Theses and Dissertations

Issuing Body

Mississippi State University

Advisor

Gary N. Ervin

Committee Member

Mark E. Welch

Committee Member

Rima D. Lucardi

Committee Member

Marcus A. Lashley

Date of Degree

8-6-2021

Original embargo terms

Visible to MSU only for 2 years

Document Type

Dissertation - Campus Access Only

Major

Biological Sciences

Degree Name

Doctor of Philosophy

College

College of Arts and Sciences

Department

Department of Biological Sciences

Abstract

Natural dispersal mechanisms and biogeographical barriers have shaped species' native distributional ranges over millions of years. However, over the last few centuries, humans have dispersed species beyond their natural ranges. Those species that undergo explosive population growth and rapid expansion in the introduced region are considered as invasive because they have the potential to cause negative effects on desirable species and/or ecosystem services. In chapter II, I identified what ecosystem characteristics are more closely associated with successful establishment of exotic and native species, to have a better idea of where to concentrate our efforts and resources to prevent invasion events while preserving native species. I found that native and exotic species were differently affected by ecosystem properties. Exotic species were favored by human activities and low native species abundance and diversity. However, in Chapter III, I found that species functional traits, such as growth form and phenology, are more important to explain their response to ecosystem characteristics than native status under certain circumstances. The abundance and reproductive capacity of the evaluated plants were reduced when disturbances occurred during their respective active growing periods. This finding suggests that we need to have into account species-specific responses to ecosystem characteristics when managing biological invasions. Chapter IV examined phenotypic differentiation of native, expansive, and introduced populations of Baccharis halimifolia L. occurring in different regions of the world. The results suggest that there are significant phenotypic differences in germination and early growth among native, expansive, and introduced populations, which could have contributed to the success of B. halimifolia in the introduced and expansive ranges. Finally, in Chapter V, I used the information that I learned in the past projects to predict the spread of 45 exotic plants across southeastern United States and evaluated what landscape factors make an area more susceptible to be invaded. I found that the influence of landscape composition and configuration on invasion risk is species-specific. This result suggests that not only we have to consider species functional traits when managing biological invasions, as we saw earlier in the experiment with disturbance timing, but also species habitat preferences.

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