tailieunhanh - Lecture Biology: Chapter 24 - Niel Campbell, Jane Reece
Chapter 24 introduce to the origin of species. This chapter define and discuss the limitations of the four species concepts, describe and provide examples of prezygotic and postzygotic reproductive barriers, distinguish between and provide examples of allopatric and sympatric speciation, explain how polyploidy can cause reproductive isolation, define the term hybrid zone and describe three outcomes for hybrid zones over time. | Chapter 24 The Origin of Species Speciation, the origin of new species, is at the focal point of Darwin’s evolutionary theory. Evolutionary theory must explain how new species originate and how populations evolve. Microevolution consists of adaptations that evolve within a population, confined to one gene pool. Macroevolution refers to evolutionary change above the species level. In the Galápagos Islands Darwin discovered plants and animals found nowhere else on Earth Figure How did this flightless bird come to live on the isolated Galápagos Islands? The Biological Species Concept emphasizes reproductive isolation Biologists compare morphology, physiology, biochemistry, and DNA sequences when grouping organisms. The biological species concept states that 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 populations. Fig. 24-2 (a) Similarity between different species (b) Diversity within a species Figure The biological species concept is based on the potential to interbreed rather than on physical similarity Gene Flow Between Populations EXPERIMENT RESULTS Example of a gene tree for population pair A-B Allele Population Gene flow event 1 B B B B 5 6 7 2 3 4 A A A Allele 1 is more closely related to alleles 2, 3, and 4 than to alleles 5, 6, and 7. Inference: Gene flow occurred. Alleles 5, 6, and 7 are more closely related to one another than to alleles in population A. Inference: No gene flow occurred. Pair of populations with detected gene flow Estimated minimum number of gene flow events to account for genetic patterns Distance between populations (km) A-B K-L A-C B-C F-G G-I C-E 5 3 2–3 2 2 2 1–2 340 720 1,390 1,190 1,110 760 1,310 Figure Does gene flow occur between widely separated populations? Reproductive Isolation = Barriers to Interbreeding Reproductive isolation is the existence of biological factors (barriers) that . | Chapter 24 The Origin of Species Speciation, the origin of new species, is at the focal point of Darwin’s evolutionary theory. Evolutionary theory must explain how new species originate and how populations evolve. Microevolution consists of adaptations that evolve within a population, confined to one gene pool. Macroevolution refers to evolutionary change above the species level. In the Galápagos Islands Darwin discovered plants and animals found nowhere else on Earth Figure How did this flightless bird come to live on the isolated Galápagos Islands? The Biological Species Concept emphasizes reproductive isolation Biologists compare morphology, physiology, biochemistry, and DNA sequences when grouping organisms. The biological species concept states that 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 populations. Fig. 24-2 (a) Similarity between .
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