Castle Pines North, CO, United States
Castle Pines North, CO, United States

Time filter

Source Type

Devries P.,University of New Orleans | Walla T.,Mesa State College | Greeney H.,Yanayacu Biological Station and Center for Creative Studies | Chao A.,National Tsing Hua University | Ricotta C.,University of Rome La Sapienza
Diversity and Distributions | Year: 2010

Aim Differentiation of sites or communities is often measured by partitioning regional or gamma diversity into additive or multiplicative alpha and beta components. The beta component and the ratio of within-group to total diversity (alpha/gamma) are then used to infer the compositional differentiation or similarity of the sites. There is debate about the appropriate measures and partitioning formulas for this purpose. We test the main partitioning methods, using empirical and simulated data, to see if some of these methods lead to false conclusions, and we show how to resolve the problems that we uncover. Location South America, Ecuador, Orellana province, Rio Shiripuno. Methods We construct sets of real and simulated tropical butterfly communities that can be unambiguously ranked according to their degree of differentiation. We then test whether beta and similarity measures from the different partitioning approaches rank these datasets correctly. Results The ratio of within-group diversity to total diversity does not reflect compositional similarity, when the Gini-Simpson index or Shannon entropy are used to measure diversity. Additive beta diversity based on the Gini-Simpson index does not reflect the degree of differentiation between N sites or communities. Main conclusions The ratio of within-group to total diversity (alpha/gamma) should not be used to measure the compositional similarity of groups, if diversity is equated with Shannon entropy or the Gini-Simpson index. Conversion of these measures to effective number of species solves these problems. Additive Gini-Simpson beta diversity does not directly reflect the differentiation of N samples or communities. However, when properly transformed onto the unit interval so as to remove the dependence on alpha and N, additive and multiplicative beta measures yield identical normalized measures of relative similarity and differentiation. © 2009 Blackwell Publishing Ltd.

Rodriguez-Castaneda G.,Umeå University | Dyer L.A.,University of Nevada, Reno | Brehm G.,Friedrich - Schiller University of Jena | Connahs H.,University of North Dakota | And 2 more authors.
Ecology Letters | Year: 2010

Ecologists debate whether tropical insect diversity is better explained by higher plant diversity or by host plant species specialization. However, plant-herbivore studies are primarily based in lowland rainforests (RF) thus excluding topographical effects on biodiversity. We examined turnover in Eois (Geometridae) communities across elevation by studying elevational transects in Costa Rica and Ecuador. We found four distinct Eois communities existing across the elevational gradients. Herbivore diversity was highest in montane forests (MF), whereas host plant diversity was highest in lowland RF. This was correlated with higher specialization and species richness of Eois / host plant species we found in MF. Based on these relationships, Neotropical Eois richness was estimated to range from 313 (only lowland RF considered) to 2034 (considering variation with elevation). We conclude that tropical herbivore diversity and diet breadth covary significantly with elevation and urge the inclusion of montane ecosystems in host specialization and arthropod diversity estimates. © 2010 Blackwell Publishing Ltd/CNRS.

Dyer L.A.,University of Nevada, Reno | Walla T.R.,Mesa State College | Greeney H.F.,University of Nevada, Reno | Greeney H.F.,Yanayacu Biological Station and Center for Creative Studies | And 2 more authors.
Biotropica | Year: 2010

Multitrophic interactions play key roles in the origin and maintenance of species diversity, and the study of these interactions has contributed to important theoretical advances in ecology and evolutionary biology. Nevertheless, most biodiversity inventories focus on static species lists, and prominent theories of diversity still ignore trophic interactions. The lack of a simple interaction metric that is analogous to species richness is one reason why diversity of interactions is not examined as a response or predictor variable in diversity studies. Using plant-herbivore-enemy trophic chains as an example, we develop a simple metric of diversity in which richness, diversity indices (e.g., Simpson's 1/D), and rarefaction diversity are calculated with links as the basic unit rather than species. Interactions include all two-link (herbivore-plant and enemy-herbivore) and three-link (enemy-herbivore-plant) chains found in a study unit. This metric is different from other indices, such as traditional diversity measures, connectivity and interaction diversity in food-web studies, and the diversity of interaction index in behavioral studies, and it is easier to compute. Using this approach to studying diversity provides novel insight into debates about neutrality and correlations between diversity, stability, productivity, and ecosystem services. © 2010 The Author(s). Journal compilation © 2010 by The Association for Tropical Biology and Conservation.

