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Is spatial autocorrelation an intrinsic property of territory size?

Valcu M, Kempenaers B - Oecologia (2010)

Bottom Line: In animals, competition for space and resources often results in territorial behaviour.We found significant positive SAC in a wide array of competition-simulated conditions.Our results strongly suggest that SAC is an intrinsic trait of any territory measure.

View Article: PubMed Central - PubMed

Affiliation: Department of Behavioural Ecology and Evolutionary Genetics, Max Planck Institute for Ornithology, Seewiesen, Germany. valcu@orn.mpg.de

ABSTRACT
In animals, competition for space and resources often results in territorial behaviour. The size of a territory is an important correlate of fitness and is primarily determined by the spatial distribution of resources and by interactions between competing individuals. Both of these determinants, alone or in interaction, could lead to spatial non-independence of territory size (i.e. spatial autocorrelation). We investigated the presence and magnitude of spatial autocorrelation (SAC) in territory size using Monte Carlo simulations of the most widely used territory measures. We found significant positive SAC in a wide array of competition-simulated conditions. A meta-analysis of territory size data showed that SAC is also a feature of territories mapped based on behavioural observations. Our results strongly suggest that SAC is an intrinsic trait of any territory measure. Hence, we recommend that appropriate statistical methods should be employed for the analysis of data sets where territory size is either a dependent or an explanatory variable.

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IM of kernel territory size at the scale of closest neighbours as a function of territory overlap. The confidence envelope (greyarea) represents simulated 95% confidence limits. The upper thin horizontal line shows the IM of Thiessen territory size constructed from territory centres under complete spatial randomness. The lower thin horizontal line is the expected value of IM under the  hypothesis of no autocorrelation
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Fig2: IM of kernel territory size at the scale of closest neighbours as a function of territory overlap. The confidence envelope (greyarea) represents simulated 95% confidence limits. The upper thin horizontal line shows the IM of Thiessen territory size constructed from territory centres under complete spatial randomness. The lower thin horizontal line is the expected value of IM under the hypothesis of no autocorrelation

Mentions: The level of SAC decreased with decreasing competition, that is, with increasing territory overlap, starting with a territory overlap of 15% (Fig. 2). Only at levels of territory overlap above 62% did IM become non-significant.Fig. 2


Is spatial autocorrelation an intrinsic property of territory size?

Valcu M, Kempenaers B - Oecologia (2010)

IM of kernel territory size at the scale of closest neighbours as a function of territory overlap. The confidence envelope (greyarea) represents simulated 95% confidence limits. The upper thin horizontal line shows the IM of Thiessen territory size constructed from territory centres under complete spatial randomness. The lower thin horizontal line is the expected value of IM under the  hypothesis of no autocorrelation
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2821514&req=5

Fig2: IM of kernel territory size at the scale of closest neighbours as a function of territory overlap. The confidence envelope (greyarea) represents simulated 95% confidence limits. The upper thin horizontal line shows the IM of Thiessen territory size constructed from territory centres under complete spatial randomness. The lower thin horizontal line is the expected value of IM under the hypothesis of no autocorrelation
Mentions: The level of SAC decreased with decreasing competition, that is, with increasing territory overlap, starting with a territory overlap of 15% (Fig. 2). Only at levels of territory overlap above 62% did IM become non-significant.Fig. 2

Bottom Line: In animals, competition for space and resources often results in territorial behaviour.We found significant positive SAC in a wide array of competition-simulated conditions.Our results strongly suggest that SAC is an intrinsic trait of any territory measure.

View Article: PubMed Central - PubMed

Affiliation: Department of Behavioural Ecology and Evolutionary Genetics, Max Planck Institute for Ornithology, Seewiesen, Germany. valcu@orn.mpg.de

ABSTRACT
In animals, competition for space and resources often results in territorial behaviour. The size of a territory is an important correlate of fitness and is primarily determined by the spatial distribution of resources and by interactions between competing individuals. Both of these determinants, alone or in interaction, could lead to spatial non-independence of territory size (i.e. spatial autocorrelation). We investigated the presence and magnitude of spatial autocorrelation (SAC) in territory size using Monte Carlo simulations of the most widely used territory measures. We found significant positive SAC in a wide array of competition-simulated conditions. A meta-analysis of territory size data showed that SAC is also a feature of territories mapped based on behavioural observations. Our results strongly suggest that SAC is an intrinsic trait of any territory measure. Hence, we recommend that appropriate statistical methods should be employed for the analysis of data sets where territory size is either a dependent or an explanatory variable.

Show MeSH