Theories of density-dependent natural selection predict that evolution should favor those genotypes with the highest per capita rates of population growth under the current density conditions. These theories are silent about the mechanisms that may give rise to these increases in density-dependent growth rates. We have observed the evolution of six populations of Drosophila melanogaster recentl...

T HIS an REPORT presents the first results investigation into the effects of of 1. population size on the adrenal glands, and on the reproductive function of mammals. The present study is restricted to mice in confined populations of fixed sizes. This study was prompted by the suggestion that stress was produced in the individuals of a mammalian population in proportion to the population densit...

While worldwide census data provide statistical evidence that firmly link the population density with several indicators of social welfare, the precise mechanisms underlying these observations are largely unknown. Here we study the impact of population density on the evolution of public cooperation in structured populations and find that the optimal density is uniquely related to the percolatio...

Average population density has been a traditional urban sprawl indicator, but it is insufficient to encapsulate its detrimental impacts. We demonstrate that cities of identical average may be subject very different levels car dependency, CO2 emissions and public budget deficits. To capture this, we shed light into the properties two “density-allocation” indicators: percentage land in which fall...

Aflatoxins are secondary metabolites produced by Aspergillus flavus, A. parasiticus, A. tamari, A. bombycis and A. nomius species. Relative humidity (RH) is one of the most important parameters influencing the development of aflatoxins in pistachio orchards by Aspergillus species. The type of irrigation system affects density and frequency of the Aspergillus species in the soil. In the current ...

In the celebrated thesis of Thomas Malthus, vice and misery impose the ultimate natural limit on the growth of populations. Students of the subject have given most of their attention to misery, that is, to predation, disease and food supply as forces that operate to adjust the size of a population to its environment. But what of vice? Setting aside the moral burden of this word, what are the ef...

We use panel data from Germany to analyze the effect of population density on urban air pollution (nitrogen oxides, particulate matter, ozone, and an aggregate index for bad quality [AQI]). To address unobserved heterogeneity omitted variables, we present long difference/fixed effects estimates instrumental variables estimates, using historical soil as instruments. Using our preferred find that...