Data from: Repeated polyploidization shapes divergence in floral morphology in Lithophragma bolanderi (Saxifragaceae)

Polyploidization is an important driver of evolution and diversification
in flowering plants. Here, we assess how repeated polyploidization may
have shaped diversification of floral morphology in Lithophragma bolanderi
(Saxifragaceae). This species comprises multiple cytotypes and varies
geographically in its interactions with specialized pollinating moths in
the genus Greya (Prodoxidae). Past studies have shown that coevolution
with these moths has favored particular suites of floral characters but
does not fully explain local and regional floral diversification. We
combined phenotypic and genomic data from more than 1800 individuals from
40 L. bolanderi populations spread across its entire range.
Flow-cytometric analyses revealed a geographic mosaic of populations
comprising one to four of three dominant (diploid, tetraploid, hexaploid)
and three rare (triploid, pentaploid, octoploid) cytotypes. Whole-genome
resequencing of a subset of populations suggested that polyploids arose
from multiple autopolyploidization events, rather than a single event
and/or through hybridization, albeit with some signals consistent with low
levels introgression from the congener Lithophragma glabrum.
Quantification of flower traits from plants grown in a common garden
showed that cytotype explained more than 15% of the variation in floral
morphology, with polyploids showing more variability than diploids.
Experimental induction of neopolyploids directly induced phenotypic
changes but also indicated that local selection may have favored
subsequent convergence in floral morphology among cytotypes in natural
populations. Collectively, this comprehensive and integrative approach
provides novel insights into how variability generating processes, such as
polyploidization integrates with selection from species interactions to
shape local floral diversification.