Neighborhood effects on territorial aggregations of the burrowing wolf spider Geolycosa xera archboldi McCrone (Araneae: Lycosidae)

1999 ◽  
Vol 77 (6) ◽  
pp. 1006-1012 ◽  
Author(s):  
Samuel D Marshall

The effects of territorial neighbors on the foraging success of a burrowing wolf spider, Geolycosa xera archboldi McCrone, were examined in the field in central Florida, U.S.A. The rates of mass gain by juveniles were quantified and related to the following burrow neighborhood characteristics: mean nearest-neighbor size, mean nearest-neighbor distance, and mean number of neighbors within 1 m of the focal animal's burrow. Only nearest-neighbor size was correlated (negatively) with mass gain. Field tests with provisioned prey showed that larger neighbors were both more likely to take prey in a zone of territorial overlap and to do so sooner than smaller neighbors. Tests for exploitative competition using paired adhesive traps to mimic pairs of neighboring spiders were conducted at the mean nearest-neighbor distance for the population (30 cm) to model territorial dyads and pairs of traps at random smaller distances to model nonterritorial dyads. There was no difference in rates of prey capture by pairs of traps at the territorial distance and the shorter distances, indicating that resource depletion may not explain the patterns observed.

2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
Xing Hu ◽  
Shiqiang Hu ◽  
Xiaoyu Zhang ◽  
Huanlong Zhang ◽  
Lingkun Luo

We propose a novel local nearest neighbor distance (LNND) descriptor for anomaly detection in crowded scenes. Comparing with the commonly used low-level feature descriptors in previous works, LNND descriptor has two major advantages. First, LNND descriptor efficiently incorporates spatial and temporal contextual information around the video event that is important for detecting anomalous interaction among multiple events, while most existing feature descriptors only contain the information of single event. Second, LNND descriptor is a compact representation and its dimensionality is typically much lower than the low-level feature descriptor. Therefore, not only the computation time and storage requirement can be accordingly saved by using LNND descriptor for the anomaly detection method with offline training fashion, but also the negative aspects caused by using high-dimensional feature descriptor can be avoided. We validate the effectiveness of LNND descriptor by conducting extensive experiments on different benchmark datasets. Experimental results show the promising performance of LNND-based method against the state-of-the-art methods. It is worthwhile to notice that the LNND-based approach requires less intermediate processing steps without any subsequent processing such as smoothing but achieves comparable event better performance.


1999 ◽  
Vol 29 (4) ◽  
pp. 446-450 ◽  
Author(s):  
Gilles Houle ◽  
Mario Duchesne

We performed a nearest-neighbor analysis to determine the population dispersion pattern and the association between males and females in a Juniperus communis L. var. depressa Pursh population occupying a continental dune in subarctic Quebec, Canada. The overall dispersion pattern was contagious, and males (or females) were proportionately as likely to have a male as they were to have a female nearest neighbor. Crown size was positively related to nearest-neighbor distance for the male-male comparison only, suggesting a somewhat stronger intrasex competition between males. Nearest-neighbor distance increased with crown size (significantly related to age) suggesting a change in the intensity of aggregation with age possibly related to self-thinning. Higher mortality as a result of stronger male-male competition could explain the female-biased sex ratio and the absence of spatial segregation between sexes. The overall contagious dispersion pattern in the population may be related to the fact that most seed cones fall directly underneath the mother plant. Birds can eat the cones of J. communis and thus disperse seeds. However, these seeds are deposited in clumps, a process that may also explain contagion within the population.


2019 ◽  
Vol 256 (6) ◽  
pp. 1800522 ◽  
Author(s):  
Mariko Murayama ◽  
Kensaku Yoda ◽  
Keita Shiraishi ◽  
Iain F. Crowe ◽  
Shuji Komuro ◽  
...  

1988 ◽  
Vol 20 (5) ◽  
pp. 609-620 ◽  
Author(s):  
A Okabe ◽  
T Yoshikawa ◽  
A Fujii ◽  
K Oikawa

The objective of this paper is to formulate a statistical method of testing the hypothesis that the distribution of activity points (such as retail stores) is independent of location of ‘surface-like’ infrastructural elements (such as parks). In order to do this, first, the probability density function of a distance from a random point to the nearest surface-like element is derived. Second, through the use of this function, a measure, R, of spatial dependency on the surface-like elements is defined as the ratio of the average nearest-neighbor distance to the expected average nearest-neighbor distance. This measure is an extension of the ordinary nearest-neighbor distance measure frequently referred to in geography and ecology. Third, the statistical use of measure R is shown. Fourth, as this measure is difficult to compute geometrically, the computational method of calculating the value of R is developed. Last, by use of this method, a test is conducted to decide whether or not the distribution of high-class apartment buildings in Setagaya, Tokyo, is affected by the location of big parks.


1998 ◽  
Vol 58 (5) ◽  
pp. 6821-6823 ◽  
Author(s):  
Zbigniew Koza ◽  
Tomer Yanir ◽  
Haim Taitelbaum

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