Immune function does not trade-off with reproductive effort in a semelparous wolf spider with parental care

Trade-offs between negatively associated traits underlie life history evolution. Immune function is often involved in life history trade-offs, because of the energetic and nutritional costs of mounting and maintaining immune responses. Reproductive strategies exist on a continuum between semelparity and iteroparity. While immune function is often downregulated in semelparous organisms because they do not have to account for future survival or reproduction, those organisms that also provide parental care may retain the strength of immune responses. Wolf spiders (family: Lycosidae) are semelparous yet provide parental and provide a good system to evaluate trade-offs between immune responses and reproductive effort. We measured encapsulation response and reproductive effort of female wolf spiders from three reproductive classes: nongravid, gravid, and carrying young. To our knowledge, this is the first investigation of the immune responses of female wolf spiders carrying young. We hypothesized female T. georgicola derive the allocate resources to reproduction at the expense of immune function. However, we found reproductive effort had no relationship with encapsulation response in spiders carrying young. There was also no difference in the encapsulation response between reproductive classes. Individual differences in resource acquisition may explain the lack of a relationship between reproductive effort and encapsulation in spiders carrying young. Spiders with larger resource pools have more resources to devote to reproduction and immunity. Maintaining resources to mount immune responses across reproductive stages could also increase the fitness of female wolf spiders because they must survive to carry and disperse the young, which reduces kin competition among spiderlings.

Automated summary

Trade-offs between immune function and reproductive effort were investigated in female wolf spiders, revealing that reproductive effort did not impact immune function in spiders carrying young. Individual differences in resource acquisition may explain the lack of relationship between reproductive effort and immune response in spiders carrying young. Maintaining resources for immune responses across reproductive stages could increase fitness in female wolf spiders, reducing kin competition among spiderlings.