BIO 06 - 24 SEP - 6-tradeoffs&constraints survival of...

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04/26/10 1 survival of the fit enough September 24 Lecture 6
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04/26/10 2 Relevant readings 1. Read Freeman 24.5 The nature of natural selection and adaptation Also read: 2. Constraints http://evolution.berkeley.edu/evolibrary/article/_0/constraint_01 3. Misconceptions about natural selection and adaptation http://evolution.berkeley.edu/evolibrary/article/misconcep_01
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04/26/10 3 Tutorial 3 Quiz online Thursday 12 noon – Friday 9:30 am (TUT webpage—quiz folder) Quiz to cover lectures 5 &6 plus Tutorial 3 readings Readings listed (BIO152 Homepage-- tutorial readings folder)
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04/26/10 4 natural selection—simple, but misunderstood Natural selection acts on individuals, but populations & species evolve
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04/26/10 5 Evolution is not progressive Evolution is not progressive or ‘goal oriented’—neither is the process of natural selection Adaptations do not happen because organisms need or want them
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04/26/10 6 Natural selection in not a random process based on chance Why?
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04/26/10 7 Not all traits are adaptive! Give some examples:
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04/26/10 8 Not all traits are adaptive Give some examples: Vestigial traits Developmental dead ends (male mammalian nipples) Neutral changes in DNA
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04/26/10 9 4 factors limit adaptation 1. Gene flow 2. Time 3. Tradeoffs 4. Constraints
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04/26/10 10 4 factors limit adaptation 1. Gene flow may cause maladaptation Movement of related organisms between habitats also transport their genes which may not be as successful in the other environment Gene flow introduces novel genetic variation into local populations some may be advantageous, others not
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04/26/10 11 2. Time Takes time to respond to selection If environment changes faster than a generation time those born may not be the most reproductively successful
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04/26/10 12 Prospects for surviving climate change in Antarctic aquatic species
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04/26/10 13 Animals have 3 mechanisms for coping with change: they can 1) use physiological flexibility 2) have sufficient variation so populations evolve new adaptations 3) migrate to better sites
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This note was uploaded on 04/25/2010 for the course BIO BIO152 taught by Professor Cordon during the Fall '09 term at University of Toronto- Toronto.

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BIO 06 - 24 SEP - 6-tradeoffs&constraints survival of...

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