Search

Climate change is associated with the increase in both the mean and variability of thermal conditions. Therefore, the use of more realistic fluctuating thermal regimes is the most appropriate laboratory method for predicting population responses to thermal heterogeneity. However, the long- and short-term implications of evolving under such conditions are not well understood. Here, we examined differences in key life-history traits among populations of seed beetles (Callosobruchus maculatus) that evolved under either constant control conditions or in an environment with fluctuating daily temperatures. Specifically, individuals from two distinct genetic backgrounds were kept for 19 generations at one of two temperatures, a constant temperature (T  = 29 °C) or a fluctuating daily cycle (T mean = 33 °C, T max = 40 °C, and T min = 26 °C), and were assayed either in their evolved environment or in the other environment. We found that beetles that evolved in fluctuating environments but were then switched to constant 29 °C conditions had far greater lifetime reproductive success compared with beetles that were kept in their evolved environments. This increase in reproductive success suggests that beetles raised in fluctuating environments may have evolved greater thermal breadth than control condition beetles. In addition, the degree of sexual dimorphism in body size and development varied as a function of genetic background, evolved thermal environment, and current temperature conditions. These results not only highlight the value of incorporating diel fluctuations into climate research but also suggest that populations that experience variability in temperature may be better able to respond to both short- and long-term changes in environmental conditions. [ABSTRACT FROM AUTHOR]

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.anbehav.2004.11.008 Byline: Elena C. Berg Abstract: I conducted a 3-year study investigating parentage in a Costa Rican population of white-throated magpie-jays, a cooperatively breeding corvid inhabiting the tropical dry forests of Central America. This species is unusual among avian cooperative breeders in that helpers are mostly females. Using 12 microsatellite loci, I estimated parentage for 110 offspring in 32 broods and eight social groups. Primary breeders were not the sole producers of offspring within a brood. At the 95% confidence level, female helpers within the group produced 16% of young, and floater males sired approximately 30% of young. Helpers that bred mated either with the primary male (three cases) or with floaters (five cases). When the analysis was limited to the most reliable data, the 20 nests and 63 offspring where all candidate mothers had been sampled, at the 95% confidence level only one helper produced young, while floater males sired 22% of offspring. The results of this study cast doubt on the simple classification of white-throated magpie-jays as cooperative breeders and suggest a more complex combination of cooperative and parasitic behaviours. Author Affiliation: Center for Animal Behavior, University of California at Davis, U.S.A. Article History: Received 9 July 2004; Revised 18 September 2004; Accepted 2 November 2004 Article Note: (miscellaneous) MS. number: A9934R

A study was conducted to investigate parentage in a Costa-Rican population of white-throated magpie-jays, a co-operative breeder in the tropical dry forest of Central America. The results showed that a more complex combination of co-operative and parasitic behaviors were suggested instead of simple classification of white-throated magpie-jays, as co-operative breeders.