Dept.of Ecology and Evolutionary Biology
321 Steinhaus Hall
University of California-Irvine
Irvine , California   92697
ph. 949-824-6581, fax  949-824-2181
Ann K.Sakai
Stephen G. Weller
[Ann Sakai] [Stephen Weller] [Research-Dioecy] [Research-Heterostyly] [Research-Conservation]

[Grad students] [Undergraduates] [Publications] [Main Lab Page]

Welcome to the webpage of the combined laboratory of Stephen Weller and Ann Sakai.  Our research interests are in the complementary areas of plant population biology, evolutionary ecology, and conservation biology.  Our specific interests include studies of the evolution of plant breeding systems and conservation and invasion biology. Publications are listed on a separate page.
Photo by S. Weller
Photo by S. Weller
Honckenya peploides (Caryophyllaceae), a native of coastal Alaska, is shown here (left) in its natural habitat near Seward, Alaska (right). Strange as it seems, Honckenya is a member of the closest sister clade to the monophyletic native Hawaiian genus, Schiedea. The Sakai/Weller lab is interested in the evolution of breeding systems in Schiedea.
The 34 species of Schiedea (Caryophyllaceae) exhibit a variety of breeding systems, including hermaphroditism, gynodioecy (females and hermaphrodites in populations), and dioecy (females and males in populations). We have used an interdisciplinary approach, including phylogenetic methods, physiological ecology, and quantitative genetics, to examine factors associated with the evolution of dioecy in this group.

About half of the native Hawaiian flora, including most Schiedea species, are at risk. S. viscosa (left) is a rare understory vine endemic to Kaua’i. It was considered extinct until it was rediscovered in 1991, 75 years after the last collection. Our interests include research in conservation, restoration, and the population biology of invasive species.

Photo by Nobumitsu Kawakubo
Heterostyly is a breeding system where differences in floral morphology are linked to self-incompatibility, and pollinations that lead to seed production are usually those between flowers with anthers (yellow) and stigmas (green) at the same height (see below). In Oxalis alpina, some populations have three floral morphs in the population (upper left), while other populations have only two floral morphs (the mid morph with stigmas in the middle position is missing (below left). We are investigating changes in self-incompatibility that may result in the evolution of distyly from tristyly. Populations of Oxalis alpina occur on isolated mountain ranges throughout the Sky Islands of Arizona, New Mexico, and Sonora.
Photo by Nobumitsu Kawakubo
Photo by Nobumitsu Kawakubo