spider populations indicates genetic basis (Criterion 2 met).

  • Spiders from different populations retained differences in behavior when raised in a common environment.

Selection Pressure and Agents of Selection

Criterion 3 Verification

  • Riechert and Hedrick (1990) investigated predation risks:

    • Conducted experiments with bird-exclusion cages to measure spider vulnerability.

    • Determined that spiders in different habitats face different predation pressures (Criterion 3 met).

Summary of Local Adaptation in Agelenopsis aperta

  • Geographic variations in traits indicate riparian spiders are more cautious than grassland spiders.

  • Genetic variations endure in controlled experiments, reflecting local adaptation.

Case Study 2: Fine-Scale Local Adaptation in Brown Trout

Invasive Species Study

  • Westley et al. (2012): Investigated brown trout (Salmo trutta) in Newfoundland.

  • Used reciprocal transplant experiments to test juvenile survival and growth in varied habitats.

  • Findings: Evidence for increased survival of 'home' environments over 'away' in 2 of 3 populations.

Implications of Local Adaptation in Killer Whales

  • Different ecotypes: Resident, Transient, Offshore.

  • Genetic distinctiveness observed through mtDNA analysis.

    • Resident and transient populations show greater mtDNA divergence than between humans and chimpanzees.

    • Behavioral differences are currently untested for genetic basis (Criterion 2 not yet met).

Gene Flow and Local Adaptation in Great Tits

  • Study by Postma and van Noordwijk (2005) explores gene flow's role:

    • Variation among populations reflects local selection's balance with gene flow.

    • Immigrant genes affect populations differently depending on immigration rates.

Geographic Mosaic of Coevolution

Implications on Human Populations and Adaptation

  • Highlights the significance of local adaptation in humans: e.g., adaptations to high altitude environments.

  • Warns of high altitude hazards such as altitude sickness and advises caution.

  • Overall, the lecture emphasizes the importance of observing adaptation in both controlled and natural environments. It provides a comprehensive investigation into local adaptation processes across various species while systematically applying the criteria for determining if local adaptation occurs.