Cross-generation effects due to cold exposure in Drosophila serrata

1. Environmental variation experienced in the parental and grandparental generation can affect progeny phenotype, performance and response to selection. Here the effects of parental and grandparental exposure to a non-lethal cold shock are considered in Drosophila serrata Malloch. Development time, viability and early age productivity were measured in flies originating from border and central locations in the distribution of this species that had been held under two separate laboratory maintenance schedules. 2. Cross-generation effects were detected for several traits. Development time usually decreased following maternal and/or grandmaternal cold exposure. Parental cold exposure negatively influenced viability while grandparental effects on viability were negligible. Early female productivity showed opposing responses depending on generation; maternal cold exposure increased progeny productivity while grandmaternal exposure decreased it. Male parental and grandparental exposure to cold shock decreased male productivity, although this pattern may have been partly confounded by size effects. 3. Population effects, reflecting geographical origin, were limited to development time, while selective background effects were demonstrated for most traits. The influence these factors had on the expression of cross-generation effects was negligible, given interactions with treatment were not evident. These responses suggest that environmental variation experienced in preceding generations can influence progeny phenotype in a manner that is complex and difficult to predict.