Life Sciences Commons^™

Modelling Pollinator And Nonpollinator Selection On Flower Colour Variation, Brigitte Tenhumberg, Agnes S. Dellinger, Stacey D. Smith

School of Biological Sciences: Faculty Publications

1. Flower colour variation is ubiquitous within and between populations, which is why it has long been a focal point for studies of natural selection. This body of work has uncovered a wide range of selective agents, including pollinators, herbivores, and various abiotic factors. Nevertheless, we lack an integrative framework for predicting the phenotypic outcome in terms of floral pigmentation when these forces act collectively and often in opposition. 2. We here present such a framework through a model that incorporates selection on pigmentation at the vegetative phase (i.e., through survival to reproduction) and at the flowering phase (i.e., on …

Seed Rain–Successional Feedbacks In Wet Tropical Forests, Nohemi Huanca Nuñez, Robin L. Chazdon, Sabrina E. Russo

School of Biological Sciences: Faculty Publications

Abstract

Tropical forest regeneration after abandonment of former agricultural land depends critically on the input of tree seeds, yet seed dispersal is increasingly disrupted in contemporary human-modified landscapes. Here, we introduce the concept of seed rain–successional feedbacks as a deterministic process in which seed rain is shaped by successional dynamics internal to a forest site and that acts to reinforce priority effects. We used a combination of time series and chronosequence approaches to investigate how the quantity and taxonomic and functional composition of seed rain change during succession and to evaluate the strength of seed rain–successional feedbacks, relative to other …

First Record On Secondary Pollen Presentation In The Cucurbitaceae Family, Shivani Jadeja

School of Biological Sciences: Faculty Publications

Aim – Secondary pollen presentation in flowers has been described only in a few species across about 25 plant families. The first report of secondary pollen presentation in the Cucurbitaceae family is given here.

Key result – Sechium talamancensis, endemic to high elevations in Costa Rica, presents nearly 39% of its pollen secondarily on the distal ends of its petals. The remaining pollen is presented on the anthers, the primary pollen presenters.

Significance – Closely related and commercially important congeners of S. talamancensis do not show secondary pollen presentation. Potential selective advantages of the phenomenon that differentiates S. talamancensis …

Host Range Extension For Chlorochlamys Chloroleucaria (Geometrinae, Geometridae) To Include Eriogonum Alatum (Polygonaceae), Kathleen H. Keeler, George J. Balogh

School of Biological Sciences: Faculty Publications

In 2001 and 2002 we collected specimens of Chlorochlamys chloroleucaria from Eriogonum alatum Torr., winged false buckwheat. Eriogonum alatum occurs at elevations of 5000-10,000 feet on both sides of the Rocky Mountains, from Utah (Welsh et al. 1987) to western Nebraska, southeastern Wyoming (Dorn 1977) to western Oklahoma and the Texas panhandle to Arizona (Great Plains Flora Association 1986).

Clone Size Of Andropogon Gerardii Vitman (Big Bluestem) At Konza Prairie, Kansas, Kathleen H. Keeler, Charles F. Williams, Linda S. Vescio

School of Biological Sciences: Faculty Publications

Clone size of plants of Andropogon gerardii from Konza Prairie Biological Station, Manhattan, Kansas was estimated from spatial patterns of genetic variation, using proteins detected by starch gel electrophoresis and DNA content (ploidy) measured by flow cytometry. Unique multi-locus protein banding patterns and differences in ploidy were used to exclude plants as members of the same clone. Individual clones averaged about 2 m in diameter and areas of prairie of 100 m² were calculated to contain an average of 31.8 genetic individuals.

