Use of Host-Plant Trait Space by Phytophagous Insects during Host-Associated Differentiation: The Gape-and-Pinch Model

Table 4

Tests of trait-space use on Solidago altissima and S. gigantea for four Solidago herbivores. 𝑃-values in bold are significant at α = 0.05.

Herbivore	Host	# Attacked plants^1	Distance from available centroid^2		Marginal trait-space test P	Restricted trait-space test P	Distance between attacked trait-spaces^3	Distant; trait-spaces; test P
			PC1	PC2
Philaenus	S. altissima	25	1.00	−0.50	<0.001	— ^4	Small	0.71
	S. gigantea	22	1.11	−0.52	0.001	—
Exema	S. altissima	59	0.30	0.05	0.023	—	Small	0.14
	S. gigantea	33	0.65	0.04	0.023	—
Uroleucon	S. altissima	9	1.39	−0.10	0.007	—	Large	0.86
	S. gigantea	8	2.32	−0.62	<0.001	—
Rhopalomyia	S. altissima	27	0.09	0.35	0.21	0.18	Large	0.80
	S. gigantea	8	0.66	−0.05	0.31	1.0

¹Of 92 available S. altissima and 175 available S. gigantea ramets.
²Attacked centroid minus available centroid (PC1 and PC2 components). A positive entry means that ramets with a large PC score are more likely to be attacked.
³“Small” if the two attacked trait spaces are adjacent (Figure 2(b)), and “large” if the two attacked trait spaces are distant (Figure 2(c)).
⁴This test is informative only when the marginal trait-space test is not significant.