Bennett Et Al., Abundance, Rarity and Invasion Debt Among Exotic Species in a Patchy Ecosystem

Bennett et al., Abundance, rarity and invasion debt among exotic species in a patchy ecosystem

Electronic Supplementary Material 1. Study patches, sampling protocol and patch sizes

Fig. ES1: Map showing location of study patches with respect to Vancouver Island, BC (inset, top), and detail of the northern (inset, A) and southern (B) study patch locations. Patch sizes are given in Table S1 below.

1 Quadrat Sampling Protocol

Quadrats for intra-patch surveys were established using a stratified-random sampling protocol, in which the number of quadrats was scaled by area. Patches were divided a priori into grids based on UTM coordinates in site maps. Patches <1 ha were divided into 25-m grids; patches 1-5 ha were divided into 50-m grids; and patches >5 ha were divided into 100-m grids. In the field, sample points were navigated to using a handheld GPS. As soon as the UTM coordinates for an exact grid intersection point were displayed on the GPS (e.g. UTM northing ending in “00”, easting ending in “00”), a plot was established. Spatial error on the initial GPS readings (±~10m) and navigation to the first GPS reading showing specific grid points introduced randomness, while ensuring adequate spatial coverage. Quadrats were placed on as many grid intersections as possible within sites. Locations that had >50% cover rock, had slope >45 degrees, or were obscured by shrub cover >1.5 m high were rejected.

Table ES1: Patch numbers and sizes. Italicized sites were included in the subset of 22 isolated/least disturbed small-island patches.

Site Site Number Area (ha) Number Area (ha) 1 0.32 35 0.77 2 6.52 36 1.22 3 1.84 37 1.07 4 5.03 38 0.62 5 0.39 39 0.64 6 0.3 40 0.63 7 5.89 41 1.1 8 1.17 42 0.57 9 3.48 43 0.34 10 1.2 44 0.26 11 1.35 45 0.34 12 1.27 46 0.59 13 3.19 47 1.96 14 5.88 48 1.62 15 2.03 49 1.26 16 1.31 50 0.56 17 1.15 51 0.68 18 1.48 52 3.37 19 16.38 53 3.83 20 0.18 54 0.17 21 0.6 55 4.02 22 2.77 56 1.93 23 8.72 57 0.42 24 17.68 58 0.59 25 8.82 59 0.84 2 26 1.22 60 3.72 27 1.73 61 2.84 28 1.11 62 3.81 29 4.43 63 3.83 30 4.48 64 1.07 31 2.15 65 3.01 32 1.55 66 11.54 33 0.49 67 3.66 34 0.72

3 Bennett et al., Abundance, rarity and invasion debt among exotic species in a patchy ecosystem

Electronic Supplementary Material 2. Phylogenetic Analyses

Creation of Phylogenetic Tree

We created a phylogenetic tree of our species using the Angiosperm Phylogeny Group III (2009) phylogeny. Where there was no sub-family phylogenetic information, species within genera were assumed to be more closely related than genera within families. Internal nodes were dated using fossil evidence where available (Wikstrom et al. 2001), and the branch lengths for the tree were scaled to the dated nodes and made ultrametric via Bladj software (Webb 2000). Phylogenetic distances among species were subsequently used to test intra- versus inter-group distances and to test for a phylogenetic signal in abundance differences.

Tests for Phylogenetic Relatedness Within and Among Groups

We tested for significant differences in intra- versus inter-group phylogenetic distances using permutation tests (permuting group identities 10 000 times) of mean within-group distances versus means of all other distances. Apart from native long dispersers, selected groups exhibited lower intra-group than inter-group phylogenetic distances (Table S3). As reported in the main article, we also tested for a phylogenetic signal in abundance differences at both scales, using

Mantel tests.

4 Table ES2: Permutation test results for intra- versus inter-group phylogenetic distances

Group Intra-Group vs. Z P Inter-Group Difference (%)

Exotic Long -3.1 -7.82 <0.0001 Dispersers Exotic Short -5.9 -8.55 <0.0001 Dispersers

Native Long 0.2 0.53 0.60 Dispersers Native Short -1.0 -3.01 0.0032 Dispersers

References

Angiosperm Phylogeny Group III phylogeny (2009) An update of the Angiosperm Phylogeny Group classiﬁcation for the orders and families of ﬂowering plants: APG III. Bot J Linn Soc 161:105–21

Wikstrom, N, Savolainen V, Chase, MW (2001) Evolution of the angiosperms: calibrating the family tree. Proc R Soc Lond Ser B 268:2211–2220

Webb, CO (2000) Exploring the phylogenetic structure of ecological communities: an example for rain forest trees. Am Nat 156:145-155

5 Bennett et al., Abundance, rarity and invasion debt among exotic species in a patchy ecosystem Electronic Supplementary Material 3. Tests for all variables from most parsimonious models

Table ES3: Significant and non-significant coefficients from the most parsimonious models for numbers of occurrences and forms of rarity/commonness. P<0.1 are italicized; P<0.05 are bolded and italicized.

