Evolution of the mitonuclear genetic interaction

Abstract

Coevolution is fundamental to life. In the case of the mitochondrion, it dates back to the very origin of the eukaryotic cell, when the organelle became a symbiotic partner with the nucleus. Part of the mitichondria's genetic material was incorporated by the nucleus, so that both entities have since evolved in a coordinated fashion to maintain respiration function - a requirement for survival of the cell and the individual as a whole. We propose to study the coevolution between cells and mitochondria by adapting these existing models of coevolution between antagonistic species. We will modify these models to characterize coevolution of symbiotic interactions. In particular, we will work with the adaptive model described in Nourmohammad et al. (2016), which measures adaptation by the fitness flux, dynamically quantifying the coevolution between pathogen and host by means of their binding affinities. Following the strategies proposed in Princepe and de Aguiar (2019) and Nourmohammad et al. (2016), we describe the mitochondrial and the nuclear genome as binary chains, with separated fitness assigned according to matching of each corresponding pair of sites. We will quantify the coevolution between these two genetic materials through the fitness flux, given that each cell possesses a population of mitochondria. Under different modes of selection, either favoring the individual with the highest fitness, enhancing the matching between nucleus and mitochondria, or favoring broad affinities to allow the maintenance of mitochondrial diversity, we aim to understand the evolution of the mitonuclear interaction and the mechanisms for the emergence of mitochondrial heterogeneity. This work will have broad implications across biology, including in cellular biology, physiology, aging, and even speciation. (AU)