Search

In seasonal environments, phenotypic plasticity in response to gradual changes in environmental variables may result in the production of discrete seasonal morphs. Production of the appropriate seasonal morph at the correct time relies on individuals interpreting environmental cues during their development. The speckled wood butterfly Pararge aegeria (L.) has previously been shown to have developmental and phenotypic plasticity across seasons and space (habitats). Here, we examine the developmental sensitivity of different seasonal cohorts of female P. aegeria to changes in local weather conditions over time (1989-1999) and determine how such temporal climatic variation affects adult phenotype development. We observed trait- and cohort-specific changes of adult phenotype development in response to local temporal changes in temperature and rainfall levels. We discuss our findings using current life-history theory and consider the potential for changes in local weather conditions to influence population variability in butterfly morphology and performance. [ABSTRACT FROM AUTHOR]

In this study we investigate how the need for seasonal timing of diapause and sexual maturation have selected for plasticity in life history traits in two butterfly species, Lasiommata maera and Lopinga achine. We test the general hypothesis that insects living in temperate areas should have shorter development times at progressively later dates of the growth season, and that they use daylength as a cue to determine the date. Both species have two different larval growth periods, the first in autumn and the second after termination of diapause in spring. Due to the difference in photoperiodic change in autumn andspring, we expected larvae to interpret daylengths qualitatively differently in the two growth periods. In other words, developmental decisions in response to daylength should depend on the seasonal state (autumn or spring) of larvae. In laboratory experiments we investigated the reaction norms relating larval development times to daylength. In both species the slopes of these reaction norms were different in autumn and in spring. The results of the experiment on L. maera supported specific predictions both in autumn and in spring. The same was true in autumn for L. achine but development time in spring seemed tobe insensitive to daylength. In all cases, short development times were associated with high larval growth rates rather than with small final body sizes. Growth and development in these species can be described as state-dependent decision processes, where information about the external and internal environment is used at several points in development. [ABSTRACT FROM AUTHOR]

Presents a study in biology to determine whether eyespots defend peacock butterflies against foraging blue tits. Procedure taken by the scientists on the experimentation process; Detail of the result of the experiment on the determination of the eyespot as the scare factor for the butterflies' attackers; Conclusion of the research.

In the Eurasian Arctic, the most common lemming species are the Siberian lemming (Lemmus sibiricus) and the collared lemming (Dicrostonyx torquatus). Lemmings constitute the main food item for 5 common predators in the area: arctic fox; snowy owl; rough-legged buzzard; long-tailed skua; and pomarine skua. Hence, these predators form a foraging guild. We have studied factors influencing the structure of this guild. When comparing co-occurrence of the predators between 17 sites across Siberia, there were positive associations between the snowy owl and the two skuas, and a negative association between snowy owl and rough-legged buzzard. There was also a large variation in local population density among the predators, conceivably, due to the risk of intra-guild predation as well as the variation in food supply. There were significant relationships between lemming abundance and the abundance of each predator. An analysis of the predatory response by the arctic fox indicated a response pattern similar tothat of a delayed numerical response to lemming abundance. For this and other reasons, we propose that the arctic fox is a resident specialist predator on microtine rodents. Further, the birds appeared to be nomadic specialist predators with, perhaps, one exception, the rough-legged buzzard. [ABSTRACT FROM AUTHOR]