The full text of this item is not available at this time because the student has placed this item under an embargo for a period of time. The Libraries are not authorized to provide a copy of this work during the embargo period, even for Texas A&M users with NetID.
Effects of Heterogeneity on Phenology and Dispersal of Agents in Two Model Systems: A Landscape Ecology Approach
Abstract
Landscapes vary across space and through time, impacting many biological processes. Landscape ecology provides an investigative framework through which landscapes themselves can be characterized, and complex organismal responses to their environments can be studied. Many agricultural pest and pathogen systems involve agent development and movement, both of which depend on environmental inputs and therefore landscape configurations. Environmental dependence of these processes’ outcomes is well documented from laboratory studies: disease occurrence varies when controlled conditions are manipulated, and arthropod pests or vectors develop at varying rates depending on changing inputs. However, environmental dependence of the processes themselves in the field is not well understood, due to several limitations: experimental tractability, resolution of data, and applicability of existing models. In this research, a unified experimental and simulation modeling approach was taken to study processes’ dependence on the configuration and dynamics of landscapes. Two model systems were chosen: a soilborne fungal pathogen (Fusarium oxysporum f. sp. vasinfectum) whose dispersal through heterogeneous landscapes is critical to its spatial epidemiology, and an order (Diptera) of arthropods including industrially and forensically relevant species known to behaviorally thermoregulate in variable environments. In both systems, movement through variable space was studied as a core process affecting epidemiology and phenology. Fungal propagules were experimentally investigated for their ability to move through soils, and results support movement being dependent on soil type. Dipteran larvae were experimentally observed for the purpose of relating development rates to complex environmental variation that was generated in the laboratory, and results showed that environmental configuration affects not only the distribution of development rates, but also the process through which larvae interact with variable environments in the course of development. Finally, processes of development and thermoregulatory behavior were extensively simulated to study the consequences of hypothetical mechanisms at scales and resolutions that are beyond the reach of current experimental feasibility. Through simulation, I complement field and laboratory findings with detailed representations of hypothetical landscape ecological processes, describe roles of these processes in shaping field-scale variation, and provide improved predictive understanding of phenology and dispersal for broad application to vector-borne disease epidemiology, forensic entomology, and pest/disease management.
Subject
Landscape ecologyentomology
forensic entomology
mycology
thermal ecology
edaphology
plant pathology
fungal pathogen
epidemiology
simulation
Citation
Hayter, Jensen Todd (2022). Effects of Heterogeneity on Phenology and Dispersal of Agents in Two Model Systems: A Landscape Ecology Approach. Doctoral dissertation, Texas A&M University. Available electronically from https : / /hdl .handle .net /1969 .1 /198116.