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 …

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 …

Clonal Growth Of Lithospermum Caroliniense (Boraginaceae) In Contrasting Sand Dune Habitats, Stephen G. Weller, Kathleen H. Keeler, Barbara A. Thomson

School of Biological Sciences: Faculty Publications

The occurrence of clonal growth of distylous Lithospermum caroliniense was investigated in a population in the Nebraska Sandhills, an area where sand dunes have been relatively stable for at least 1,500–3,000 yr, and compared to a population occurring at the Indiana Dunes, an area of active sand dune formation. Spatial autocorrelation analysis indicated the occurrence of significant clonal propagation of genetically based floral morphs at Arapaho Prairie, but not for the Indiana Dunes. Apparent clonal growth in the Sandhills population had no overall negative effect on pollen deposition or fecundity relative to the Indiana population, although in some large clones …

Population Biology Of Intraspecific Polyploidy In Grasses, Kathleen H. Keeler

School of Biological Sciences: Faculty Publications

Polyploidy is the duplication of an entire nuclear genome, whether diploid or higher level (Stebbins, 1971; Thompson & Lumaret, 1992) and a frequent occurrence in plants. Stebbins (1971) estimated that 30-35% of flowering plant species are polyploid, and that many more had a polyploid event in their evolutionary history, including all members of such important families as the Magnoliaceae, Salicaceae, and Ericaceae. Goldblatt (1980) estimated 55%, but probably up to 75%, of monocotyledons had at least one polyploid event in their history, using the criterion that if the species has a base number higher than n=13 it is derived …

Evolutionary Implications Of Meiotic Chromosome Behavior, Reproductive Biology, And Hybridization In 6x And 9x Cytotypes Of Andropogon Gerardii (Poaceae), Guillermo A. Norrmann, Camilo L. Quarín, Kathleen H. Keeler

School of Biological Sciences: Faculty Publications

Andropogon gerardii, big bluestem, has 60 and 90 chromosome cytotypes. Meiosis in the hexaploid was shown to be regular, although some secondary associations of bivalents form. Meiosis in the enneaploid (2n = 9x = 90) is irregular, leading to most gametes having unbalanced chromosome complements. Both cytotypes show considerable self-incompatibility. Cytotypes crossed freely, forming a variety of fertile euploids and aneuploids. Indistinguishable exomorphology, intermixing in natural populations, and compatibility suggest that A. gerardii is best understood as a cytotypically complex single species.

Reproductive Structure And Organogenesis In A Cottonwood, Populus Deltoides (Salicaceae), Robert B. Kaul

School of Biological Sciences: Faculty Publications

The organogenesis of inflorescences, flowers, and fruits was followed for two years in a male and a female tree of eastern cottonwood, Populus deltoides. Soon after anthesis, an inflorescence for the next year is initiated as a continuation of the apical meristem in most axillary buds of the extension shoot of the current year. Bract and then floral primordia arise helically, and by the end of summer all floral appendages are evident. Individual perianth parts are evident early in ontogeny but not at anthesis; they are vascularized independently by distal traces of discrete vascular strands that also serve the …

Introduction From The Changing Prairie: North American Grasslands, Anthony Joern, Kathleen H. Keeler

School of Biological Sciences: Faculty Publications

Preserving remaining North American grasslands requires a multiability approach. In this book, we investigate three aspects of an admittedly larger problem: (1) how we as humans perceive grasslands; (2) the ecology of grasslands, in order to define the framework within which conservation and preservation efforts must operate; and (3) conservation issues. Additional sociological, economic, philosophical, and cultural considerations will provide important additional insights to preserving and managing grasslands, but are not included here. By restricting our focus to only three issues, we feel that we can provide a basic, but appropriate, understanding of grassland ecosystems for the prairie enthusiast. This …

Getting The Lay Of The Land: Introducing North American Native Grasslands, Anthony Joern, Kathleen H. Keeler

School of Biological Sciences: Faculty Publications

The expected catastrophic extinction of species (already under way in many places) will alter the planet’s biological diversity so profoundly that, at the known rate of extinction, it will take millions of years to recover. Yet few ecologists study extinction. Indeed, very little ecology deals with any processes that last more than a few years, involve more than a handful of species, and cover an area of more than a few hectares. The temporal, spatial and organizational scales of most ecological studies are such that one can read entire issues of major journals and see no hint of impending catastrophe. …

