Santos, E. S. A. | Search bioRxiv

bioRxiv2017

Helpers increase daily survival rate of Southern Lapwing (Vanellus chilensis) nests during the incubation stage

Cooperative breeding is characterized by reproduction in the presence of helpers. What impact these helpers have on the reproductive success of group members is one of the long-standing questions in the cooperative breeding literature. In cooperative species, helpers are known to provide benefits during multiple stages or at a particular stage of the reproductive cycle. The aim of this study was to investigate whether helpers increased the daily survival rate of nests during the incubation stage in the Southern Lapwing (Vanellus chilensis), a crested plover with a cooperative breeding system. Southern Lapwings have a variable mating system, with some breeding groups composed of unassisted pairs, and others that breed in the presence of helpers. Our best supported model indicated a positive effect of the presence of helpers on the daily survival rate of nests, leading to a probability of nest success (i.e., survival until hatching) of 83%, compared to 51% for nests of unassisted pairs. But a null model had a similar model weight as the best supported model and was the second-best model. Our study provides evidence that helpers influence egg survival during the egg-incubation stage, which could influence the fitness of breeders.

animal behavior and cognition↗

bioRxiv2017

Facultative adjustment of paternal care in the face of female infidelity in dunnocks

A much-debated issue is whether or not males should reduce parental care when they lose paternity (i.e. the certainty of paternity hypothesis). While there is general support for this relationship across species, within-population evidence is still contentious. Among the main reasons behind such problem is the confusion discerning between-from within-individual patterns. Here, we tested this hypothesis empirically by investigating the parental care of male dunnocks (Prunella modularis) in relation to paternity. We used a thorough dataset of observations in a wild population, genetic parentage, and a within-subject centring statistical approach to disentangle paternal care adjustment within-male and between males. We found support for the certainty of paternity hypothesis, as there was evidence for within-male adjustment in paternal care when socially monogamous males lost paternity to extra-pair sires. There was little evidence of a between-male effect overall. Our findings show that monogamous males adjust paternal care when paired to the same female partner. We also show that - in monogamous broods - the proportion of provisioning visits made by males yields fitness benefits in terms of fledging success. Our results suggest that socially monogamous females that engage in extra-pair behaviour may suffer fitness costs, as their partners reduction in paternal care can negatively affect fledging success.

animal behavior and cognition↗