Abstract Detail

Pollination Biology

Steiner, Kim E. [1], Cruz, Boni C. [1].

The evolution of stylar polymorphisms in Hemimeris (Scrophulariaceae).

Hemimeris is a genus of four annual species endemic to the Winter Rainfall Region of South Africa. Flowers are characterized by the presence of twin sacs or spurs that contain glands that secrete non-volatile oil as a pollinator reward. All species are pollinated by oil-collecting bees. One species, H. racemosa, is characterized by the presence of a unique type of stylar polymorphism that has been termed “inversostyly”. We report another type of stylar polymorphism, i.e., “enantiostyly”, for the genus in which the style is deflected to the right or left rather than up or down. This polymorphism is associated with pollen transport on the legs of pollinating bees. We investigated the evolution of the two types of stylar polymorphism and other floral characters using multiple samples for each species from throughout their distributional ranges with molecular data from two nuclear (ITS & ETS) and four plastid gene regions (trnC-trnD, matK, trnL-trnF, trnS-trnG) using phylogenies derived both from parsimony and maximum likelihood. Our data suggest that homostyly has evolved repeatedly from inversostyly in different clades and is associated with selfing both within H. racemosa and in the clades leading to another species (H. sabulosa). They also suggest an independent origin for the new type of stylar polymorphism. Finally, the phylogenies also indicate that three of the four currently recognized species are polyphyletic and need to be re-circumscribed.

Broader Impacts:

1 - California Academy of Sciences , Botany, 55 Music Concourse Dr., San Francisco, CA, 94118, USA

Keywords:
stylar polymorphism
evolution of selfing
floral evolution
oil-secreting flowers
Hemimeris
pollination.

Presentation Type: Oral Paper:Papers for Topics
Session: 13
Location: 553A/Convention Center
Date: Monday, August 2nd, 2010
Time: 2:00 PM
Number: 13003
Abstract ID:427