What This Document Is
This is a laboratory exercise designed to accompany a course in phylogenetics – the study of evolutionary relationships. Specifically, this lab focuses on methods for evaluating whether observed patterns in character distributions (traits) among organisms are due to shared evolutionary history or random chance. It explores the use of “null models” – statistical comparisons against randomized data – to test for phylogenetic signal. The lab utilizes the software package Mesquite for data analysis and visualization.
Why This Document Matters
This resource is ideal for students enrolled in evolutionary biology, ecology, or phylogenetics courses. It’s particularly helpful for those seeking practical experience in applying statistical methods to phylogenetic data. This lab will be most beneficial when you are learning to interpret phylogenetic trees and assess the strength of evidence for evolutionary relationships, and when you need to understand how to rigorously test hypotheses about character evolution. Access to the full content will allow you to build a strong foundation in phylogenetic analysis.
Topics Covered
* Phylogenetic signal detection
* Null model generation and application
* Parsimony reconstruction of ancestral states
* Discrete character evolution
* Tree simulation methods (Yule, Equiprobable Trees)
* Statistical hypothesis testing in a phylogenetic context
* Evaluating the impact of tree topology on character evolution
What This Document Provides
* A step-by-step guide to using Mesquite for phylogenetic analysis.
* Detailed instructions for generating and comparing different null models.
* Exercises designed to help you interpret the results of statistical tests.
* Questions prompting critical thinking about the assumptions and limitations of different analytical approaches.
* A framework for understanding how to assess the significance of evolutionary patterns.
