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Full-Text Articles in Life Sciences

Invasion Is Contingent On Species Assemblage And Invasive Species Identity Inexperimental Rehabilitation Plots, A. Joshua Leffler, Eamonn D. Leonard, Jeremy J. James, Thomas A. Monaco Nov 2014

Invasion Is Contingent On Species Assemblage And Invasive Species Identity Inexperimental Rehabilitation Plots, A. Joshua Leffler, Eamonn D. Leonard, Jeremy J. James, Thomas A. Monaco

Natural Resource Management Faculty Publications

Ecological studies often suggest that diverse communities are most resistant to invasion by exotic plants, but relatively few local species may be available to a rehabilitation practitioner. We examine the ability of monocultures and diverse assemblages to resist invasion by an exotic annual grass (cheatgrass) and an exotic biennial forb (dyer’s woad) in experimental rehabilitation plots. We constructed seven assemblages that included three monocultures of grass, forb, or shrub; three four-species mixtures of grasses, forbs, or shrubs; and a three-species mixture of one species from each growth form in an experimental field setting to test resistance to invasion. Assemblages were …


Ad Hoc Smoothing Parameter Performance In Kernel Estimates Of Gps-Derived Home Ranges, Krysten L. Schuler, Greg M. Schroeder, Jonathan A. Jenks, John G. Kie Oct 2014

Ad Hoc Smoothing Parameter Performance In Kernel Estimates Of Gps-Derived Home Ranges, Krysten L. Schuler, Greg M. Schroeder, Jonathan A. Jenks, John G. Kie

Natural Resource Management Faculty Publications

Accuracy of home-range estimates in animals is influenced by a variety of factors, such as method of analysis and number of locations, but animal space use is less often considered and frequently over-generalized through simulations. Our objective was to assess effect of an ad hoc (h_ad hoc)smoothing parameter in kernel analysis from two species that were predicted to have different patterns of utilization distributions across a range of sample sizes. We evaluated variation in home-range estimates with location data collected from GPS collars on two species: mule deer Odocoileus hemionus and coyotes Canis latrans. We calculated home ranges using …


Re-Evaluating Neonatal-Age Models For Ungulates: Does Model Choice Affect Survival Estimates?, Troy W. Grovenburg, Kevin L. Monteith, Christopher N. Jacques, Robert W. Klaver, Christopher S. Deperno, Sophie L. Gilbert, Todd J. Brinkman, Kyle B. Monteith, Joshua B. Smith, Vernon C. Bleich, Christopher C. Swanson, Jonathan A. Jenks Sep 2014

Re-Evaluating Neonatal-Age Models For Ungulates: Does Model Choice Affect Survival Estimates?, Troy W. Grovenburg, Kevin L. Monteith, Christopher N. Jacques, Robert W. Klaver, Christopher S. Deperno, Sophie L. Gilbert, Todd J. Brinkman, Kyle B. Monteith, Joshua B. Smith, Vernon C. Bleich, Christopher C. Swanson, Jonathan A. Jenks

Natural Resource Management Faculty Publications

New-hoof growth is regarded as the most reliable metric for predicting age of newborn ungulates, but variation in estimated age among hoof-growth equations that have been developed may affect estimates of survival in staggered-entry models. We used known-age newborns to evaluate variation in age estimates among existing hoof-growth equations and to determine the consequences of that variation on survival estimates. During 2001–2009, we captured and radiocollared 174 newborn (#24-hrs old) ungulates: 76 white-tailed deer (Odocoileus virginianus) in Minnesota and South Dakota, 61 mule deer (O. hemionus) in California, and 37 pronghorn (Antilocapra americana) in South Dakota. Estimated age of known-age …


A New Perspective On Trait Differences Between Native And Invasive Exotic Plants, A. Joshua Leffler, Jeremy J. James, Thomas A. Monaco, Roger L. Sheley Feb 2014

A New Perspective On Trait Differences Between Native And Invasive Exotic Plants, A. Joshua Leffler, Jeremy J. James, Thomas A. Monaco, Roger L. Sheley

Natural Resource Management Faculty Publications

Functional differences between native and exotic species potentially constitute one factor responsible for plant invasion. Differences in trait values between native and exotic invasive species, however, should not be considered fixed and may depend on the context of the comparison. Furthermore, the magnitude of difference between native and exotic species necessary to trigger invasion is unknown. We propose a criterion that differences in trait values between a native and exotic invasive species must be greater than differences between co-occurring natives for this difference to be ecologically meaningful and a contributing factor to plant invasion. We used a meta-analysis to quantify …


Disease And Predation: Sorting Out Causes Of A Bighorn Sheep (Ovis Canadensis) Decline, Joshua B. Smith, Jonathan A. Jenks, Troy Grovenburg, Robert W. Klaver Feb 2014

Disease And Predation: Sorting Out Causes Of A Bighorn Sheep (Ovis Canadensis) Decline, Joshua B. Smith, Jonathan A. Jenks, Troy Grovenburg, Robert W. Klaver

Natural Resource Management Faculty Publications

Estimating survival and documenting causes and timing of mortality events in neonate bighorn sheep (Ovis canadensis) improves understanding of population ecology and factors influencing recruitment. During 2010–2012, we captured and radiocollared 74 neonates in the Black Hills, South Dakota, of which 95% (70) died before 52 weeks of age. Pneumonia (36%) was the leading cause of mortality followed by predation (30%). We used known fate analysis in Program MARK to estimate weekly survival rates and investigate the influence of intrinsic variables on 52-week survival. Model {S1 wk, 2–8 wks, .8 wks} had the lowest AICc (Akaike’s Information Criterion corrected for …


