Treesearch

Different analytical techniques used on the same data set may lead to different conclusions about the existence and strength of genetic structure. Therefore, reliable interpretation of the results from different methods depends on the efficacy and reliability of different statistical methods. In this paper, we evaluated the performance of multiple analytical methods to detect the presence of a linear barrier dividing populations. We were specifically interested in determining if simulation conditions, such as dispersal ability and genetic equilibrium, affect the power of different analytica...

Restoration projects can have varying goals, depending on the specific focus, rationale, and aims for restoration. When restoration projects use project-specific goals to define activities and gauge success without considering broader ecological context, determination of project implications and success can be confounding. We used case studies from the Middle Rio Grande (MRG), southwest USA, to demonstrate how restoration outcomes can rank inconsistently when narrowly-based goals are used. Resource managers have chosen MRG for restoration due to impacts to the natural flood regime, reduced...

Lizards from the Sceloporus undulatus complex have been the subject of many studies on lizard ecology (Hager 2001; Rosenblum 2006; Rosenblum et al. 2007), behavior (Hein and Whitaker 1997; Robertson and Rosenblum 2009), and reproduction (Vinegar 1975; Robertson and Rosenblum 2010). However, genetic data (Leache and Reeder 2002) support reallocation of the subspecies of the S. undulatus complex (e.g., S. undulatus consobrinus, S. u. tristichus, and S. u. cowlesi) as distinct species (e.g., S. consobrinus. S. tristichus, and S. cowlesi). One of these species, S. cowlesi, occupies a variety...

Due to global warming spruce-fir forest and associated vegetation may experience elevational displacement and altered species composition at the timberline-treeline ecotone. These forests and their component species are predicted to migrate upslope and thus landscape features such as timberline and treeline may move upslope as well. Prior to this study, baseline data on forest stand structure, plant species distributions, soil temperatures, and soil carbon pools did not exist across these habitats in the La Sal Mountains. This study will provide data that allows land managers, researchers,...

Loss of genetic variation through genetic drift can reduce population viability. However, relatively little is known about loss of variation caused by the combination of fluctuating population size and variance in reproductive success in age structured populations. We built an individual-based computer simulation model to examine how actual culling and hunting strategies influence the effective population size (Ne) and allelic diversity in Yellowstone bison over 200 years ( 28 generations). The Ne for simulated populations ranged from 746 in stable populations of size 2000 up to 1165 in...

Conservation biology research exhibits a striking but unhelpful dichotomy. Analyses of species decline, extinction risk, and threat mitigation typically encompass broad taxonomic and spatial scales. By contrast, most studies of recovery lack generality, pertaining to specific species, populations, or locales. Narrowly focused analyses offer a weak empirical basis for identifying generic recovery correlates across species, particularly in cases where recovery is not effected by an abatement of threats. We present a research framework for multi-species metaanalyses to identify early-warning...

Throughout much of the interior western United States, Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis) is a keystone species, serving an important ecological role in sagebrush steppe and Great Basin sagebrush vegetation types (Lysne 2005, Lambrecht et al. 2007). Over the past century, these ecosystems have been degraded by fire, invasive species, and destructive land use including livestock-inflicted grazing pressure. Because of overgrazing and the low resilience of these ecosystems, invasive species, such as cheatgrass (Bromus tectorum), are able to establish, increasing...

The developmental response of insects to temperature is important in understanding the ecology of insect life histories. Temperature-dependent phenology models permit examination of the impacts of temperature on the geographical distributions, population dynamics and management of insects. The measurement of insect developmental, survival and reproductive responses to temperature poses practical challenges because of their modality, variability among individuals and high mortality near the lower and upper threshold temperatures. We address this challenge with an integrated approach to the...

The health and growth of forests depends upon soil nutrients. Calcium (Ca) is a cation - positive ion - used by plants to build cell walls (Marschner 1986). It is also involved in root and leaf development and the activation of plant enzymes (Potash and Phosphate Institute 1995). Soils that develop in areas with low rainfall tend to have greater Ca supplies than soils that form in humid regions of the country, and within any one soil profile, more Ca typically is found in lower parts of the soil profile than at the surface (Pritchett and Fisher 1987). Acidic deposition leads to soil Ca...

Two prairie-clovers, Dalea ornata (Douglas ex Hook.) Eaton & J. Wright and Dalea searlsiae (A. Gray) Barneby, are perennial forbs found sporadically in the U.S. Intermountain West. Their seed is desirable for use in rangeland restoration. We experimentally characterized the breeding biologies of D. ornata and D. searlsiae in a common garden, surveyed their pollinator guilds, and sampled their seed predators. The 2 Dalea species, being primarily xenogamous, have comparable pollination requirements. For flowers manually pollinated with outcross pollen, an average of 42% of D. ornata flowers...