BIOL211#20 - Chapter 25 Origin of Species and...

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1 Chapter 25 Origin of Species and Macroevolution Macroevolution – Evolutionary changes that create new species Speciation – The process by which one species splits into two or more species Identification of Species The most common characteristics used to identify species are: – Morphological traits – The ability to interbreed – Molecular features – Ecological factors – Evolutionary relationships The morphological species concept – Characterizes a species in terms of its body shape, size, and other unique physical features – In practice, this is how most scientists distinguish most species The biological species concept – Defines a species as a group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring but are unable to produce viable, fertile offspring with members of other such groups Reproductive isolation – The existence of biological factors that impede members of two species from producing viable, fertile offspring – Block gene flow – Limit the formation of hybrids
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2 Prezygotic isolating mechanisms – Impede members of different species from attempting to mate – Prevent attempted mating from being completed successfully – Hinder fertilization if mating is completed
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This note was uploaded on 10/02/2011 for the course BIOL 211 taught by Professor Boury during the Spring '08 term at Iowa State.

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BIOL211#20 - Chapter 25 Origin of Species and...

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