For much of the past century, evolutionary biology has operated on the assumption that all heritable variation is genetic - i.e., based on DNA-sequence variation and transmitted across generations in accordance with Mendelian rules. This fundamental assumption is now recognized to be violated in many cases, opening up fascinating questions about the role of heritable nongenetic variation in evolution. Nongenetic inheritance has the potential to alter basic evolutionary predictions and resolve long-standing puzzles. This phenomenon is also of increasing interest to medical researchers.
We're using insect model systems (neriid flies and bruchid beetles), as well as theoretical approaches, to investigate the role and implications of nongenetic inheritance. Several ongoing projects in our lab focus on understanding the nongenetic paternal transmission of acquired conditions. We've found that males of the neriid fly Telostylinus angusticollis (a native Australian species that we have developed into a model for research on plasticity and nongenetic inheritance) that have been reared on a nutrient-rich larval diet sire larger offspring than males reared on a resource-poor diet, despite the lack of any conventional form of paternal investment in this species. Our aim is to understand both the proximate mechanisms mediating the transmission of this effect and its implications for evolution. In particular, theoretical modelling suggests that nongenetic paternal inheritance of fitness can have interesting consequences for sexual coevolution. We are currently extending our investigations of this phenomenon using the nutritional geometry framework and, ultimately, aim to explore the role of nongenetic inheritance in natural T. angusticollis populations. We are also investigating nongenetic maternal and paternal effects in a very different species – the bruchid beetle Callosobruchus maculatus.
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