Whence came these plants most foul? Phylogenomics and biogeography of Lowiaceae (Zingiberales)

Lowiaceae (order Zingiberales) is a small family of forest herbs in Southeast Asia. All
species belong to the genus Orchidantha. They are known for possessing orchid-like
flowers that are smelly, apparently mimicking dead animals, feces, or mushrooms.
Little is known of the biogeographic patterns or character evolution of the family.
We sampled the family extensively, including many recently discovered species, and
reconstructed the phylogeny of the family using HybSeq with Lowiaceae-specific RNA
baits. Our phylogenetic reconstructions confirm that the family is most closely related to
Strelitziaceae, and that species with dark, foul-smelling flowers form a grade in which a
clade of species with paler smelling flowers are embedded. The pale-flowered species
produce a distinct odor, resembling edible mushrooms. Apart from a single species, the
species from Borneo form a clade, and the same is true for Indochinese species. The
remaining species form a more widespread clade. A biogeographic analysis shows that
the distribution of Lowiaceae can explained by vicariance and gradual dispersal from a
shared ancestral range of Borneo and Indochina. There is no evidence of long-distance
dispersal, only a later extension in distribution to Peninsular Malaysia which coincides
with the presence of a land bridge. Different directions of spread are possible, but none
require long-distance dispersal. The results are consistent with the geological history of
Southeast Asia. In particular, the relatively early isolation between Indochina and Borneo
could be explained by the presence of a sea barrier that developed 10–15 MYA, and the
continuous movement of plant species between Borneo and Peninsular Malaysia could
be explained by a land bridge that existed until c. 5 MYA. The lack of an extensive land
bridge with a suitable habitat may explain the absence of this genus from Sumatra and
other Indonesian islands aside from Borneo. The strict reliance on a continuous habitat
for the range expansion of Lowiaceae can be explained by their fruits and seeds, which
lack obvious adaptations for long-distance dispersal. The inability to disperse to new
areas may also explain why the extant species have very restricted distributions.

Methods
DNA sequence data, phylogenetic analyses, and trait data.