Watts S.M.,Santa Clara University | Dodson C.D.,Mesa State College | Reichman O.J.,University of California at Santa Barbara
PLoS ONE | Year: 2011

Background: There is conclusive evidence that there are fitness costs of plant defense and that herbivores can drive selection for defense. However, most work has focused on above-ground interactions, even though belowground herbivory may have greater impacts on individual plants than above-ground herbivory. Given the role of belowground plant structures in resource acquisition and storage, research on belowground herbivores has much to contribute to theories on the evolution of plant defense. Pocket gophers (Geomyidae) provide an excellent opportunity to study root herbivory. These subterranean rodents spend their entire lives belowground and specialize on consuming belowground plant parts. Methodology and Principal Findings: We compared the root defenses of native forbs from mainland populations (with a history of gopher herbivory) to island populations (free from gophers for up to 500,000 years). Defense includes both resistance against herbivores and tolerance of herbivore damage. We used three approaches to compare these traits in island and mainland populations of two native California forbs: 1) Eschscholzia californica populations were assayed to compare alkaloid deterrents, 2) captive gophers were used to test the palatability of E. californica roots and 3) simulated root herbivory assessed tolerance to root damage in Deinandra fasciculata and E. californica. Mainland forms of E. californica contained 2.5 times greater concentration of alkaloids and were less palatable to gophers than island forms. Mainland forms of D. fasciculata and, to a lesser extent, E. californica were also more tolerant of root damage than island conspecifics. Interestingly, undamaged island individuals of D. fasciculata produced significantly more fruit than either damaged or undamaged mainland individuals. Conclusions and Significance: These results suggest that mainland plants are effective at deterring and tolerating pocket gopher herbivory. Results also suggest that both forms of defense are costly to fitness and thus reduced in the absence of the putative target herbivore. © 2011 Watts et al.

Richards L.A.,University of Nevada, Reno | Dyer L.A.,University of Nevada, Reno | Smilanich A.M.,University of Nevada, Reno | Dodson C.D.,Mesa State College
Journal of Chemical Ecology | Year: 2010

Plants use a diverse mix of defenses against herbivores, including multiple secondary metabolites, which often affect herbivores synergistically. Chemical defenses also can affect natural enemies of herbivores via limiting herbivore populations or by affecting herbivore resistance to parasitoids. In this study, we performed feeding experiments to examine the synergistic effects of imides and amides (hereafter "amides") from Piper cenocladum and P. imperiale on specialist (Eois nympha, Geometridae) and generalist (Spodoptera frugiperda, Noctuidae) lepidopteran larvae. Each Piper species has three unique amides, and in each experiment, larvae were fed diets containing different concentrations of single amides or combinations of the three. The amides from P. imperiale had negative synergistic effects on generalist survival and specialist pupal mass, but had no effect on specialist survival. Piper cenocladum amides also acted synergistically to increase mortality caused by parasitoids, and the direct negative effects of mixtures on parasitoid resistance and pupal mass were stronger than indirect effects via changes in growth rate and approximate digestibility. Our results are consistent with plant defense theory that predicts different effects of plant chemistry on generalist versus adapted specialist herbivores. The toxicity of Piper amide mixtures to generalist herbivores are standard bottom-up effects, while specialists experienced the top-down mediated effect of mixtures causing reduced parasitoid resistance and associated decreases in pupal mass. © 2010 Springer Science+Business Media, LLC.

