نتایج جستجو برای: dispersal
تعداد نتایج: 19935 فیلتر نتایج به سال:
BACKGROUND AND AIMS Dispersal and establishment ability can influence evolutionary processes such as geographic isolation, adaptive divergence and extinction probability. Through these population-level dynamics, dispersal ability may also influence macro-evolutionary processes such as species distributions and diversification. This study examined patterns of evolution of dispersal-related fruit...
Seed dispersal is a key ecological process in tropical forests, with effects on various levels ranging from plant reproductive success to the carbon storage potential of tropical rainforests. On a local and landscape scale, spatial patterns of seed dispersal create the template for the recruitment process and thus influence the population dynamics of plant species. The strength of this influenc...
Climate change is increasingly affecting the structure and dynamics of ecological communities both at local and at regional scales, and this can be expected to have important consequences for their robustness and long-term persistence. The aim of the present work is to analyse how the spatial structure of the landscape and dispersal patterns of species (dispersal rate and average dispersal dist...
Frugivorous birds provide important ecosystem services by transporting seeds of fleshy fruited plants. It has been assumed that seed-dispersal kernels generated by these animals are generally leptokurtic, resulting in little dispersal among habitat fragments. However, little is known about the seed-dispersal distribution generated by large frugivorous birds in fragmented landscapes. We investig...
Based on a marginal value approach, we derive a nonlinear expression for evolutionarily stable (ES) dispersal rates in a metapopulation with global dispersal. For the general case of density-dependent population growth, our analysis shows that individual dispersal rates should decrease with patch capacity and-beyond a certain threshold-increase with population density. We performed a number of ...
The hypothesis that patterns of sex-biased dispersal are related to social mating system in mammals and birds has gained widespread acceptance over the past 30 years. However, two major complications have obscured the relationship between these two behaviors: 1) dispersal frequency and dispersal distance, which measure different aspects of the dispersal process, have often been confounded, and ...
Damavand volcano is located 60 km to the East North- East of Tehran. It is a dormant stratovolcano outcrop in the Alborz Mountains of northern Iran and is the highest mountain (5670 m) in the Middle East and West Asia. Mazandaran Province, one of the most populous provinces by population density, Semnan and Gorgan provinces further east are neighbours of the Damavand. Volcanism in Damavand goes...
To assess seed dispersal by domestic herbivores (sheep and goat) in Central Zagros region, 12 different rangeland sites, located 200 km west of Isfahan city, were studied. For each site, a pooled dung sample of 10 freshly pellet groups from domestic herbivores was collected in four different periods (mid June, July, August and September) during grazing season (in total, 48 pooled dung samples)....
Dispersal between different habitats influences the dynamics and stability of populations considerably. Furthermore, these effects depend on the local interactions of a population with other species. Here, we perform a general and comprehensive study of the simplest possible system that includes dispersal and local interactions, namely a 2-patch 2-species system. We evaluate the impact of dispe...
An ab-initio numerical study of the density-dependent, evolutionary stable dispersal strategy is presented. The simulations are based on a simple discretei generation island model with four processes: reproduction, dispersal, competition and local catastrophe. We do not impose any a priori constraints on the dispersal schedule, allowing the entire schedule to evolve. We find that the system con...
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