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Spatial Heterogeneity, Not Visitation Bias, Dominates Variation In Herbivory: Comment & Reply, James F. Cahill, Brenda B. Casper, David S. Hik, Svata M. Louda, Anne M. Parkhurst, Kate L. Bradley, Elisabeth S. Bakker, Johannes M. H. Knops, Ellen I. Damschen, Lauren M. Young

School of Biological Sciences: Faculty Publications

An exchange regarding the article: Bradley, K. L., E. I. Damschen, L. M. Young, D. Kuefler, S. Went, G. Wray, N. M. Haddad, J. M. H. Knops, and S. M. Louda. 2003. Spatial heterogeneity, not visitation bias, dominates variation in herbivory. Ecology 84:2214–2221.

Cahill et al. write:
Here we show that the experimental design and statistical analysis used by Bradley et al. (2003) do not adequately control for Type II experimental error (accepting the null hypothesis when it is in fact false). This is particularly important when responses have low effect sizes such as those previously demonstrated for visitation effects …

The Sweet Tooth Of Adult Parasitoid Cotesia Rubecula: Ignoring Hosts For Nectar?, Gitta Siekmann, Michael A. Keller, Brigitte Tenhumberg

School of Biological Sciences: Faculty Publications

Investing time and energy into survival and reproduction often presents a trade-off to many species of animals. In parasitic wasps, both hosts and sugar sources contribute to the forager’s fitness but are often found in different locations. The decision to search for hosts or for food can have a strong impact on fitness when the forager’s lifetime is short and resources are not abundant. We investigated the tendency of flowers and hosts to attract 1-day-old female Cotesia rubecula Marshall (Hymenoptera: Braconidae) with different feeding histories in a wind tunnel. Only well-fed wasps exhibited a preference for hosts. In comparison, unfed …

Exotic Weed Invasion Increases The Susceptibility Of Native Plants To Attack By A Biocontrol Herbivore, Tatyana A. Rand, Svata M. Louda

School of Biological Sciences: Faculty Publications

Landscape change has great, yet infrequently measured, potential to influence the susceptibility of natural systems to invasive species impacts. We quantified attack by an invasive biological control weevil (Rhinocyllus conicus) on native thistles in relation to two types of landscape change: agricultural intensification and invasion by an exotic thistle, Carduus nutans, the original target of biological control. Weevil egg load was measured on native thistles in three landscape types: (1) agriculture dominated, (2) grassland dominated with exotic thistles, and, (3) grassland dominated without exotic thistles. We found no difference in egg load on native thistles within grassland …

How Predation Risk Affects The Temporal Dynamics Of Avian Leks: Greater Sage Grouse Versus Golden Eagles, Adam R. Boyko, Robert M. Gibson, Jeffrey R. Lucas

School of Biological Sciences: Faculty Publications

Leks often attract predators as well as mates, yet most evolutionary models have assumed that sexual selection, not predation, drives lekking behavior. We explored the influence of predation on lek dynamics using a stochastic dynamic game model based on the lek-breeding greater sage grouse (Centrocercus urophasianus) and its principal avian predator, the golden eagle (Aquila chrysaetos). The model predicts time-dependent male lek attendance as a function of factors affecting both mating success (female arrival rate, male numbers, and social status) and predation risk (eagle arrival rate and group size). Dominant males are predicted to arrive sooner …

Ecological Effects Of Transgenic Crops And The Escape Of Transgenes Into Wild Populations, Diana Pilson, Holly R. Prendeville

School of Biological Sciences: Faculty Publications

Ecological risks associated with the release of transgenic crops include nontarget effects of the crop and the escape of transgenes into wild populations. Nontarget effects can be of two sorts: (a) unintended negative effects on species that do not reduce yield and (b) greater persistence of the crop in feral populations. Conventional agricultural methods, such as herbicide and pesticide application, have large and well- documented nontarget effects. To the extent that transgenes have more specific target effects, transgenic crops may have fewer nontarget effects. The escape of transgenes into wild populations, via hybridization and introgression, could …

