Amid persistently high population growth rates in developing countries, people have questioned whether the recent change from a fertility-reduction oriented family planning program strategy to a reproductive health-oriented and meeting-unmet-needs based program of contraceptive services will slow the pace of fertility decline, exacerbating population problems and developmental issues in develop...

Compensatory or 'catch-up' growth may be an adaptive mechanism that buffers the growth trajectory of young organisms from deviations caused by reduced food availability. Theory generally assumes that rapid juvenile compensatory growth impacts reproduction only through its positive effects on age and size at maturation, but potential reproductive costs to juvenile compensatory growth remain virt...

Standard laboratory toxicity tests assess the physiological responses of individual organisms to exposure to toxic substances under controlled conditions. Time and space restrictions often prevent the assessment of population-level responses to a toxic substance. Contaminants can affect various biological functions (e.g. growth, fecundity or behavior), which may alter different demographic trai...

in order to investigate drought stress and plant density the yield, yield components and protein of spotted bean grain (cultivar talash), an experiment was carried out as split plots in randomized complete blocks with three replications in yasouj, in 2012. factors of the test including irrigation in three levels; without stress (control treatment), water stress in vegetative stage (interrupting...

It is often presumed that infertility is not a problem in resource-poor areas where fertility rates are high. This is challenged by consistent evidence that the consequences of childlessness are very severe in low-income countries, particularly for women. In these settings, childless women are frequently stigmatized, isolated, ostracized, disinherited and neglected by the family and local commu...

Fertility levels remain high in most of sub-Saharan Africa, despite recent declines, and even in a large capital city such as Accra, Ghana, women are having children at a pace that is well above replacement level and this will contribute to significant levels of future population growth in the city. Our purpose in this paper is to evaluate the way in which neighborhood context may shape reprodu...

This article studies reproductive externalities within rural communities in poor countries. It is shown that such externalities create a link between household poverty, household size, and the local natural-resource base, each of which is viewed as being endogenous. The models presented here o!er an explanation for the fact that in recent decades large groups of people in various parts of the w...

In New Zealand, as elsewhere, research on rare species has been dominated by autecological studies of individual threatened species. Limitations of this approach are that it involves no comparison with related common species which may have similar traits, and that the minimal sample size prevents generalisation about causes and consequences of rarity. We report on experimentally determined grow...

It is often assumed that larval food stress reduces lifetime fitness regardless of the conditions subsequently faced by adults. However, according to the environment-matching hypothesis, a plastic developmental response to poor nutrition results in an adult phenotype that is better adapted to restricted food conditions than one having developed in high food conditions. Such a strategy might evo...

Freshwater fish that live exclusively in rivers are at particular risk from fragmentation of the aquatic system, mainly the species that migrate upriver for reproduction. That is the case of Salminus hilarii, an important migratory species currently classified as "almost threatened" in the São Paulo State (Brazil), facing water pollution, dam construction, riparian habitat destruction and envir...