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Madison, IN, United States

Nunziata S.O.,Eastern Kentucky University | Nunziata S.O.,Savannah River Ecology Laboratory | Lannoo M.J.,Indiana University School of Medicine - Terre Haute | Robb J.R.,Big Oaks National Wildlife Refuge | And 3 more authors.
Journal of Herpetology | Year: 2013

Crawfish Frogs (Lithobates areolatus) are a North American ranid, considered near threatened globally with populations in decline throughout their range. We studied populations of Crawfish Frogs on local and regional scales at their northeastern range limit to (1) assess the level of genetic diversity within populations, (2) estimate fine-scale genetic structure, and (3) estimate genetic differentiation between populations at the regional level. We used 10 microsatellite loci to genotype frogs collected from three regional sites in Indiana separated by 50-172 km and at one of these sites within a network of three breeding ponds <1 km apart. Heterozygosity estimates revealed high levels of diversity within these populations (mean HO: 0.54-0.67 per site), which is encouraging for future management. The degree of population subdivision was low at the regional level (FST = 0.071 for sites within 172 km). Genetic differentiation was related to geographic distance between sampling sites, as predicted by an isolation-by-distance model. We observed no genetic differentiation between individuals sampled from ponds approximately 250 m apart and slight divergence of individuals from a pond approximately 750 m away. This suggests ponds within 1 km form a genetically distinct single breeding unit composed of multiple subpopulations. Finally, we observed high genetic differentiation between southwest and southeast Indiana sites indicating historical (rather than recent) isolation of these sites. These data will be applied to a regional management plan in an attempt to recover Crawfish Frogs along the northeastern extreme of their range. © 2013 Society for the Study of Amphibians and Reptiles. Source


Emery S.M.,University of Louisville | Luke Flory S.,University of Florida | Clay K.,Indiana University Bloomington | Robb J.R.,Big Oaks National Wildlife Refuge | Winters B.,Big Oaks National Wildlife Refuge
Forest Ecology and Management | Year: 2013

Management of invasive species in forests often includes combinations of prescribed fire and herbicides. However for most efficient management, evaluations of these tools should include whole-population responses of targeted plants. In this study, we evaluated how the timing and frequency of prescribed fire and herbicide application affected population growth of the invasive annual grass Microstegium vimineum (stiltgrass) using periodic matrix population models. We conducted an experiment in M. vimineum-invaded deciduous forests in Indiana, USA to compare effects of spring and fall prescribed fires combined with pre- or post-emergent herbicide on M. vimineum populations and to build matrix population models predicting long-term population responses to these management treatments across multiple life-history stages. We found that spring fires were effective at reducing population growth rates during the year of treatment but there was no effect of burning on M. vimineum populations the following year. Similarly, fall prescribed fires were effective at reducing seed production, as well as numbers of seedlings and adults following fires, but had no long-term effect on population growth rates. Post-emergent herbicide alone was the only treatment that reduced M. vimineum population growth beyond 1. year. Seedbank survival had the highest life-stage elasticity across all treatments, indicating that novel management methods specifically designed to exhaust seedbanks for three or more years may be needed to prevent M. vimineum population resurgence after cessation of treatments. © 2013 Elsevier B.V. Source


Williams P.J.,Big Oaks National Wildlife Refuge | Williams P.J.,Colorado State University | Robb J.R.,Big Oaks National Wildlife Refuge | Karns D.R.,Hanover College
Journal of Herpetology | Year: 2012

Our objective was to examine breeding dispersal, burrow-use characteristics, and burrow habitat selection by Crawfish Frogs (Lithobates areolatus) in two distinct vegetation types (open grasslands and a mosaic of forest and transitioning grasslands) in southeastern Indiana, from March to August 2009 and 2010. We captured 14 frogs at their breeding ponds and tracked them to their burrows using radio telemetry. Once we identified their burrows, we compared habitat metrics at the burrows to random locations. We used an information-theoretic model selection approach to approximate the parsimony of logistic regression models comparing the habitat features of burrows to random, available sites. Frogs dispersed a straight-line average distance of 215 m and used an average of four burrows. They generally did not change burrows after June. Our top model included covariates for the number of burrows, canopy cover, and a site covariate. Our results suggested that habitat selection by Crawfish Frogs occurred hierarchically; in mixed grassland/forest habitats, they first selected areas with low canopy cover, and then selected areas with many available burrows. To manage habitat for Crawfish Frogs, we recommend preventing woody encroachment and reducing canopy cover in grassland areas occupied by Crawfish Frogs. Additionally, areas with a large number of burrows appear to provide the most suitable Crawfish Frog habitat. © 2012 Society for the Study of Amphibians and Reptiles. Source

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