Date of Completion

5-8-2014

Embargo Period

11-4-2014

Keywords

bats, functional, fragmentation, forest loss, matrix effects, meso-scale structure, phylogenetic, taxonomic

Major Advisor

Dr. Michael R. Willig

Associate Advisor

Dr. Robin L. Chazdon

Associate Advisor

Dr. Mark C. Urban

Field of Study

Ecology and Evolutionary Biology

Degree

Doctor of Philosophy

Open Access

Open Access

Abstract

Anthropogenic modification of landscapes is global and pervasive. Such landscapes comprise more native vegetation than do landscapes with no human impact. Moreover, these alterations have contributed to the accelerated loss of biodiversity and compromised ecosystem services. Consequently, development of appropriate conservation policies requires an understanding of how communities are affected by human-modified landscapes.

Despite considerable efforts towards understanding the effects of human-modified landscapes on communities, two critical aspects of landscape ecology have received scant attention. First, little is known about the effects of landscape modification on ecological and evolutionary characteristics of assemblages, as most studies have focused on taxonomic biodiversity (e.g. species diversity). The effects of environmental variation, including that produced by land conversion, is dependent on species characteristics (e.g. physiological constraints, habitat requirements, dispersal abilities). Thus, inclusion of ecological functions and evolutionary histories into biodiversity assessments (i.e. functional and phylogenetic dimensions) provide insight into mechanisms that drive species assembly. Second, little is known about structuring mechanisms that operate at landscape scales (meso-scales) via effects on distributional patterns of species across a suite of sites that are potentially connected by dispersal (i.e. metacommunity structure). Most studies of fragmentation have focused on local species composition, as opposed to metacommunity structure, consequently ignoring effects of processes (e.g. environmental heterogeneity, landscape connectivity) that operate at larger scales. As such, I evaluated the effects of landscape structure on multiple dimensions of biodiversity and metacommunity structure of Neotropical bats —important seed dispersal and pollination agents— within a human-modified landscape.

The linkages between biodiversity or metacommunity structure and landscape variation were complex, but strong. The taxonomic dimension was not a reasonable surrogate for the functional or phylogenetic dimension. Rather, the effects of landscape structure on local variation in communities were dependent on the dimension of biodiversity and season (dry versus wet). Landscape effects emerged at meso-scales through effects on metacommunity structure. Similarly, landscape effects at meso-scales were dependent on the guild affiliation of species and season. These findings demonstrate that comprehensive understanding of the effects of human-modified landscapes on biotas requires a multifaceted framework that considers multiple dimensions of biodiversity and community structure at multiple scales.

Download

Share

COinS