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BIOL 1001 (162)
Tamara Kelly (110)
Chapter 18

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York University
BIOL 1001
Tamara Kelly

Chapter 18 Species 2202012 120200 PM 181 whats in a Name Humans use names to distinguish between different categories of objects Scientists use a scientific name to describe a species Latinized name 182 Definition of Species The Biological Species Concept defines species as a group of organisms that can successfully interbreed and produce offspring The Phylogenetic Species Concept defines species as a group of organisms bound by a unique ancestry The Ecological Species Concept defines species as a group of organisms that share a distinct ecological niche Androdioecy organisms that exist as functional males and hermaphrodites but no true females eg clam shrimps Gynogenetic species organisms that have only females and no males These females seduce males of other species for sperm to fertilize eggs Hybridization when two species interbreed and produce fertile offspring It can also produce sterile offspring eg mating horse and a donkey Asexually reproducing populations have a higher frequency of mutations in mitochondrial proteincoding genes than sexual reproducing organisms 183 One size does not fit all The process of speciation is defined as the evolution of reproductive isolation between populations they cannot exchange genetic information Individual of different species do not resemble each other because they do not share many genetic characteristics Morphological Species Concept idea that all individuals of a species share measurable traits that distinguish them from individuals of other species 186 Geographic Variation Subspecies local variants of a species Individuals from different subspecies usually interbreed where their geographic distributions meet and their offspring often exhibit intermediate phenotypes Ring Species geographic distribution that surrounds uninhabitable terrain these species can exchange genetic material directly but gene flow between distant populations occurs through intermediary populations Cline Species a pattern of smooth variation along the geographical gradient of a large area Results from gene flow between adjacent populations that are each adapting to slightly different conditions Geographical variation can mask difference between species Pop at opposite ends may be different
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