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991.
Charles J. Frost Scott E. Hygnstrom Andrew J. Tyre Kent M. Eskridge David M. Baasch Justin R. Boner Gregory M. Clements Jason M. Gilsdorf Travis C. Kinsell Kurt C. Vercauteren 《Ecological modelling》2009,220(19):2481-2490
Movements of deer can affect population dynamics, spatial redistribution, and transmission and spread of diseases. Our goal was to model the movement of deer in Nebraska in an attempt to predict the potential for spread of chronic wasting disease (CWD) into eastern Nebraska. We collared and radio-tracked >600 white-tailed deer (Odocoileus virginianus) and mule deer (Odocoileus hemionus) in Nebraska during 1990–2006. We observed large displacements (>10 km) for both species and sexes of deer, including migrations up to 100 km and dispersals up to 50 km. Average distance traveled between successive daily locations was 166 m for male and 173 for female deer in eastern Nebraska, and 427 m for male and 459 for female deer in western Nebraska. Average daily displacement from initial capture point was 10 m for male and 14 m for female deer in eastern Nebraska, and 27 m for male and 28 m for female deer in western Nebraska. We used these data on naturally occurring movements to create and test 6 individual-based models of movement for white-tailed deer and mule deer in Nebraska, including models that incorporated sampling from empirical distributions of movement lengths and turn angles (DIST), correlated random walks (CRW), home point fidelity (FOCUS), shifting home point (SHIFT), probabilistic movement acceptance (MOVE), and probabilistic movement with emigration (MOVEwEMI). We created models in sequence in an attempt to account for the shortcomings of the previous model(s). We used the Kolmogrov–Smirnov goodness-of-fit test to verify improvement of simulated annual displacement distributions to empirical displacement distributions. The best-fit model (D = 0.07 and 0.08 for eastern and western Nebraska, respectively) included a probabilistic movement chance with emigration (MOVEwEMI) and resulted in an optimal daily movement length of 350 m (maximum daily movement length of 2800 m for emigrators) for eastern Nebraska and 370 m (maximum of 2960 m) for western Nebraska. The proportion of deer that moved as emigrators was 0.10 and 0.13 for eastern and western Nebraska, respectively. We propose that the observed spread of CWD may be driven by large movements of a small proportion of deer that help to establish a low prevalence of the disease in areas east of the current endemic area. Our movement models will be used in a larger individual-based simulation of movement, survival, and transmission of CWD to help determine future surveillance and management actions. 相似文献
992.
David F. Staples Mark L. Taper Brian Dennis Robert J. Boik 《Environmental and Ecological Statistics》2009,16(4):547-560
Estimates of a population’s growth rate and process variance from time-series data are often used to calculate risk metrics
such as the probability of quasi-extinction, but temporal correlations in the data from sampling error, intrinsic population
factors, or environmental conditions can bias process variance estimators and detrimentally affect risk predictions. It has
been claimed (McNamara and Harding, Ecol Lett 7:16–20, 2004) that estimates of the long-term variance that incorporate observed
temporal correlations in population growth are unaffected by sampling error; however, no estimation procedures were proposed
for time-series data. We develop a suite of such long-term variance estimators, and use simulated data with temporally autocorrelated
population growth and sampling error to evaluate their performance. In some cases, we get nearly unbiased long-term variance
estimates despite ignoring sampling error, but the utility of these estimators is questionable because of large estimation
uncertainty and difficulties in estimating correlation structure in practice. Process variance estimators that ignored temporal
correlations generally gave more precise estimates of the variability in population growth and of the probability of quasi-extinction.
We also found that the estimation of probability of quasi-extinction was greatly improved when quasi-extinction thresholds
were set relatively close to population levels. Because of precision concerns, we recommend using simple models for risk estimates
despite potential biases, and limiting inference to quantifying relative risk; e.g., changes in risk over time for a single
population or comparative risk among populations. 相似文献
993.
