Ch23 Part 2 Post Lecture Version - 23 BIOA02H 2011 Species...

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2 3 Species and Their Formation Part II BIOA02H 2011 K. Persaud
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23 Species and Their Formation • What Are Species? • How Do New Species Arise? • What Happens when Newly Formed Species Come Together? • Why Do Rates of Speciation Vary? • Why Do Adaptive Radiations Occur?
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23.3 What Happens when Newly Formed Species Come Together? When populations become isolated … differences in the genetic structures accumulate… the probability that they can mate and produce viable offspring within each isolated gene pool, genotype frq’s change (due to evolutionary mech’s) Reproductive isolation evolves as an incidental byproduct of genetic changes in allopatric populations
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23.3 What Happens when Newly Formed Species Come Together? Evolution occurring in populations independently (accumulation of mutations, translocations, migrants into the population, etc.) NOTE: Geographic isolation does not necessarily have to lead to reproductive isolation
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23.3 What Happens when Newly Formed Species Come Together? operate before fertilization occurs. So HOW does reproductive isolation come about? Mechanisms of reproductive incompatibility fall into 2 categories: 1. PREZYGOTIC Reproductive Barriers (a) Habitat Isolation Therefore never come into contact (b) Temporal Isolation mating periods do not overlap. Apple maggot flies
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23.3 What Happens when Newly Formed Species Come Together? (d) Gametic Isolation (c) Mechanical Isolation differences in size and shape of reproductive organs. e.g. Duck genitalia: male penis &
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This note was uploaded on 04/17/2011 for the course BIO 103 taught by Professor Cummings during the Spring '11 term at American College of Computer & Information Sciences.

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Ch23 Part 2 Post Lecture Version - 23 BIOA02H 2011 Species...

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