Document: SUS-3-36-12

Potential physiological efficiency of reproduction in native and alien plant species.

MCDOWELL, S.C.L.*

Oregon State University, Corvallis, OR ¹

Abstract:
Mechanisms of alien invasive plant success are not adequately explained by current theories. I tested the hypothesis that invasive alien species have higher physiological efficiency of reproduction than closely related native species due to the higher physiological capacity of the alien species. To test this hypothesis, I compared physiological traits of multiple alien and native congener species of Rubus and Cirsium with overlapping ranges in the Pacific Northwest and quantified the efficiency of reproduction for each species. I measured leaf-level traits, including photosynthetic capacity (A_max), instantaneous net assimilation (A), and leaf water potential, on both reproductive and non-reproductive plants, as well as net carbon allocated to reproductive tissues. Carbon allocation to reproduction was greater for the alien species. There are negative physiological effects of reproduction for both native and alien species. Water stress, as indicated by leaf water potential, was 10- 25% greater for reproductive plants than non-reproductive plants. A_max was 15- 40 % lower for reproductive plants than non-reproductive plants. These effects of reproduction appear greater for native than alien species. Therefore, in spite of the higher carbon costs of reproduction in the alien species, increases in A offset the increased reproductive allocation. Invasive alien plants have higher physiological efficiency of reproduction. High reproductive efficiency and physiological capacity of invasive alien plants combine as a strategy that may contribute to the success of these invasive species.

Keywords: reproductive efficiency, invasive plants, carbon allocation, photosynthesis

This abstract is being presented at: 3:30 PM in session:
REPRODUCTIVE ECOLOGY