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Optimal foraging, not biogenetic law, predicts spider orb web allometry.
Matjaž Gregorič1, Heine C Kiesbüy, Shakira G Quiñones Lebrón
1Institute of Biology, Scientific Research Centre, Slovenian Academy of Sciences and Arts, Ljubljana, Slovenia. matjaz.gregoric@gmail.com
Die Naturwissenschaften
|January 29, 2013
Summary
The biogenetic law does not explain changes in spider web asymmetry during development. Instead, orb-weaving spiders adjust web shape to optimize foraging based on gravity and their own size.
Area of Science:
- Evolutionary biology
- Animal behavior
- Arachnology
Background:
- The biogenetic law suggests development mirrors evolution, but evidence is mixed, especially in behavior.
- Spider web development offers a model for studying ontogenetic behavioral changes.
- Previous studies linked web asymmetry in orb-weaving spiders to the biogenetic law.
Purpose of the Study:
- To test the biogenetic law against the optimal foraging hypothesis for spider web allometry.
- To investigate ontogenetic changes in web symmetry in Leucauge venusta.
- To determine if web allometry relates to developmental stage or gravitational effects.
Main Methods:
- Studied the allometry of Leucauge venusta orb webs across different inclinations (vertical, tilted, horizontal).
- Analyzed changes in web symmetry throughout the spiders' ontogeny.
- Compared predictions of the biogenetic law (allometry related to ontogeny) with optimal foraging theory (allometry related to gravity).
Main Results:
- Vertical webs in Leucauge venusta showed increasing asymmetry through ontogeny.
- Tilted and horizontal webs did not exhibit the same pattern of increasing asymmetry.
- Results support the optimal foraging hypothesis over the biogenetic law.
Conclusions:
- The biogenetic law does not explain the observed web allometry in Leucauge venusta.
- Web asymmetry is influenced by gravity, supporting the optimal foraging hypothesis.
- Spider size and foraging efficiency are key factors driving web structural adaptations.
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