Effects of maternal care on the lifetime reproductive success of females in a neotropical harvestman

Authors

  • BRUNO A. BUZATTO,

    1. Programa de Pós-graduação em Ecologia, Instituto de Biologia, CP 6109, Universidade Estadual de Campinas, Campinas, 13083-970, São Paulo, Brazil; *Programa de Pós-graduação em Ecologia e Conservação de Recursos Naturais, Instituto de Biologia, Universidade Federal de Uberlândia, Brazil; and †Departamento de Ecologia, Instituto de Biociências, Universidade de São Paulo, São Paulo, Brazil
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  • GUSTAVO S. REQUENA,

    1. Programa de Pós-graduação em Ecologia, Instituto de Biologia, CP 6109, Universidade Estadual de Campinas, Campinas, 13083-970, São Paulo, Brazil; *Programa de Pós-graduação em Ecologia e Conservação de Recursos Naturais, Instituto de Biologia, Universidade Federal de Uberlândia, Brazil; and †Departamento de Ecologia, Instituto de Biociências, Universidade de São Paulo, São Paulo, Brazil
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  • * EDUARDO G. MARTINS,

    1. Programa de Pós-graduação em Ecologia, Instituto de Biologia, CP 6109, Universidade Estadual de Campinas, Campinas, 13083-970, São Paulo, Brazil; *Programa de Pós-graduação em Ecologia e Conservação de Recursos Naturais, Instituto de Biologia, Universidade Federal de Uberlândia, Brazil; and †Departamento de Ecologia, Instituto de Biociências, Universidade de São Paulo, São Paulo, Brazil
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  • GLAUCO MACHADO

    1. Programa de Pós-graduação em Ecologia, Instituto de Biologia, CP 6109, Universidade Estadual de Campinas, Campinas, 13083-970, São Paulo, Brazil; *Programa de Pós-graduação em Ecologia e Conservação de Recursos Naturais, Instituto de Biologia, Universidade Federal de Uberlândia, Brazil; and †Departamento de Ecologia, Instituto de Biociências, Universidade de São Paulo, São Paulo, Brazil
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Glauco Machado, Departamento de Ecologia, Instituto de Biociências, Rua do Matão, trav. 14, n°321, Cidade Universitária, 05508-900, São Paulo, SP, Brazil. E-mail: glaucom@ib.usp.br

Summary

  • 1Few studies have experimentally quantified the costs and benefits of female egg-guarding behaviour in arthropods under field conditions. Moreover, there is also a lack of studies assessing separately the survival and fecundity costs associated with this behavioural trait.
  • 2Here we employ field experimental manipulations and capture–mark–recapture methods to identify and quantify the costs and benefits of egg-guarding behaviour for females of the harvestman Acutisoma proximum Mello-Leitão, a maternal species from south-eastern Brazil.
  • 3In a female removal experiment that lasted 14 days, eggs left unattended under natural conditions survived 75·6% less than guarded eggs, revealing the importance of female presence preventing egg predation.
  • 4By monitoring females’ reproductive success for 2 years, we show that females experimentally prevented from guarding their eggs produced new clutches more frequently and had mean lifetime fecundity 18% higher than that of control guarding females.
  • 5Regarding survival, our capture–mark–recapture study does not show any difference between the survival rates of females prevented from caring and that of control guarding females.
  • 6We found that experimentally females prevented from guarding their eggs have a greater probability to produce another clutch (0·41) than females that cared for the offspring (0·34), regardless of their probability of surviving long enough to do that.
  • 7Our approach isolates the ecological costs of egg-guarding that would affect survival, such as increased risk of predation, and suggests that maternal egg-guarding also constrains fecundity through physiological costs of egg production.
  • 8Weighting costs and benefits of egg-guarding we demonstrate that the female's decision to desert would imply an average reduction of 73·3% in their lifetime fitness. Despite the verified fecundity costs of egg-guarding, this behaviour increases female fitness due to the crucial importance of female presence aimed to prevent egg predation.

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