Preface From The Changing Prairie: North American Grasslands, Kathleen H. Keeler, Anthony Joern

School of Biological Sciences: Faculty Publications

North American grasslands have figured prominently in our North American heritage. Prairies first provided significant barriers to westward expansion, and then offered both economic and sociological opportunity, as well as heartache, for settlers. Many artists have gained significant inspiration from the beauty as well as the harshness of this region and its biota. And because of ideal climate and soil conditions, these grasslands have provided the agricultural foundation of which much of the economic growth and stability of the United States has historically depended.

Yet many see North American prairies as beautiful only when manipulated or exploited: Green croplands or …

Population Processes, Kathleen H. Keeler, Anthony Joern

School of Biological Sciences: Faculty Publications

Within the prairies, myriad populations of plants, insects, small mammals, and other organisms form distinct levels of organization. The physical forces of weather and fire and the complex networks of species interactions control each species’s structure and dynamics and determine its abundance or rarity. Variation in population dynamics and interactions over time and space determine the distribution and abundance of species, and ultimately the composition and dynamics of entire prairie communities.

To the casual observer, plant populations on prairies may seem quite static, like museums containing a diverse collection of specimens that can be seen again and again on repeated …

Wild Medicine: Review Of Medicinal Wild Plants Of The Prairie By Kelly Kindscher, Kathleen H. Keeler

School of Biological Sciences: Faculty Publications

I am highly enthusiastic about this book as a reference work. It summarizes the literature on the medicinal uses for more than 103 prairie plants. For 43 species, Kindscher gives common, Indian, and scientific names; description; habitat; parts used; Indian uses; medical history; scientific research and cultivation; and information on about 100 of their relatives. Another 60 entries are condensed to 24 paragraphs. Full-page line drawings by William S. Whitney of the major species are generally excellent, and all 103 entries have distribution maps. The introduction discusses the region covered, with helpful maps. There's an index, a glossary and a …

Meristic And Organogenetic Variation In Ruppia Occidentalis And R. Maritima, Robert B. Kaul

School of Biological Sciences: Faculty Publications

Floral meristic and organogenetic variation was sampled in Ruppia occidentalis from an alkaline lake of the Nebraska Sandhills and in Ruppia maritima var. rostrata from a saline, non-Sandhills lake nearby. The androecium is meristically stable, always having two stamens, but the gynoecium is not. Seventy-two percent of the flowers of R. maritima had four carpels and the others had three, and in 80% of inflorescences the two flowers had the same number. In about one-third of inflorescences having dissimilar carpel numbers, the four-carpellate flower was uppermost. The number of carpels in each flower of R. occidentalis ranged from four to …

Molecular Approaches For Control Of Tomato Bushy Stunt Virus, H. B. Scholthof, M. Borja, Thomas Jack Morris, A. O. Jackson

School of Biological Sciences: Faculty Publications

I N this overview strategies are discussed that are currently being tested in our laboratory in an effort to engineer resistance against tomato bushy stunt virus (TBSV) in plants. TBSV is chosen as a model-system since this is an economically important RNA virus that is well characterized at the molecular level and the virus has some interesting and potentially useful features that can be exploited to produce resistant plants. Moreover, we anticipate that the information derived from our studies with TBSV will be applicable in developing resistance to other plant viruses. Some approaches that we are attempting to apply to …

Local Polyploid Variation In The Native Prairie Grass Andropogon Gerardii, Kathleen H. Keeler

School of Biological Sciences: Faculty Publications

The microscale distribution of polyploid variants of the dominant grass big bluestem (Andropogon gerardii) in virgin tallgrass prairie was mapped using flow cytometry. The correlation between DNA content and polyploidy allows the use of flow cytometry for nondestructive determination of polyploidy in intact plants. At Konza Prairie, local plots contained from 0 to 100% hexaploid cytotypes but most showed fine-scale mixing of the polyploid variants. The relationship of cytotype frequency to moisture availability or burning history was nonsignificant

