1. The existence of a trade-off between current and future reproduction is a fundamental prediction of life-history theory. Support for this prediction comes from brood size manipulations, showing that caring for enlarged broods often reduces the parent’s future survival or fecundity. However, in many species, individuals must invest in competing for the resources required for future reproduction. Thus, a neglected aspect of this trade-off is that increased allocation to current reproduction may reduce an individual’s future competitive ability.

2. We tested this prediction in the burying beetle, Nicrophorus vespilloides, a species where parents care for their offspring and where there is fierce competition for resources used for breeding.

3. We manipulated reproductive effort by providing females with either a small brood of 10 larvae or a large brood of 40 larvae and compared the ability of these females, and virgin females that had no prior access to a carcass, to compete for a second carcass against a virgin competitor.

4. We found that increased allocation to current reproduction reduced future competitive ability, as females that had cared for a small brood were more successful when competing for a second carcass against a virgin competitor than females that had cared for a large brood. In addition, the costs of reproduction were offset by the benefits of feeding from the carcass during an initial breeding attempt, as females that had cared for a small brood were better competitors than virgin females that had no prior access to a carcass, whilst females that had cared for a large brood were similar in competitive ability to virgin females.

5. Our results add to our understanding of the trade-off between current and future reproduction by showing that this trade-off can manifest through differences in future competitive ability and that direct benefits of reproduction can offset some of these costs. 16-Apr-2020

Read me for “Data from RichardsonStephensSmiseth_JournalofAnimalEcology.csv” 

This data file consists of a comma separated values spreadsheet (.csv), which provides data for the effects of allocation to reproduction via brood size manipulation on future competitive ability in contests for a carcass. Each line in the spreadsheet represents an individual, experimental female. 

female_id – individual ID of the female. 

eclosion – date of eclosion. 

death – date of death. 

lifespan – number of days lived from eclosion to death. 

treatment_code – experimental treatment (control = no breeding attempt, ten = brood of ten larvae, forty = brood of forty larvae). 

won – outcome of the contest (Y = female won, N = female lost, NA = unclear). 

outcome_clear – was the outcome of the contest clear? (Y = yes, N = no). 

size – size of the female, measured as pronotum width (mm). 

competitor_size – size of the virgin female competitor measured as pronotum width (mm). 

size_difference – absolute difference in size between focal female and her competitor (mm). 

brood_size – number of larvae in the experimental brood at dispersal. 

dot – number and placement of identifying marks (1 or 2 = number of dots, L or R = left or right elytra). 

female_pre_mass – female mass prior to initial reproductive attempt (g). 

female_post_mass – female mass after initial reproductive attempt (g). 

female_mass_change – female mass change during initial reproductive attempt (g). 

brood_mass_pre – mass of the brood of larvae when cross fostered and given to the female (g). 

brood_mass_post – mass of the brood of larvae at dispersal from the carcass (g). 

breeding_carcass_mass – mass of the mouse carcass used for breeding (g). 

competition_carcass_mass – mass of the mouse carcass females competed for (g).