Date of Award
9-1-2011
Document Type
Thesis
Degree Name
Master of Science (MS)
Department
Biology
First Advisor
David Clark
Abstract
The southeastern shrew (Sorex longirostris) is considered uncommon and a Species of Greatest Conservation Need in Arkansas, exhibiting an apparent gap in eastern Arkansas. Soricinae are exceptionally small and short-lived with limited dispersal, making them especially prone to speciation through long-term zoogeographic barriers to gene flow consistent with phylogeographic category 1. Therefore, I compiled Arkansas occurrences, evaluated persistence at previous capture sites in the state, surveyed additional counties, quantified microhabitat at my capture locations, and evaluated systematic status of S. longirostris east and west of the Mississippi River using mitochondrial DNA. Number of documented specimens in Arkansas has increased to 17 in 11 counties within the Ozark, Ouachita-Appalachian Forests Ecoregion, but trapping efforts within the distribution gap produced only specimens of other shrew species. Topologies from all phylogenetic analyses, genetic-distance using two methods, Mayr's (1969) coefficient of difference, and AMOVA concur, indicating greater divergence of western specimens from eastern specimens than is found for specimens of Sorex longirostris fisheri, from eastern S. l. longirostris. Comparison with subspecies divided by the Mississippi River within Blarina suggests similar divergence for S. longirostris. Possible factors affecting gene flow across the Mississippi Alluvial Plain and River are discussed and the Genetic and Ecological Species Concepts are considered. The degree of genetic differentiation between specimens east and west of the Mississippi River is of interest and an appropriate topic for further investigation. Recognition for this disjunct or effectively isolated and ecologically restricted clade of S. longirostris as a Species of Greatest Conservation Need in Arkansas is warranted. Microhabitat measured for all shrew captures and randomly selected unsuccessfully trapped (negative) sites across Arkansas were compared using principal component, factor, discriminant function, and canonical analyses. Blarina species captures were the only captures numerous enough for relevant statistical comparison between species. Blarina hylophaga is found in the presence of a developed canopy with thick leaf litter and Blarina carolinensis is found in the presence of moderately decayed course woody debris. As compared with negative sites, all species are associated with proximity to free water and a sparse understory, suggesting occupation of more mature forest ecosystems. Shrew foraging methods and prey types make them valuable components of an ecosystem and recommendations are for water-course protection and management that develops and maintains forest openings creating diversity of habitats and microhabitats.
Recommended Citation
Mikel, Garrett Adam, "Analyses of Sorex longirostris Distribution in Arkansas and Across the Mississippi River" (2011). Theses and Dissertations. 308.
https://research.ualr.edu/etd/308
