Speciation The process by which one species splits

Speciation The process by which one species splits into two or more species

Biological Species Reproductive Isolation � A group of � The existence of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring biological factors (barriers) that impede members of two species from producing viable, fertile, offspring Microevolution to Macroevolution

Prezygotic Barriers Postzygotic Barriers � Habitat Isolation � Reduced Hybrid � Temporal Isolation � Behavioral Isolation � Mechanical Isolation � Gametic Isolation Viability � Reduced Hybrid Fertility � Hybrid Breakdown Reproductive Barriers

AP Edition Campbell Biology 9 th edition Reproductive Barriers

Allopatric http: //www. csus. edu/indiv/l/loom/preview%2027. ht m Speciation Sympatric http: //study. com/academy/lesson/sympatricspeciation-example-definition-quiz. html

https: //www. boundless. com/biology/textbooks/boundless-biology-textbook/evolution-and-the-origin-ofspecies-18/reconnection-and-rates-of-speciation-126/varying-rates-of-speciation-506 -11732/ Speciation Rates Vary

http: //news. mongabay. com/2007/0312 interview_peter_raven. html Species Extinction Rates

Possible Causes Catastrophic Methane Release, Flood basalt eruptions, Climate change, & Impact Events. Five Major Extinctions (names & dates of these extinctions are beyond the scope of this course and the AP exam) http: //www. bbc. co. uk/nature/extinction_causes

The Five greatest mass extinctions Ordivician- Late silurian Devonian Permiantriassic Late Triassic Final Cretaceous When Occurred 439 million years ago 365 million years ago 251 million years ago 199– 214 million years ago 65 million years ago Casualties Up to estimated 85% species and 45– 60% of marine genuses killed. 70– 80% of all species and 30% of families vanish; marine life more decimated than freshwater and land fauna. Most devastating of all, eliminating 85– 90% of all marine and land vertebrate species, 95% of marine species. End of trilobites and many trees. More than three quarters of all species and one quarter of families disappear. End of mammallike reptiles and eel–like conodonts, leaving mainly dinosaurs. 47% of marine genuses and 18% of land vertebrates wiped out, including the dinosaurs, leaving mainly turtles, lizards, birds, and mammals. http: //www. deathreference. com/En-Gh/Extinction. html

http: //www. britannica. com/EBchecked/topic/5310/adaptive-radiation Adaptive Radiation - new niches open after mass extinctions to allow for evolution of organisms that are adapted to specialized modes of life.