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61.
ERIC PASQUET 《Ibis》1998,140(1):150-156
A phylogeny of ten species of nuthatch (Sittidae), including the newly described Kabylie Nuthatch Sitta ledanti of North Africa, was constructed using a sequence of 491 bp of the cytochrome-b gene of mtDNA. On the basis of trees derived using parsimony analysis and neighbour-joining methods, and assessments of robustness based on bootstrap analysis, the following phylogenetic relationships were inferred: the five species of the Sitta canadensis group are a monophyletic group, within which S. canadensis, S. whiteheadi and S. villosa form the sister clade of S. krueperi and S. ledanti; the other relations are not so well supported. These phylogenetic relationships are congruent with morphology. Differences in behavioural and ecological characters as well as biogeographic patterns are discussed. 相似文献
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ABSTRACT Traditionally, seasons for animals have been designated based on single external variables such as climate or plant phenology, rather than an animal's response to the dynamic environments within which it lives. By interpreting a rate of movement function of cumulative movement through time we established a method that distinguishes transitions between behaviors limited by winter habitat conditions from those present during summer. Identification of these time periods provides temporal definition to subsequent home-range analyses and use-availability comparisons. We used location data from 32 Global Positioning System-collared female moose (Alces alces) to demonstrate the method. We used model selection (Akaike's Information Criterion) to differentiate between candidate rate of movement response curves. Of 32 moose, 29 clearly conformed to an annual movement pattern described by a logistic curve, with increased rates of movement in summer compared to winter. Conversely, 3 aberrant individuals did not alter their movement rate through the year and were best fit with a linear response curve. The seasonal rate of movement model we developed suggests an average summer period of 122 days (median = 119 days, range = 96–173 days) for moose in northwestern Ontario, Canada. The rate of movement model we applied to individuals indicated 1 May as the median date for the winter-summer transition (range = 2 Apr–24 May), and the median transition from summer to winter was 25 August (range = 1 Aug–23 Oct). Wide variation in timing and duration of summer and winter seasons among individuals demonstrates potential failure of the single external variable approach to capture the suite of factors potentially influencing animal behaviors. By plotting cumulative distance moved throughout the year, we elucidated individual variation in response to known and unknown variables that affect animal movement. Accounting for variability among individuals in designation of biologically significant temporal boundaries is critical to delineation of seasonally important habitats for conservation and sustainability of healthy wildlife populations. 相似文献
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DUANE R. DIEFENBACH ERIC S. LONG CHRISTOPHER S. ROSENBERRY BRET D. WALLINGFORD DAVID R. SMITH 《The Journal of wildlife management》2008,72(6):1296-1303
Abstract: Dispersal distances and their distribution pattern are important to understanding such phenomena as disease spread and gene flow, but oftentimes dispersal characteristics are modeled as a fixed trait for a given species. We found that dispersal distributions differ for spring and autumn dispersals of yearling male white-tailed deer (Odocoileus virginianus) but that combined data can be adequately modeled based on a log-normal distribution. We modeled distribution of dispersal distances from 3 distinct populations in Pennsylvania and Maryland, USA, based on the relationship between percent forest cover and mean dispersal distance and the relationship between mean and variance of dispersal distances. Our results suggest distributions of distances for dispersing yearling male white-tailed deer can be modeled by simply measuring a readily obtained landscape metric, percent forest cover, which could be used to create generalized spatially explicit disease or gene flow models. 相似文献
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MICHAEL V. HURLEY ERIC K. RAPAPORT CHRIS J. JOHNSON 《The Journal of wildlife management》2009,73(2):278-286
