TitleThe influence of propagule pressure on community diversity and invasion success in an aquatic protist system
NameMaier, Caroline Alexandra (author), Morrison, Douglas (chair), Holzapfel, Claus (internal member), Russell, Gareth (internal member), Morin, Peter (outside member), Rutgers University, Graduate School - Newark,
DescriptionPropagule pressure, the size and frequency with which invaders enter an area, may influence many aspects of invasion. Using a bacterivorous protist model system, this study examines the effect of propagule pressure on the diversity of established communities, the success of invaders, and the effect invaders have on the established community.
Increasing propagule size and frequency significantly increased diversity and species richness and decreased dominance in three experimental protist communities. Propagule pressure also significantly influenced invasion. Increasing propagule pressure promoted establishment and invasion success, and reduced probability of stochastic extinction, of slow-growing invaders. Increasing propagule pressure also enhanced the growth of fast-growing invaders, but only up to a point. Further increase in propagule pressure diminished growth. Propagule size and frequency interacted in influencing invasion, with the outcome related to the invader’s growth rate. Fast-growing protist invaders achieved the greatest success when introduced in one large inoculation, while the success of the slow-growing invaders was enhanced by high propagule frequency. In this study, high values of propagule pressure enhanced the coexistence of protist species, established and invasive, and might therefore create a positive regional diversity-invasibility relationship in natural protist communities.
Invasion success might be described by a general Gaussian dose-response curve, the placement of specific propagule pressure values on the curve determined by a species’ realized growth rate. Slow-growing invaders reach saturation at high values of propagule size and frequency, while fast-growing invaders show saturation at much lower values.
In this system, propagule pressure has a strong indirect influence on the growth of individual established species and the degree to which invasion affects community diversity, richness, and evenness. Invaders have a particularly strong effect on slow-growing established species. Fast-growing invaders have especially powerful effects on established species. The effect the invader has on the specific species composing the community determines species richness and evenness, and ultimately, community diversity. In this way, propagule pressure plays an important role in the complex interaction of factors that influence the effect invasion has on the established community.
NoteIncludes bibliographical references (p. 303-314)
Noteby Caroline Alexandra Maier
CollectionGraduate School - Newark Electronic Theses and Dissertations
Organization NameRutgers, The State University of New Jersey
RightsThe author owns the copyright to this work.