Organisms must make important decisions on how to allocate resources to reproduction. We investigated allocation decisions in the social wasp Vespula maculifrons to understand how social insects make reproductive choices. We first determined how annual colonies apportioned resources to growth and reproduction by analysing developing brood. In contrast to expectations, colonies invested in both ...

The white pine weevil, Pissodes strobi, severely restricts the growth and range of Sitka spruce (Picea sitchensis) in British Columbia. Knowledge of the patterns of male and female mating success is important for designing biocontrol programs and for understanding the reproductive potential of this weevil. To examine patterns of male and female reproductive success, we performed experiments in ...

The natural estrogen 17 -estradiol (E2) is responsible for the endocrine disruption and also has potential effect on the reproduction of vertebrate. However, its effect on invertebrate reproduction has scarcely been studied. The present study was conducted to determine the effect of E2 on survival, egg production and egg hatch of calanoid copepod, Acartia omorii under bath administration. Survi...

Theory predicts that sexual reproduction can increase population viability relative to asexual reproduction by allowing sexual selection in males to remove deleterious mutations from the population without large demographic costs. This requires that selection acts more strongly in males than females and that mutations affecting male reproductive success have pleiotropic effects on population pr...

BACKGROUND Maternal age is an important factor in reproduction. Can assisted reproduction technologies (ART) fully compensate for the decline in fertility with age? METHODS We used a computer simulation (Monte Carlo) model of reproduction, combining the monthly probabilities of conceiving, the risk of miscarriage and the probability of becoming age-dependently permanently sterile. RESULTS U...

Extremely hot events (usually involving a few hours at extreme high temperatures in summer) are expected to increase in frequency in temperate regions under global warming. The impact of these events is generally overlooked in insect population prediction, since they are unlikely to cause widespread mortality, however reproduction may be affected by them. In this study, we examined such stress ...

Life-history theory predicts trade-offs between reproductive and survival traits such that different strategies or environmental constraints may yield comparable lifetime reproductive success among conspecifics. Food availability is one of the most important environmental factors shaping developmental processes. It notably affects key life-history components such as reproduction and survival pr...

Reproduction is known to increase the basal metabolic rate and generate oxidative stress, a possible proximate cost of reproduction. Carotenoids have been shown to be in vitro antioxidant molecules and, in a number of instances, to contribute in vivo to the antioxidant protection of the organism against the deleterious effects of free radicals and oxidative stress. These compounds are also invo...

The quality of the environment individuals experience during development is commonly regarded as very influential on performance in later life. However, studies that have experimentally manipulated early-life and subsequently measured individual all components fitness over complete life course are scarce. In this study, we incubated fertile eggs Japanese quail ( Coturnix japonica ) at substanda...

We evaluated covariation between Chinook salmon (Oncorhynchus tshawytscha) abundance and seabird breeding success in central California, USA, and compared potential forecasts to predictive models based on jack (2-year-old male) returns in the previous year. Stepwise regression models based on seabird breeding success in the previous year were comparable to or stronger than jack-based models. In...