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PREMISE OF THE STUDY: We tested 25 classic and novel hypotheses regarding
trait-origin, trait-trait, and trait-environment relationships to account
for flora-wide variation in life history, habit, and especially
reproductive traits using a plastid DNA phylogeny of most native (96.6%,
or 1494/1547 species) and introduced (87.5%, or 690/789 species)
angiosperms in Wisconsin, USA. METHODS: We assembled data on life history,
habit, flowering, dispersal, mating system, and occurrence across
open/closed/mixed habitats across species in the state phylogeny. We used
phylogenetically structured analyses to assess the strength and
statistical significance of associations predicted by our models. KEY
RESULTS: Introduced species are more likely to be annual herbs, occupy
open habitats, have large, visually conspicuous hermaphroditic flowers,
and bear passively dispersed seeds. Among native species, hermaphroditism
is associated with larger, more conspicuous flowers; monoecy, with small
inconspicuous flowers and passive seed dispersal; and dioecy, with small
inconspicuous flowers and fleshy fruits. Larger flowers with more
conspicuous colors are more common in open habitats, and in understory
species flowering under open (spring) canopies; fleshy fruits are more
common in closed habitats. Wind pollination may help favor dioecy in open
habitats. CONCLUSIONS: These findings support predictions regarding how
breeding systems depend on flower size, flower color, and fruit type, and
how those traits depend on habitat. This study is the first to combine
flora-wide phylogenies with complete trait databases and phylogenetically
structured analyses to provide powerful tests of evolutionary hypotheses
about reproductive traits and their variation with geographic source, each
other, and environmental conditions.
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