SYNOPSIS. Body size and temperature are the two most important variables affecting nearly all biological rates and times, especially individual growth or production rates. By favoring an optimal maturation age and reproductive allocation, natural selection links individual growth to the mortality schedule. A recent model for evolution of life histories for species with indeterminate growth, whi...

Perinatal undernutrition is known to disturb reproductive development, in particular by delaying the onset of puberty in certain species. Using a rat model, we studied whether hypernutrition after birth can rescue the delayed onset of puberty in intrauterine undernourished female rats. Pregnant rats were divided into two groups: the maternal normal nutrition (mNN, n = 8) and maternal undernut...

Density, distribution, and nutritional quality of plants are the causal basis of host plant selection in aphids. Nutritional qualities of a plant vary according to its growth stage and also in response to seasonal variation. How host plant growth stages shape aphid performance was studied in Aphis spiraecola Patch (Homoptera: Aphididae) on the perennial Siam weed, Chromolaena odorata (L.) King ...

Diagnosing the status of crop nitrogen (N) helps to optimize crop yield, improve N use efficiency, and reduce the risk of environmental pollution. The objectives of the present study were to develop a critical N (Nc) dilution curve for winter wheat (based on spike dry matter [SDM] during the reproductive growth period), to compare this curve with the existing Nc dilution curve (based on plant d...

In many organisms survival depends on body size. We investigate the implications of size-selective mortality on life-history evolution by introducing and analysing a new and particularly flexible life-history model with the following key features: the lengths of growth and reproductive periods in successive reproductive cycles can vary evolutionarily, the model does not constrain evolution to p...

Offspring begging and parental provisioning are the two central social behaviours expressed during the period of parental care. Both behaviours influence each other and it is, therefore, hypothesized that they should ultimately become (genetically) correlated, stabilized by fitness costs to parents and/or offspring. By reciprocally exchanging entire clutches in canaries (Serinus canaria), we te...

Salinity is considered as one of important physical factors influencing rice (Oryza sativa L.) production. Knowledge of salinity effects on rice seedling growth and yieldcomponents would improve management practices in fields andincrease our understanding of salt tolerance mechanisms in rice. This study was designed to assess the role of Saltol QTL in regards to effects of salinity on plant gro...

Reproductive cessation is perhaps the earliest aging phenotype that humans experience. Similarly, reproduction of Caenorhabditis elegans ceases in mid-adulthood. Although somatic aging has been studied in both worms and humans, mechanisms regulating reproductive aging are not yet understood. Here, we show that TGF-β Sma/Mab and Insulin/IGF-1 signaling regulate C. elegans reproductive aging by m...

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...