Lecture 05 Outline Chapter 24

Lecture 05 Outline Chapter 24 - Lecture 5 MACROEVOLUTION...

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Lecture 5: MACROEVOLUTION Slide 1 (a repeat from earlier) Natural selection: generates phenotypic adaptation Adaptations are traits or suites of traits that are favored by natural selection. Morphological adaptation e.g. cryptic skin color Behavioral Adaptation e.g. mutual grooming - Physiological Adaptations e.g. enzyme synthesis in a biochemical pathway Slide 2 Summary: Microevolution: Changes over time in allele frequencies in a population evolutionary change below the level of speciation. Microevolution processes that change gene frequencies include: Migration Non-random mating Genetic Drift – including bottleneck effect Mutation – THE SOURCE OF NOVEL VARIATION Natural Selection – THE SOURCE OF ADAPTATION Slide 3 Macroevolution: Broad patterns of evolution over long time spans: à the origin of new taxonomic groups (new species, new genera, new families, new kingdoms) Evolutionary theory explains macroevolution Slide 4 What is a species? Species from latin “kind or type” Forms with distinct: Morphology, Physiology, Behavior, DNA sequences, usually species exhibit distinct differences in some or all of these parameters Slide 5 The Biological Species Concept (the most commonly used species concept) “a group of interbreeding natural populations that are reproductively isolated from other such groups”
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Slide 6 What makes us a species?: 1. all populations have the capacity to interbreed Humans: Several genetic groups (races) – interbreed freely Slide 7 Humans are undergoing genetic coalescence due to extensive gene flow between races Races become decreasingly distinct Slide 8 What makes us a species?: 1. all populations have the capacity to interbreed. 2. We do not interbreed with other species. e.g. Amphibians and Humans: Very distantly related, different genome, karyotype, anatomy, ecology etc. Slide 9 e.g. arrow poison frogs. closely related. live together. but do not interbreed. Each is a biological species. Slide 10 Where do new species come from? New breeding population à Evolution à Reproductive isolate à New Species à Biodiversity Slide 11 New breeding population – reduced gene flow Slide 12-13 Micro evolution ; Bottleneck Genetic Drift (small population) Mutation Slide 14-15 Reproductive Isolation (following microevolution) when populations in this case come together by ‘secondary contact’ Slide 16 Reproductive Isolation: barriers to gene flow
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Prezygotic barriers impede mating or fertilization Postzygotic barriers prevents successful propagation of
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Lecture 05 Outline Chapter 24 - Lecture 5 MACROEVOLUTION...

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