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

Abstract

Summary1. Few studies have experimentally quantified the costs and benefits of female eggguarding 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. 2. Here 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. 3. In 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. 4. By 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. 5. Regarding 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. 6. We 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. 7. Our 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. 8. Weighting 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.

Description of Mitogoniella mucuri sp. nov. (Opiliones: Gonyleptidae) and considerations on polymorphic traits in the genus and Gonyleptidae

“…Taxonomic studies on Opiliones contribute to ecological and behavioral studies, including those in caves, as shown by intensive work in recent years, especially with Goniosomatinae species (e.g., Gnaspini & Cavalheiro 1998;Machado & Oliveira 1998;Machado et al 2000;Machado 2002;Willemart & Gnaspini 2004;Ferreira et al 2005;Buzatto et al 2007;Buzatto & Machado 2009). Harvestmen use caves as refuges during the day, form large aggregates on cave walls and leave them at night to forage in the epigean environment (Gnaspini 1995;Gnaspini et al 2003;Machado et al 2003;Willemart & Gnaspini 2004;Ferreira et al 2005;Chelini et al 2011).…”

Investimento parental e papéis sexuais em opiliões com cuidado paternal exclusivo

“…Therefore, maternal care is energetically costly for females, especially in the case of iteroparous species [4], since it reduces the available energy to produce additional eggs, negatively affecting females' future reproduction and fecundity [e.g., [5][6][7][8][9]. Among species exhibiting exclusive paternal care, the available data do not seem consensual.…”

“…7,9,57]. Given that the production of sperm and other seminal products generally requires fewer nutrients than does the production of eggs [58], care-related reductions in feeding activities are predicted to be less costly for male reproductive potential than they are for female reproductive potential [1].…”

Flexible compensation of uniparental care: things are not always what they seem

“…At the beginning of the breeding season (i.e., September-October), territorial males engage in ritualistic fights using their second pair of legs in order to monopolize oviposition sites at the margin of forest streams (Buzatto & Machado 2008). When arriving at a territory, a female may copulate with the harem-owning male and lay a clutch of eggs, usually, on the underside surface of a leaf (Buzatto et al 2007). Females provide care for the offspring until nymphal hatching and dispersal by standing on the eggs and aggressively repelling any egg predators in the close vicinity, which improve offspring survival (Buzatto et al 2007).…”

“…When arriving at a territory, a female may copulate with the harem-owning male and lay a clutch of eggs, usually, on the underside surface of a leaf (Buzatto et al 2007). Females provide care for the offspring until nymphal hatching and dispersal by standing on the eggs and aggressively repelling any egg predators in the close vicinity, which improve offspring survival (Buzatto et al 2007). Although eggs can be attacked by fungal infections, parental females are not able to prevent this threat (as it occurs in other harvestmen; Mora 1990), and maternal care seems to be restricted to protection against offspring predators.…”