BIOB51H3 Lecture Notes - Lecture 19: Allele Frequency, Phylogenetic Tree, Directional Selection
Document Summary
Speciation: species lineage of populations that maintains its identity from other lineages and has its own evolutionary tendencies and historical fate, populations with a shared past and shared future on a phylogenetic tree, species are, 1. Evolutionarily independent: mutation, migration, selection and drift operate within each species separately, leads to differences in allele frequencies and genotype across species, species are defined by unique, shared, derived traits, have their own evolutionary tendencies, 2. Species consist of populations connected by gene flow: maintain coherence, gene flow among populations within a species homogenizes allele frequencies, genotypes and phenotypes remain similar within species, shared past and shared future. Hawaiian drosophila: 500-900 species in 2 generations, diverse morphology and habitat use, many endemic to one island, founder hypothesis, predicts, 1. Most closely related species should be found on adjacent islands: 2. Phylogenetic branching (speciation events) correspond to island formation sequence.
