Inbreeding depression can be reduced, or purged, by selection against deleterious alleles. This prediction is the basis of the recommendation that captive wildlife populations suffering from inbreeding depression be intentionally bred from healthy inbred animals. Yet data on the effectiveness of purging inbreeding depression are few. In this study I present and use two different regression mode...

Pig breeders have successfully selected for higher litter size, reduced backfat and improved growth rate (Hermesch, 2006). These outcomes imply that modern sows have higher nutrient demands in comparison to sows of 20 years ago. For example, genetic improvement of litter size has been 0.10 to 0.20 piglets per year in maternal lines. This implies that sows need to eat 50 to 100 grams more feed p...

BACKGROUND Individual variation in both survival and reproduction has the potential to influence extinction risk. Especially for rare or threatened species, reliable population models should adequately incorporate demographic uncertainty. Here, we focus on an important form of demographic stochasticity: variation in litter sizes. We use terrestrial carnivores as an example taxon, as they are fr...

The cliff-edge hypothesis introduces the counterintuitive idea that the trait value associated with the maximum of an asymmetrical fitness function is not necessarily the value that is selected for if the trait shows variability in its phenotypic expression. We develop a model of population dynamics to show that, in such a system, the evolutionary stable strategy depends on both the shape of th...

Berry, C. L. (1971). Archives of Disease in Childhood, 46, 709. Cyclophosphamide therapy in prepubertal rats and subsequent reproductive performance. In an experimental system using rats, prepubertal treatment with cyclophosphamide was associated with slightly reduced fertility of the adult female. No malformations were noted in the offspring, and there was no change in the size of the rat pups...

Stereotypic behaviors are repetitive invariant behaviors that are common in many captive species and potentially indicate compromised welfare and suitability as research subjects. Adult laboratory mice commonly perform stereotypic bar-gnawing, route-tracing, and back-flipping, although great individual variation in frequency occurs. Early life factors (for example, level of maternal care receiv...

As part of a series of studies investigating the genetic basis of prolificacy in the non-inbred QS strain of mice, a line has been selected for increased average litter size over the first 5 litters, and seven sublines have been created by full-sib inbreeding with selection for litter size. Six generations of selection have resulted in an increase of average litter size from 16.0 to 18.1, indic...

Knowledge of factors influencing the timing of reproduction is important for animal conservation and management. Brown bears (Ursus arctos) are able to vary the birth date of their cubs in response to their fat stores, but little information is available about the timing of implantation and parturition in free-ranging brown bears. Body temperature and activity of pregnant brown bears is higher ...

This study evaluated the effects of chronic treadmill training on body mass gain and visceral fat accumulation in overfed rats. Overfeeding was induced by reducing the litter size to 3 male pups per mother during the suckling period. The litter size of control rats was adjusted to 10 male pups per mother. Seven weeks after birth overfed and normally fed rats were selected and assigned to a sede...

The idea that oxidative stress may underpin life history trade-offs has become extremely popular. However, experimental support for the concept has proved equivocal. It has recently been suggested that this might be because of flaws in the design of existing studies. Here, we explore the background to the oxidative stress hypothesis and highlight some of the complexities in testing it. We concl...