Whenever a female mates with more than one male during the same breeding event, males must compete with one another to fertilise the ova (Parker 1970, 1998). Recent work has emphasised that a male's success at competing with rivals for fertilisations derives not only from his investment in high quality sperm but from his ability to manipulate female fecundity as well (e.g., Cameron et al. 2007; Parker and Pizzari 2010; Alonzo and Pizzari 2010; Perry et al. 2013). By inducing a female to produce more eggs, through courtship feeding or nuptial gifts or through direct physiological manipulation via components of his ejaculate, a male can potentially increase the number of offspring he sires—even if his share of paternity remains relatively low.

In theory, the extent to which males should invest in simulating female fecundity depends on the male's mating role, that is whether his mating behaviour consistently places him at an advantage or disadvantage in sperm competition (Cameron et al. 2007; Parker and Pizzari 2010; Alonzo and Pizzari 2010). A male's mating role might be conferred on him by his social status. For example, dominant males consistently occupy the favoured role through their ability to mate more frequently, and last, with the female (e.g., Lemaitre et al. 2012). Holding a particular mating role changes the payoffs derived from investing in fecundity stimulation relative to other strategies for enhancing fertilisation success (Cameron et al. 2007; Alonzo and Pizzari 2010; Lemaitre et al. 2012). It also sets up producer-scrounger dynamics between rival males, in which a later mating male can potentially parasitise any previous investment in female fecundity stimulation by earlier mates of the same female (Alonzo and Pizzari 2010). However, whether socially dominant and subordinate males differ in the extent to which they invest in fecundity stimulation is not yet known.

A major consequence of male fecundity stimulation, which has thus far been relatively neglected, is the effect on the offspring (Crean et al. 2016). The potential for males to alter female physiology in this way provides a mechanism for the phenomenon known as telegony. This arises when a female's previous mates influence her offspring's phenotype even if they sire none of her offspring. Telegony could occur if components of the male's ejaculate have a direct effect on the offspring's phenotype, and this has been investigated in previous work (e.g., Garcia-Gonzalez and Dowling 2015; Crean et al. 2016). More simply, telegony could arise through the very well-characterised trade-off between offspring number and offspring size (Stearns 1992; Rollinson and Rowe 2015). By stimulating female fecundity, males could cause each egg to be relatively under-nourished (e.g., Nager et al. 2000) or each offspring to face increased competition with siblings for limited resources during development (e.g., Mock and Parker 1997). Through this simple mechanism, males could influence the offspring's phenotype, even without siring them. However, whether this second mechanism for telegony actually occurs in nature is unknown.

Here, we determine whether males of different social status differ in the extent of their fecundity stimulation and whether the stimulation of female fecundity alone is sufficient to change the offspring's phenotype. Our experiments focus on burying beetles, Nicrophorus vespilloides. Burying beetles breed on a small dead vertebrate, like a mouse, which they require to provision their larvae (Scott 1998). There is competition for this scarce resource and disputes are settled by fighting within each sex. The outcome determines an individual's social status during that breeding event (Müller et al. 1990; Eggert and Müller 1992; Pettinger et al. 2011). The winners are usually the largest male and female (Scott 1998; Hopwood et al 2016a) and they become the dominant pair on the carcass. They gain most reproductive success on the carcass, and stay to defend and care for the larvae (Eggert and Müller 1997). Defeated, usually smaller, individuals become subordinate satellites. Subordinate males gain reproductive success by sneaking matings with the dominant and other females (e.g., Müller et al. 2007). Females become subordinate cobreeders (Eggert and Müller 1992) or intraspecific brood parasites (Müller et al. 1990), depending on the size of the carcass. Regardless of their social status, females are highly promiscuous (Müller and Eggert 1989; Müller et al. 2007; House et al. 2007, 2009). Furthermore, previous work has shown that female fecundity is increased by multiple mating in a dose-dependent way (House et al. 2009).