Response Variable Predictor Final Coefficient Coefficient Standard T P Variables Model Value Error EL 0.364 0.169 2.161 0.0342 Number of Occurrences in ES -0.756 0.192 3.948 0.0003 O, D, G O × D Patches f NL -0.010 0.143 0.070 0.9443 NS 0.081 0.254 0.321 0.7491 EL 0.626 0.368 1.698 0.0940 Number of Occurrences in ES -1.109 0.418 2.654 0.0114 O, D, G O × D Quadrats f NL -0.202 0.312 0.649 0.5176 NS 0.271 0.553 0.490 0.6256 EL 0.510 0.397 1.283 0.2037 Commonness on Both Inter- ES -1.626 0.472 3.443 0.0014 O, D, G O × D and Intra-Patch Scales f NL -0.047 0.362 0.129 0.8979 NS 0.434 0.649 0.669 0.5053 EL -1.008 0.365 2.765 0.0073 Rarity on Both Inter- and ES 0.334 0.411 0.812 0.4216 O, D, G O × D Intra-Patch Scales f NL 0.385 0.302 1.276 0.2047 NS 0.211 0.518 0.407 0.6853 Number of Occurrences in Full Surveys (Exotic spp. D, G , T D + T T only; including estim. time f a a a -0.453 0.103 4.399 <0.0001 since arrival) Number of Occurrences in Quadrats (Exotic spp. only; D, G , T D + T T including estim. time since f a a a -1.479 0.280 5.275 <0.0001 arrival) Minimum Convex Polygon Size (Exotic spp. only; D, G , T D + T T including estim. time since f a a a -0.210 0.095 2.218 0.0292 arrival) EL 0.326 0.225 1.448 0.1522 Number of Occurrences on ES -1.500 0.259 5.798 <0.0001 Patches (22 Small-Island O, D, G O × D f NL Patches Only) 0.207 0.194 1.066 0.2888 NS 0.217 0.346 0.629 0.5312 EL 0.385 0.425 0.906 0.3682 Number of Occurrences in ES -2.003 0.484 4.135 0.0002 Quadrats (22 Small-Island O, D, G O × D f NL Patches Only 0.223 0.362 0.616 0.5391 NS 0.398 0.644 0.618 0.5383

6 Notes:

-Predictor variables: O = origin (native or exotic); D = dispersal ability (short or long); Gf = growth form (forb, grass, shrub, tree); Ta = estimated time since arrival

-Predictor variable categories: E = exotic; N = Native; S = short dispersers; L = long dispersers (i.e., EL = coefficient for exotic long dispersers in O×D interaction term)

7 Bennett et al., Abundance, rarity and invasion debt among exotic species in a patchy ecosystem

Electronic Supplementary Material 4. Patch-level analysis using mean proportion of quadrats occupied per patch.

Table ES4: Significant and non-significant coefficients from the most parsimonious models for numbers of occurrences and forms of rarity/commonness. P<0.1 are italicized; P<0.05 are bolded and italicized.

Response Variable Predictor Final Coefficient Coefficient Standard T P Variables Model Value Error EL 0.015 0.012 1.212 0.229 ES -0.023 0.014 1.690 0.099 NL -0.009 0.010 0.907 0.367 NS 0.010 0.018 0.582 0.562 Commonness O, D, G O × D + G f f F -0.005 0.003 1.628 0.105 G 0.047 0.013 3.721 0.001 S -0.012 0.014 0.860 0.396 T -0.020 0.020 0.979 0.344

8 Bennett et al., Abundance, rarity and invasion debt among exotic species in a patchy ecosystem

Electronic Supplementary Material 5. Alternate forms of rarity/commonness

Conservative estimate (fewer common, more rare):

Common (patch-level) = 20 or more patches Rare (patch-level) = 4 or fewer patches Common (quadrat-level) = greater than one occurrence in quadrats from at least one patch Rare (quadrat-level) = never found in more than one quadrat per patch Liberal estimate (more common, fewer rare): Common (patch-level) = 10 or more patches Rare (patch-level) = 1 or 0 patches Common (quadrat-level) = greater than one occurrence in quadrats from at least one patch Rare (quadrat-level) = never found in more than one quadrat per patch

Table ES5a: Coefficients from most parsimonious models for rarity/commonness (conservative estimate)

Response Variable Predictor Final Coefficient Coefficient Standar T P Variables Model Value d Error EL 0.389 0.414 0.940 0.3507 ES -1.330 0.490 2.714 0.0098 NL -0.066 0.374 0.177 0.8601 NS 0.413 0.669 0.617 0.5393 Commonness O, D, G O × D + G f f F -0.198 0.095 2.080 0.0388 G 0.760 0.324 2.343 0.0244 S 0.563 0.374 1.504 0.1432 T -0.375 0.642 0.584 0.5686 EL -0.803 0.311 2.580 0.0120 ES 0.448 0.352 1.274 0.2099 Rarity O, D, G O × D f NL 0.334 0.260 1.281 0.2032 NS 0.045 0.456 0.098 0.9221

9 Table ES5b: Most parsimonious models for rarity/commonness (liberal estimate)

Response Variable Predictor Final Coefficient Coefficient Standar T P Variables Model Value d Error EL 0.433 0.380 1.141 0.2576 ES -1.342 0.446 3.009 0.0045 NL -0.163 0.339 0.481 0.6316 NS 0.499 0.605 0.825 0.4115 Commonness O, D, G O × D + G f f F -0.180 0.093 1.943 0.0534 G 0.757 0.321 2.355 0.0238 S 0.567 0.365 1.554 0.1307 T -0.605 0.638 0.948 0.3590 E -0.536 0.207 2.587 0.0110 Rarity O, D, G O f N 0.322 0.124 2.587 0.0105

Notes:

-Predictor variables: O = origin (native or exotic); D = dispersal ability (short or long); Gf = growth form (forb, graminoid, shrub, tree) -Predictor variable categories: E = exotic; N = native; S = short dispersers; L = long dispersers; F = forb; G = graminoid; S = shrub; T = tree

10 Bennett et al., Abundance, rarity and invasion debt among exotic species in a patchy ecosystem

Electronic Supplementary Material 6. Patterns on small-island patches.

Fig. ES1. Frequencies of long- and short-dispersing exotic and native species in the subset of 22 small-island patches. a) number of patches per species in full patch surveys; b) number of quadrats per species in quadrat-level surveys. Error bars indicate ±1 standard error.