Oecologia最新文献

In ectothermic animals, elevational gradients, such as mountainous environments, are often associated with shifts in body size, although patterns differ across taxa and contexts. Mountain landscapes are characterised by relatively rapid shifts in biotic and abiotic conditions along an elevational gradient, commonly referred to as elevational zonation. Such zonation can reduce the geographic scale at which organisms experience the effects of climate change. The upslope range shifts will expose organisms at the colonization front to sub-optimal conditions. We can expect these challenging conditions to influence many life-history traits including growth rates and reproductive output. We tested the hypothesis that body size varies across elevational gradients in a contemporary montane colonizer, the common wall lizard (Podarcis muralis). Further, we assessed active body temperatures and available environmental temperatures in an attempt to discern a potential abiotic factor that might drive such a pattern. We quantified body size in lizards along four replicate transects ranging from 400 to 2400 m above sea level in the Pyrenees. Male body size decreased with increasing elevation. While female body size was invariant, females at higher elevation exhibited lower body condition. These results suggest that the effects of abiotic limitations or selective pressures experienced at the high-elevation colonisation front are sex-specific. Furthermore, lizards from both sexes were able to maintain similar field active body temperatures across elevation, despite reduced ambient temperature. If available temperatures limit activity periods or necessitate higher thermoregulatory investment, as suggested by our results, then further warming may benefit lizards and favour further upslope migration.

Monochamus alternatus is a notorious pest of the pine forests across East Asian countries. Both large and small individuals of either sex coexist in the wild. However, whether and how body size affects sexual selection outcomes and longevity remains unknown. In this study, we allowed a male or a female of small or large size to choose between two mates of varying sizes, which were from a wild-caught population. Our results revealed that mating latency and frequency of mating attempts varied across different social environments. Both large males and large females preferred larger mates, whereas this preference was not observed for the small males and small females. Male-male competition had no significant effect on ejaculation duration and frequency or sperm number in ejaculates. When a single male had an opportunity to choose between two females of different sizes, the reproductive investment of small males towards the small females was almost doubled compared to that of the large males, i.e., longer ejaculation duration, higher ejaculation frequency, and greater numbers of sperm transferred. However, the greater mating efforts of small males did not translate to greater fecundity/fertility of small females. We also showed that regardless of their body size, females always had greater fertility when they mated with large males but evidence for a trade-off between fecundity and longevity was not found. Alternatively, female fecundity was positively associated with longevity, and fertility was negatively associated with longevity and fecundity. We discussed these results placing it in a broader context of mate choice evolutionary dynamics.