BIOL1012 Lecture Notes - Lecture 6: Allopatric Speciation, Trichoderma Reesei, Grizzly Bear
Document Summary
Hybridization: biological barriers are not always complete and hybridization can occur. Systematics is the science dedicated to discovering, organizing and interpreting biological diversity. Phylogenetics is central to contemporary systematics and forms the basis for modern systems of classi cation. Nodes on the tree of life correspond to past speciation events. Phylogenetic inference must be based on homologous character. Convergent evolution can result in analogous character states, which undermine attempts to resolve evolutionary relationships (phylogeny) Molecular characters are typically superior (but not perfect) for resolving evolutionary relationships. In sympatric speciation: a reproductive barrier isolates a subset of a population without geographic separation from the parent species, occurs in the presence of gene ow, sympatric speciation can result from polyploidy, natural selection, or sexual selection. Hybrids are the offspring of crosses between different species with incomplete reproductive barriers. At times stable hybrid populations can be established between two species.
