PPT-Population Genetics, Speciation, and Classification

Population Genetics Definition study of evolution from a genetic point of view Microevolution Change in the collective genetic material of a population Within a population individuals may vary in observable traits Scientists use a . The rise and fall of biodiversity. Four major . mass extinctions . of marine organisms:. End of Silurian Devonian, Permian, and Cretaceous). Rise in diversity during Cambrian, Silurian, Cretaceous, and Paleogene. Evolution. Results of evolution. New species (speciation). Causes of evolution. Barriers between same species (gene pools). Geographical isolation -> leads to . allopatric. speciation. Temporal isolation -> leads to sympatric speciation. I. Species Definitions. Species represent the boundary for the spread of alleles . and define the unit in which the modes of evolution operate. Biological Species Concept. Individuals belong to the same species if they can interbreed with each other. Brian O. ’. Meara. EEB464 Fall . 2015. http://www.youtube.com/watch?v=lopTMhAbXoI. Initiation of speciation. Maintenance of current species. Prezygotic. Postzygotic. Zygote image © Laboratoire de Biologie de la Reproduction; Lausanne, image downloaded from . Concept 22.2: Speciation can take place with or without geographic separation. Speciation can occur in two ways. Allopatric speciation. Sympatric speciation. Allopatric (. “. Other Country. ”. ) Speciation. Species. == “kind” or “type” in Latin. Typological . (morphological) species. . == a group of organisms that share certain characteristics which are different than other groups—usually differences in anatomy. . Species. – group of organisms that interbreed and produce fertile offspring. Subspecies. – groups that are on the way to being separate species; have started being genetically different. Individuals in the same species share a common gene pool. Temporal – crickets mature at different times. Prezygotic. isolation. Habitat – land vs. water garter snakes. Prezygotic. isolation. Behavioral – firefly mating. Prezygotic. isolation. Gametic. Objectives. Identify. traits that vary in populations and that may be studied.. Explain. the importance of the bell curve to population genetics.. Compare . three causes of genetic variation in a population.. Reduction in . gene . flow, genetic and phenotypic change in populations. The study of speciation requires that species be real. Speciation. Speciation is the antidote to sex. Keeps together adaptive groups of traits. I. Species Definitions. Species represent the boundary for the spread of alleles . and define the unit in which the modes of evolution operate. Biological Species Concept. Individuals belong to the same species if they can interbreed with each other. Populations must become isolated. Reproductive isolation is key!. Once isolated, populations will evolve independently (different factors affecting each). Two types of speciation. allopatric. geographic separation. In evolutionary terms a . species . is a group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring; they do not breed successfully with other . (Unit 10, species concept. Sympatric speciation . Sympatric speciation, (from the Greek ‘same place’) involves the splitting of an ancestral species into two or more reproductively isolated groups without geographical isolation of those groups..