PPT-Chapter 16 Population Genetics and Speciation

Section 1 Vocabulary Pretest Population Genetics Microevolution Gene Pool Allele Frequency Phenotype Frequency Total genetic information in a population Portion of gene copies of a given allele. The Origin of Species. Overview: That “Mystery of Mysteries”. In the Galápagos Islands Darwin discovered plants and animals found nowhere else on Earth. Video: Galápagos Tortoise. Fig. 24-1. Speciation. 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. 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. 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 . Part C. Allopatric. and Sympatric Speciation: . A Review. In . allopatric. speciation, geographic isolation restricts gene flow between populations. Reproductive isolation may then arise by natural selection, genetic drift, or sexual selection in the isolated populations. Part C. Allopatric. and Sympatric Speciation: . A Review. In . allopatric. speciation, geographic isolation restricts gene flow between populations. Reproductive isolation may then arise by natural selection, genetic drift, or sexual selection in the isolated populations. KEY CONCEPTS. • Although many species persist for long periods of time both genotypic and phenotypic changes occur over time.. • Even if change is occurring, individuals that interbreed within a population(s) maintain the status of the population(s) as a species.. 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.. 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.. Species. Part B. How do species occur?. Concept . 24.2: Speciation can take place with or without geographic separation. Speciation can occur in two ways:. Allopatric. speciation. Sympatric . speciation. Part 2. Condition 5: . No. Natural Selection. Balanced polymorphism . occurs when natural selection favors heterozygous individuals in a population.. Heterozygotes are selected for by the environment.. . . . 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 . Avneet. Singh, Steven . Ancheta. , Giovanni . Corralhejo. , Katie . Laackmann. Definition. Origin of new species in evolution. There are two general modes of speciation. Allopatric. speciation. Sympatric speciation.