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Gene flow and speciation
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Mechanism for speciation Allopatric speciation Sympatric speciation
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A group of individual organisms that are capable of interbreeding to produce fertile offspring in nature.
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Chamaeleo chamaeleon recticrista (CCR) Chamaeleo chamaeleon musae (CCM)
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AFLP- Amplified fragment length polymorphism Restriction enzyme and PCR- based tool Good for species with little or no genetic data. Sample multiple random loci in the genome simultaneously.
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Principal coordinates analysis (PCA) based on 323 AFLP loci
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The mitochondrial DNA (mtDNA) Transmitted only through the maternal germline Mutations accumulate over evolutionary time scale faster than in the nucleus (one order of magnitude) Most (90%) of the mtDNA constitutes coding sequences
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mtDNA sequence analysis
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2 distinct genetic groups emerged: 1. Ranging from the Jezreel valley to the north 2. Ranging from the Jezreel Valley to the South 1 Analysis of 600 bp in 90 morphologically identical chameleons
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Data Analysis 19 fixed mutations Phylogenetic and Statistical analysis Sharp gene flow arrest PORTUGAL TURKEY 99 88 99
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The whole mtDNA of well dispersed 11 chameleons was sequenced 325 fixed mutations defined the 2 groups (1.8% of the mtDNA) Is 1.8% a big difference (in the mtDNA)? Whole mtDNA sequence
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Is 1.8% a big difference (in the mtDNA)? ~ 1.2% Homo neanderthalensis Homo sapiens
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Is 1.8% a big difference? ~3% Chamaeleo arabicusChamaeleo calyptratus
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AFLP analysis of 66 C.c.recticrista According to more than 300 Random nuclear loci: No differentiation pattern was observed!
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Adopted from García-Veigas J et al (2000) What could underlie the divergence of the mtDNA clusters?
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Wide marine barrier Existed ~ 4.5 – 2 MYA 6 km wide Prevent movement mtDNA divergence Adopted from García-Veigas J et al (2000) What could underlie the divergence of the mtDNA clusters?
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Dating with BEAST Indicate ancient separation in the mtDNA: 3±2 million years – fits to the ancient marine barrier What could underlie the divergence of the mtDNA clusters?
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Clear correlation between the geographic distribution of morphological characters and nuclear DNA data (AFLP). Different pattern in mtDNA sequence data. Genetic differentiation based on mtDNA and nuclear DNA- encoded markers are due to differences in mutation rates of the two genomes. Mitochondrial related selection??? Conclusions:
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