BEARDSLEY, PAUL M.*, ALAN YEN, and RICHARD G. OLMSTEAD. Botany Department, University of Washington, Seattle, WA, 98195. - Patterns of speciation and the evolution of hummingbird and self-pollination in the Erythranthe clade of Mimulus (Phrymaceae)as inferred from an AFLP phylogeny.
The Erythranthe clade in Mimulus contains species are
adapted to different pollinators and one species that reproduces
mainly through self-pollination. Section Erythranthe contains
six species, five of which are hummingbird pollinated and one is bee
pollinated. The estimated phylogeny of this group using data from ITS,
ETS, and trnL/F shows no resolution for relationships among species,
but does support the monophyly of the Erythranthe clade if the
highly selfing, annual, desert-adapted M. parishii is included.
Sister to Erythranthe is a clade that includes M.
bicolor, M. filicaulis, and M. rubellus. 488 AFLP
bands were scored for all of the species in Erythranthe and its
sister clade, including multiple populations for most species. Results
of analyses of AFLP fragment data indicate: 1) Erythranthe is
monophyletic, 2) a high amount of genetic differentiation exists
between M. lewisii populations in the Sierra Nevada and those
in the Pacific Northwest and Rocky Mountains. To further investigate
the relationships among species, DNA from each species (including both
races of M. lewisii) was combined and an additional 400 AFLP
fragments were collected which resulted in a phylogeny for the group.
A well-resolved clade containing species in the Sierra Nevada, the
Pacific Northwest and the Rockies is sister to another well-resolved
clade containing species in Mexico, Arizona, and Utah. The highly
selfing M. parishii is resolved as sister to all other species
or as sister to a clade containing M. lewisii and M.
cardinalis . The common ancestor of the Erythranthe clade
is inferred to be annual, insect-pollinated and from the Sierra
Nevada. Hummingbird pollination is inferred to be derived within the
clade and may have arisen twice independently. Allopatric speciation
is suggested to be the major mode of speciation in the clade.
Key words: AFLP, Erythranthe, hummingbird pollination, Mimulus, self-pollination, speciation