Most marine benthic macroinvertebrate species reproduce via a larval phase but attempts to explain the occurrence of different
larval strategies (feeding or non-feeding, pelagic or benthic) in different habitats have been largely inconclusive. There
have been very few year-round surveys of meroplankton at any latitude and in consequence fundamental data on the diversity,
abundance, and timings of larval life history phases are lacking. There has been considerable debate regarding the viability
of pelagic larvae in cold waters with highly seasonal primary production but there has been only one year-round study of meroplankton
in the Southern Ocean, and that was outside of the Antarctic Circle. We present data from the first year-round survey of meroplankton
assemblages at a location within the Antarctic Circle. We surveyed abundances of meroplanktonic larvae over 1.5 year at Rothera
Point, West Antarctic Peninsula (67°34′S, 68°07′W). Larvae were collected in monthly diver-towed net samples close to the
seabed at 20 and 6 m total water depths at each of three locations and were identified and counted live immediately after
sampling. A total of 99 operationally defined taxonomic types representing 11 phyla were recorded but this is likely to be
an underestimate of true diversity because of inherent difficulties of identification. Larvae were present in all months of
the year and although planktotrophic larvae were more abundant in summer, both feeding and non-feeding types were present
in all months. Comparisons of seasonal larval abundances with data from a settlement study at the same sites and from the
literature show that larvae of mobile adults settle in summer regardless of developmental type, whereas sessile taxa settle
in all seasons. We suggest that this is a consequence of differences in the food requirements of mobile and sessile fauna
and that the availability of food for post-larval juveniles is more critical for survival than factors affecting the larval
stage itself. 相似文献
994.
Gael Dur Sami Souissi David Devreker Vincent Ginot François G. Schmitt Jiang-Shiou Hwang 《Ecological modelling》2009
Limited empirical studies have elucidated the daily egg production and associated reproductive processes of egg bearing copepod. Herein, we present an individual-based model which constitutes a realistic representation of the reproduction in egg bearing copepods. The model has been parameterized using an extensive set of experimental data obtained from the literature and from the laboratory and field experiments on the estuarine copepod Eurytemora affinis. The proposed model takes into account the adult female longevity, the clutch size and interclutch duration, which is a function of egg maturation time and latency time required by the female after egg hatching to produce a new clutch. The embryonic development time and hatching success are also taken into account. The effect of temperature on the means and variances of above-mentioned reproductive parameters has been also incorporated. A multi agent system based generic platform “Mobidyc” has been used to generate and calibrate the model. The model demonstrates the reproductive parameters of females of E. affinis which is validated through individual based experiments. Temperature specific simulations provide a dynamical explanation of temperature effect on the cumulative egg production. The daily survival principally affects the number of clutches produced per female during its life span. The results obtained in the present study by combining temperature and survival effects reveal the relatively greater importance of the first factor on the daily egg production of egg-carrying copepods. The present model is generic and hence easily applicable to other animals with comparable reproductive strategy. 相似文献
995.
Love bites: male fang use during coercive mating in wolf spiders 总被引:1,自引:1,他引:0
Julianna L. Johns J. Andrew Roberts David L. Clark George W. Uetz 《Behavioral ecology and sociobiology》2009,64(1):13-18
Evolutionary conflicts of interest between the sexes are common, as mating tactics and strategies that increase fitness benefits
for one sex may incur costs for the other. As a consequence, antagonistic coevolution between the sexes often results in a
complex arms race between male persistence and female resistance. Coercive mating (e.g., forced copulation) likely benefits
males by increasing the probability of mating; however, costs to females may be high, including injury or even death. Here,
we report on a study of the use of fangs by males of the wolf spider Schizocosa ocreata (Hentz) during forcible mating with resistant females, which results in hemolymph loss and scar tissue formation in females.
Microscopic inspection revealed that fang wounds (evidenced by scar tissue) were absent on unmated (virgin) females but were
found on mated females and were significantly more frequent in coercively mated females. Experimental fang immobilization
studies found no difference in copulation success between experimental (fangs immobilized) and control (sham manipulation)
males. However, males that had use of their fangs had significantly longer copulation duration. These findings represent a
previously unknown male mating tactic in spiders and an unrecognized potential cost of mating for female spiders. 相似文献
996.
