Abstract Detail

Systematics Section / ASPT

Meyers, S.C. [2], Liston, Aaron [1].

The biogeography of Plantago ovata Forssk. (Plantaginaceae).

Plantago ovata Forssk. (Plantaginaceae) is a winter annual desert species which, in North America, inhabits desert and Mediterranean habitats of the southwestern United States, Baja California and the Channel Islands of southern California. In the eastern hemisphere P. ovata inhabits desert regions ranging from the Canary Islands, across northern Africa to west India. The wide disjunction between P. ovata in the western and eastern hemispheres poses an interesting question as to the origin and biogeography of the species in North America. Previous authors have hypothesized that P. ovata was introduced to North America over the Bering land bridge, from Asia, during the Miocene, or introduced anthropogenically from Europe during the 18th century by Spanish settlers. In this study we examined sequence data from the chloroplast trnL-trnF, trnS-trnG and nuclear ribosomal internal transcribed spacer regions. Using a molecular clock based on an ITS calibration within the Plantago genus, and a clock for plant chloroplast, we date a non-anthropogenic introduction event, from the Old World to North America, of approximately 200,000 years ago. This is consistent with a Pleistocene origin, and does not support a Miocene origin of the disjunction. Based on a morphological survey of 552 specimens, from throughout the world range of P. ovata, we suggest the recognition of four subspecific taxa. Furthermore, the morphological data suggests the origin of North American P. ovata may be the result of hybridization between Old World P. ovata varieties, and a subsequent long distance dispersal event.

1 - Oregon State University, Department of Botany and Plant Pathology, 2082 Cordley Hall, Corvallis, Oregon, 97331-2902, USA
2 - Oregon State University, Genetics Program, 2082 Cordley Hall, Corvallis, Oregon, 97331-2902, USA

Keywords:
biogeography
long distance dispersal
hybridization
desert disjunct
Plantago ovata.

Presentation Type: Paper
Session: 43-6
Location: Cottonwood A (Snowbird Center)
Date: Wednesday, August 4th, 2004
Time: 9:15 AM
Abstract ID:702