DOI: 10.5061/dryad.jsxksn0dm
title: Data for: Cytogeography of naturalized Solidago canadensis populations in Europe

description: Autopolyploidization has driven the successful invasion of Solidago
 canadensis in East Asia. However, it was believed that only diploid S.
 canadensis invaded Europe, whereas polyploids never did. In this study, we
 aim to investigate whether polyploidy S. canadensis invaded Europe and
 compare the ecological niche differentiation pattern driven by ploidy in
 Asia and Europe and North America.Here, molecular identification
 (combination of ribosomal ITS and psbA-trnH intergenic spacer), ploidy
 level, and morphological traits of ten S. canadensis populations collected
 in Europe were compared with previously identified S. canadensis
 populations from other continents and S. altissima populations.
 Furthermore, the ploidy-driven geographical differentiation pattern of S.
 canadensis in different continents was investigated. Results showed that
 all ten European populations were identified as S. canadensis with five
 diploid and five hexaploid populations. Significant differences in
 morphological traits existed among diploids and polyploids (tetraploids
 and hexaploids), rather than between polyploids from different introduced
 ranges and between S. altissima and polyploidy S. canadensis populations.
 The invasive hexaploids and diploids had few differences in latitudinal
 distributions in Europe which was similar to the native range but
 absolutely different from a distinct climate-niche differentiation in
 Asia. This may be attributed to the bigger difference in climate between
 Asia and Europe and North America.The above morphological and molecular
 evidences proved the invasion of polyploid S. canadensis in Europe and
 suggest that S. altissima may be merged into a complex of S. canadensis
 species. Our study may be concluded that geographical and ecological niche
 differentiation of an invasive plant driven by ploidy depends on the
 degree of difference in the environmental factors between the introduced
 range and the native range, which provides new insight into the invasive
 mechanism.
description: Diploid (2n = 2x = 18), tetraploid (2n = 4x = 36), and hexaploid
 (2n = 6x = 54) seeds of S. canadensis were collected from the native
 region (North Amercia) and invasive region (Europe and Asia). The detailed
 descriptions of material collection and identification had been presented
 by Cheng et al. (2021). These seeds were stored in refrigerator at 4℃ in
 the Weed Research Laboratory, Nanjing Agricultural University, China. The
 NA2x, NA4x, NA6x, IN2x, IN4x and IN6x were used to represent the native
 diploid, native tetraploid, native hexaploid, introduced diploid,
 introduced tetraploid, and introduced hexaploid, respectively. NA
 represents the population of North America, CN represents the population
 of China, JP represents the population of Japan, EU represents the
 population of Europe, and RUS represents the population of
 Russia.  Molecular markers and phylogenetic
 analysis: To confirm the correct identification of the
 ten populations, we sequenced the ribosomal ITS (608bp) and trnH-psbA
 intergenic spacer (213bp) of three individuals from each population. To
 further verify the species identity of our samples, we conducted a BLAST
 search in the database of the National Center for Biotechnology
 Information (NCBI) to determine the species with the most similar
 identities. We built phylogenetic trees for all 152 S. canadensis
 populations, 7 S. altissima populations and closely related species with
 the ITS-psbA-trnH sequences, using the MEGA 4.1 Beta 3 software based on
 the maximum likelihood (ML) analyses, using a GTR substitution model as
 determined. Ploidy level of S. canadensis populations
 in Europe: We grew up plants from each seed family in
 the greenhouse. Fresh leaf material was held in self-sealing plastic bags
 containing silica and transported to the laboratory for ploidy level
 determination. We applied a modified flow cytometry method by Galbraith et
 al. (Galbraith et al., 1983) for the determination of ploidy level. The
 native diploid population (CA09) was used as an internal reference to
 measure the ploidy of ten populations. Glycine max Merr. 'Polanka is
 used as an internal reference to measure the DNA content of diploids
 (Dolezel et al., 2007). Comparison of the morphological
 traits of different geo-cytotype populations: After
 plant establishment, three individuals of each population were selected,
 and three replicates of each individual were used to measure the 7
 vegetative traits: height, stem, leaf length, leaf width, number of
 epidermal hairs of the main vein (per 2 mm length), number of epidermal
 hairs of the lateral vein (per 2 mm length), and number of epidermal hairs
 of the netted venation (per 4 mm2). During the flowering period,  three
 individuals of each population were selected, and three replicates of each
 individual were used to measure the 4 floral traits: length of the ray
 floret, height of the involucre, number of ray florets, and number of disc
 florets. Geographical distribution in Europe and global
 differentiation of ecological niches of different ploidy
 populations: The geographical differentiation of
 different ploidy populations in Europe and other regions was analyzed by
 combining with our previous research (Cheng et al., 2020a) and literature
 records. Climatic factors of all occurrences were extracted from worldclim
 (https://www.worldclim.org/) for the analysis of differences in climatic
 factors between the distribution ranges of different ploidy populations.
 In addition, the ecological niche differentiation pattern of different
 ploidy populations in Europe, North America, and Asia are
 compared. Methods for processing the data: 
 The average and square deviation of morphological traits and
 climate factors for different geo-cytotypes of S. canadensis in different
 regions were calculated, and the significance of the differences
 (P&lt;0.05) between geo-cytotypes in different regions was analyzed
 using using one-way ANOVA with Least Significant Difference
 (LSD).
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