Predicting Predation Efficiency Of Biocontrol Agents: Linking Behavior Of Individuals And Population Dynamics, Brigitte Tenhumberg

School of Biological Sciences: Faculty Publications

Behavioral ecology and population ecology are two separate branches of ecology; studies linking the effect of individual behavior and population dynamics are rare. This paper connects a stochastic optimal foraging model of insect predators with an age structured population model of its prey. I modeled syrphid larvae feeding on cereal aphids, an interaction critical to cereal crops in Germany. The key stochastic element in this model is the foraging success of predators, which influences survival and developmental time of predators and mortality of the prey population. The model predicts that the level of control incurred by predators is highest if …

Book Review: Tangled Trees: Phylogeny, Cospeciation, And Coevolution, Federico G. Hoffmann

School of Biological Sciences: Faculty Publications

Host-parasite associations and the study of their coevolution and cospeciation have long been of strong interest to evolutionary biologists. This book does an excellent job of bringing readers up to date in the field, including both theoretical and empirical reports, the development of novel methodological approaches, and the incorporation of molecular data. The book is divided into 2 sections; the first presents theoretical developments in the field, while the second focuses on experimental results.

Phylogenetic Relationships Of Malvatheca (Bombacoideae And Malvoideae; Malvaceae Sensu Lato) As Inferred From Plastid Dna Sequences, David A. Baum, Stacey Dewitt Smith, Alan Yen, William S. Alverson, Reto Nyffeler, Barbara A. Whitlock, Rebecca L. Oldham

School of Biological Sciences: Faculty Publications

Previous molecular phylogenetic analyses have revealed that elements of the former families Malvaceae sensu stricto and Bombacaceae together form a well-supported clade that has been named Malvatheca. Within Malvatheca, two major lineages have been observed; one, Bombacoideae, corresponds approximately to the palmate-leaved Bombacaceae, and the other, Malvoideae, includes the traditional Malvaceae (the mallows or Eumalvoideae). However, the composition of these two groups and their relationships to other elements of Malvatheca remain a source of uncertainty. Sequence data from two plastid regions, ndhF and trnK/matK, from 34 exemplars of Malvatheca and six outgroups were analyzed. Parsimony, likelihood, and …

How Predation Risk Affects The Temporal Dynamics Of Avian Leks: Greater Sage Grouse Versus Golden Eagles, Adam R. Boyko, Robert M. Gibson, Jeffrey R. Lucas

School of Biological Sciences: Faculty Publications

Leks often attract predators as well as mates, yet most evolutionary models have assumed that sexual selection, not predation, drives lekking behavior. We explored the influence of predation on lek dynamics using a stochastic dynamic game model based on the lek-breeding greater sage grouse (Centrocercus urophasianus) and its principal avian predator, the golden eagle (Aquila chrysaetos). The model predicts time-dependent male lek attendance as a function of factors affecting both mating success (female arrival rate, male numbers, and social status) and predation risk (eagle arrival rate and group size). Dominant males are predicted to arrive sooner …

Aggregated Seed Dispersal By Spider Monkeys Limits Recruitment To Clumped Patterns In Virola Calophylla, Sabrina E. Russo, Carol K. Augsperger

School of Biological Sciences: Faculty Publications

The initial spatial pattern of seed deposition influences plant population and community structure, particularly when that pattern persists through recruitment. In a vertebrate-dispersed rain forest tree, Virola calophylla, we found that spatially aggregated seed deposition strongly influenced the spatial structure of later stages. Seed dispersion was clumped, and seed densities were highest underneath V. calophylla females and the sleeping sites of spider monkeys (Ateles paniscus), the key dispersal agent. Although these site types had the lowest per capita seed-to-seedling survival, they had the highest seedling/sapling densities. Conversely, seed and seedling/sapling densities were lowest, and seed survival was …

