Appendix A. Results from statistical models testing for changes in selection on Ruellia nudiflora fruit number across trophic scenarios and levels of plant genotype diversity.

Results from statistical models testing for changes in selection on Ruellia nudiflora fruit number across trophic scenarios and levels of plant genotype diversity

Climatic predictors of masting

Climatic predictors of mastin

Least-square means (± S.E.) of density (# insects per kg of dry shoot biomass) of the generalist aphid <i>Aphis gossypii</i> (A), the specialist aphid <i>Uroleucon macolai</i> (B), ants (<i>Linepithema humile</i>; C), <i>A</i>. <i>gossypii</i> parasitoids (Braconidae; D), and mycorrhizal percent root colonization (E) for growth rate monocultures (“mono”) and polycultures (“poly”) of fast- and slow-growing plant genotypes, and plant sex monocultures and polycultures of male and female genotypes of the shrub <i>Baccharis salicifolia</i> Least-square means account for the effects of plot.

<p>* = Significant (<i>P</i> < 0.05). The mean of sex and growth rate monocultures is the mean of male and female monocultures or the mean of slow- and fast-growing monocultures, respectively.</p

Traits underlying community consequences of plant intra-specific diversity

<div><p>A plant’s performance and interactions with other trophic levels are recorgnized to be contingent upon plant diversity and underlying associational dynamics, but far less is known about the plant traits driving such phenomena. We manipulated diversity in plant traits using pairs of plant and a substitutive design to elucidate the mechanisms underlying diversity effects operating at a fine spatial scale. Specifically, we measured the effects of diversity in sex (sexual monocultures vs. male and female genotypes together) and growth rate (growth rate monocultures vs. fast- and slow-growing genotypes together) on growth of the shrub <i>Baccharis salicifolia</i> and on above- and belowground consumers associated with this plant. We compared effects on associate abundance (# associates per plant) vs. density (# associates per kg plant biomass) to elucidate the mechanisms underlying diversity effects; effects on abundance but not density suggest diversity effects are mediated by resource abundance (i.e. plant biomass) alone, whereas effects on density suggest diversity effects are mediated by plant-based heterogeneity or quality. Sexual diversity increased root growth but reduced the density (but not abundance) of the dietary generalist aphid <i>Aphis gossypii</i> and its associated aphid-tending ants, suggesting sex mixtures were of lower quality to this herbivore (e.g. via reduced plant quality), and that this effect indirectly influenced ants. Sexual diversity had no effect on the abundance or density of parasitoids attacking <i>A</i>. <i>gossypii</i>, the dietary specialist aphid <i>Uroleucon macolai</i>, or mycorrhizae. In contrast, growth rate diversity did not influence plant growth or any associates except for the dietary specialist aphid <i>U</i>. <i>macolai</i>, which increased in both abundance and density at high diversity, suggesting growth rate mixtures were of higher quality to this herbivore. These results highlight that plant associational and diversity effects on consumers are contingent upon the source of plant trait variation, and that the nature of such dynamics may vary both within and among trophic levels.</p></div

Least-square means (± S.E.) for total biomass (A), shoot biomass (B), and root biomass (C; g, dry weight in all cases) for growth rate monocultures (“mono”) and polycultures (“poly”) of fast- and slow-growing genotypes, and plant sex monocultures and polycultures of male and female genotypes of the shrub <i>Baccharis salicifolia</i>.

<p>Least-square means account for the effect of plot to control for effects of spatial heterogeneity. * = significant (<i>P</i> < 0.05); ms = marginally significant (0.05 < <i>P</i> < 0.10). The mean of sex and growth rate monocultures is the mean of male and female monocultures or of slow- and fast-growing monocultures, respectively.</p

Appendix A. Classification of mast and non-mast years by using the number of standardized deviations of the annual cone production from the long-term mean seed production.

Classification of mast and non-mast years by using the number of standardized deviations of the annual cone production from the long-term mean seed production

Diversity effect on growth and herbivore damage.

<p>Summary of results from generalized linear mixed models testing for the effects of (a) big-leaf mahogany (<i>Swietenia macrophylla</i> King, Meliaceae) genotypic diversity and (b) tree species diversity on mahogany growth and damage by the specialist <i>Hypsipyla grandella</i> (number of attack sites per plant). We tested the effect of mahogany genotypic diversity by comparing genotypic monocultures to genotypic polycultures, whereas to test for a species diversity effect we compared genotypic monocultures and species polycultures. F-values and associated significance levels (<i>P</i>) are shown, as well as numerator and denominator degrees of freedom (subscripts).</p

Least-square means (± S.E.) of abundance of the generalist aphid <i>Aphis gossypii</i> (A), the specialist aphid <i>Uroleucon macolai</i> (B), ants (<i>Linepithema humile</i>; C), <i>A</i>. <i>gossypii</i> parasitoids (Braconidae; D), and mycorrhizae (percent root colonization × dry root biomass; E) for growth rate monocultures (“mono”) and polycultures (“poly”) of fast- and slow-growing plant genotypes, and plant sex monocultures and polycultures of male and female genotypes of the shrub <i>Baccharis salicifolia</i>.

<p>Least-square means account for the effect of plot. * = Significant (<i>P</i> < 0.05). The mean of sex and growth rate monocultures is the mean of male and female monocultures or the mean of slow- and fast-growing monocultures, respectively.</p

<i>Hypsipyla grandella</i> damage.

<p>Damage caused by <i>Hypsipyla grandella</i> (Lepidoptera: Pyralidae), a stem-boring caterpillar specializing on tree species of the neotropical family Meliaceae. The images show a fourth-instar larva inside a terminal shoot of a big-leaf mahogany (<i>Swietenia macrophylla</i> King, Meliaceae) sapling and the damage caused. Photo credits: Luis Abdala-Roberts.</p

Diversity effect on growth and herbivore damage.

<p>Effect of mahogany genotypic and tree species diversity on: (A) mahogany sapling height and (B) the mean number of attack sites per plant by the specialist stem-boring insect <i>Hypsipyla grandella</i>. The dashed line represents the mean value for genotype monocultures (N  = 12) and the shaded area represents the standard error around that mean. Least-square means ± S.E. (N  = 20 genotypic polycultures and N  = 12 species polycultures). “(n.s.)” in the figures indicates non-significant differences (<i>P</i><0.05) between a given diversity treatment and the genotypic monoculture treatment.</p