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Nematodes in the Wild: Community Ecology and the Search for Cryptic Species Within the Family Criconematidae
Terrestrial nematodes are of interest for their role as bioindicators, because they serve as an indirect measure of soil processes and functions in relation to ecological disturbance. However, the environmental factors underlying community assemblages of plant parasitic nematodes in the Family Criconematidae are relatively unknown. Limited knowledge of plant parasitic nematode diversity restricts our understanding of anthropogenic disturbance effects above ground on the recolonization of nematodes below ground. Therefore, additional biological and ecological information on plant parasites at the level of family, genus, and species is needed. This research examined Criconematid species diversity within Great Smoky Mountains National Park. Each of the 19 All Taxa Biodiversity Inventory sites with documented historical disturbance and plant community composition, was surveyed and sampled for soil characteristics, along with other abiotic environmental variables. Nematodes were extracted, measured, photographed, and PCR was-amplified and sequenced at the mitochondrial cytochrome oxidase subunit 1 (COI) gene. A total of 245 gene sequences were analyzed using phylogenetic tree building methods to identify haplotype groups. Environmental characteristics examined included 28 soil characteristics, annual average minimum and maximum temperature, annual average precipitation, elevation, and constancy values for 362 plant species. Community assemblages and population structure were analyzed to examine relationships of nematodes with environmental features. Results indicated that disturbance did not correspond with species richness. However, soil characteristics and disturbance type were the strongest predictive variables of Criconematid community composition. A second study was conducted using a similar approach focusing on phyloecology of Mesocriconema xenoplax sensu lato. The goal was to examine the ecology of haplotype groups within this putative cryptic species. Four species delimitation analysis supported seven haplotype groups. Population structure analyses identified land use and ecoregion as the strongest predictive variables to describe M. xenoplax range and sequence variability. Knowledge of these associations further supports M. xenoplax as a cryptic species and provides information of interest for plant breeding and pest management. Collectively, results of these studies identified associations between plant parasitic nematodes and their environment, further expanding our understanding of nematode biodiversity in diverse natural and agricultural ecosystems.
Matczyszyn, Julianne N, "Nematodes in the Wild: Community Ecology and the Search for Cryptic Species Within the Family Criconematidae" (2019). ETD collection for University of Nebraska - Lincoln. AAI22616431.