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A Synopsis Of The Ferns And Fern Allies Of Nebraska, With Maps Of Their Distribution, Steven B. Rolfsmeier, Robert B. Kaul, David M. Sutherland

School of Biological Sciences: Faculty Publications

An annotated list and county-by-county distribution maps are presented for the 32 species of ferns and fern allies native to Nebraska, based upon field and herbarium studies and critical evaluation of the literature. Native to the state are Isoetes melanopoda, Selaginella rupestris, five species of Equisetum, and 25 species in 18 genera of ferns. Three native species are here verified for the first time, based upon recent collections: Matteuccia struthiopteris var. pensylvanica, Ophioglossum engelmannii, and Pellaeaglabella ssp. glabella. Isoetes melanopoda was rediscovered in 2000, the first record since 1941. Rejected are published reports …

Predicting Risk To Biodiversity As A Function Of Aquifer Pressure In Gab Mound Springs, A. J. Tyre, Brigitte Tenhumberg, H.P. Possingham

School of Biological Sciences: Faculty Publications

Plants and aquatic invertebrates endemic to mound springs of the Great Artesian Basin (GAB) of Australia are of national biodiversity significance. Springs occur in groups, and current survey data suggest that local extinction and recolonisation within a group does occur naturally. Mound spring fauna are therefore good examples of true metapopulations, and any study of the environmental impacts on these systems must take this into account. Use of GAB water leads to drawdown of the pressure in the aquifer. This can potentially impact mound spring flora and fauna in two ways. First, as pressure decreases, so does flow from spring …

The Effect Of Resource Aggregation At Different Scales: Optimal Foraging Behavior Of Cotesia Rubecula, Brigitte Tenhumberg, Michael A. Keller, Andrew J. Tyre, Hugh P. Possingham

School of Biological Sciences: Faculty Publications

Resources can be aggregated both within and between patches. In this article, we examine how aggregation at these different scales influences the behavior and performance of foragers. We developed an optimal foraging model of the foraging behavior of the parasitoid wasp Cotesia rubecula parasitizing the larvae of the cabbage butterfly Pieris rapae. The optimal behavior was found using stochastic dynamic programming. The most interesting and novel result is that the effect of resource aggregation within and between patches depends on the degree of aggregation both within and between patches as well as on the local host density in the occupied …

Diversity And Productivity In A Long-Term Grassland Experiment, David Tilman, Peter B. Reich, Johannes Knops, David A. Wedin, Troy Mielke, Clarence Lehman

School of Biological Sciences: Faculty Publications

Plant diversity and niche complementarity had progressively stronger effects on ecosystem functioning during a 7-year experiment, with 16-species plots attaining 2.7 times greater biomass than monocultures. Diversity effects were neither transients nor explained solely by a few productive or unviable species. Rather, many higher-diversity plots outperformed the best monoculture. These results help resolve debate over biodiversity and ecosystem functioning, show effects at higher than expected diversity levels, and demonstrate, for these ecosystems, that even the best-chosen monocultures cannot achieve greater productivity or carbon stores than higher-diversity sites.

Includes Supplementary Material.

Variation In Response To Artificial Selection For Light Sensitivity In Guppies (Poecilia Reticulate), John A. Endler, Alexandra Basolo, Stan Glowacki, Julianne Zerr

School of Biological Sciences: Faculty Publications

We performed artificial selection on the visual system in guppies (Poecilia reticulate), using the optomotor reaction threshold as the selection criterion. Two lines were selected for increased sensitivity to blue light, two were selected for increased sensitivity to red light, and two were unselected controls. There was significant response to selection in all four selected lines and significant heritability for sensitivity. An examination of the spectral sensitivity function showed that the form of the response differed between the red and blue lines and among the red lines. Such divergence is likely because there are many different mechanisms allowing …

Sharpening Low-Energy, Standard-Model Tests Via Correlation Coefficients In Neutron Β Decay, S. Gardner, Chi Zhang

School of Biological Sciences: Faculty Publications

The correlation coefficients a, A, and B in neutron β decay are proportional to the ratio of the axial-vector- to-vector weak coupling constants, g_A/g_V , to leading recoil order. With the advent of the next generation of neutron-decay experiments, the recoil-order corrections to these expressions become experimentally accessible, admitting a plurality of standard model (SM) tests. The measurement of both a and A, e.g., allows one to test the conserved-vector-current (CVC) hypothesis and to search for second-class currents (SCC) independently. The anticipated precision of these measurements suggests that the bounds on CVC violation and …

