نتایج جستجو برای: population growth
تعداد نتایج: 1459485 فیلتر نتایج به سال:
The phenotype of adults can be strongly influenced by the environmental conditions experienced during development. Consequently, variation in habitat quality across space and through time also leads to differences in the phenotypes of adults. This could create carry-over effects where differences in the natal habitat quality of colonizers influence population dynamics in new habitats. We tested...
Abstract. First, we systematize earlier results on the global stability of the model ẋ + μx = f(x(· − τ)) of population growth. Second, we investigate the effect of delay on the asymptotic behavior when the nonlinearity f is a unimodal function. Our results can be applied to several population models [7, 9-13] because the function f does not need to be monotone or differentiable. Specifically, ...
During man’s relatively brief existence on this planet, he has relied on the bounty of its flora and fauna for his existence. He has harvested wildlife for food, clothing, shelter, medicines, beasts of burden, pets, and companionship. Over most of this period, this harvesting and exploitation had little impact on those resources. Human population was very low, and most animal and plant populati...
This paper develops a uni ̄ed growth model that captures the historical evolution of population, technology, and output. It encompasses the endogenous transition between three regimes that have characterized economic development. The economy evolves from a Malthusian regime, where technological progress is slow and population growth prevents any sustained rise in income per capita, into a Post-M...
The population dynamics of preindustrial societies depend intimately on their surroundings, and food is a primary means through which environment influences population size and individual well-being. Food production requires labor; thus, dependence of survival and fertility on food involves dependence of a population's future on its current state. We use a perturbation approach to analyze the e...
In this paper, I present and discuss a potentially useful modeling approach for investigating population dynamics in the presence of disturbance. Using the motivating example of wildfire, I construct and analyze a deterministic model of population dynamics with periodic disturbances independent of spatial effects. Plant population growth is coupled to fire disturbance to create a growth-disturb...
Although earnings generally increased in rural areas in the 1990s, Hispanic population growth led to lower wages for at least one segment of the rural population—workers with a high school degree (skilled workers), particularly men in this skill group. Using data from the Bureau of Economic Analysis and the Current Population Survey, this report examines the effects of Hispanic population growt...
Spatial population models predict strong density-dependence and relatively stable population dynamics near the core of a species' distribution with increasing variance and importance of density-independent processes operating towards the population periphery. Using a 10-year data set and an information-theoretic approach, we tested a series of candidate models considering density-dependent and ...
To explain the links between population distribution and economic integration, we construct a spatial economics model with endogenous fertility. A higher population concentration increases real wages and child-raising costs, thus lowering the fertility rate. However, people migrate to more populated regions to obtain higher real wages. We show that mobility across regions results in more people...
The source populations of tigers are mostly confined to protected areas, which are now becoming isolated. A landscape scale conservation strategy should strive to facilitate dispersal and survival of dispersing tigers by managing habitat corridors that enable tigers to traverse the matrix with minimal conflict. We present evidence for tiger dispersal along transboundary protected areas complexe...
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