BIOL 1107 1nd Edition Lecture 35Outline of Last LectureI. Hardy-Weinberg II. Non-random mating III. Changes in allele frequency (definitions)Outline of Current LectureI. Populations and Change II. Variations III. Pre-zygotic and Post-zygotic Mechanisms IV. Speciation Current LectureI. Populations and Change - What can cause populations to change? - Selective breeding: common ancestor (Ex: mustard seeds) -> (a), (b) and (c) o Take place with dogs as well - Chickens with large breasts and cows that produce more milk -> selectively bred - Change requires variationII. Variations - Mutations: from replication errors - Meiosis: new allele combinations o Independent assortment (causes large variations in # of gametes) - Fertilization: (of the egg)- Variation is important for the species as a whole - Preserving variation: o Ex: people resistant to bubonic plague are resistant to HIVo Speciation: as a result of natural selection - What are species?o Viceroy vs Monarch buttery (which is poisonous) -> two different species Viceroy mimics Monarch so that it doesn’t get eaten These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.o Bluebirds (same species-> see pic on elc New) – male (blue) vs. female ( dull color)- Biological species concept- bases species on its ability to reproduce (fertile offspring)III. Pre-zygotic and Post-zygotic Mechanisms - Pre-zygotic mechanisms:o They stop species from interbreeding o One of the biggest barriers from speciation = separation (geographic barriers)o Habitat isolation: lion (grassy areas) vs. tiger (jungle areas)o Gametic isolation: egg and sperm just not compatible - Post-zygotic mechanisms: o Hybrid invariability o Hybrid sterility – horse + donkey -> mule (sterile) Horse has 32 pairs of chromosomes, donkey has 31 and mule has 30 pairs and 3 single chromosomes Mules -> formation of gametes cannot occur (meiosis cannot take place) IV. Speciation - Allopatric- (ex: squirrels & lizards) populations are geographically separated - Sympatric- habitat differences (lion vs. tiger; tree beetle vs. ground beetle), sexual selection (appearance of mate)- How quickly does speciation occur? Two competing
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