Meeting Abstract
Eukaryotic performance hinges on the coordinated function of the products of the nuclear and mitochondrial genomes in achieving oxidative phosphorylation. Because two genomes are involved, function is maintained only through perpetual selection for mitonuclear coadaptation. I propose that these fundamental features of the genomic architecture of eukaryotes results in both pre- and post-zygotic sorting for coadapted mitonuclear genotypes leading to both speciation and sexual selection. Mitonuclear coevolution in isolated populations leads to speciation because population-specific mitonuclear coadaptations create between-population mitonuclear incompatibilities and hence barriers to gene flow between populations. In addition, selection for adaptive divergence of products of mitochondrial genes, particularly in response to climate or altitude, can lead to rapid fixation of novel mitochondrial genotypes between populations and consequently to disruption in gene flow between populations as the initiating step in animal speciation. Selection for pre-zygotic sorting of mitochondrial and nuclear genotypes for functional compatibility is also proposed to lead to the evolution of ornaments. By this model, the defining characteristic of a metazoan species is a coadapted mitonuclear genotype that is incompatible with the coadapted mitochondrial and nuclear genotype of any other population.
