Graphs show the distribution of the number of fish that went to the food patch for each group size (<i>n</i>) for (a) no leader, (b) one leader and (c) two leaders.

<p>Model predictions based on the outcomes of 10,000 runs of the quorum response model are indicated by a solid line in each case.</p

The fraction of all test fish that followed replica leaders towards the food patch.

<p>The numerator is the number of test fish going to the food patch across all trials, the denominator is the number of test fish that started the trial. Tests to compare the number of fish that went to the food patch in the presence of 0 versus 1 leader, 0 versus 2 leaders and 1 versus 2 leaders between were carried out using a χ² test of independence. Two-tailed <i>P</i> values are presented for comparisons at each group size.</p

Proportion of fish at the food patch that left the food patch immediately following the departure of the replica leader(s) are marked by crosses for (a) no leaders (b) one leader and (c) two leaders.

<p>The number directly above the crosses is the number of observations in which this number of fish was observed at the food patch. Model predictions based on a quorum response are indicated by the solid line.</p

Experimental set-up.

<p>Experimental set-up.</p

The fraction of all test fish that followed replica leaders away from the food patch according to their initial group size.

<p>The numerator is the number of test fish leaving the food patch across all trials, the denominator is the number of test fish that went to the food patch. Tests to compare the number of fish that left the food patch in the presence of 0 versus 1 leader, 0 versus 2 leaders and 1 versus 2 leaders between were carried out using a χ² test of independence. Two-tailed <i>P</i> values are presented for comparisons at each group size.</p

Rainbowfish positional and feeding data and Matlab scripts

Rainbowfish positional and feeding data and Matlab script

Supplementary Information: Data and Calculations Used from Familiarity affects collective motion in shoals of guppies (<i>Poecilia reticulata</i>)

The supplementary information contains full details of the calculations used in the analysis of the data as well as the data itsel

Location of the landmarks used in the morphological analysis.

<p>Line diagram of the left flank of a threespine stickleback, showing the locations of the 20 landmarks that were used in the morphological analyses. These landmarks correspond to: (1) the tip of the premaxilla, (2) the axis of the jaws, (3–6) the anterior-most, uppermost, posterior-most and lowermost point of the orbital circumference, (7–9) the posterior most edge of the first, second and third dorsal spines, at the points where they emerge from the dorsal surface, (10–11) the anterior- and posterior-most edges of the dorsal fin, at the points where it emerges from the dorsal surface, (12) the beginning of the caudal fin, where the membrane contacts the dorsal surface, (13–14) the upper- and lowermost points of the hypural fan, (15) the beginning of the caudal fin, where the membrane contacts the ventral surface, (16–17) the posterior- and anterior-most edges of the anal fin, at the points where it emerges from the ventral surface, (19) the posterior most edge of the left pelvic spine, (19–20) the lower and uppermost points of the pectoral fin base.</p

Morphological index 3.

<p>The mean scores (+/− standard error) of fish from each of the six collection sites for the third morphological index, describing described 22.1% of the morphological variation in the sample. Morphological index 3 describes variation in the form of the caudal peduncle, as well as the degree of tapering posterior of the pelvic spine. The deformation plots on the right of the figure show the morphologies associated with the positive-most and negative-most scores. Tukey post-hoc analyses: * indicates P<0.05.</p

Plots showing consistency of landmark location.

<p>In order to confirm that landmarks could be identified precisely and consistently, both within and between samples, we repeatedly digitised landmarks on the same images. Five images were selected at random. For each image, the same 20 landmarks were digitised each day, for five consecutive days (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0021060#s2" target="_blank">Methods</a> and <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0021060#pone-0021060-g001" target="_blank">Figure 1</a> for discussion of the landmark selection criteria). The order in which each image was landmarked was randomised for each day. Landmark locations for days 1 to 5 are represented by blue, red, yellow, purple and black markers respectively. Each image represents a fish 36–40 mm in length.</p