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Abstract

We examined distributions of 33 gall forming insect species on parent
species and three hybrid phenotypes in two Eucalyptus hybrid zones in Australia.
Variation in insect abundance among hybrid classes was greater than variation
between species suggesting that hybrid zones are sites of dynamic interactions
between plants and herbivores. For instance, of 25 galling species in Victoria, 52%
showed significant differences in abundance among hybrid classes, whereas only
24% differed between pure host species. While some components of hybrid use
were very predictable, others were not. Based on galler use of pure species, we
could accurately predict which hybrid phenotype would be most used. Our data
show that most gall species concentrate on the hybrid class that is most similar to
the parent species on which it is most abundant. However, species related
taxonomically or by feeding guild did not exhibit consistent responses to hybrid and
parent hosts. Thus pooling either hybrid classes or insect species for statistical
analysis may mask underlying patterns. Overall, galler responses to three hybrid
phenotypes are consistent with the hypothesis that plant hybrid zones and
especially backcross hybrids are centers of insect species richness and abundance.
Furthermore, galler response to hybrids plants suggests that the narrow host
specificity characteristic of gallers may be less strongly influenced by plant
developmental processes than generally thought.
Our observations support the hypothesis that genetic

Item Type:	Book Section
Authors/Creators:	Morrow, PA and Whitham, TG and Potts, BM and Ladiges, PY and Ashton, DH and Williams, JB
Keywords:	ecology, Eucalyptus, gall, hybrid,insect,phenotype
Journal or Publication Title:	No Info
Publisher:	USDA Forestry Services Technical Report NC
Additional Information:	BM Potts.
Item Statistics:	View statistics for this item

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