Interplay of cooperative breeding and predation risk on egg allocation and reproductive output

Rita Fortuna; Rita Covas; Pietro B D'Amelio; Liliana R Silva; Charline Parenteau; Louis Bliard; Fanny Rybak; Claire Doutrelant; Matthieu Paquet

doi:10.1093/beheco/arae010

Interplay of cooperative breeding and predation risk on egg allocation and reproductive output

Behav Ecol. 2024 Feb 28;35(2):arae010. doi: 10.1093/beheco/arae010. eCollection 2024 Mar-Apr.

Authors

Rita Fortuna^{1

2

3

4}, Rita Covas^{1

3

5}, Pietro B D'Amelio^{6

7}, Liliana R Silva^{1

3}, Charline Parenteau⁸, Louis Bliard⁹, Fanny Rybak⁷, Claire Doutrelant^{5

6}, Matthieu Paquet^{10

11}

Affiliations

¹ CIBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, InBIO Laboratório Associado, Campus de Vairão, Universidade do Porto, 4485-661, Vairão, Portugal.
² Departamento de Biologia, Faculdade de Ciências, Universidade do Porto, 4099-002, Porto, Portugal.
³ BIOPOLIS Program in Genomics, Biodiversity and Land Planning, CIBIO, Campus de Vairão, 4485-661, Vairão, Portugal.
⁴ Centre for Biodiversity Dynamics, Institutt for Biologi, NTNU, 7491, Trondheim, Norway.
⁵ FitzPatrick Institute, DST-NRF Centre of Excellence, University of Cape Town, 7701, Cape Town, South Africa.
⁶ CEFE, Univ Montpellier, CNRS, EPHE, IRD, 34293, Montpellier, France.
⁷ Université Paris-Saclay, CNRS, Institut des Neurosciences Paris-Saclay, 91400, Saclay, France.
⁸ Centre d'Etudes Biologiques de Chizé, CNRS-La Rochelle Université, 79360, Villiers-en-Bois, France.
⁹ Department of Evolutionary Biology & Environmental Studies, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland.
¹⁰ Institute of Mathematics of Bordeaux, University of Bordeaux, CNRS, Bordeaux INP, 33405, Talence, France.
¹¹ Theoretical and Experimental Ecology Station (SETE), CNRS, 09200, Moulis, France.

Abstract

Predation risk can influence behavior, reproductive investment, and, ultimately, individuals' fitness. In high-risk environments, females often reduce allocation to reproduction, which can affect offspring phenotype and breeding success. In cooperative breeders, helpers contribute to feed the offspring, and groups often live and forage together. Helpers can, therefore, improve reproductive success, but also influence breeders' condition, stress levels and predation risk. Yet, whether helper presence can buffer the effects of predation risk on maternal reproductive allocation remains unstudied. Here, we used the cooperatively breeding sociable weaver Philetairus socius to test the interactive effects of predation risk and breeding group size on maternal allocation to clutch size, egg mass, yolk mass, and yolk corticosterone. We increased perceived predation risk before egg laying using playbacks of the adults' main predator, gabar goshawk (Micronisus gabar). We also tested the interactive effects of group size and prenatal predator playbacks on offspring hatching and fledging probability. Predator-exposed females laid eggs with 4% lighter yolks, but predator-calls' exposure did not clearly affect clutch size, egg mass, or egg corticosterone levels. Playback-treatment effects on yolk mass were independent of group size, suggesting that helpers' presence did not mitigate predation risk effects on maternal allocation. Although predator-induced reductions in yolk mass may decrease nutrient availability to offspring, potentially affecting their survival, playback-treatment effects on hatching and fledging success were not evident. The interplay between helper presence and predator effects on maternal reproductive investment is still an overlooked area of life history and physiological evolutionary trade-offs that requires further studies.

Keywords: clutch size; cooperative breeding; corticosterone; egg mass; group size; maternal allocation; playback experiment; predation risk; reproductive output; yolk mass.