BIOL 120 Macroevolution Notes
BIOL 120 Macroevolution Notes BIOL 120
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This 2 page Class Notes was uploaded by Angela Potter on Wednesday January 27, 2016. The Class Notes belongs to BIOL 120 at Towson University taught by Christa. Partain in Fall 2014. Since its upload, it has received 12 views. For similar materials see Principles of Biology in Biology at Towson University.
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Date Created: 01/27/16
BIOL 120 MACROEVOLUTION Macroevolution: Big changes New species (speciation) Over a very long time What is a species? A group of individuals that, in nature, can interbreed & produce fertile offspring but cannot reproduce with members of other species. A single species makes up an impermeable container for its gene pool. Reproductive Isolation ▯ • Temporal Isolation Different breeding seasons No mating • Behavioral Isolation No mate attraction due to behavioral differences No mating • Ecological Isolation Different microclimates No mating • Mechanical Isolation Physical incompatibility of reproductive structures Attempted mating • Gamete Isolation Mating No fertilization Gametes don’t fuse – sperm does not penetrate egg • Hybrid Inviability Mating Fertilization Hybrid doesn’t survive long after conception • Hybrid Infertility Mating Fertilization Hybrid offspring survives Hybrid is sterile 3 Conditions MUST occur for speciation (macroevolution) 1. Separation of population into 2 groups 2. Environmentally different in the 2 areas causing genetic divergence 3. Development of mechanisms for reproductive isolation ▯ To become truly distinct species, diverging populations must become reproductively isolated either by their behavior or by genetic incompatibility. There is no specific rule for how much divergence is required. Humans Races are not Biological Groups • No race-specific alleles have been identified • Populations classified in the same race do not have similar allele frequencies. Populations within “races” are not necessarily more similar to each other than they are to populations of different races.. • Humans races have never been truly isolated
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