Life-history theory predicts that mothers should allocate resources to their young in any way that maximises their lifetime reproductive success. However, mothers are not the only one with a vested interest in how much effort they put into raising their young –the father and the offspring may benefit from a greater share of resources than a mother would like to impart leading to conflicts of interests between all the parties involved. Selection will therefore act on the ability of all with a vested interest to influence allocation traits.

We’re examining how conflict between the sexes can impacts on allocation strategies at pre-copulatory and post- copulatory stages in various taxa and how conflict between siblings can affect parental allocation strategies in different environmental conditions. For example, in birds, females sometimes alter their nutritional investment levels delivered to the egg when partnered with different males. This may be because males differ in the reources they will be able to provide and females are allocating accordingly - however, this affects the survival prospects of the offspring they produce that have different energy reserves when they hatch - this therefore affects the father's, mother's and offspring's fitness. In Drosophila, costs of mating can reduce both female longevity and reproductive output over her lifetime. This arises from adaptaions in male seminal fluids that increase their success at fertilising eggs. However, females are responding by limiting the fertilisation success of harmful males demonstrating selection acting on females can limit male success and vice versa.