نتایج جستجو برای: exotic
تعداد نتایج: 15313 فیلتر نتایج به سال:
Time-dependent wormhole solution of the BD theory in an anisotropic radiation background is presented. It is also found that the BD scalar field depends only on time. This time dependency is in power-law form. It is shown that the wormhole geometry is valid for ω ≥ -3/2, and for any arbitrary positive values of . The GR limit of our solution is obtained for ω=0 , not for ω→∞ . Though the BD f...
Exotic species are widely assumed to thrive because they lack natural enemies in their new ranges. However, a meta-analysis of 63 manipulative field studies including more than 100 exotic plant species revealed that native herbivores suppressed exotic plants, whereas exotic herbivores facilitated both the abundance and species richness of exotic plants. Both outcomes suggest that plants are esp...
Alien tick species of the genera Ixodes, Amblyomma, Hyalomma and Rhipicephalus are sporadically transferred to the territories of the Central European countries. A biological-medical review of the following alien tick species transferred to Poland is presented: Ixodes eldaricus, Ixodes festai, Amblyomma sphenodonti, Amblyomma exornatumn, Amblyomma flavomaculatum, Amblyomma latum, Amblyomma nutt...
Generally, non-human primates are social species. Literature indicates that suboptimal housing conditions and social deprivation may lead to the development of abnormal behaviour, which is considered a sign of impaired welfare (Shyne, 2006; Novak et. al, 2002; Novak, 2003; Dellinger-Ness and Handler, 2006). Most non-human primates that are rescued by AAP, a rescue centre for exotic animals, hav...
The Royal Menagerie of England was established at the Tower of London in the 13th Century and served as a home of exotic animals until it was closed on behalf of the Duke of Wellington in 1835. Two well-preserved lion skulls recovered from the moat of the Tower of London were recently radiocarbon-dated to AD 1280-1385 and AD 1420-1480, making them the earliest con rmed lion remains in the Brit...
Since Milnor’s discovery of exotic spheres [Mi], one of the most intriguing problems in Riemannian geometry has been whether there are exotic spheres with positive curvature. It is well known that there are exotic spheres that do not even admit metrics with positive scalar curvature [Hi] . On the other hand, there are many examples of exotic spheres with positive Ricci curvature (cf. [Ch1], [He...
While exotic plant species often come to dominate disturbed communities, long-term patterns of invasion are poorly known. Here we present data from 40 yr of continuous vegetation sampling, documenting the temporal distribution of exotic plant species in old field succession. The relative cover of exotic species decreased with time since abandonment, with significant declines occurring 20 yr pos...
Identifying impacts of exotic species on native populations is central to ecology and conservation. Although the effects of exotic predators on native prey have received much attention, the role of exotic prey on native predators is poorly understood. Determining if native predators actively prefer invasive prey over native prey has implications for interpreting invasion impacts, identifying th...
1. Biological invasions threaten biodiversity, and understanding the factors that influence a community’s susceptibility to invasion informs both management of invasive species and conservation efforts towards promoting biodiversity. 2. In this study, we examined the native–exotic richness relationships (NERR) at two spatial scales and asked what variables mediate the relationship between nativ...
Exotic species dominate many communities; however the functional significance of species' biogeographic origin remains highly contentious. This debate is fuelled in part by the lack of globally replicated, systematic data assessing the relationship between species provenance, function and response to perturbations. We examined the abundance of native and exotic plant species at 64 grasslands in...
نمودار تعداد نتایج جستجو در هر سال
با کلیک روی نمودار نتایج را به سال انتشار فیلتر کنید