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Published on: May 21, 2019
Fecundity increase supports adaptive radiation hypothesis in spider web evolution.
Todd A Blackledge1, Jonathan A Coddington, Ingi Agnarsson
1Department of Biology and Integrated Bioscience Program, University of Akron, Akron, OH, USA. blackledge@uakron.edu
Communicative & Integrative Biology
|March 3, 2010
Summary
Spiders that evolved new silk uses, like orb weavers and RTA clade spiders, show increased diversity and higher reproduction rates. This suggests escaping costly silk led to greater evolutionary success.
Area of Science:
- Evolutionary Biology
- Arachnology
- Ecology
Background:
- Adaptive radiations explain Earth's biodiversity.
- Spiders' reliance on silk offers insights into diversification linked to silk use evolution.
- Two major spider lineages, orb weavers and RTA clade spiders, display distinct silk ecologies compared to ancestral spiders.
Purpose of the Study:
- To investigate the link between adaptive changes in silk use and diversification in spiders.
- To test the hypothesis that orb and RTA clade spiders exhibit higher fecundity due to their evolutionary innovations in silk utilization.
- To explore how escaping the constraints of ancestral cribellate silk influenced spider reproductive strategies.
Main Methods:
- Comparative analysis of fecundity across different spider lineages.
- Examining silk ecology differences between ancestral spiders and derived lineages (orb weavers, RTA clade).
- Statistical evaluation of reproductive output in relation to silk-based adaptive innovations.
Main Results:
- RTA clade spiders demonstrate an average fecundity increase of 23% compared to their ancestors.
- Orb spiders exhibit a significant average fecundity increase of 123% compared to their ancestors.
- These findings support a functional connection between abandoning ancestral silk strategies and enhanced reproductive allocation.
Conclusions:
- The evolution of novel silk utilization strategies in orb and RTA clade spiders is strongly associated with increased species diversity and reproductive success.
- Escaping the limitations of ancestral, costly silk types appears to be a key innovation driving adaptive radiation in these spider groups.
- This study highlights the significant role of silk-based adaptations in shaping the evolutionary trajectories and diversification patterns of spiders.
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