Abstract:
Fitness can be comprehensively defined in terms of reproductive value or the expected
future reproductive contribution of an individual, as a function of its age, expectation of
survival and expectation of reproduction (Reznick and Travis, 1996). Thus, the study of lifehistory traits like reproductive age, number of offspring, life span and other traits which
affect these indirectly, like resistance of an organism to various biotic and abiotic stresses or
traits affecting resource acquisition and utilization, is important to both ecology and
evolution. However, it was Mac Arthur and Wilson’s (1967) theory of density-dependent
selection which for the first time formally brought together population genetics and
population ecology, as it considered the impact of population density on evolutionary trends.
Since then, many theoretical models have been developed for life-history evolution over the
course of time and under different environmental conditions (Gadgil and Bossert, 1970;
Roughgarden, 1971; Asmussen, 1983; Boyce, 1984; Charlesworth 1994). These models
predict the life-history expected to evolve under some defined selection regime. However,
these models typically do not explicitly consider the genetic architecture of fitness-related
traits. This lacuna has been addressed by many empirical studies on life-history evolution
done in field, semi-natural or laboratory conditions (Rose 1984; Vasi et al. 1994; Hoffmann
et al. 2003; van der Linde, 2005; Nussey et al. 2008).
