Life history strategies and habitat templets of tropical butterflies in north-eastern Australia

Abstract

Three multivoltine species of satyrine butterflies in the genus Mycalesis (Lepidoptera: Nymphalidae) are narrowly sympatric in the wet–dry tropics of north-eastern Australia. They show a range of ecological strategies and adaptations associated with contrasting habitats and varying selective pressures. Two abiotic factors, namely favorability (the reciprocal of seasonal adversity) and predictability (broadly the reciprocal of disturbance), were examined as potential environmental selective forces in shaping their life histories. Comparison of several key life history traits of the lsquowet-season formrsquo revealed that the life histories of each species corresponded well with their habitat characteristics. M. perseus, which lives in habitats which are less favorable (i.e. adverse) and more unpredictable (i.e. temporary), shows many traits of an r-type strategy: smaller size, faster development, earlier maturation, higher fecundity, smaller egg size, and rapid population increase. By contrast, M. sirius and M. terminus, which live in more favorable and predictable (i.e. permanent) habitats, have many life history attributes and other characteristics in common which link them closer to K-type strategies. The only discrepancy is lower potential reproductive effort of M. perseus, which may be accounted for in terms of an evolutionary trade-off, such as with dispersal or dormancy. Other correlates associated with the M. perseus life history tactic include higher sex-size dimorphism, greater dispersal ability, better tolerance to adverse conditions, stronger phenotypic variation, greater degree of polyandry, and a more flexible breeding strategy. The life history patterns of these species are discussed in the context of evolutionary life history models, particularly the Southwood–Greenslade habitat templet.