By Sean Henahan, Access Excellence

ALBUQUERQUE, NM (5/20/96)- A comparison of tropical daisy genes across the Pacific suggests plant evolution may occur at a far faster rate than previously believed possible.

Image: NASA Shuttle View of Kauai

University of New Mexico biologist Tim Lowrey conducted a comparison study of the genetics of a species of tropical daisy known as tetramolopium. He began studying the daisies in New Guinea and later identified tetramolopium derivatives in the Hawaiian and Cook Islands, a discovery indicating that a few genes are in control. One clue was the age of the Hawaiian tetramolopium, estimated at less than 700,000 years.

The standard consensus among evolutioary botanists has been that just one speciation event should occur every million years or so. Lowrey found that in the space of 700,000 to one million years there have been a minimum of 11 speciation events in the Hawaiian Islands.

"The discovery that these major morphological changes are taking place so rapidly indicates that all traits in plants are not controlled by a large number of genes because the process would require more time," explains Lowrey.

Lowrey's colleague, Richard Whitkus, a professor in the Department of Botany and Plant Science at the University of California/Riverside, is using genetic markers to map the Tetramolopium chromosomes to see how may control particular traits such as flower color, height, sex or size.

The team recently learned that some of the female tetramolopium in Hawaii had undergone a sex change and lost their ability to produce seed.

"One of the major innovations in sunflower breeding is the development of male sterility," Lowrey says. "It we can figure out what the genetic control of female sterility is , it could be useful for plant breeders. We have good evidence now to show that the sex change is controlled by two major genes."

Lowrey says his research on genetic variation will also be important to conservation biologists. All but one of the 11 species in Hawaii are rare and endangered; several are already federally listed with others proposed candidates for protection under the Rare and Endangered Species Act.

Researchers need to understand the genetic variation of a species in order to determine its evolutionary potential. It is welle stablished that populations lacking variation have a much greater chance of becoming extinct.

"We're trying to use the tetramolopium as a model organism to look at how much genetic variation there is in rare plants with very small population sizes," he says.

This fall Lowrey plans to collect possible relatives of the tetramolopium, and, using molecular methods, try to determine its family tree.

"Once we have a better idea of what the evolutionary relationships are we can look for similar changes in related plant groups to see if what we've found in the tetramolopium has more of a general application," he said. "What we're always searching for is, 'Are these general principles or is it just some weird genetic system that is happening here?"

The details of Dr. Lowrey's NSF-funded study were released by the University of New Mexico.

Related information on the Internet

Plant Resources Information Lab

Ag. Network Info. Center

Virtual Hawaii