MITONUC · The evolutionary and ecological implications of mito-nuclear epistasis

The evolutionary and ecological implications of mito-nuclear epistasis

Our understanding of the evolutionary significance of mtDNA is currently being revised. The traditional view that sequence variation found within the mitochondrial genome is selectively neutral is being displaced by a growing body of evidence for selection on mitochondrial genes from a variety of empirical domains. The MITONUC project added a novel and critical piece to our understanding of mtDNA evolution by (i) assessing environmental- and sex-specificity of mito-nuclear phenotypic effects and by (ii) experimentally demonstrating that selection acts upon mtDNA and, perhaps most importantly, by testing whether negative frequency dependent selection acts to maintain non-neutral mitochondrial genetic variation. Thus, this research project is very timely indeed and contains several important novel elements. (1) The importance of improving our understanding of the maintenance of genetic diversity cannot be overemphasized and the scientific implications of a shifting view of mtDNA are multifaceted and equally consequential: every year, some 4500 scientific papers rely directly upon mtDNA data. (2) The MITONUC results represents has an important and novel addition to fundamental importance of the mito-nuclear epistatic interactions. (3) The MITONUC project document multivariate phenotypic effects of mito-nuclear epistatic interactions in order to fully understand selection on mitonuclear genotypes.The main findings showed no significance of genetic effect (nuclear and mitochondrial) and there interaction so we can conclude that mito-nuclear epistasis seems to be no responsible for the shape of reaction norms. However, we have detect a significant environmental effect (food and temperature) which suggest parental effect on phenotypic variation in offspring. The recent integration of epigenetics into developmental psychobiology illustrates the processes by which environmental conditions in early life structurally alter DNA, providing a physical basis for the influence of the perinatal environmental signals on phenotype over the life of the individual. (4) The crucial project result is novel experimental proof that t balancing selection acts to maintain mitochondrial DNA variation within populations of Drosophila subosbcura. We experimentally confirmed that starting frequencies in population cages were changed from 20:80 and 80:20 to almost equal (50:50) which is unique experimental proof that mtDNA variability in population has adaptive response and that is maintained by negative frequency dependent selection (NFDS). Second, there is a significant interaction between starting frequencies and environment on the strength for NFDS, but it is weaker in the heterogeneous environment when mitochondrial haplotype I is started as common in population. This research will have a range of biological implications, ranging from applied medical genetics over our use of mitochondrial genetic markers in population genetics/biology to speciation and our understanding of thermal adaptation to climate change.

Data: CORDIS, © European Union