BIOLOGY 1M03 Lecture Notes - Lecture 5: Species Complex, Reproductive Isolation, Synapomorphy
Document Summary
1:11 am: 4 constructs for identifying evolutionary change, biological species concept, critical criterion for identifying species is reproductive isolation, no gene flow occurs b/w populations that are reproductively isolated from each other. Placenta is a synapomorphy that distinguishes placental mammals as a monophyletic group, distinct from monophyletic group called marsupials. Synapomorphies can be identified at the genetic, developmental, or structural level. Researchers use dna sequencing to identify synapomorphies and estimate phylogenetic trees. Species are defined as the smallest monophyletic groups on the tree of life: case study (application of all 4 concepts) dusky seaside sparrows. Isolation and divergence in allopathy: genetic isolation happens routinely when populations become physically separated. Physical isolation, in turn, occurs in one of two ways: dispersal(colonist establish new population in novel location) Natural selection may extend rapid divergence to population: vicariance(widespread population becomes fragmented into isolated subgroups; via.