Phylogenetically structured damage to Asteraceae: susceptibility of native and exotic species to foliar herbivores
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Invasive plants often lose natural enemies while moving to new regions; however, once established in a new area, these invaders may be susceptible to attack by locally occurring enemies. Such damage may be more likely for exotics with close native relatives in the invaded area, since shifts of enemies should be more likely among closely related hosts. In this study, we evaluated whether exotics experience less herbivore damage than natives, and whether phylogenetically novel exotics experience less damage that those that are more closely related to locally occurring family members. Foliar damage was measured on 20 native and 15 exotic Asteraceae that co-occur locally in southern Ontario, Canada. The phylogenetic structure of this damage was quantified using an eigenvector decomposition method, and the relationship between damage and phylogenetic novelty of exotics was evaluated based on phylogenetic distances to other locally occurring Asteraceae. Our results show that 32% of the variation in damage was explained by phylogenetic relationship; similarity in damage tended to be associated with tribes. As predicted, exotics experienced lower damage than native species, even when the dataset was corrected for phylogenetic nonindependence. Contrary to our prediction, however, exotics that were more phylogenetically isolated from locally occurring relatives did not experience less damage. These results suggest that, though exotic Asteraceae may escape many of their natural enemies, this is not in general more likely for species phylogenetically distant from locally occurring native confamilials.
KeywordsAsteraceae Community phylogenetics Enemy release hypothesis Exotic species Invasion biology
This research was supported by NSERC Research and Equipment Grants (PMK), an NSERC PGS-D (SBH), and the Koffler Scientific Reserve at Jokers Hill. Thanks to Kateryna Kostyukova for her continuous help, and Andrew MacDonald and Megan Saunders for their support, discussions, and field assistance, and to two anonymous reviewers for their comments. All of the experiments conducted in this study comply with the current laws of Canada. This is a publication of the Koffler Scientific Reserve.
- Bernays EA, Chapman RF (1994) Host plant selection by phytophagous insects. Chapman and Hall, New YorkGoogle Scholar
- Funk VA, Bayer RJ, Kelley S, Chan R, Watson L, Gemeinholzer B, Schilling E, Panero JL, Baldwin BG, Garcia-Jacas N, Susanna A, Jansen RK (2005) Everywhere but Antarctica: using a supertree to understand the diversity and distribution of the Compositae. Biol Skr 55:343–374Google Scholar
- Mason PG, Huber JT (2002) Biological control programmes in Canada 1981–2000. CABI, OttawaGoogle Scholar
- Semple JC, Cook RE (2006) Solidago. In: Committee FNAE (ed) Flora of North America. Oxford University Press, Oxford, pp 107–166Google Scholar
- Strong DR, Lawton JH, Southwood R (1984) Insects on plants. Harvard University Press, CambridgeGoogle Scholar
- R Development Core Team (2009) R: a language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria, URL: http://wwwR-projectorg