BIOSC 0160 Lecture Notes - Species Problem, Anagenesis, Introgression
Document Summary
Chapter 26: speciation: production of two or more new species from a single ancestral species. What is a species: biological species concept, pioneered by ernst mayr, groups of co-specifics (same species, potential to interbreed, cannot interbreed with other such groups, problems with this theory. Can"t be done for all species in the world there are too many: other concepts, morphological. Uses anatomical differences to establish a species. Most common method in practice: cohesion. Integrated sets of adaptations: different from species to species, species cannot interbreed because the adaptations that one have may not work together with another species. Hybrids are at a great selective disadvantage. Isolating mechanisms: species are sexually isolated why, prezygotic mechanisms: before fertilization. Isolation via : habitat; two different species never have the opportunity to interact and mate, behavior; species-specific mating habits, time; different reproductive seasons between species. Incompatible reproductive anatomy: gamete incompatibility, postzygotic mechanisms: after fertilization.
