Loss of infection in sexually produced seedlings.

<p>Proportional (%) loss of endophyte infection in <i>Festuca rubra</i> seedlings (F₂ generation). Of the 47 endophyte-infected (E+) mother plants (F₁ generation), 14 produced offspring of exclusively endophyte-infected seedlings (total = 20), 13 produced offspring of exclusively endophyte-free seedlings (total = 19), while 20 mother plants produced progenies consisting of both E+ and E- seedlings (44 and 37, respectively) in the F₂ generation. Similarly, three and four out of 12 manipulatively endophyte-infected (ME+) mother plants produced offspring of exclusively endophyte-infected (total = 3) or –free (total = 4) seedlings, and five of the mother plants produced progenies consisting of both E+ and E- seedlings (10 and 13, respectively) in the F₂ generation. In total, E+ mother plants produced 63 and 57, and ME+ mother plants, 21 and 16 established E+ and E- seedlings, respectively.</p

Effects of original habitat and endophyte status on inflorescence production of <i>Festuca rubra</i> grasses grown in a common garden in different years.

<p>Abbreviations: Exp.Var. = explanatory variable, Endo = Endophyte status.</p

Inflorescence production of plants.

<p>The number of inflorescences of infected (E+), manipulatively infected (ME+), endophyte-free (E-) and manipulatively endophyte-free (ME-) <i>Festuca rubra</i> plants (F₁ generation) originating from meadow and river bank habitats (parental generation) growing in a common garden between 2004–2008 (yearly means ± S.E.).</p

Repeated measures analysis for inflorescence production of <i>Festuca rubra</i> grasses in a common garden.

<p>Repeated measures analysis for inflorescence production of <i>Festuca rubra</i> grasses in a common garden.</p

Individual sheep reactions to ergoty feed.

<p>Single rams' (A–F) actions relating to ergot-containing feed on different rounds of a food choice test. The column colours indicate the proportion of actions within trials: white, ergoty feed not approached; grey, ergoty feed rejected; black, ergoty feed chosen.</p

Host fitness and context dependency in defensive symbiosis.

<p>Average host fitness with or without a protective symbiont in relation to risk of attack. Defensive mutualism assumes that the symbiont improves host fitness in the presence of the enemy (h = 1), however the symbiont itself may (A) or may not (B) incur a fitness cost for the host in the absence of the enemy (h = 0).</p

Overall reaction of sheep to ergoty feed.

<p>A decision tree representing the average probabilities of rams' (n = 6) approaches and decisions between ergoty and control forage in a food choice test. The final choice signifies the alternative eventually chosen for eating.</p

Effect of ergot on host fitness.

<p>Parameter space where ergot infection has a positive (below the lines) or negative (above the lines) net effect on host fitness. β = relative loss of seeds due to ergot infection, d = protective effect of ergot infection, hα = cost of herbivory.</p

Individual VOCs of meadow fescue which changed significantly in response to endophyte infection and 12 days of aphid feeding.

<p>E-: naturally endophyte free; E+: naturally endophyte infected; C: untreated control; A: aphid damage. Statistical details are shown <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0101331#pone.0101331.s010" target="_blank">table S5</a>.</p

PLS-DA plots based on comparisons among VOC blends emitted by differently treated plants at 12 days after aphid addition.

<p>E-: naturally endophyte free; E+: naturally endophyte infected; ME-: manipulatively endophyte free; C: control; A: aphid feeding. For tall fescue (upper panel), a clear separation was seen between control and infested plants, which clustered mainly on the right and left side of the plot, respectively, whereas plants of different endophyte status within each damage treatment largely overlapped. For meadow fescue (lower panel), E- and E+ plants grouped separately while overlapping somewhat, with the strongest separation occurring between infested E- plants and any other treatment. Statistical details concerning compounds responsible for the clustering are given in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0101331#pone.0101331.s006" target="_blank">tables S1</a> and <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0101331#pone.0101331.s010" target="_blank">S5</a>.</p