Female foraging impairment related to reproduction in a neotropical spider

Abstract

Females not only produce costly gametes, but also store the eggs until laying them, a period called gravidity. The volume that eggs occupy in the female abdomen may decrease female foraging ability by making them slower. Although females of all species are subjected to these potential costs, it remains an unexplored matter in invertebrates. Females of the spider Paratrechalea ornata carry their egg sac after oviposition and thus represent a unique opportunity to evaluate gravidity costs because females carry an extra volume before and after laying eggs. We conducted foraging ability experiments using P. ornata females on different treatments regarding gravidity and maternal care. We first hypothesized that internal egg load and egg sac carrying decrease female foraging ability. We also hypothesized that greater egg sac size decreases female foraging ability. We found that both internal egg load and egg sac carrying decreased female foraging ability, and females about to oviposit had a similar foraging ability to females carrying an egg sac. Egg sac size did not influence female foraging ability. Our results show that females’ foraging ability changes before the maternal care period and therefore may influence their life-history evolution. The little support for our second hypothesis may also suggest that the decrease in foraging ability is not due to the volume being carried per se, but possibly an associated physiological state.

KEY WORDS:

• fecundity
• gravid
• life-history evolution
• parental care
• physical burden
• reproductive cost

ACKNOWLEDGEMENTS

We thank Alexandre Kuhn for helping with the collection of spiders and during the experiments. We are thankful for insightful comments and ideas on this project by Gustavo “Billy” Requena. We also thank Louise M. Alissa, Solimary García-Hernández, Eduardo S.A. Santos, Diego Solano-Brenes, Nathan Burke and Michael Kasumovic for feedback on the manuscript. We are thankful for inspiring thoughts during the development of this work by Aldo M. de Araújo.

DISCLOSURE STATEMENT

The authors declare no conflict of interest.

ETHICAL STANDARD

This research was approved by Chico Mendes Biodiversity Conservation Institute (permit 32291-3).

AUTHOR CONTRIBUTION

P. Pollo, C.S. Spindler and L.E. Costa-Schmidt conceived the idea of the study; P. Pollo and C.S. Spindler collected the data; P. Pollo analysed the data; P. Pollo wrote the manuscript with input from L.E. Costa.Schmidt.

DATA ACCESSIBILITY

Data and analysis scripts are available at https://osf.io/thmx6/

Additional information

Funding

C.S. Spindler received a grant from Fundo Padre Milton Valente de Apoio Acadêmico/UNISINOS. L.E. Costa.Schmidt received a postdoctoral grant from Capes/Brazil [PNPD 20132737].