ABSTRACT Wildlife-vehicle collisions have important ecological, economic, and social effects. In North America and across northern Europe, moose (Alces alces) are one of the largest ungulates hit by motor vehicles. The force and increasing frequency of these collisions has resulted in a commitment by wildlife and transportation agencies to limit or reduce causal factors. In an effort to improve these mitigation strategies, we used the most readily available source of knowledge of collision factors, expert opinion, to develop a series of models that explained and predicted location of moose-vehicle collisions (MVC). We developed expert-based models using the Analytical Hierarchy Process (AHP) and we used a structured survey approach where experts could assess criteria relevancy, weight criteria, and review weights for consistency. We hypothesized that collisions were the product of habitat- or driver-related factors and we formulated the survey accordingly. We used the receiver operating characteristic to validate the resulting models and the Kappa index of agreement to quantify differences among spatial predictions originating from the experts. Local and nonlocal experts weighted the moose habitat classification as the most important criterion for identifying MVC. Among driver-related criteria, speed limit was weighted as the most important factor. Overall, habitat-based models were more proficient than driver-based models in predicting MVC within Mount Revelstoke and Glacier National Parks, Canada. Both local and nonlocal expert models were excellent predictors of MVC, with local experts slightly outperforming nonlocal experts. Considering that habitat-related criteria were more powerful for predicting MVC, and that habitat can vary considerably across study areas, we suggest that local experts be used when possible. The AHP is a valuable tool for wildlife, highway, and park managers to better understand why and where wildlife-vehicle collisions occur. Adopting this process, our data suggested that MVC were most strongly correlated with highway attractants associated with habitat. Vegetation management or alternative routing could minimize spatial juxtaposition of moose and motor vehicles. 相似文献
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RICHARD LINDROTH SHERRY ROTH ERIC KRUGER JOHN VOLIN & PATRICK KOSS 《Global Change Biology》1997,3(3):279-289
We investigated the effects of long-term CO2 enrichment on foliar chemistry of quaking aspen ( Populus tremuloides ) and the consequences of chemical changes for performance of the gypsy moth ( Lymantria dispar ) and susceptibility of the gypsy moth to a nucleopolyhedrosis virus (NPV). Foliage was collected from outdoor open-top chambers and fed to insects in a quarantine rearing facility. Under enriched CO2 , levels of leaf nitrogen declined marginally, levels of starch and phenolic glycosides did not change, and levels of condensed tannins increased. Long-term bioassays revealed reduced growth (especially females), prolonged development and increased consumption in larvae fed high-CO2 foliage but no significant differences in final pupal weights or female fecundity. Short-term bioassays showed weaker, and sex-specific, effects of CO2 treatment on larval performance. Correlation analyses revealed strong, negative associations between insect performance and phenolic glycoside concentrations, independent of CO2 treatment. Larval susceptibility to NPV did not differ between CO2 treatments, suggesting that effects of this natural enemy on gypsy moths are buffered from CO2 -induced changes in foliar chemistry. Our results emphasize that the impact of enriched CO2 on plant–insect interactions will be determined not only by how concentrations of plant compounds are altered, but also by the relevance of particular compounds for insect fitness. This work also underscores the need for studies of genetic variation in plant responses to enriched CO2 and long-term population-level responses of insects to CO2 -induced changes in host quality. 相似文献
67.
CLAIRE DETRAIN FRANÇOIS J. VERHEGGEN LISE DIEZ BERNARD WATHELET ERIC HAUBRUGE 《Physiological Entomology》2010,35(2):168-174
Honeydew is the keystone on which ant–aphid mutualism is built. The present study investigates how each sugar identified in Aphis fabae Scopoli honeydew acts upon the feeding and the laying of a recruitment trail by scouts of the aphid‐tending ant Lasius niger Linnaeus, and thus may enhance collective exploitation by the ant mutualists. The feeding preferences shown by L. niger for honeydew sugars are: melezitose = sucrose = raffinose > glucose = fructose > maltose = trehalose = melibiose = xylose. Although feeding is a prerequisite to the launching of trail recruitment, the reverse is not necessarily true: not all ingested sugar solutions elicit a trail‐laying behaviour among fed scouts. Trail mark laying is only triggered by raffinose, sucrose or melezitose, with the latter sugar being specific to honeydew. By comparing gustatory and recruitment responses of ant foragers to sugar food sources, the present study clarifies the role of honeydew composition both as a source of energy and as a mediator in ant–aphid interactions. Lasius niger feeding preferences can be related to the physiological suitability of each sugar (i.e. their detection by gustatory receptors as well as their ability to be digested and converted into energy). Regarding recruitment, the aphid‐synthesized oligosaccharide (melezitose) could be used by ant scouts as a cue indicative of a long‐lasting productive resource that is worthy of collective exploitation and defence against competitors or aphid predators. 相似文献
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