Extension Of Life-Span By Loss Of Chico, A Drosophila Insulin Receptor Substrate Protein, David Clancy, David Gems, Lawrence G. Harshman, Sean Oldham, Hugo Stocker, Ernest Hafen, Sally Leevers, Linda Partridge

School of Biological Sciences: Faculty Publications

The Drosophila melanogaster gene chico encodes an insulin receptor substrate that functions in an insulin/insulin-like growth factor (IGF) signaling pathway. In the nematode Caenorhabditis elegans, insulin/IGF signaling regulates adult longevity. We found that mutation of chico extends fruit fl y median life-span by up to 48% in homozygotes and 36% in heterozygotes. Extension of life-span was not a result of impaired oogenesis in chico females, nor was it consistently correlated with increased stress resistance. The dwarf phenotype of chico homozygotes was also unnecessary for extension of life-span. The role of insulin/IGF signaling in regulating animal aging is therefore evolutionarily …

Molecular Phylogenetics Of Western North American Frogs Of The Rana Boylii Species Group, J. Robert Macey, Jared L. Strasburg, Jennifer A. Brisson, Vance T. Vredenburg, Mark Jennings, Allan Larson

School of Biological Sciences: Faculty Publications

Phylogenetic relationships among frogs of the genus Rana from western North America are investigated using 2013 aligned bases of mitochondrial DNA sequence from the genes encoding ND1 (subunit one of NADH dehydrogenase), tRNA^Ile, tRNA^Gln, tRNA^Met, ND2, tRNA^Trp, tRNA^Ala, tRNA^Asn, tRNA^Cys, tRNA^Tyr, and COI (subunit I of cytochrome c oxidase), plus the origin for light-strand replication (OL) between the tRNA^Asn and tRNA^Cys genes. The aligned sequences contain 401 phylogenetically informative characters. A well-resolved phylogenetic hypothesis in which the Rana boylii species group ( …

Disrupting Evolutionary Processes: The Effect Of Habitat Fragmentation On Collared Lizards In The Missouri Ozarks, Alan R. Templeton, Robert J. Robertson, Jennifer A. Brisson, Jared Strasburg

School of Biological Sciences: Faculty Publications

Humans affect biodiversity at the genetic, species, community, and ecosystem levels. This impact on genetic diversity is critical, because genetic diversity is the raw material of evolutionary change, including adaptation and speciation. Two forces affecting genetic variation are genetic drift (which decreases genetic variation within but increases genetic differentiation among local populations) and gene flow (which increases variation within but decreases differentiation among local populations). Humans activities often augment drift and diminish gene flow for many species, which reduces genetic variation in local populations and prevents the spread of adaptive complexes outside their population of origin, thereby disrupting adaptive processes …

Mean Time To Extinction Of A Metapopulation With An Allee Effect, Chad Brassil

School of Biological Sciences: Faculty Publications

The incorporation of Allee effects into a simple metapopulation extinction model reveals a large non-linear reduction in mean time to extinction with small changes in an Allee limit. The extent of this reduction is dependent on the level of migration in the metapopulation. With small amounts of migration, small changes in the Allee limit result in large changes in the meantime to extinction. With higher levels of migration, the mean time to extinction is not as sensitive to changes in the Allee limit, becoming more similar to the single population case. The metapopulation modeled here is a set of nine …

A Synopsis Of The Ferns And Fern Allies Of Nebraska, With Maps Of Their Distribution, Steven B. Rolfsmeier, Robert B. Kaul, David M. Sutherland

School of Biological Sciences: Faculty Publications

An annotated list and country-by-country distribution maps are presented for the 32 species of ferns and fern allies native to Nebraska, based upon field and herbarium studies and critical evaluation of the literature. Native to the state are Isoëtes melanopoda, Selaginella rupestris, five species of Equisetum, and 25 species in 18 genera of ferns. Three native species are here verified for the first time, based upon recent collections: Matteuccia struthiopteris var. pensylvanica, Ophioglossum engelmannii, and Pellacaglabella ssp. glabella. Isoëtes melanopoda was rediscovered in 2000, the first record since 1941. Rejected are published reports of …

