Xanthium strumarium

Manzo, Eleonora & Tomasello, Salvatore, 2025, Recent Long-Distance-Dispersal Explains the Range Disjunction of the Old-Word Cockleburs (Xanthium strumarium), Journal of Biogeography (e 15104) 52 (5), pp. 1-16 : 9

3.3 | Phylogeny of X. strumarium

The Bayesian analysis ( Figure 4A ), revealed various well supported clades and showed a clear geographic pattern. The earliest diverging clade included samples from India and Sri Lanka, followed by a split in which samples from East Asia and Mauritius separated from other clades (posterior probability of 0.99). In the latter clades, sample X353, from Siberia, is found to be sister to the rest of the samples, which are divided into three other clades: a first including samples collected in the Horn of Africa (posterior probability of 1.0); a second counting specimens originated in the Mediterranean (along with the two Brazilian samples; posterior probability of 0.99) and a third including specimens from the continental Europe, and X355, collected in Ethiopia (posterior probability of 1.00).

Figures

FIGURE 4 | (a) Ancestral range reconstruction of the X. strumarium complex as estimated in BioGeoBEARS using the DIVALIKE+j model. For visualisation convenience, the most-likely range is shown only when a change in the reconstructed area occurs. Results are shown on the ultrametric Bayesian tree estimated in Beast2, based on 744 nuclear loci and including 54 individuals from Xanthium strumarium, along with outgroup samples. Posterior probability support values above 0.7 are shown under or beside branches. Capital letters and colours indicate the areas defined for the analysis as in Table 1, Table S3 and Figure 2. Accordingly, red is for American, orange for Indian, acid-green for Sino-Japanese, green for Malaysian, dark green for Indochinese, light blue for Madagascan, ochre for Siberian, blue for African, violet for Mediterranean and pink for European. (b) Plot of the most-likely geographical range at each node (just before speciation) and post-split (just after speciation). Pie charts represent the probabilities of each possible geographical range for a given node. For representation convenience, only pie at every node where a change in the ancestral area occurred are shown.