Sex-specific influence of communal breeding experience on parenting performance and fitness in a burying beetle

Abstract

Communal breeding, wherein multiple conspecifics live and reproduce together, may generate short-term benefits in terms of defence and reproduction. However, its carry-over effects remain unclear. We experimentally tested the effects of communal breeding on parental care and reproduction in burying beetles (Nicrophorus vespilloides), which use carcasses as breeding resources and provide parental care to offspring. We subjected individuals to communal or non-communal breeding (i.e. pair breeding) during their first breeding event and to non-communal breeding during their second breeding event. We measured the parental care of individuals and of groups and the reproductive success of groups during both breeding events. In communal groups, large individuals became dominant and largely monopolized the carcass, whereas small individuals (i.e. subordinates) had restricted access to the carcass. At the first breeding event, large males in communal groups spent more time providing care than large males in non-communal groups, whereas such an effect was not observed for large females and small individuals. Reproductive successes were similar in communal and non-communal groups, indicating no short-term benefits of communal breeding in terms of reproduction. Compared with males from non-communal groups, males originating from communal groups produced a larger size of brood during their second breeding event, whereas such an effect was not observed for females. Our results demonstrate the sex-specific effects of communal breeding experience on parenting performance and fitness.

Keywords: burying beetle; carry-over effects; communal breeding; parental investment; previous breeding experience; sexual conflict.

Figure 1.

Schematic overview of the experimental set-up. (a) Experiment 1: Short-term implications of communal (double-pair) versus non-communal breeding (single-pair) on parental care and reproduction. To investigate the short-term implications of communal breeding on parental investment and reproduction, we performed double-pair (consisting of one large pair and one small pair) and single-pair (one male and one female) treatments to create communal and non-communal breeding events, respectively. (b) Experiment 2: Carry-over effects of communal versus non-communal breeding on parental care and reproduction. To examine the effects of previous breeding experience (communal versus non-communal breeding) on parental investment and reproduction in the subsequent breeding event (i.e. non-communal breeding), orthogonal experiments were performed using beetles from experiment 1.

Figure 2.

Mean (±s.e.) burial degree of the mouse carcass in communal and non-communal groups of burying beetles over time. See electronic supplementary material, table S1 for statistical analysis. Asterisks indicate significance p < 0.05.

Figure 3.

Short-term implications of communal versus non-communal breeding on individual parental investment. (a) Time spent on the carcass and (b) weight change for individuals, for pairs of different size and breeding groups. In (a) and (b), white boxes are females and grey boxes are males. Sample sizes are shown in graphics. Table 1a is for statistical analysis. Asterisks indicate significance p < 0.05.

Figure 4.

Carry-over effects of communal breeding on parental investment. Effects of previous breeding experience (communal versus non-communal breeding) on mean (±s.e.) burial degree by (a) females and (b) males, time spent on carcasses by females and males (c,d). In (c) and (d), grey (females) and black (males) dots indicate raw data. Sample sizes are shown in graphics. Table 1b and electronic supplementary material, tables S2 and S3 are for statistical analysis. Asterisks indicate significance p < 0.05.

Figure 5.

Carry-over effects of communal breeding on future fitness. Effects of previous breeding experience on (a) larvae-hatching time, (b) larvae-dispersing time for large and small females from communal or non-communal groups, (c) brood size and (d) average larval weight for large and small males from communal or non-communal groups in burying beetles. Table 1b and electronic supplementary material table S3 are for statistical analysis. Asterisks indicate significance p < 0.05.