Accumulating evidence suggests that, in contrast to earlier assumptions, juvenile growth rates are optimised by means of natural and sexual selection rather than maximised to be as fast as possible. Owing to the generally accepted advantage of growing fast to adulthood, such adaptive variation strongly implies the existence of costs attached to rapid growth. By using four populations of protandrous copper butterflies with known differences in intrinsic growth rates within and across populations, we investigate a potential trade-off between rapid growth and the proportionate weight loss at metamorphosis. While controlling for effects of pupal time and mass, we demonstrate that (1) protandrous males, exhibiting higher growth rates, suffer a higher weight loss than females throughout, that (2) population differences in weight loss generally follow known differences in growth rates, and that (3) males have by 6% higher metabolic rates than females during pupal development. These results support the notion that a higher weight loss during the development to adulthood may comprise a physiological cost of rapid development, with the payoff of accelerated growth being reduced by a disproportionally smaller adult size.

Abstract.  Larvae of the butterfly Lycaena tityrus (Poda) are reared at 20 or 27 °C until adult eclosion, after which they are maintained at the same temperature or are transferred to the alternate temperature. The resulting adults are exposed to −20 °C for 8 min, returned to ambient temperature, and the recovery time to standing position is recorded. On the day of eclosion, individuals reared at 20 °C show 19% shorter recovery times than individuals reared at 27 °C. This effect of developmental temperature disappears when the same animals are tested 3 and 6 days later. However, adult temperature did not affect recovery time in these animals, presumably due to over‐riding effects of previous cold shocks. This is suggested by another set of animals, not having experienced previous cold shocks, demonstrating recovery times that are 28% shorter in individuals maintained as adults for 3 days at 20 compared to 27 °C. Thus, L. tityrus appears to be capable of adapting to local temperatures.

No abstract

No abstract

1. While there has been considerable focus on prey occurrence as a factor determining the habitat preference of predators, the roles of other factors related to the habitat are less well characterised.2. In aphidophagous ladybird beetles (Coleoptera: Coccinellidae), a number of species are more restricted in the habitats in which they live than are their prey. A number of such ladybirds appear to show geographic variation in habitat preference.3. To better understand these phenomena, this study considered geographic variation in habitat preference in one such species, the 5-spot ladybird Coccinella quinquepunctata. Because of this ladybird's scarcity, a combination of over 20 years' observations, habitat surveys and online data was used to reach the study's conclusions.4. The data collected indicate that the ladybird is specialised in pioneer habitats close to water, but broadens its range to non-riverine pioneer habitats in north-west continental Europe, where it is likely that a damper (micro)climate allows it to do so. Thus, microclimatic factors appear to be important in determining the habitat of this and probably other predators that are not constrained by prey occurrence. 5. Although threatened by river management elsewhere, in north-western Europe, this species clearly benefits from human activity, which creates many of the disturbed habitats it colonises there. This finding provides further support for the contention that many ladybirds are net beneficiaries of human influence, although they are often characterised as threatened.