Abstract. Ecological niche modeling (and the related species distribution modeling) has been used as a tool with which to assess potential impacts of climate change processes on geographic distributions of species. However, the factors introducing variation into niche modeling outcomes are not well understood: To this end, we used seven algorithms to develop models (Maxent, GARP, BIOCLIM, artificial neural networks, support-vector machines, climate envelope, and environmental distance) to estimate the potential geographic distribution of olives (Olea europaea sensu lato, including Olea ferruginea) under two climatic data sets (current 2000 and future 2050). Five general circulation models and two representative concentration pathway scenarios were used as predictor variables in future projections of the geographic potential of this species; models were fit at global extents (10 0 spatial resolution) but transferred and interpreted for a region of particular interest in Central Asia, which largely avoids problems with truncation of niche estimates. We found marked differences among approaches in predicted distributions and model performance, as well as in the future distributional pattern reconstructed, from one algorithm to another. These general approaches, when model-to-model variation is managed appropriately, appear promising in predicting the potential geographic distribution of O. europaea sensu lato and thus can be an effective tool in restoration and conservation planning for wild populations, as well as possible commercial plantations of this species.
Abstract:The potential distribution of Olea ferruginea was predicted by Maxent model for present and the upcoming hypothetical (2050) climatic scenario. O. ferruginea is an economically beneficial plant species. For predicting the potential distribution of O. ferruginea in Pakistan, Worldclim variables for current and future climatic change scenarios, digital elevation model (DEM) slope, and aspects with the occurrence point were used. Pearson correlation was used to reject highly correlated variables. A total of 219 sighting points were used in the Maxent modeling. The area under curve (AUC) value was higher than 0.98. The approach used in this study is considered useful in predicting the potential distribution of O. ferruginea species, and can be an effective tool in the conservation and restoration planning for human welfare. The results show that there is a significant impact under future bioclimatic scenarios on the potential distribution of O. ferruginea in Pakistan. There is a significant decrease in the overall distribution of O. ferruginea due to loss of habitats under current distribution range, but this will be compensated by gain of habitat at higher altitudes in the future climate change scenario (habitat shift). It is recommended that the areas predicted suitable for the O. ferruginea may be used for plantation of this species while the deforested land should be restored for human welfare.
The filtering rates of 14 C labelled Chlamydomonas sp . by 3 dominant species of rotifers were studied in eutrophic Lake Aydat . They varied from 4 to 53 µl ind -' h -' for Keratella cochlearis, from 2 to 56 ul . -'h -' for Keratella quadrata and from 3 to 52 µl ind -1 h -' for Kellicottia longispina . Their maximum assimilation efficiency was 32% . At the measured grazing rates, these populations could clear the water in less than two days during July . In Lake Aydat, the rotifers community could play an important role in the regulation of seasonal succession of phytoplankton and bacteria .
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Grey langurs (Semnopithecus spp.) occupy a variety of habitats, ranging from lowland forests and semi-desert to alpine forests. Little is known about their foraging and ranging in alpine forests, which appear to contain less food than lowland forests. We conducted a 1-year study of Himalayan grey langurs (Semnopithecus ajax) in Machiara National Park, Pakistan, where they occur at relatively high altitudes (range 2000-4733 m). We followed three groups of different sizes and compositions and examined the effects of ecological and social factors on ranging and feeding. The home-range sizes of a small bisexual group (SBG), a large bisexual group (LBG), and an all-male group (AMG) were 2.35 ± 0.92 (mean ± SD; average of four seasons), 3.28 ± 0.55, and 3.52 ± 1.00 km(2), respectively, and were largest in winter for all groups. The daily path lengths of the SBG, LBG, and AMG were 1.23 ± 0.28 (mean ± SD; average of four seasons), 1.75 ± 0.34, and 1.84 ± 0.70 km, respectively; that of the LBG was longer in winter, while that of the AMG was shorter in summer. Both the home-range size and daily path length of the AMG were larger than those of the other groups, even after partialling out the effect of group size differences. The mean altitude used by the langurs and the proportion of animals seen feeding did not differ among seasons or group types. As the mean temperature increased, the altitude used by langurs significantly increased for the SBG and LBG, but not for the AMG. On the other hand, as the temperature increased, the home-range sizes significantly decreased for the SBG and AMG, but not for the LBG. Rainfall did not show any correlation with ranging or feeding in any of the groups. Our results suggested that grey langurs in Machiara National Park employ a high-cost, high-return foraging strategy in winter, and that the ranging of the AMG also reflects its reproductive strategy.
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