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...

The emergence and abundance of cooperation in nature poses a tenacious and challenging puzzle to evolutionary biology. Cooperative behaviour seems to contradict Darwinian evolution because altruistic individuals increase the fitness of other members of the population at a cost to themselves. Thus, in the absence of supporting mechanisms, cooperation should decrease and vanish, as predicted by c...

Group size is an important variable describing behavioural ecology of animals. A variety of factors such as habitat characteristics, life history, spatio-temporal resource dynamics, population density, predation risk, competition with kin, and social learning often determine group size in large mammals. We studied temporal dynamics of group size in Siberian Ibex (Capra sibirica) in a protected ...

two iranian strains of brachionus rotifers were cultured under different food and salinity regimes. the rotiferswere fed with five algal types (freshwater and marine chlorella vulgaris, nannochloropsis occulata, isochrysisgalbana and scenedesmus obliquus) at three different salinities (5, 15 and 25 g/l) and their reproductive and growth parameters were assessed. the maximum number of ovigerous ...