Gene flow and speciation

Mechanism for speciation Allopatric speciation Sympatric speciation

A group of individual organisms that are capable of interbreeding to produce fertile offspring in nature.

Chamaeleo chamaeleon recticrista (CCR) Chamaeleo chamaeleon musae (CCM)

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.

Principal coordinates analysis (PCA) based on 323 AFLP loci

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

mtDNA sequence analysis

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

Data Analysis 19 fixed mutations Phylogenetic and Statistical analysis Sharp gene flow arrest PORTUGAL TURKEY

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

Is 1.8% a big difference (in the mtDNA)? ~ 1.2% Homo neanderthalensis Homo sapiens

Is 1.8% a big difference? ~3% Chamaeleo arabicusChamaeleo calyptratus

AFLP analysis of 66 C.c.recticrista According to more than 300 Random nuclear loci: No differentiation pattern was observed!

Adopted from García-Veigas J et al (2000) What could underlie the divergence of the mtDNA clusters?

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?

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?

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: