Consequences of combining sex-specific life-history traits

Abstract

Males and females evolved distinct life-history strategies, reflected in diverse life-12 history traits, summarized as sexual dimorphism. Life-history traits are highly interlinked. 13 The sex that allocates more resources towards offspring is expected to increase its life 14 span, and this might require an efficient immune system. However, the other sex might 15 allocate its resources towards ornamentation, and this might have immunosuppressive 16 effects. Activity of immune response may not be specific to the sex that produces the 17 eggs but could correlate with the amount of parental investment given. Informed by 18 experimental data, we designed a theoretical framework that combines multiple life-19 history traits. We disentangled sex-biased life-history strategies from a particular sex to 20 include species with reversed sex-roles, and male parental investment. We computed the 21 lifetime reproductive success from the fitness components arising from diverse sex-biased 22 life-history traits, and observed a strong bias in adult sex ratio depending on sex-specific 23 resource allocation towards life-history traits. Overall, our work provides a generalized 24 method to combine various life-history traits with sex-specific differences to calculate the 25 lifetime reproductive success. This was used to explain certain empirical observations as 26 a consequence of sexual dimorphism in life-history traits. 27 28 lifetime reproductive success, adult sex ratio 29 life-history traits. Theoretical models assessing the interaction of multiple life-history traits are 33 thus crucial to understand organisms' overall life-history and how they impact fitness. Theoretical 34 and experimental studies have shown how multiple life-history traits define an individual's lifetime 35 reproductive success (MooreIn this study, we present a model that addresses the interaction of essential sex-specific life-history 39 traits aiming to obtain the lifetime reproductive success of both sexes. This sheds light on how these 40 traits are contributing to an individual's life-history. We further present the consequences of various 41 sex-specific strategies affecting an evolving population. 42Most life-history traits have sex-specific differences. Sex-specific life histories have evolved in 43 the animal kingdom as a consequence of difference in gamete size known as anisogamy (Bell, 44 1978); females contribute large costly eggs to reproduction and males small cheap sperm. The 45 distinct resource allocation into the offspring asks for sex-specific life-history strategies (Trivers, 46 we focus on the sex-specific differences in three life history traits namely 1. Parental investment 2. 48Ornamentation and 3. Immunocompetence 49In many species, parental investment is not restricted to sperm and egg production. Parental 50 investment (PI) is any behavioural and physiological investment by a parent provided to the off-51 spring (Trivers, 1972(Trivers, , 2002. The sex that needs to allocate more resources towards the offspring 52 strives...