Occurrence And Characterization Of Mercury Resistance In The Hyperthermophilic Archaeon Sulfolobus Solfataricus By Use Of Gene Disruption, James Schelert, Vidula Dixit, Viet Hoang, Jessica Simbahan, Melissa Drozda, Paul H. Blum

School of Biological Sciences: Faculty Publications

Mercury resistance mediated by mercuric reductase (MerA) is widespread among bacteria and operates under the control of MerR. MerR represents a unique class of transcription factors that exert both positive and negative regulation on gene expression. Archaea and bacteria are prokaryotes, yet little is known about the biological role of mercury in archaea or whether a resistance mechanism occurs in these organisms. The archaeon Sulfolobus solfataricus was sensitive to mercuric chloride, and low-level adaptive resistance could be induced by metal preconditioning. Protein phylogenetic analysis of open reading frames SSO2689 and SSO2688 clarified their identity as orthologs of MerA and MerR. …

Mark–Recapture And Behavioral Ecology: A Case Study Of Cliff Swallows, C. R. Brown, Mary Bomberger Brown

School of Biological Sciences: Faculty Publications

Mark–recapture and behavioral ecology: a case study of Cliff Swallows.— Mark–recapture and the statistical analysis methods associated with it offer great potential for investigating fitness components associated with particular behavioral traits. However, few behavioral ecologists have used these techniques. We illustrate the insights that have come from a long–term mark–recapture study of social behavior in Cliff Swallows (Petrochelidon pyrrhonota). The number of transient swallows passing through a colony per hour increased with colony size and was responsible in part for increased rates of ectoparasite introduction from outside the group into the larger colonies. Annual survival probabilities of …

Juvenile And Adult Survival In The Sociable Weaver (Philetairus Socius), A Southern-Temperate Colonial Cooperative Breeder In Africa, Rita Covas, Charles R. Brown, Mark D. Anderson, Mary Bomberger Brown

School of Biological Sciences: Faculty Publications

We used capture–recapture analyses to describe juvenile and adult survival from 1993 to 2001 in a population of Sociable Weavers (Philetairus socius), a colonial, cooperatively breeding passerine of southern Africa. We examined temporal variation in survival and the role that the breeding season’s length and environmental factors play in determining survival patterns in the population. Annual survival probability (mean ± SE) was 0.66 ± 0.02. In contrast to most passerines, juveniles and adults had similar survival probabilities; survival rates did not vary significantly between years. We found no relationship among temperature, rainfall, and survival. Relatively high survival rates …

Group Size And Ectoparasitism Affect Daily Survival Probability In A Colonial Bird, Charles R. Brown, Mary Bomberger Brown

School of Biological Sciences: Faculty Publications

Little is known in general about how group size or ectoparasitism affect survival in colonial animals. We estimated daily within-season survival probabilities for nesting adult and recently fledged juvenile cliff swallows (Petrochelidon pyrrhonota) at 239 colonies from 1983 to 2003 in southwestern Nebraska, USA. Some colonies had been fumigated to remove ectoparasites. We conducted mark-recapture at each colony site to estimate daily survival. There were no systematic differences between males and females in daily survival. Adults and juveniles occupying parasite-free colonies had, on average, 4.4% and 62.2% greater daily survival, respectively, than their counterparts in naturally infested colonies. …

Culture-Independent Analysis Of Fecal Enterobacteria In Environmental Samples By Single-Cell Mrna Profiling, Han Chen, Gomathinayagam Ponniah, Nancy Salonen, Paul H. Blum

School of Biological Sciences: Faculty Publications

A culture-independent method called mRNA profiling has been developed for the analysis of fecal enterobacteria and their physiological status in environmental samples. This taxon-specific approach determines the single-cell content of selected gene transcripts whose abundance is either directly or inversely proportional to growth state. Fluorescence in situ hybridization using fluorochrome-labeled oligonucleotide probes was used to measure the cellular concentration of fis and dps mRNA. Relative levels of these transcripts provided a measure of cell growth state and the ability to enumerate fecal enterobacterial cell number. Orthologs were cloned by inverse PCR from several major enterobacterial genera, and probes specific for …

Mercury Inactivates Transcription And The Generalized Transcription Factor Tfb In The Archaeon Sulfolobus Solfataricus, Vidula Dixit, Elisabetta Bini, Melissa Drozda, Paul H. Blum

School of Biological Sciences: Faculty Publications

Mercury has a long history as an antimicrobial agent effective against eukaryotic and prokaryotic organisms.

