Data from: The roles of ecological and evolutionary processes in plant community assembly: the environment, hybridization and introgression influence co-occurrence of Eucalyptus

Introgressive hybridization is increasingly recognized as having
influenced the gene pools of large genera of plants, yet it is rarely
invoked as an explanation for why closely related plant species do not
co-occur. Here, we asked how the environment and tendency to interbreed
relate to neighborhood co-occurrence patterns for Eucalyptus species in
the Grampians National Park, Victoria, Australia. We identified species
pairs that have experienced ongoing hybridization and introgression on the
basis of the extent of incongruence between chloroplast DNA (JLA+ region)
and nuclear ribosomal DNA (internal transcribed spacer region)
phylogenies, geographic patterns of gene sharing, and field observation of
intermediate morphologies. Co-occurrence, trait data (specific leaf area
[SLA], maximum height, and seed mass), and environmental data were
measured in plots distributed along environmental gradients. Trait and
habitat similarity influenced species co-occurrence the most overall
(e.g., co-occurring species had similar SLA). Reproductively compatible
species were an exception; they rarely co-occurred despite being
functionally similar. The negative effect of reproductive compatibility
was stronger than the positive effect of SLA on co-occurrence. Our results
emphasize the dominant roles of the environment and the importance of
evolution in structuring local assemblages. We argue that the mechanism
responsible for preventing closely related species from co-occurring in
this system is reproductive interference rather than competitive
exclusion. Reproductive interference should be considered more generally
as a potential cause of phylogenetic overdispersion.