Environmental Variables Measured At Multiple Spatial Scales Exert Uneven Influence On Fish Assemblages Of Floodplain Lakes, Daniel J. Dembkowski, L.E. Miranda Jan 2014

Environmental Variables Measured At Multiple Spatial Scales Exert Uneven Influence On Fish Assemblages Of Floodplain Lakes, Daniel J. Dembkowski, L.E. Miranda

Natural Resource Management Faculty Publications

We examined the interaction between environmental variables measured at three different scales (i.e., landscape, lake, and in-lake) and fish assemblage descriptors across a range of over 50 floodplain lakes in the Mississippi Alluvial Valley of Mississippi and Arkansas. Our goal was to identify important local- and landscape-level determinants of fish assemblage structure. Relationships between fish assemblage structure and variables measured at broader scales (i.e., landscape-level and lake-level) were hypothesized to be stronger than relationships with variables measured at finer scales (i.e., in-lake variables). Results suggest that fish assemblage structure in floodplain lakes was influenced by variables operating on three different …


Phenology Of Annulus Formation In Walleye And Smallmouth Bass Otoliths, Brianna J. Graff, Daniel J. Dembkowski, Melissa R. Wuellner Jan 2014

Phenology Of Annulus Formation In Walleye And Smallmouth Bass Otoliths, Brianna J. Graff, Daniel J. Dembkowski, Melissa R. Wuellner

Natural Resource Management Faculty Publications

Walleye Sander vitreus and smallmouth bass Micropterus dolomieu were sampled monthly (May-October) from Lake Sharpe, South Dakota during 2006 and 2007 to estimate the timing of otolith annulus formation and to evaluate the influence of fish age, sex, and sample location (walleye only) on the timing and detection of annulus formation. Timing of annulus formation was evaluated using marginal increment analysis. Walleye samples were stratified by age, sex, and sample location (i.e., upper and lower Lake Sharpe) and smallmouth bass samples were stratified by age and sex. Monthly mean marginal increment measurements for both species generally increased from May to …


Gape:Body Size Relationship For Smallmouth Bass, Craig L. Schake, Daniel J. Dembkowski, Melissa R. Wuellner Jan 2014

Gape:Body Size Relationship For Smallmouth Bass, Craig L. Schake, Daniel J. Dembkowski, Melissa R. Wuellner

Natural Resource Management Faculty Publications

The types and sizes of prey fishes consumed by predatory fish often are limited by gape dimensions of the predator (Slaughter and Jacobson 2008). In general, the size of prey consumed is positively related to predator size when prey are available across a wide range of sizes (Werner and Hall 1974). Opportunistic predators with large gape dimensions, such as smallmouth bass (Micropterus dolomieu), may consume a wide range of prey types and sizes, thereby exerting top-down influences on prey population dynamics and potentially restructuring aquatic communities (e.g., Werner and Hall 1974, Jackson 2002). Although feeding ecology of smallmouth bass varies …


Bed-Site Selection By Neonatal White-Tailed Deer In Central North Dakota, Brian A. Schaffer, Jonathan A. Jenks, Troy Grovenburg, William F. Jensen Jan 2014

Bed-Site Selection By Neonatal White-Tailed Deer In Central North Dakota, Brian A. Schaffer, Jonathan A. Jenks, Troy Grovenburg, William F. Jensen

Natural Resource Management Faculty Publications

Understanding bed-site selection and vegetation characteristics provides valuable information for population management (Verme 1977, Huegel et al. 1985a, Nelson and Woolf 1987). Predation and other natural-caused mortalities of white-tailed deer (Odocoileus virginianus) neonates are most likely to occur within the first 60 days of life; a time period when selected habitat characteristics are vital to survival (Verme 1977, Huegel et al. 1985a, Nelson and Woolf 1987, Grovenburg et al. 2010). Prior to the study of Grovenburg et al. (2010), limited research had been completed on bed-site selection of neonatal white-tailed deer in the grasslands of the Northern Great Plains. In …


Wetland Issues Affecting Waterfowl Conservation In North America, Heath M. Hagy, Scott C. Yaich, John W. Simpson, Eduardo Carrera, David A. Haukos, W.Carter Johnson, Charles R. Loesch, Fritz A. Reid, Scott E. Stephens, Ralph W. Tiner, Brett A. Werner, Greg S. Yarris Jan 2014

Wetland Issues Affecting Waterfowl Conservation In North America, Heath M. Hagy, Scott C. Yaich, John W. Simpson, Eduardo Carrera, David A. Haukos, W.Carter Johnson, Charles R. Loesch, Fritz A. Reid, Scott E. Stephens, Ralph W. Tiner, Brett A. Werner, Greg S. Yarris

Natural Resource Management Faculty Publications

This paper summarises discussions by invited speakers during a special session at the 6th North American Duck Symposium on wetland issues that affect waterfowl, highlighting current ecosystem challenges and opportunities for the conservation of waterfowl in North America. Climate change, invasive species, U.S. agricultural policy (which can encourage wetland drainage and the expansion of row-crop agriculture into grasslands), cost and competition for water rights, and wetland management for non-waterfowl species were all considered to pose significant threats to waterfowl populations in the near future. Waterfowl populations were found to be faced with significant threats in several regions, including: the Central …