Molecular Characterization Of Cephalothorax, The Tribolium Ortholog Of Sex Combs Reduced, Carmelle D. Curtis, Jennifer A. Brisson, Mark A. Decamillis, Teresa D. Shippy, Susan J. Brown, Robin E. Denell

School of Biological Sciences: Faculty Publications

Sex combs reduced (Scr), a Hox gene located in the Antennapedia complex of Drosophila melanogaster, is required for the proper development of the labial and first thoracic segments. The Tribolium castaneum genetically defined locus Cephalothorax (Cx) is a candidate Scr ortholog based on the location of Cx in the beetle Homeotic complex and mutant effects on the labial and first thoracic segments. To address this hypothesis, we have cloned and characterized the Tribolium ortholog of Scr (TcScr). The transcription unit is less complex and encodes a smaller protein than Scr. The predicted …

Secreted Euryarchaeal Microhalocins Kill Hyperthermophilic Crenarchaea, Cynthia Haseltine, Tiffany Hill, Rafael Montalvo-Rodriguez, Samantha K. Kemper, Richard F. Shand, Paul H. Blum

School of Biological Sciences: Faculty Publications

Few antibiotics targeting members of the archaeal domain are currently available for genetic studies. Since

bacterial antibiotics are frequently directed against competing and related organisms, archaea by analogy

might produce effective antiarchaeal antibiotics. Peptide antibiotic (halocin) preparations from euryarchaeal

halophilic strains S8a, GN101, and TuA4 were found to be toxic for members of the hyperthermophilic

crenarchaeal genus Sulfolobus. No toxicity was evident against representative bacteria or eukarya. Halocin S8

(strain S8a) and halocin R1 (strain GN101) preparations were cytostatic, while halocin A4 (strain TuA4)

preparations were cytocidal. Subsequent studies focused on the use of halocin A4 preparations and Sulfolobus …

Microsatellite Analysis Of Female Mating Behaviour In Lek-Breeding Sage Grouse, Katy Semple, Robert K. Wayne, Robert M. Gibson

School of Biological Sciences: Faculty Publications

We used microsatellite DNA markers to genotype chicks in 10 broods of lek-breeding sage grouse, Centrocercus urophasianus, whose mothers’ behaviour was studied by radio tracking and observing leks. Previous behavioural studies suggested that almost all matings are performed by territorial males on leks and that multiple mating is rare. Two broods (20%) were sired by more than one male. Genetic analyses of the broods of eight females that visited an intensively studied lek were consistent with behavioural observations. Four females observed mating produced singly sired broods and males other than the individual observed copulating were excluded as sires for most …

Biodiversity And Decomposition In Experimental Grassland Ecosystems, Johannes M. H. Knops, David A. Wedin, David Tilman

School of Biological Sciences: Faculty Publications

We examined the impact of biodiversity on litter decomposition in an experiment that manipulated plant species richness. Using biomass originating from the experimental species richness gradient and from a species used as a common substrate, we measured rates of decomposition in litterbags in two locations: in situ in the experiment plots and in an adjacent common garden. This allowed us to separate the effects of litter quality and decomposition location on decomposition. We found that plant species richness had a significant, but minor negative effect on the quality (nitrogen concentration) of the biomass. Neither litter type nor location had a …

Using Cox’S Proportional Hazard Models To Implement Optimal Strategies: An Example From Behavioral Ecology, Brigitte Tenhumberg, M. A. Keller, Hugh P. Possingham

School of Biological Sciences: Faculty Publications

Simple behavioral rules, or “rules of thumb,” which lead to behavior that closely approximates an optimal strategy, have generated a lot of recent interest in the field of foraging behavior. In this paper, we derive rules of thumb from a stochastic simulation model in which the foragers behave optimally. We use a particular biological system: the patch leaving behavior of a parasitoid. We simulate parasitoids whose patch leaving behavior is determined by a stochastic dynamic programming (SDP) model, while allowing parasitoids to make mistakes in their estimation of host density when arriving in a patch We use Cox’s proportional hazards …

Rhinocyllus Conicus: Initial Evaluation And Subsequent Ecological Impacts In North America, A. Gassmann, Svata M. Louda

