Download Phylogeography: The Historical Biogeography of Species and more Study notes Geography in PDF only on Docsity! 1 Historical biogeography traditionally deals with relationships among species, genera, and higher taxonomic groups and the areas they occupy Phylogeography — Historical Biogeography of the Species Phylogeography — Historical Biogeography of the Species Due to advances in DNA sequencing and fingerprinting methods, historical biogeography has recently begun to integrate relationships of populations within species and the areas they occupy Historical biogeography traditionally deals with relationships among species, genera, and higher taxonomic groups and the areas they occupy Phylogeography — Historical Biogeography of the Species John Avise, animal geneticist at University of Georgia, coined the termed “phylogeography” to describe “the history and formation of species” from a geographical perspective Phylogeography — Historical Biogeography of the Species The classic phylogeographic analysis by Avise and his students involved the identification of a strong geographical signal within species separating populations from the Atlantic seacoast from the Gulf of Mexico seacoast. The presence of two quite distinct genotypes within all these unrelated species has been explained by Pleistocene glacial and inter-glacial events 2 Phylogeography — Historical Biogeography of the Species One of the most debated, and still unresolved, issues in phylogeography is the geographical origin of Homo sapiens - the “Eve hypothesis” as maternally inherited mitochondrial DNA (mtDNA) is often used Phylogeography — Historical Biogeography of the Species The “out-of-Africa” scenario is often supported - as shown here - and is consistent with the fossil record. However, different ways of analyzing DNA support an “out-of-Asia” scenario as well. Phylogeography — Historical Biogeography of the Species Steps in a phylogeographic study 1. Sample populations widely across geographical range of species 3. Identify and quantify genotypes for each population [haplotypes if cpDNA or mtDNA] 2. Sample multiple individuals from each population to access levels of variation in cpDNA, mtDNA, or nuclear genes Map of the populations and distribution of haplotypes of Cedrela odorata (Spanish cedar) across Mesoamerica (Cavers et al. 2003) Phylogeography — Historical Biogeography of the Species Steps in a phylogeographic study 4. Construct minimum spanning tree for the haplotypes 5. Overlay geographical distributions onto the tree (or use Nested Clade Analysis in complicated studies) Minimum spanning tree of five haplotypes and their geographic locations for Cedrela odorata (Spanish cedar) (Cavers et al. 2003)
