Mean rainfall (triangles) and temperature (diamonds—mean maximum monthly temperature, circles—mean minimum monthly temperature), for high elevation (white) sites (Katoomba; ca. 10km from sites; elevation 1000m; 1907 to 2010) and low elevation (grey) sites (Penrith Lakes; ca. 10km from sites; elevation 25m; 1995 to 2010) from the Australian Bureau of Meteorology.

<p>Mean rainfall (triangles) and temperature (diamonds—mean maximum monthly temperature, circles—mean minimum monthly temperature), for high elevation (white) sites (Katoomba; ca. 10km from sites; elevation 1000m; 1907 to 2010) and low elevation (grey) sites (Penrith Lakes; ca. 10km from sites; elevation 25m; 1995 to 2010) from the Australian Bureau of Meteorology.</p

MDS plots of ant communities at low elevation c. 200 m a.s.l. (grey; n = 8) and high elevation sites c. 700 m a.s.l. (white; n = 8) in the Greater Blue Mountains World Heritage Area; a) includes all ant genera, b) includes only the seed-dispersing ant genera.

<p>MDS plots of ant communities at low elevation c. 200 m a.s.l. (grey; n = 8) and high elevation sites c. 700 m a.s.l. (white; n = 8) in the Greater Blue Mountains World Heritage Area; a) includes all ant genera, b) includes only the seed-dispersing ant genera.</p

Total mean percentage (± SE) of seeds removed at day five of the exclusion experiment from low elevation sites (grey) and high elevation sites (white).

<p>The four exclusion treatments were closed to both invertebrates and vertebrates (None); open to both vertebrates and invertebrates (vertebrates & invertebrates); vertebrates allowed access and invertebrates excluded (vertebrates only); invertebrates allowed access and vertebrates excluded (Invertebrates only).</p

Results of the two binomial linear regressions for the observation experiment on the proportion of seeds found or moved by ants, across low and high elevations in the Greater Blue Mountains World Heritage Area, including coefficients (±SE), z-value and probability.

<p>Temperature is the temperature at time of observation. Significant <i>P</i>-values are in bold.</p

Mean abundances (± standard error) of ant genera collected from pitfall traps at low and high elevations sites in the Greater Blue Mountains World Heritage Area.

<p>Superscript numbers 1, 2, 3 indicate the top three genera that differ between low and high elevation communities. The genera that contain seed-removalists (MYR) are indicated (Y = yes). Superscript letters indicate: a genera that moved seeds, and b genera known as seed predators [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0157632#pone.0157632.ref031" target="_blank">31</a>]. The functional group [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0157632#pone.0157632.ref043" target="_blank">43</a>] abbreviations are: dominant Dolichoderinae (DD); opportunists (O); subordinate Camponotini (SC); hot & cold climate specialists (HCS & CCS); cryptic species (CS); specialist predators (SP); generalized Myrmicinae (GM).</p

Comparison of native and introduced species’ dispersal distances, plant height and seed mass.

<p>Black dashed lines represent mean values. The boxes represent the 25^th, 50^th and 75^th percentiles. Whiskers represent the 10^th and 90^th percentiles, outliers are represented as points. Sample sizes are number of species. </p

Are Introduced Species Better Dispersers Than Native Species? A Global Comparative Study of Seed Dispersal Distance

<div><p>We provide the first global test of the idea that introduced species have greater seed dispersal distances than do native species, using data for 51 introduced and 360 native species from the global literature. Counter to our expectations, there was no significant difference in mean or maximum dispersal distance between introduced and native species. Next, we asked whether differences in dispersal distance might have been obscured by differences in seed mass, plant height and dispersal syndrome, all traits that affect dispersal distance and which can differ between native and introduced species. When we included all three variables in the model, there was no clear difference in dispersal distance between introduced and native species. These results remained consistent when we performed analyses including a random effect for site. Analyses also showed that the lack of a significant difference in dispersal distance was not due to differences in biome, taxonomic composition, growth form, nitrogen fixation, our inclusion of non-invasive introduced species, or our exclusion of species with human-assisted dispersal. Thus, if introduced species do have higher spread rates, it seems likely that these are driven by differences in post-dispersal processes such as germination, seedling survival, and survival to reproduction.</p> </div

The total number of seeds removed during the observation experiment at low (grey) and high elevation (white) sites by the top three seed-removing ant genera: <i>Rhytidoponera</i>, <i>Aphaenogaster</i> and <i>Pheidole</i>.

<p>The total number of seeds removed during the observation experiment at low (grey) and high elevation (white) sites by the top three seed-removing ant genera: <i>Rhytidoponera</i>, <i>Aphaenogaster</i> and <i>Pheidole</i>.</p

Partial contributions to Observed vs. Fitted tree occurrences within the simplified BRT model.

<p>The graphs show Observed vs. Fitted tree occurrences (A) and smoothed partial contributions within the simplified BRT model for (B) mean annual temperature (C) percentage woody cover in a 25 m radius and (D) distance to nearest forest. The smoothed partial contribution plots reflect the influence of a predictor variable when all other variables are held constant. CVROC is the cross-validated receiver operator curve (ROC) for the final boosted regression tree model. ROC is a measure of discrimination accuracy when predicting a binary response.</p

Map of survey plots used in boosted regression tree modeling.

<p>Vegetation classes for New Zealand survey plots are mapped based on a reclassification of Dymond and Shepherd [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0075219#B58" target="_blank">58</a>]. ‘Other’ is all non-forest vegetation except subalpine scrub.</p