Can Genetically Engineered Crops Become Weeds?, Kathleen H. Keeler

School of Biological Sciences: Faculty Publications

There are significant differences if the distribution of weedy characteristics among weeds, normal plants, and crops. The world’s most serious weeds possess on the average 10 or 11 of these characters, a random collection of British plants have an average seven of the traits, and crop plants only five. For the average crop to become as “weedy” as the average weed, it would need to acquire five weedy traits. Even using the unlikely assumption that those traits are single loci in which a dominant mutation would provide the weedy character, this would require the simultaneous acquisition of five gene substitutions. …

Cupular Structure In Paleotropical Castanopsis (Fagaceae), Robert B. Kaul

School of Biological Sciences: Faculty Publications

The structure and some developmental aspects of the cupules of 22 species of paleotropical Castanopsis are discussed and illustrated. Some species have cupules massively invested with strong, sharp spines, but others are less spiny, and some are nearly smooth. Most cupular armament results from spines produced axillary to the valvular scales and basally adnate to them. Columns of scales straddling the sutures between the cupular valves do not become spines, but the numerous scales elsewhere on the valves become somewhat spiny with age. Dehiscence in the spiny-valved species is mostly along the sutures. The smooth cupules of some species have …

Reproductive Structure Of Lithocarpus Sensu Lato (Fagaceae): Cymules And Fruits, Robert B. Kaul

School of Biological Sciences: Faculty Publications

Seventy-three species were examined for structural and developmental details of the cymules and fruits. The cymules bear one to seven or more flowers and are subtended by one to nine or more bracteoles. Generally, the number of flowers and bracteoles in the pistillate cymules is the same or less than in the staminate ones. Some of the latter have an inner set of bracteoles that could be homologous to the pistillate cupule. Scales are present at anthesis on the cupules of all species examined, but in some species they fail to enlarge, are torn or disintegrate, or fall away as …

Evolution And Reproductive Biology Of Inflorescences In Lithocarpus, Castanopsis, Castanea, And Quercus (Fagaceae), Robert B. Kaul

School of Biological Sciences: Faculty Publications

Of Lithocarpus, Castanopsis, Castanea, and Quercus, only Lithocarpus frequently bears branched spikes suggestive of the primitive condition in the Fagaceae; the other genera sometimes have them in some individuals. Simple and branched spikes can occur on the same tree. Evolution of the simple spike is interpreted as the loss of branching capacity in the branched spikes. The Fagaceae show various transitional stages from perfect, entomophilous to imperfect, anemophilous flowers and from mixed-sex to unisexual spikes. Complete separation of staminate from pistillate function into separate spikes and catkins occurs only in Quercus, which is also the only …

Extrafloral Nectaries On Plants In Communities Without Ants: Hawaii, Kathleen H. Keeler

School of Biological Sciences: Faculty Publications

Since the Hawaiian Islands lack native ants, it was hypothesized that extrafloral nectaries, an ant-related mutualistic trait, should be lacking on native species. Presence of extrafloral nectaries (EFNs) on plants was determined by direct observation and related to vegetation structure and floral composition. Frequency of plants with EFNs was low by all possible comparisons. However, several endemic species had functional EFNs. The hypotheses to explain these anomalies are (1) phylogenetic inertia or (2) mutualism with some other organism than ants.

