BIOLOGY 1M03 Lecture Notes - Lecture 1: Ichthyosaur, Ribosomal Rna, Even-Toed Ungulate
11 Dec 2015
School
Department
Course
Professor
Document Summary
Estimating phylogies: maximum parsimony (cladistics) and phonetics (distance) analysis. Researchers analyze characteristics of species (genetic, morphological, behavioural, etc) to infer phylogenetic relationships among species. There are four general strategies for using data to estimate trees: the phonetic (distance), cladistics (maximum parsimony), maximum likelihood, and bayesian. The phonetic approach is based on computing a statistic that summarizes the overall similarity among taxa. A maximum parsimony approach attempts to minimize the number of changes on a tree that are needed to explain the observed: data consider trait evolution on many phylogenies select the phylogeny with the least number of changes. The cladistics (maximum parsimony) approach to inferring trees focuses on synapomorphies, the share derived characters of the species under study. Said another way, a synapomorphy is a trait that certain groups of organisms have that exists in no others. There are many cases where characteristics are similar but did not arise together.
