نتایج جستجو برای: metapopulation
تعداد نتایج: 1826 فیلتر نتایج به سال:
Ecological risk assessment at the population level often involves predicting the effects of a particular change in the land-use patterns on the viability of native species. A common method of addressing such questions is modeling the metapopulation dynamics of the species in the landscape. However, the landscape and, as a result, the spatial structure of the metapopulation usually do not remain...
In this paper we present a deterministic, discrete-time model for a two-patch predator–prey metapopulation. We study optimal harvesting for the metapopulation using dynamic programming. Some rules are established as generalizations of rules for a single-species metapopulation harvesting theory. We also establish rules to harvest relatively more (or less) vulnerable prey subpopulations and more ...
In this paper, we introduce a Levins-type metapopulation model with empty and occupied patches, and dispersing population. We structure the proportion of occupied patches according to the patch-occupancy age. We observe that patch-occupancy age may destabilize the metapopulation, leading to persistent oscillations. We also allow for the dispersal rate to vary with the proportion of empty patche...
Despite the considerable evidence showing that dispersal between habitat patches is often asymmetric, most of the metapopulation models assume symmetric dispersal. In this paper, we develop a Monte Carlo simulation model to quantify the effect of asymmetric dispersal on metapopulation persistence. Our results suggest that metapopulation extinctions are more likely when dispersal is asymmetric. ...
Theory predicts that founder effects have a primary role in determining metapopulation genetic structure. However, ecological factors that affect extinction-colonization dynamics may also create spatial variation in the strength of genetic drift and migration. We tested the hypothesis that ecological factors underlying extinction-colonization dynamics influenced the genetic structure of a tiger...
Abstract Context Metapopulation theory makes useful predictions for conservation in fragmented landscapes. For randomly distributed habitat patches, it predicts that the ability of a metapopulation to recover from low occupancy level (the “metapopulation capacity”) linearly increases with amount. This prediction derives describing dispersal between two patches as function their features and dis...
We propose and analyze a discrete time model for metapopulation on two patches with local logistic dynamics. The model carries a delay in the dispersion terms, and our results on this model show that the impact of the dispersion on the global dynamics of the metapopulation is complicated and interesting: it can affect the existence of a positive equilibrium; it can either drive the metapopulati...
Simple analytical models assuming homogeneous space have been used to examine the effects of habitat loss and fragmentation on metapopulation size. The models predict an extinction threshold, a critical amount of suitable habitat below which the metapopulation goes deterministically extinct. The consequences of non-random loss of habitat for species with localized dispersal have been studied ma...
we quantified the distribution, abundance and assemblage structure of macrofauna at 22 stations in gorgan bay, seasonally in 2012-2013. also, depth, temperature, salinity, do, tom and sediment particle size were measured in each station. the highest concentration of tom was measured near the western littoral zone (10.22) while the mouth part and north-eastern area was characterized by the lowes...
We assessed the utility of simple metapopulation models in an analysis of a decade (1976–86) of stream-fish censuses at 10 sites on the Cimarron River, Oklahoma. This assemblage is a good candidate for metapopulation analysis because there was substantial annual turnover of population, with frequent local extinctions and recolonizations. However, annual probabilities of colonization and extinct...
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