Vegetation Patterns In Relation To Topography And Edaphic Variation Nebraska Sandhills Prairie, P. W. Barnes, A. T. Harrison, S. P. Heinisch

School of Biological Sciences: Faculty Publications

Detailed studies on soil texture and moisture retention indicate a close association between edaphic features and the distribution and composition of plant communities along topographic gradients at Arapaho Prairie, a typical, semi-arid Nebraska Sandhills prairie. The vegetation characteristics of three major habitat types (ridge, slope, and valley) and several minor subtypes (swale, stable ridge, and eroding ridge) are recognized and quantitatively described. Texture analysis indicates that the soils of dune slopes and ridges are largely azonal and are very coarse with substantially lower fine fractions (silt-clay ~ 13-15%) than soils of the more lowland swale and valley sites where surfact …

Inflorescence Architecture And Evolution In The Fagaceae, Robert B. Kaul, Ernst C. Abbe

School of Biological Sciences: Faculty Publications

First paragraph:

Inflorescence architecture is receiving increasing attention with respect to its role in the life of plants, but much remains to be learned of its effects on pollination and dispersal biology (see Wyatt, 1982). Little is known of the biology of fagaceous inflorescences or of their relationships with the growth or the reproductive patterns of the trees. Most studies (Abbe, 1974; Macdonald, 1979; Fey & Endress, 1983) have concentrated on the nature of the flower clusters (often called dichasia or partial inflorescences) and cupules. Hjelmqvist (1948) and Soepadmo (1972) briefly reviewed the variety of inflorescences in the Fagaceae. Čelakovský …

Comparison Of Old Field Succession On A Tallgrass Prairie And A Nebraska Sandhills Prairie, Mary Bomberger Brown, Shelly L. Shields, A. Tyrone Harrsion, Kathleen H. Keeler

School of Biological Sciences: Faculty Publications

Long held to be reasonably well understood, the process of ecological succession has recently come under attack. The predictability of successional changes has been doubted (Walker 1970), the mechanism of species replacement has been questioned (Connell and Slatyer 1977), and the reality of steady-state (climax) challenged (Botkin and Sobel 1975, Connell and Slatyer 1977, Connell 1978). In particular, several communities are presently recognized as having "cyclic succession" (Ricklefs 1973), in which the process is continually repeating. Such communities include heaths (Watt 1947), prairie pot-hole marshes (Vander Valk and Davis 1978), spruce-fir forests (Sprugel 1976, Sprugel and Bormann 1981), and intertidal …

Legume Distribution And Nodulation In Arapaho Prairie, Arthur County, Nebraska, L. A. Kapustka, J. D. Dubois

School of Biological Sciences: Faculty Publications

Vegetational sampling of the legumes of Arapaho Prairie, located in the southwest portion of the Sand Hills of Nebraska, was conducted in June 1980. Lathyrus polymorphus, Petalostemon purpureum, Psoralea digitata and Amorpha canescens were the leading dominants. The overall density of legumes was 0.309 plants m^-2.

Of eight examined, only Petalostemon villosum and Glycyrrhiza lepidota supported large numbers of nodules. The others including the dominant legumes were unnodulated or had only a few, usually degenerate nodules.

It appears that the legumes are of minor importance in the overall N economy of Arapaho Prairie. Nevertheless since many …

Function Of Mentzelia Nuda (Loasaceae) Postfloral Nectaries In Seed Defense, Kathleen H. Keeler

School of Biological Sciences: Faculty Publications

Mentzelia nuda is a coarse, short-lived perennial of the High Plains of North America. The flowers secrete nectar which serves as an attractant for pollinating bees. Postfloral nectar secretion attracts ants whose presence significantly enhances seed set. This is the first demonstration of advantage to postflowering activity of a floral nectary.

Cover Of Plants With Extrafloral Nectaries At Four Northern California Sites, Kathleen H. Keeler

School of Biological Sciences: Faculty Publications

Percent cover of plants with extrafloral nectaries was investigated in three California habitats with the same physiognomy as habitats previously studied in Nebraska (perennial native grassland, riparian forest, deciduous forest). In contrast to Nebraska where cover of plants with extrafloral nectaries reached 14 percent, no plants with extrafloral nectaries were found in any California transect. Chaparral was also studied; no plants with extrafloral nectaries were found.