Frey M.,Bucknell University | Collins D.,Mesa State College | Gerlach K.,ITT Corporation
Journal of Physics A: Mathematical and Theoretical | Year: 2011

For the quantum depolarizing channel with any finite dimension, we compare three schemes for channel identification: unentangled probes, probes maximally entangled with an external ancilla, and maximally entangled probe pairs. This comparison includes cases where the ancilla is itself depolarizing and where the probe is circulated back through the channel before measurement. Compared on the basis of (quantum Fisher) information gained per channel use, we find broadly that entanglement with an ancilla dominates the other two schemes, but only if entanglement is cheap relative to the cost per channel use and only if the external ancilla is well shielded from depolarization. We arrive at these results by a relatively simple analytical means. A separate, more complicated analysis for partially entangled probes shows for the qudit depolarizing channel that any amount of probe entanglement is advantageous and that the greatest advantage comes with maximal entanglement. © 2011 IOP Publishing Ltd.

Tufto J.,Norwegian University of Science and Technology | Lande R.,Imperial College London | Ringsby T.-H.,Norwegian University of Science and Technology | Engen S.,Norwegian University of Science and Technology | And 3 more authors.
Journal of Animal Ecology | Year: 2012

1.We develop a Bayesian method for analysing mark-recapture data in continuous habitat using a model in which individuals movement paths are Brownian motions, life spans are exponentially distributed and capture events occur at given instants in time if individuals are within a certain attractive distance of the traps. 2.The joint posterior distribution of the dispersal rate, longevity, trap attraction distances and a number of latent variables representing the unobserved movement paths and time of death of all individuals is computed using Gibbs sampling. 3.An estimate of absolute local population density is obtained simply by dividing the Poisson counts of individuals captured at given points in time by the estimated total attraction area of all traps. Our approach for estimating population density in continuous habitat avoids the need to define an arbitrary effective trapping area that characterized previous mark-recapture methods in continuous habitat. 4.We applied our method to estimate spatial demography parameters in nine species of neotropical butterflies. Path analysis of interspecific variation in demographic parameters and mean wing length revealed a simple network of strong causation. Larger wing length increases dispersal rate, which in turn increases trap attraction distance. However, higher dispersal rate also decreases longevity, thus explaining the surprising observation of a negative correlation between wing length and longevity. © 2012 The Authors. Journal of Animal Ecology © 2012 British Ecological Society.

Snow A.F.,University of Houston | Bozeman J.M.,Mesa State College
Critical Care Nursing Quarterly | Year: 2010

Emergency department registered nurses treat victims of violent acts because the emergency department is usually the initial area of treatment. The nursing care of gunshot wound victims includes not only physical and immediate needs but also forensic and anticipated needs. The purpose of this article is to describe 3 types of gunshot wound forensic evidence and the nurses' roles when treating victims of gunshot wounds. Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins.

Shiekh A.Y.,Mesa State College
Canadian Journal of Physics | Year: 2011

It may be possible to use operator regularization with Feynman diagrams, which would greatly simplify its use, as it has so far been limited to the more complicated Schwinger approach. Operator regularization, unlike z-function regularization, is not limited to one-loop order and preserves supersymmetry, unlike dimensional regularization. In practice, the use of operator regularization in the context of Feynman diagrams is found not to complicate the calculation.

Collins D.,Mesa State College
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2010

A general framework for regarding oracle-assisted quantum algorithms as tools for discriminating among unitary transformations is described. This framework is applied to the Deutsch-Jozsa problem and all possible quantum algorithms which solve the problem with certainty using oracle unitaries in a particular form are derived. It is also used to show that any quantum algorithm that solves the Deutsch-Jozsa problem starting with a quantum system in a particular class of initial, thermal equilibrium-based states of the type encountered in solution-state NMR can only succeed with greater probability than a classical algorithm when the problem size n exceeds 105. © 2010 The American Physical Society.

Loading Mesa State College collaborators
Loading Mesa State College collaborators