Date of Completion

5-5-2016

Degree Type

Honors Thesis

Discipline

Biology (BIOL)

First Advisor

Victor Carmona

Abstract

The increase in atmospheric CO2 levels due to climate change may greatly impact invasive plant species, which are non-native organisms that spread unchecked in space and negatively impact native organisms. The success of these invasives may be related to specific traits, such as their photosynthetic pathway. We acquired the specimen information for invasive species registered in the Consortium for California Herbaria of the University of California Berkeley to evaluate the community dynamics of 1,000 invasive species in Los Angeles County. We found that both diversity and richness of invasive plant species has increased over a period of 180 years. We hypothesize that the pattern of occurrence of a given photosynthetic pathway may correspond with historical increases in atmospheric CO2 concentrations, therein favoring invasives with a C3 photosynthetic strategy. We utilized the primary literature to identify the photosynthetic pathway for all of the invasive plant species in our database, then used curve-fitting techniques to evaluate the change in richness for C3, C4, and CAM. We found evidence to support that C3 invasives were indeed favored over C4 and CAM. We are currently examining stomatal densities of historical specimens in order to link this finding to CO2 levels. If stomatal densities of these C3 invasives has decreased, they have been responding to increased CO2, supporting our hypothesis.

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