BioLect7 - 1 Speciation Odds and Ends New reading posted on...

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Unformatted text preview: 1 Speciation Odds and Ends New reading posted on e-learning! Finishing CH 24 on Friday Will post HW answers tomorrow Review Monday (CH22-24) Exam Wednesday Geographical Variation Fig. 23-4 1.0 0.8 0.6 0.4 0.2 46 44 42 40 38 36 34 32 30 Georgia Warm (21C) Latitude (N) Maine Cold (6C) Ldh-B b allele frequency Cline- a graded change in a character along a geographical axis Speciation, Ring Species and California Salamanders 2 What is a species? morphological species concept- characterizes a species by morphological characteristics (shape, structure etc.) ecological species concept- species recognized by its ecological niche = the abiotic and biotic environment phylogenetic species concept- smallest group of individuals that share a common ancestor biological species concept- a group of populations who can interbreed in nature and produce viable, fertile offspring but do not produce viable fertile offpsring with individuals from other groups Species Concepts fossil record asexual organisms same species if they can mate even if very different hard to note if 2 species can mate genetic basis cryptic species objective biological subjective depends on species in phylogeny asexual can be genetic basis fossil record phylogenetic can miss cryptic species fossil record asexual ecological subjective misses cryptic species fossil record asexual organisms morphological + Fig. 24.2 Different Species? No Yes Biological Species . Reproductive Isolation 1. Prezygotic-before fertilization, impede mating or hinder fertilization if mating occurs 2. Postzygotic-after fertilization, prevent hybrid zygote from developing into viable, fertile adult species defined by reproductive isolation- biological factors that impede members of two species from producing viable, fertile offpsring Types of Reproductive Barriers 2 What is a species? morphological species concept- characterizes a species by morphological characteristics (shape, structure etc.) ecological species concept- species recognized by its ecological niche = the abiotic and biotic environment phylogenetic species concept- smallest group of individuals that share a common ancestor biological species concept- a group of populations who can interbreed in nature and produce viable, fertile offspring but do not produce viable fertile offpsring with individuals from other groups Species Concepts fossil record asexual organisms same species if they can mate even if very different hard to note if 2 species can mate genetic basis cryptic species objective biological subjective depends on species in phylogeny asexual can be genetic basis fossil record phylogenetic can miss cryptic species fossil record asexual ecological subjective misses cryptic species fossil record asexual organisms morphological + Fig. 24.2 Different Species?...
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This note was uploaded on 01/27/2011 for the course BIOL 112 taught by Professor Vaughn during the Spring '08 term at Texas A&M.

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BioLect7 - 1 Speciation Odds and Ends New reading posted on...

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