A new study conducted by UCSB’s National Center for Ecological Analysis and Synthesis indicates that low plant extinction rates spanning the last 45 million years have led to more diverse plant life in California.
According to the study, rates of increase in new species of plants are highest in the state of California, which contains over 5,500 native plant species — 40 percent of these being endemic, or occurring solely in California. Findings suggest that California acted as a safe haven for endangered plant species during climate changes in the past.
According to Kathleen Kay, co-author of the study and an assistant professor of ecology and evolutionary biology at UC Santa Cruz, the study utilized phylogenetic analysis to find information on the evolutionary relationships among organisms.
Kay said she and Lesley Lancaster, first author of the study and postdoctoral researcher in molecular ecology at Lund University in Sweden, started working on this project due to their common interest in plants of the Californian region.
“Lancaster was a grad student here at UC Santa Cruz,” Kay said. “She took a course with me and I got to know her that way and discovered we had a shared love of California flora. The thing that is really unique is that so many people have studied the California flora. I guess the time was right to do a more large-scale analysis to put all that information together in one analysis and try to reevaluate some of the well-accepted ideas of how the plants had diversified over periods of time.”
According to Kay, the last time this analysis was attempted across all species was in 1978 by Peter Raven and Daniel Axelrod. Their findings showed that Mediterranean climate had fostered speciation — the area being only one out of about five places on the planet with this climate — but does not affect California’s plant diversification rates, according to Kay.
“What we found in our study was that the diversification in California wasn’t really affected by the onset of the Mediterranean climate, which is a relatively new thing,” Kay said. “It has actually been a much older process. In the past, most of the focus has been on speciation of California plants because a lot of endemic plants are present. What our study showed is that it’s actually not true — plants aren’t speciating faster than other plants outside of California. Instead, the reason why California is so much more diverse is because they are going extinct a lot less often.”
Kay said topography plays an important role in preserving many of the species. Mountains in California, for example, allow plants to migrate in a smaller scale as opposed to migration rate on a flat land. Kay said mountainous regions make it easier for plant species to find their niche by locating appropriate elevations and temperatures necessary for survival.
According to Kay, the landscape, such as the mountain areas with different types of soils and provisions for plants, needs to be protected in order for the range of habitats present in California to remain available.
“Our study really shows that California has been a refuge in the past and so it should continue being a refuge, but we have to protect the natural areas for it to continue serving as a refuge,” Kay said. “The other thing found in our study is that California is a net exporter of species to surrounding areas, so it’s also served as an important source for surrounding areas that may have a higher extinction rate.”
Third-year environmental studies major Selena Ellis said information from the study allows readers to look at the environment from a different perspective.
“Knowing that California has one of the most diverse numbers of plants really makes you appreciate the beauty it has to offer,” Ellis said. “This new information may also shed new light on extinction by bringing knowledge about extinction rates and the causes of it.”
A version of this article appeared on page 3 of January 15th, 2013’s print edition of the Nexus.