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. Species Richness and the Extinction Crisis. How many species are there?. Species richness . – the total number of species in an area.. 5-10 million is best guess, but may be anywhere from 3-100 million.. Evolution. Speciation Basics. Individuals of different species cannot . interbreed. under natural conditions . Described as being . reproductively isolated . from one another. Populations of different species do . 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. 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. Remember. Operant conditioning extinction differs from classical conditioning extinction. During extinction, responding decreases to baseline levels for both classical and operant conditioning. BUT: Operantly conditioned behavior shows:. DARWIN’S UNDERSTANDING VS. PRESENT DAY. How are inheritable traits passed?. How do variations appear?. Today’s understanding of genes, DNA, variation, and mutations is central to our understanding of how evolution works . 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. Chapter 11 Biology Textbook. KEY CONCEPT . Hardy-Weinberg equilibrium provides a framework for understanding how populations evolve.. . Hardy-Weinberg equilibrium describes populations that are not evolving. . Background vs. Mass Extinction. Background extinction. = species gradually and continuously go extinct, creating a turnover of species through time.. Background extinction and mass extinction. 0. 600. . . . Species. . A. . group of living organisms consisting of similar individuals capable of exchanging genes or interbreeding. .. Speciation. . It.  is the . evolutionary.  process by which populations evolve to become distinct . (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.. Science. Lesson 8: challenge answer. Investigate and make note of other species that have evolved due to parapatric speciation. . Typically seen in species of fish.. Learning intention. To know what sympatric speciation is and how it occurs. . Where did all these species come from?. Can new species form?. How do humans effect biodiversity?. How do we prevent extinction?. Why is it important to have so many different species? (in other words, what roles do they play in an ecosystem?. 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.