Comparative ecological and genetic studies between a native (Lonicera sempervirens L.) and an introduced congener (Lonicera japonica Thunb.).

摘要

I conducted ecological and genetic comparisons between an invasive species, Lonicera japonica, and its native congener, L. sempervirens (Caprifoliaceae), to identify traits that contribute to a plant species' ability to invade. Both species are long-lived perennial vines common to mid-successional disturbed areas throughout the southeastern United States.; Species-level genetic variation as measured by allozyme diversity in both L. japonica and L. sempervirens is that expected for species with similar life history traits; however, levels of genetic variation are high when compared to other invasive species.; A comparison between L. japonica and L. sempervirens for photosynthetic patterns, stomatal conductance and water-use efficiency over one year under open and closed forest canopies found few significant differences in ecophysiological traits. However, a subtle difference in leaf phenology, the retention of old leaves during new leaf formation in early spring, results in a carbon gain advantage for Lonicera japonica.; A comparison of growth and biomass parameters between the two species under different herbivory treatments showed that herbivory significantly affects growth in L. sempervirens but not in L. japonica. In the absence of herbivory, L. sempervirens had higher leaf area, relative growth rates and total biomass than L. japonica. Lonicera japonica showed evidence of a compensatory response to herbivory, with an increase in total biomass and allocation to leaf tissue.; Although both L. japonica and L. sempervirens have high genetic variability, it is probably less important in explaining their relative success in the Southeast than life history traits. The traits that contribute to the invasive ability of Lonicera japonica are the retention of old leaves and photosynthetic capacity during new leaf formation, intrinsic biomass allocation patterns, and a compensatory response to herbivory.; The vulnerability of a community to invasion can be heightened by native species lacking specific features which an invader possesses. Congeneric studies such as conducted here provide a perspective with which to identify characters that make invaders compatible with the communities they are invading.