Despite its prolonged use, the basis for mercury toxicity in prokaryotes is not well understood. Archaea, like

bacteria, are prokaryotes but they use a simplified version of the eukaryotic transcription apparatus. This

study examined the mechanism of mercury toxicity to the archaeal prokaryote Sulfolobus solfataricus. In vivo

challenge with mercuric chloride instantaneously blocked cell division, eliciting a cytostatic response at

submicromolar concentrations and a cytocidal response at micromolar concentrations. The cytostatic response

was accompanied by a 70% reduction in bulk RNA synthesis and elevated …

Landscape Vs. Local Habitat Scale Influences To Insect Communities From Tallgrass Prairie Remnants, Kristal J.L. Stoner, Anthony Joern

School of Biological Sciences: Faculty Publications

Habitat loss and fragmentation currently threaten ecosystems worldwide, yet remain difficult to quantify because within-fragment habitat and landscape-scale influences often interact in unique ways. Although individual species respond to fragmentation differently, large-scale conservation planning must unavoidably target multiple species. Although information on a population’s response to fragmentation is critical, and measurements of species richness provide useful insights, exclusive reliance on these responses may mask important information about the taxonomic composition of assemblages in response to fragmentation. The North American tallgrass prairie ecosystem is one of the most threatened and fragmented ecosystems in the world, and insects are significant contributors to …

Book Review: Los Mamíferos De La Provincia De Jujuy, Argentina, Federico G. Hoffmann

School of Biological Sciences: Faculty Publications

The province of Jujuy lies in the northwestern corner of Argentina, abutting Chile and Bolivia in the west and northeast, and ranging from 500 to 6,000 m in elevation. As a result of its location and topography, vegetation ranges from subtropical forests in the lowlands to high-altitude grasslands on the slopes of the Andes, and more than 130 mammalian species can be encountered in the province, from mice-eating bats to forest and pampas deer to llamas and guanacos. This book defies pigeonholing as a single-purpose guide, and contains a wider range of information than biogeographical and identification data. There is …

Host–Symbiont Stability And Fast Evolutionary Rates In An Ant–Bacterium Association: Cospeciation Of Camponotus Species And Their Endosymbionts, Candidatus Blochmannia, Patrick H. Degnan, Adam B. Lazarus, Chad D. Brock, Jennifer J. Wernegreen

School of Biological Sciences: Faculty Publications

Bacterial endosymbionts are widespread across several insect orders and are involved in interactions ranging from obligate mutualism to reproductive parasitism. Candidatus Blochmannia gen. nov. (Blochmannia) is an obligate bacterial associate of Camponotus and related ant genera (Hymenoptera: Formicidae). The occurrence of Blochmannia in all Camponotus species sampled from field populations and its maternal transmission to host offspring suggest that this bacterium is engaged in a long-term, stable association with its ant hosts. However, evidence for cospeciation in this system is equivocal because previous phylogenetic studies were based on limited gene sampling, lacked statistical analysis of congruence, and have …

Isolation And Characterization Of 11 Polymorphic Microsatellite Loci In Collared Lizards (Crotaphytus Collaris), Delbert W. Hutchison, Jared L. Strasburg, Jennifer A. Brisson, Shawn Cummings

School of Biological Sciences: Faculty Publications

We identified 11 polymorphic microsatellite loci in collared lizards (Crotaphytus collaris). Polymorphism assessment in 512 individuals from 52 populations sampled across much of the species distribution revealed a fairly high degree of genetic diversity (six to 20 alleles per locus) and a wide range of average expected heterozygosity values (0.143–0.530). We found no evidence for linkage, very few deviations from HW expectation (two of 572 possible population/locus analyses) and thus no evidence for null alleles. There was a tendency for reduced polymorphism towards the northern periphery.

