Investimento parental e papéis sexuais em opiliões com cuidado paternal exclusivo

Abstract

Exclusive paternal care is the rarest form of post-zygotic parental investment in nature, which has independently evolved in no more than 14 arthropod lineages. Although many of those species are easily observed and manipulated, only recently researchers have started to pay attention and test hypotheses on parental investment and evolution of sex roles in such interesting biological systems. The main goal of this thesis was investigating individual and population characteristics that affect the reproductive success of males of harvestmen (Arachnida: Opilioes) with paternal care. In the first chapter, we revise the theory in details, since seminal works on sex roles until the most recent advances in the area, sistematically approaching the current knowledge abot costs and benefits of paternal care in arthropods, as well as the role of sexual selection on the evolution of parental behavior and sex roles. Then, in chapters 2 and 3, we access energetic and survival costs of paternal care in the harvestmen Iporangaia pustulosa and Zygopachylus albomarginis.Comparing these two species, that show different levels of parental investment, we test directional predictions that males which invest more should also pay more intense costs rekated to care. In the fourth chapter, based on natural history information and population parameters for I. pustulosa, we predict which sex should be choosier when selecting sexual partners, and test such predictions using behavioral data on male-female interactions.Finally, in chapter 5, we evaluate the relative importance of oviposition site, males' body size and males' parental state on their attractiveness. At the end, we integrate all the results obtained during the five chapters into a theoretical framework about the interdependence among trade-offs between parental and mating efforts, paternal care and sex roles, not only regarding the pair od species studied, but in a broad way. Key-words:Costs of care; Iporangaia pustulosa; Parental effort, Reproductive effort, Sexual selection; Zygopachylus albomarginis. APRESENTAÇÃO GERALO comportamento de cuidado paternal exclusivo à prole é provavelmente a forma mais rara de investimento parental pós-zigótico na natureza. A maioria dos casos ocorre entre anfíbios e peixes (revisões em Coleman & Jones, 2011), porém o cuidado paternal está presente também em algumas poucas espécies de poliquetos, artrópodes e aves (revisões em Ridley, 1978;, Owens, 2002. Independentemente do grupo, o que sempre chamou a atenção dos pesquisadores nos casos de cuidado paternal é suposta discrepância em relação a um padrão generalizado na natureza, segundo o qual os machos investiriam principalmente em estratégias competitivas para garantir seu acesso a parceiras e pouco ou quase nada em cuidado à prole. As primeiras explicações teóricas para a evolução do cuidado paternal surgiram no final da década de 60, com um período de efervescência de idéias ao longo da década de 70 (Williams, 1966;. As teorias sobre investimento parental e papéis sexuais lançadas nessa época...