Separating differential allocation by females from direct effects of male condition in a beetle

Abstract

Differential allocation is the adjustment of reproductive allocation, typically by a female, in response to the quality of her male partner. A recent theoretical model suggests that differential allocation may influence trade-offs between reproductive traits within a breeding attempt. Furthermore, it is often difficult to distinguish differential allocation from direct effects of male condition. We address these gaps using a novel cross-fostering design to exclude direct effects of male condition and to test whether differential allocation affects trade-offs between and within breeding attempts. This design detects differential allocation as effects of a female’s mating partner and direct effects of male condition as effects of the larvae’s sire. We used the burying beetle Nicrophorus vespilloides, a species which adjusts reproductive allocation by culling some larvae after hatching. We used food deprivation to manipulate the nutritional condition of both the female’s mating partner and the larvae’s sire. We find clear evidence for differential allocation as females mating with food-deprived males had fewer larvae than females mating with control males. There was a trade-off between number and size of larvae when females mated with control males, but a positive relationship when females mated with food-deprived males. Thus, differential allocation influenced relationships between reproductive traits within a breeding attempt, but not necessarily through trade-offs. Instead, we suggest that there may be cryptic heterogeneity in quality among females or their mating partners that was only exposed when females mated with a male in poor condition.

The impact of acoustic signalling on offspring performance varies between three biparentally caring species

“…If both parents are silenced, this communication might not be possible, and "mishaps" could happen in which the father accidentally kills the brood. It is also possible that the female deems the brood or mating partner unsuitable and decides to invest in future reproductive opportunities instead (Richardson & Smiseth, 2021;Sahm, Prang, & Steiger, 2022).…”

Temperature impacts how sugar resources alter reproductive investment in the European corn borer moth

“…While differential allocation is most frequently studied in iteroparous species with parental care (Sheldon 2000), it has also been shown to play a role in short-lived insects both with and without parental care. For example, Nicrophorus burying beetles, females allocate less care to offspring when they are mated with unpreferred, food-deprived males (Richardson and Smiseth 2021). Female crickets have been found to allocate more eggs to attractive mates under high resource conditions (Stahlschmidt et al 2020) and female butterflies allocate more eggs to males reared on higher quality diets (Wedell 1996).…”