We conducted two ship-based surveys of the nearshore ecosystem north of Livingston Island, Antarctica during 2–10 February
2005. Between the two surveys, a low-pressure system (963 mbar) passed through the area providing the opportunity to measure
ecosystem parameters before and after a near gale. A ship-based multiple-frequency acoustic-backscatter survey was used to
assess the distribution and relative abundance of Antarctic krill (Euphausia superba). Net tows, hydrographic profiles, and meteorological data were collected to measure biological and physical processes that
might affect the krill population. During the survey, the distribution and behavior of several krill predators [chinstrap
penguins (Pygoscelis antarctica), cape petrels (Daption capense), and Antarctic fur seals (Arctocephalus gazella)] were measured from the vessel by visual observations. The survey encompassed an area of roughly 2,500 km2, containing two submarine canyons with one to the west and one to the east of Cape Shirreff, which had different abundances
of krill and predators. Several aspects of the nearshore ecosystem changed after the near gale including: hydrography of the
upper 100 m of the water column, phytoplankton biomass, the abundance and distribution of krill, and the distribution of some
krill predators. Differences in these parameters were also measured between the two canyons. These changes in the physical
and biological environment during the survey period are quantified and show that the ecosystem exhibited significant changes
over relatively short spatial (tens of kilometers) and time (tens of hours) scales. 相似文献
997.
(Z)-Dodec-3-en-1-ol has been identified as the major component of the trail-following pheromone of nine species of Kalotermitidae
belonging to six different genera, suggesting that this compound represents a common signal in this family of termites. The
homogeneous nature of trail-following pheromones of Kalotermitidae well agrees with the monophyly of this family. It also
supports the postulated position of this family as a sister group of the Rhinotermitidae and Termitidae, which also secrete
C12-alcohols as trail-following pheromones. The significance of a trail pheromone in termites of the ‘one-piece’ life type,
which spend their whole life within the same piece of wood, is discussed. 相似文献
998.
Terry A. Beehr Lana Ivanitskaya Curtiss P. Hansen Dmitry Erofeev David M. Gudanowski 《组织行为杂志》2001,22(7):775-788
Feedback from 360 degree ratings based on competency principles and used for developmental purposes was investigated for interrelationships among the ratings and for its relationships with performance and selection data. Relationships among: (1) feedback ratings from supervisors, peers, and self; (2) feedback ratings and selection test data; and (3) feedback ratings and performance appraisals on about 2000 employees of a Midwestern insurance company were examined. The 360 ratings by peers and managers were related to performance appraisals. All significant correlations of manager and peer ratings with selection tests were positive, but significant correlations of 360 degree self‐ratings with selection tests were negative. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
999.
David M. Hartley David E. Funke 《Journal of the American Water Resources Association》2001,37(6):1589-1595
ABSTRACT: A “synthetic paired basin” technique that combines hydrologic monitoring and watershed modeling proves to be a useful tool in detecting hydrologic change in creeks draining basins undergoing urbanization. In this approach, measured stream flow following subbasin treatment (a period of urbanization) is compared with flow from a control subbasin over the same time period. The control subbasin is the pretreatment subbasin itself as represented by a well‐calibrated hydrologic model that is input with post‐treatment meteorological data. The technique is illustrated for stream monitoring sites at the outlets of two high‐resource sub‐basins in the Bear Creek basin of King County, Washington. Application of this technique holds promise to provide earlier warning of cumulative, human impacts on aquatic resources and to better inform adaptive watershed management for resource protection. 相似文献
1000.
David Kahler 《环境质量管理》2001,10(4):29-32
Methyl tertiary butyl ether, a gasoline additive once used to reduce air pollution, is now contaminating water sources around the United States. Monitoring for this chemical—and remediating it where it is found—should be an environmental priority. © 2001 John Wiley & Sons, Inc. 相似文献