DOI: 10.5061/dryad.m88g7
title: Data from: Deconstructing Darwin’s naturalization conundrum in the San Juan Islands using community phylogenetics and functional traits

description: Aim: Darwin posed a conundrum about species invasions, postulating the
 importance of functional distinctiveness from the receiving native
 community to avoid competition, and, at the same time, the importance of
 shared similarity to pass environmental filters and successfully
 establish. Using phylogenetic distances and functional traits, we assessed
 this conundrum in the flora of 80 mostly uninhabited islands, where over
 30% of the species are invasive. We highlight the importance of publicly
 available datasets to disentangle ecological processes that may drive
 invasion. Location: San Juan Islands archipelago, Pacific Northwest of
 North America. Methods: Using a supermatrix approach, we inferred a
 maximum-likelihood estimate of the mega-phylogeny for the vascular plants
 on the San Juan Islands. We gathered measurements for five ecologically
 relevant functional traits – seed mass, maximum height, specific leaf
 area, leaf size and leaf nitrogen content. We assessed phylogenetic and
 functional trait similarity between invasive species and the receiving
 native community, and tested the significance of the observed patterns
 against a randomly generated invading community. Results: Invasive species
 were more closely related (phylogenetically clustered) to their nearest
 native than natives were on 40 of the islands and were more clustered than
 any random invasive in the species pool on 22 islands. Despite
 phylogenetic similarity, functional traits differed between the two status
 groups, at least for maximum height and specific leaf area. When comparing
 functional differences between phylogenetically close relatives, more
 complex patterns emerge. Main conclusion: Only with the combination of
 both evolutionary history and phenotypic traits were we able to discover
 support for both sides of Darwin's conundrum – although invasive
 species have phylogenetically close native relatives, functional traits
 differ between the two status groups. This implies that both environmental
 filtering and competitive interactions may be important for invasion
 success in this archipelago.
description: Island Community
 MatrixDatamatrix of species
 occurrences (presence / absence) across all 80 sampled islands in the San
 Juan archipelago, Washington State, USADRYAD1_ComMatrix.csvFunctional TraitsMeasurements of five ecologically relevant functional traits (seed mass, maximum height, specific leaf area, leaf size, and nitrogen content) for each species occurring on the islands sampledDRYAD2_SJtraits.csvIsland MetadataMetadata and summaries of species richness for all 80 islands sampled in the San Juan Island archipelago, Washington, USADRYAD3_SJcomSummary.csvSan Juan Islands Community PhylogenyTime-calibrated maximum likelihood mega-phylogeny of the vascular flora of the San Juan IslandsDRYAD4_SJtreePL.bootstrap.treAlignmentsSequence alignments for each gene region with GenBank accession numbers for each species and the concatenated sequence alignmentTreefilesMaximum likelihood phylograms for each gene region and the concatenated alignment