BIOB51H3 Lecture Notes - Lecture 12: Common Descent, Brca1, Histidine
Document Summary
Analysis of genetic diversity helps us to understand evolutionary history: assessing genetic history within a species requires a modified interpretation of phylogeny. Phylogenies use morphology and dna: both are based on homologous characters. Morphology e. g. , phylogeny of birds and dinosaurs: character might be in the presence or absence of feathers. Dna e. g. , phylogeny of field crickets: character might be whether they have an a or g at a second position in a codon that confers whether a histidine or adenine is encoded in the protein of a gene. Common ancestry is explained by: homology in their bones, regions of their genomes. We can track the paths of alleles over time. Note, there are other alleles in the population, we are just tracking the history of for example the turquoise alleles. The change from g to t represents a genetic synapomorphy. The ancestral allele (g) now coexists with the next allele (t) creating a polymorphism in the population.
