Table 2.

NRI (a standardized measurement of mean pairwise phylogenetic distance) for yeast isolates in the two groups of communities assembled experimentally. Subsets 1 and 2 refer to data from bumble-bees captured at flowers of H. foetidus and R. officinalis, respectively. p-Values were calculated by comparing the observed mean pairwise phylogenetic distance with a null distribution for 10⁵ randomly generated phylogenies, obtained by shuffling yeast isolates across the tips of the phylogeny shown in the electronic supplementary material, appendix (phylogeny shuffle method in the Phylocom program). The p-values shown correspond to one-tailed tests, and stand for the probability of obtaining by chance alone a mean phylogenetic distance as extreme as the observed one. NRI significantly greater than 0 denote phylogenetic clustering.

	bee-only		bee + nectar
dataset	NRI	p-value	NRI	p-value
whole sample	−4.26	<0.00001	+5.17	<0.00001
subset 1	−2.17	0.013	+6.54	<0.00001
subset 2	−2.18	0.013	+0.23	0.41