the relationship between initial population density of rice white tip nematode (aphelenchoides besseyi) and yield was examined on oryzae sativa cv. alikazemi. experiments were conducted in greenhouse, micro-plot and field conditions. seinhorst’s model was used to describe the relationship between nematode population density and crop yield. the parameters of the model, minimum yield (m), constan...

the objective of this study was to evaluate the potential gain in accuracy of predictions by imputing genotypes from a low-density marker panel (6640 marker with 10 replicates) to a medium-density marker panel in a simulated population of jersey cattle using fimpute software and also to evaluate the reliability of genomic estimate of breeding values (gebv) for milk yield (h2=0.40) and fertility...

While previous empirical analysis of deforestation focused on population, this paper builds from a model of land use which suggests many determinants of deforestation in the Brazilian Amazon. I derive a deforestation equation from this model and test a number of those factors using county-level data for the period 1978]1988. The data include a satellite deforestation measure which allows improv...

Darwen, P. It has long been known that extinctions or wild oscillations in populations can occur when population density is too low, or when a population is connned to too small an area at high population density. This study discovers another cause of extinction. Cellular automata models of a single population in a landscape indicate that, if a population occupies an unconnned region smaller th...

Migration is a central determinant of population dynamics and structure. We examined whether three major temperament traits--sociability, emotionality, and activity--predicted migration propensity, selective urban-rural migration, and migration distance in a 9-year prospective study in Finland. The participants were Finnish women and men (N= 1,733) ages 15 to 30 years at baseline. The home muni...

Management agencies and quantitative ecologists need robust estimates of population density. The best way of converting population estimates of livetrapped small mammals to population density is not clear. We estimated population density on livetrapping grids with 4 estimators applied to 3 species of boreal forest and 3 species of tundra rodents to test for relative differences in density estim...

Spatio-temporal patterns of population changes within and across countries have various implications. Different geographical, demographic and econo-societal factors seem to contribute to migratory decisions made by individual inhabitants. Focusing on internal (i.e. domestic) migration, we ask whether individuals may take into account the information on the population density in distant location...