Females benefit from multiple mating but not multiple mates in the burying beetle Nicrophorus vespilloides

Abstract

Male reproductive success generally increases with number of mates but this need not be true for females. If females are the limiting sex, as few as one mate can be optimal. Despite the theoretical differences driving multiple mating in the sexes, multiple mating is the norm rather than the exception. Empirical investigations are therefore required to determine why females mate with multiple males. Both nonadaptive (correlated responses to selection on males, given the mean mating rates have to be the same) and adaptive (direct or indirect fitness benefits) can drive the evolution of multiple mating in females. Females of the burying beetle Nicorphorus vespilloides often mate repeatedly with the same male, but this appears to be a correlated response to selection on males rather than reflecting direct benefits to females for multiple mating. However, an unexamined alternative to this nonadaptive explanation is that females benefit by mating with multiple different males and therefore are selected for general promiscuity. Here we examine if mating polyandrously provides fitness benefits by examing the effects of number of mates (1, 2 or 3), mating system (monogamous, polyandrous) and their interaction. The only significant influence was mating more than once. This did not depend on type of mating. We suggest that unlike most other species examined, in N. vespilloides mating with the same male repeatedly or with several different males reflects an indiscriminate willingness to mate as a result of correlated selection on males for high rates of mating.

Development and application of 14 microsatellite markers in the burying beetleNicrophorus vespilloidesreveals population genetic differentiation at local spatial scales

“…Nevertheless, we anticipate that the microsatellites we have developed will prove most useful in future work for assigning parentage (S Pascoal, 2016, unpublished data) because the large brood size typically seen in N. vespilloides still makes other techniques prohibitively expensive. N. vespilloides mates rampantly and promiscuously in the laboratory (e.g., House et al, 2009) and in natural populations (e.g., Müller et al, 2007). Although several previous studies have analysed strategies used by males for securing paternity (e.g., Eggert, 1992; House et al, 2009), parentage has never before been assigned using microsatellites.…”

“…N. vespilloides mates rampantly and promiscuously in the laboratory (e.g., House et al, 2009) and in natural populations (e.g., Müller et al, 2007). Although several previous studies have analysed strategies used by males for securing paternity (e.g., Eggert, 1992; House et al, 2009), parentage has never before been assigned using microsatellites. The microsatellites we have developed here thus pave the way for more detailed analyses of the evolutionary causes and consequences of promiscuity in this species.…”

Determinants of female fecundity in a simultaneous hermaphrodite: the role of polyandry and food availability

“…For instance, mating with multiple males has been shown to be beneficial to females in echinoderms (Evans and Marshall 2005), insects (Tregenza and Wedell 1998;Fedorka and Mousseau 2002;Dunn et al 2005), fishes (Evans and Magurran 2000) and reptiles (LaDage et al 2008), but it can also be associated with a reduction of the female's reproductive output, as reported for many insect species (e.g., Orsetti and Rutowski 2003;Bybee et al 2005;Ronkainen et al 2010). At the same time, several studies found no effect of polyandry on female fecundity in insects (e.g., Baker et al 2001;Schwartz and Peterson 2006;House et al 2009). …”

The evolution of multiple mating

“…In the vast majority of tested species, females mated in nature produce offspring sired by more than one male. Polyandry is common in wild Drosophila, 1 - 17 but also in crickets, 18 burying beetles 19 and other insects, 20 as well as birds 21 and mammals 22 , 23 . Compared with birds, in which studies of hundreds of species in the wild demonstrate the ecological correlates of genetic polyandry, generalities about Drosophila polyandry come mostly from laboratory studies, and most generalities about Drosophila polyandry come from only two species, D. melanogaster and D. pseudoobscura , though this is changing as more behavioral and evolutionary ecologists 24 ask questions about non-model Drosophila and Drosophila species in nature.…”