Do Harvest Refuges Buffer Kangaroos Against Evolutionary Responses To Selective Harvesting?, Brigitte Tenhumberg, Andrew J. Tyre, Anthony R. Pople, Hugh P. Possingham

School of Biological Sciences: Faculty Publications

There is a wealth of literature documenting a directional change of body size in heavily harvested populations. Most of this work concentrates on aquatic systems, but terrestrial populations are equally at risk. This paper explores the capacity of harvest refuges to counteract potential effects of size-selective harvesting on the allele frequency of populations. We constructed a stochastic, individual-based model parameterized with data on red kangaroos. Because we do not know which part of individual growth would change in the course of natural selection, we explored the effects of two alternative models of individual growth in which alleles affect either the …

Linking Wild And Captive Populations To Maximize Species Persistence: Optimal Translocation Strategies, Brigitte Tenhumberg, Andrew J. Tyre, Katriona Shea, Hugh P. Possingham

School of Biological Sciences: Faculty Publications

Captive breeding of animals is widely used to manage endangered species, frequently with the ambition of future reintroduction into the wild. Because this conservation measure is very expensive, we need to optimize decisions, such as when to capture wild animals or release captive-bred individuals into the wild. It is unlikely that one particular strategy will always work best; instead, we expect the best decision to depend on the number of individuals in the wild and in captivity. We constructed a first-order Markov-chain population model for two populations, one captive and one wild, and we used stochastic dynamic programming to identify …

Genetic Discontinuities Among Populations Of Cleistes (Orchidaceae, Vanilloideae) In North America, Stacey Dewitt Smith, Robyn S. Cowan, Katharine B. Gregg, Mark W. Chase, Nigel Maxted, Michael F. Fay

School of Biological Sciences: Faculty Publications

Genetic patterns were examined in five populations of North American Cleistes with three sources of molecular data: amplified fragment length polymorphisms (AFLP), DNA sequencing, and plastid microsatellites. Populations of C. bifaria were sampled in four areas of the south-eastern US: the coastal plains of Florida and North Carolina and the mountains of North Carolina and West Virginia. A population of C. divaricata sympatric with the North Carolina coastal plain C. bifaria was also sampled. Analysis of the three types of molecular data resulted in the same relationships among the five sampled populations. The coastal plain population of C. divaricata was …

The Role Of Local Spatial Heterogeneity In The Maintenance Of Parapatric Boundaries: Agent Based Models Of Competition Between Two Parasitic Ticks, Andrew J. Tyre, Brigitte Tenhumberg, C. Michael Bull

School of Biological Sciences: Faculty Publications

Recent models of ecological parapatry, where the geographical distributions of two similar species abut without overlapping, have shown that spatial gradients in intrinsic growth rates can lead to sharp boundaries when dispersal is density dependent. However, a well documented parapatric boundary in southern Australia between two tick species that parasitise a large lizard lacks one or both of these features; dispersal of ticks is random and there may not be a gradient of population growth rates for one of the species. There is local variation in population growth rates arising from variation in the number of host lizards with overlapping …

Long-Range Visibility Of Greater Sage Grouse Leks: A Gis-Based Analysis, Andrea S. Aspbury, Robert M. Gibson

School of Biological Sciences: Faculty Publications

We investigated whether male greater sage grouse, Centrocercus urophasianus, select lek locations on the basis of topographic features that affect their visibility to both conspecific females and a major avian predator, the golden eagle, Aquila chrysaetos. We mapped locations of displaying males at all leks in a local population and used a Geographic Information System (GIS) and digital elevation model (DEM) to generate ‘viewsheds’ around male locations within a boundary set by the estimated maximal visual acuity of the viewer. Areas visible around leks were compared to those visible around random sites with the same conformation of displaying …