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Introduction to Lizard Evolution Lab

  • Objective: Understand the evolution of lizard species, particularly anoles, through various modules that simulate research methodologies.

Modules Overview

  • Module 1: Ecomorphs

    • investigates body characteristics and ecological niches of anole lizards.

    • Approximate duration: 1 hour 30 minutes.

    • Key Activity: Measure lizards from four different ecomorph groups.

  • Module 2: Phylogeny

    • explores evolutionary relationships via DNA analysis.

    • Approximate duration: 15 minutes.

    • Activity: Build a phylogenetic tree to visualize evolutionary linkage.

  • Module 3: Experimental Data

    • examines effects of habitat changes on lizards of a specific ecomorph.

    • Approximate duration: 30 minutes.

    • Activity: Collect and analyze experimental data involving lizard behavior and traits.

  • Module 4: Dewlap Colors

    • studies the role of dewlap colors in attraction and speciation.

    • Approximate duration: 15 minutes.

    • Activity: Characterize lizards based on dewlap coloration.

Module 1: Ecomorphs

  • Key Concepts:

    • Caribbean hosts about 150 species of anole lizards.

    • Observations of habitat and morphological differences lead to identification of evolutionary patterns.

    • Focus on eight species:

      • Puerto Rico: A. pulchellus, A. evermanni, A. cristatellus.

      • Hispaniola: A. cybotes, A. olssoni, A. coelestinus.

Measuring Lizards' Traits

  • Measurement of body lengths, hindlimbs, tails, and toepads using images.

  • Variability of traits can provide insights into evolutionary significance.

Module 2: Phylogeny

  • Ecomorph Group Findings:

    • Trunk-crown: A. celestinus, A. evermanni.

    • Trunk-ground: A. cybotes, A. cristatellus.

    • Twig: A. sheplani, A. occultus.

    • Ground-bush: A. pulchellus, A. olssoni.

  • Understanding of evolutionary relationships through mitochondrial DNA analysis.

Building a Phylogenetic Tree

  • Approach: Use DNA sequences from the ND2 gene and tRNA genes to show evolutionary connections.

  • Analysis: Trees depict relationships among species but can vary from one instance to another. Similar overall structures affirm evolutionary lineage.

Reading a Phylogenetic Tree

  • Structure: Closely related species appear together; branched lines indicate diverging evolutionary paths.

Hypotheses from Tree Coloration

  • Patterns in relationships can indicate:

    • Independent evolution of species.

    • Possible migration and speciation based on physical traits and island geography.

Module 3: Experimental Data

  • Investigates whether specified traits are adaptations by exploring how traits affect success in different environments.

  • Experiment setup involves monitoring the behaviors of lizards introduced to varying island environments.

Module 4: Dewlap Colors

  • Examines the correlation between dewlap color and environmental adaptations, comparing A. cristatellus and A. cooki.

  • Measurement: Assign brightness scores based on dewlap color to analyze preferences and visibility in respective habitats.

Key Findings

  • Dewlap colors are adaptive traits that assist in mate attraction within specific environments.

  • The findings emphasize the role of habitat on the evolution of visible traits, promoting reproductive isolation among anole species and potentially leading to speciation.