Maternal care in the harvestman Neosadocus maximus (Arachnida: Opiliones)

Author(s)

Marie Claire Chelini

• Document type: Master's Dissertation
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Instituto de Biociências (IBIOC/SB)
• Defense date: 2011-05-17

Examining board members

Glauco Machado; Marcelo de Oliveira Gonzaga; Rodrigo Hirata Willemart

• Advisor: Glauco Machado

Abstract

Many forms of parental care increase offspring survival, at the cost of a decrease in the parental individuals capacity to invest in a future brood. It is expected, therefore, that parental individuals adopt parental strategies that allow them to balance immediate benefits and future costs, optimizing their total reproductive success. In this thesis, we aimed to identify costs and benefits of maternal care in the harvestman Neosadocus maximus, whose females periodically desert their broods and add eggs to their clutches for up to two weeks unique characteristics among harvestmen with maternal care. We also explored which factors allow N. maximus females to desert their clutches frequently. We tested the following hypothesis: (1) maternal care protects the eggs against predators, especially at night; (2) maternal care decreases the current female fecundity; (3) the mucus coat covering the eggs protects them against predators even in the absence of the guarding female. Our results indicate that maternal care is an effective protection against egg predators, and does not decrease current female fecundity. We also demonstrated that the mucus coat provides effective protection to the eggs in the absence of the guarding female, allowing them to abandon periodically their clutches without leaving the offspring completely vulnerable to predators. The mucus coat covering N. maximus eggs allows these females to minimize the physiological costs of caring, with no severe increase in the cost of deserting in terms of brood reduction by predation. (AU)