PPT-1 1 . Patterns of speciation and extinction

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. Speciation. – formation of a new species . 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. EVOLUTION #1 (Group 3). Strawberry Frogs Forever. Participants: Lin Xiang. Ingo . Schlupp. Tiffany Roberts. Anne . Grippo. Jerry Farris. Facilitators: Brooke . 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. Meara. EEB464 Fall . 2017. http://www.youtube.com/watch?v=lopTMhAbXoI. Learning objectives. Understand factors that can lead to speciation. Consider the geography of speciation. Describe approaches to . Temporal – crickets mature at different times. Prezygotic. isolation. Habitat – land vs. water garter snakes. Prezygotic. isolation. Behavioral – firefly mating. Prezygotic. isolation. Gametic. Sympatric Speciation. Sympatric Speciation occurs . without. geographic isolation, thus it occurs at a local level. . There is something within the environment that keeps a single species separated into two or more distinct groups.. 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. What defines a species?. Species: a group of organisms that can . interbreed. and produce . fertile. offspring. “Biological Species Concept” . Human species?. Homo sapiens – “wise man” (large brains!). Essential Questions. What is extinction?. Which species have become extinct in modern times? . What are the characteristics of past mass extinctions? . How do modern extinction rates compare with natural (background) rates?. 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 . After reading this module you should be able to. Explain . the processes of allopatric and sympatric speciation.. U. nderstand . the factors that affect the pace of . evolution.. Speciation can be allopatric or sympatric. Microevolution to Macroevolution. Biological Species . Reproductive Isolation. A group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring. The existence of biological factors (barriers) that impede members of two species from producing viable, fertile, offspring.