Recent population studies show that joint nuclear-cytoplasmic surveys allow unique inferences about many important evolutionary processes. This special utility derives from the fact that genes in the nucleus are inherited through both parents, while an organism's cytoplasmically-housed genes, such as those in mitochondria and chloroplasts, are usually inherited solely through the mother. As a result of this asymmetrical transmission, a population's joint nuclear-cytoplasmic makeup can provide a new way for detecting zones of genetic admixture between two populations, and for unraveling the relative amounts of pollen and seed dispersion in plant populations. The proposed research will develop the necessary theoretical framework for unlocking the novel information encoded by nuclear-cytoplasmic data in these and other important evolutionary contexts. The practical utility of these new approaches will be demonstrated by direct applications to a variety of recent data sets. A parallel line of research will provide a conceptual framework for understanding the fundamental question of how and why cytoplasmic inheritance patterns evolve through time. This seminal theoretical study is motivated by the growing number of cases in which mitochondria and chloroplasts are inherited through the father or both parents, instead of solely through the mother. Moreover, the pattern of inheritance may evolve through time under the control of nuclear or cytoplasmic genes within the parents or progeny. These exciting experimental discoveries will form the basis of an extensive series of models designed to delimit the conditions favoring evolution among the three cytoplasmic inheritance patterns, and answer the critical and intriguing question of why strict maternal transmission now seems to predominate.
