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Are dung flies ideal-free distributed at their oviposition and mating site?


Blanckenhorn, Wolf U; Morf, Cornelia; Reuter, Max (2000). Are dung flies ideal-free distributed at their oviposition and mating site? Behaviour, 137(2):233-248.

Abstract

We experimentally tested the ideal-free distribution (IFD) using oviposition sites and mates as resources. We asked whether (1) female dung flies are distributed in an ideal-free manner among various fresh dung pats (the mating site and their resource for oviposition), and whether (2) the males are distributed likewise and consequently (3) ideal-free distributed with regard to the number of females. The last prediction links the IFD to the operational sex ratio (OSR), the number of competing males per receptive female. The flies were simultaneously offered six fresh dung pats in their natural environment, arrayed in a small and a large equalsided triangle. In one experiment all dung pats were the same size, and in another the three dung pats in each triangle had different surface areas. The large and mobile yellow dung fly, Scathophaga stercoraria, was overall evenly distributed with regard to oviposition sites and mates, whereas the distribution of the smaller and less mobile Sepsis cynipsea deviated randomly from the IFD. More flies were attracted to larger pats, but not in proportion to the pat's surface area (undermatching). Based on the speed at which an IFD was approached, individuals did not appear to sample different pats. The differences between the two species in agreement with the IFD predictions are probably quantitative rather than qualitative, relating to differences in mobility and local distribution.

Abstract

We experimentally tested the ideal-free distribution (IFD) using oviposition sites and mates as resources. We asked whether (1) female dung flies are distributed in an ideal-free manner among various fresh dung pats (the mating site and their resource for oviposition), and whether (2) the males are distributed likewise and consequently (3) ideal-free distributed with regard to the number of females. The last prediction links the IFD to the operational sex ratio (OSR), the number of competing males per receptive female. The flies were simultaneously offered six fresh dung pats in their natural environment, arrayed in a small and a large equalsided triangle. In one experiment all dung pats were the same size, and in another the three dung pats in each triangle had different surface areas. The large and mobile yellow dung fly, Scathophaga stercoraria, was overall evenly distributed with regard to oviposition sites and mates, whereas the distribution of the smaller and less mobile Sepsis cynipsea deviated randomly from the IFD. More flies were attracted to larger pats, but not in proportion to the pat's surface area (undermatching). Based on the speed at which an IFD was approached, individuals did not appear to sample different pats. The differences between the two species in agreement with the IFD predictions are probably quantitative rather than qualitative, relating to differences in mobility and local distribution.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Institute of Evolutionary Biology and Environmental Studies
Dewey Decimal Classification:570 Life sciences; biology
590 Animals (Zoology)
Scopus Subject Areas:Life Sciences > Animal Science and Zoology
Life Sciences > Behavioral Neuroscience
Uncontrolled Keywords:Animal Science and Zoology, Behavioral Neuroscience
Language:English
Date:1 January 2000
Deposited On:22 Aug 2019 12:30
Last Modified:31 Jul 2020 03:33
Publisher:Brill
ISSN:0005-7959
OA Status:Closed
Publisher DOI:https://doi.org/10.1163/156853900502051

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