ECOLOGICAL VERSUS PHYLOGENETIC DETERMINANTS OF TROPHIC ASSOCIATIONS IN A PLANT–LEAFMINER–PARASITOID FOOD WEB
Article first published online: 4 JAN 2013
© 2013 The Author(s). Evolution © 2013 The Society for the Study of Evolution.
Volume 67, Issue 5, pages 1493–1502, May 2013
How to Cite
Leppänen, S. A., Altenhofer, E., Liston, A. D. and Nyman, T. (2013), ECOLOGICAL VERSUS PHYLOGENETIC DETERMINANTS OF TROPHIC ASSOCIATIONS IN A PLANT–LEAFMINER–PARASITOID FOOD WEB. Evolution, 67: 1493–1502. doi: 10.1111/evo.12028
- Issue published online: 25 APR 2013
- Article first published online: 4 JAN 2013
- Accepted manuscript online: 11 DEC 2012 02:16PM EST
- Manuscript Accepted: 26 NOV 2012
- Manuscript Received: 28 MAR 2012
- Academy of Finland. Grant Number: 14868
- enemy-free space;
- multitrophic networks;
- vertical diversification effects
Specialized trophic interactions in plant–herbivore–parasitoid food webs can spur “bottom–up” diversification if speciation in plants leads to host-shift driven divergence in insect herbivores, and if the effect then cascades up to the third trophic level. Conversely, parasitoids that search for victims on certain plant taxa may trigger “top–down” diversification by pushing herbivores into “enemy-free space” on novel hosts. We used phylogenetic regression methods to compare the relative importance of ecology versus phylogeny on associations between Heterarthrinae leafmining sawflies and their parasitoids. We found that: (1) the origin of leafmining led to escape from most parasitoids attacking external-feeding sawflies; (2) the current enemies mainly consist of generalists that are shared with other leafmining taxa, and of more specialized lineages that may have diversified by shifting among heterarthrines; and (3) parasitoid–leafminer associations are influenced more by the phylogeny of the miners’ host plants than by relationships among miner species. Our results suggest that vertical diversifying forces have a significant—but not ubiquitous—role in speciation: many of the parasitoids have remained polyphagous despite niche diversification in the miners, and heterarthrine host shifts also seem to be strongly affected by host availability.