School of Biological Sciences: Faculty Publications

Renewed debate over the risk of non-target effects in biological control reflects, in part, the recent quantification of direct and indirect ecological effects of the flowerhead weevil, Rhinocyllus conicus Frol., in North America. To help resolve the issue, we review the published data for R. conicus from both Europe and North America: pre-release (1961-1968), post-release (1969-1985) and more recent (1986-1999). Our aim was to determine the extent to which host range expansion on to native North American species, and the associated ecological effects, were predicted or predictable. Our overall conclusion is that more was known than is generally realized, yet …

Feeding And Survival In Parasitic Wasps: Sugar Concentration And Timing Matter, Gitta Siekmann, Brigitte Tenhumberg, Michael A. Keller

School of Biological Sciences: Faculty Publications

Sugar consumption can increase the longevity and lifetime fecundity of many species of parasitic wasps. Consequently, for these insects the availability of sugar sources in the field is important for their reproductive success. As sugar sources can be highly variable in quantity, space and time, the chances of finding a sufficient amount of sugar to increase longevity might be very low. Therefore, the reward from a single feeding event can be critical for the forager’s fitness. We measured the longevity of the parasitoid Cotesia rubecula after a single honey meal differing in sugar concentration (25, 47, 86% w/w) and timing …

Contrasting Effects Of Plant Richness And Composition On Insect Communities: A Field Experiment, Nick M. Haddad, David Tilman, John Haarstad, Mark Ritchie, Johannes M.H. Knops

School of Biological Sciences: Faculty Publications

We experimentally separated the effects of two components of plant diversity—plant species richness and plant functional group richness—on insect communities. Plant species richness and plant functional group richness had contrasting effects on insect abundances, a result we attributed to three factors. First, lower insect abundances at higher plant functional group richness were explained by a sampling effect, which was caused by the increasing likelihood that one low-quality group, C4 grasses, would be present and reduce average insect abundances by 25%. Second, plant biomass, which was positively related to plant functional group richness, had a strong, positive effect on insect abundances. …

Notes And Comments: Food Web Laws Or Niche Theory? Six Independent Empirical Tests, Kirk O. Winemiller, Eric R. Pianka, Laurie J. Vitt, Anthony Joern

School of Biological Sciences: Faculty Publications

Over the past 2 decades, empirical food webs have been shown to possess regular patterns of various kinds. Some of the first food web patterns were reported as “food web laws,” the most notable being the link-species scaling law. This empirically derived law described an inverse relationship between community species richness and web connectance (Cohen and Briand 1984; Cohen and Newman 1985). Subsequent evaluation of food webs constructed with more detailed data falsified (Warren 1989; Winemiller 1989a, 1990; Hall and Raffaelli 1991; Polis 1991) and modified (Warren 1990; Martinez 1991, 1992; Pimm et al. 1991; Martinez et al. 1999) many …

Optimal Patch-Leaving Behavior: A Case Study Using The Parasitoid Cotesia Rubecula, Brigitte Tenhumberg, Mike A. Keller, Hugh P. Possingham, Andrew J. Tyre

School of Biological Sciences: Faculty Publications

1. Parasitoids are predicted to spend longer in patches with more hosts, but previous work on Cotesia rubecula (Marshall) has not upheld this prediction. Tests of theoretical predictions may be affected by the definition of patch leaving behavior, which is often ambiguous.

2. In this study whole plants were considered as patches and assumed that wasps move within patches by means of walking or flying. Within-patch and between-patch flights were distinguished based on flight distance. The quality of this classification was tested statistically by examination of log-survivor curves of flight times.

3. Wasps remained longer in patches with higher host …

Microbially Catalyzed Nitrate-Dependent Oxidation Of Biogenic Solid-Phase Fe(Ii) Compounds, Karrie A. Weber, Flynn W. Picardal, Eric E. Roden

School of Biological Sciences: Faculty Publications

The potential for microbially catalyzed NO₃^—-dependent oxidation of solid-phase Fe(II) compounds was examined using a previously described autotrophic, denitrifying, Fe(II)-oxidizing enrichment culture. The following solid-phase Fe(II)-bearing minerals were considered: microbially reduced synthetic goethite, two different end products of microbially hydrous ferric oxide (HFO) reduction (biogenic Fe₃O₄ and biogenic FeCO₃), chemically precipitated FeCO₃, and two microbially reduced iron(III) oxide-rich subsoils. The microbially reduced goethite, subsoils, and chemically precipitated FeCO₃ were subject to rapid NO₃^—-dependent Fe(II) oxidation. Significant oxidation of biogenic Fe₃O₄ was observed. Very …