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Articles 1441 - 1470 of 1684

Full-Text Articles in Ecology and Evolutionary Biology

Reproductive Ecology Of Two Common Woody Species, Juniperus Sabina And Artemisia Santolinifolia, In Mountain Steppes Of Southern Mongolia, Katrin Ronnenberg Jan 2005

Reproductive Ecology Of Two Common Woody Species, Juniperus Sabina And Artemisia Santolinifolia, In Mountain Steppes Of Southern Mongolia, Katrin Ronnenberg

Erforschung biologischer Ressourcen der Mongolei / Exploration into the Biological Resources of Mongolia, ISSN 0440-1298

The present study describes the reproductive ecology of the prostrate shrub Juniperus sabina and the dwarf shrub Artemisia santolinifolia in dry mountain steppes of southern Mongolia. Whereas stands of the juniper are located at the drought limit of the genus’ distributional range, the genus Artemisia is typical of central Asian drylands. Both species produce large numbers of reproductive organs. For Juniperus sabina, however, only 2.5% of the morphologically intact seeds were found to be viable. Correspondingly, neither seedlings nor saplings were found in the field, and recruitment by reseeding happens at most rarely under the present climatic conditions.

Instead, …


Quantitative Investigations On Bird Communities In Different Habitats In The Orkhon-Selenge-Valley In Northern Mongolia, Tobias Stenzel, Michael Stubbe, Ravčigijn Samjaa, Sundev Gombobaatar Jan 2005

Quantitative Investigations On Bird Communities In Different Habitats In The Orkhon-Selenge-Valley In Northern Mongolia, Tobias Stenzel, Michael Stubbe, Ravčigijn Samjaa, Sundev Gombobaatar

Erforschung biologischer Ressourcen der Mongolei / Exploration into the Biological Resources of Mongolia, ISSN 0440-1298

In the breeding seasons 2001 to 2003, the avifauna of a study area of about 80 km2 in the Selenge Aymag was studied.

The area is characterized by loose groves of elms (Ulmus pumila) and pine trees (Pinus sylvestris), and a chain of barchan dunes which separate the Orkhon valley from the up to 70 m higher situated forest steppe. Steppe species (Stipa spp.) dominate in the south; the northern steppe part is characterized by Caragana bushes (Caragana microphylla, locally C. stenophylla). Between Orkhon Gol and the eastern dunes, dry steppe …


Die Parasitierung Der Luzerne-Blattschneiderbiene, Megachile Rotundata (Hymenoptera: Megachilidae), Durch Physocephala Pusilla (Diptera: Conopidae) In Der Mongolei = Parasitization Of The Alfalfa Leaf-Cutter Bee, Megachile Rotundata (Hymenoptera: Megachilidae), By Physocephala Pusilla (Diptera: Conopidae) In Mongolia, Karsten Seidelmann Jan 2005

Die Parasitierung Der Luzerne-Blattschneiderbiene, Megachile Rotundata (Hymenoptera: Megachilidae), Durch Physocephala Pusilla (Diptera: Conopidae) In Der Mongolei = Parasitization Of The Alfalfa Leaf-Cutter Bee, Megachile Rotundata (Hymenoptera: Megachilidae), By Physocephala Pusilla (Diptera: Conopidae) In Mongolia, Karsten Seidelmann

Erforschung biologischer Ressourcen der Mongolei / Exploration into the Biological Resources of Mongolia, ISSN 0440-1298

Physocephala pusilla Meigen (Diptera: Conopidae) was found to be a dangerous endoparasitoid of the alfalfa leafcutter bee Megachile rotundata F. (Hymenoptera: Megachilidae) in Mongolia. The conopid fly parasitizes adults and causes their early death. In 1989 and 1990, 16% and 15% respectively of the M. rotundata females were found dead in front of the bee shelter. However, the number of bees (females and males) dying in the field is unknown. These bees cause a contamination of the alfalfa fields due to an increase of the conopid population. Therefore, Ph. pusilla becomes a serious problem for the management of M. rotundata …


Natürliche Und Nutzungsbedingte Land- Und Bodendegradationsprozesse, Untersucht Am Unteren Orchon (Nord-Mongolei) = Naturally And Land Use Caused Land And Soil Degradation Processes, Studied At The Lower Orchon (Northern Mongolia), Christian Opp Jan 2005

Natürliche Und Nutzungsbedingte Land- Und Bodendegradationsprozesse, Untersucht Am Unteren Orchon (Nord-Mongolei) = Naturally And Land Use Caused Land And Soil Degradation Processes, Studied At The Lower Orchon (Northern Mongolia), Christian Opp

Erforschung biologischer Ressourcen der Mongolei / Exploration into the Biological Resources of Mongolia, ISSN 0440-1298

Landscape-ecological investigations were carried-out within the forest steppe of Northern Mongolia. The site conditions of the partly by agriculture used area of Cagaan Tolgoj at the Lower Orchon (Aimag Selenge) were analysed in seven test areas. Results of soil analysis are given. The evaluation of soil cover and partly vegetation cover was carried-out with special regard, to degradation phaenomena. It is based on field analysis, measurements during the soil survey and the detection of soil degradation parameter with the help of laboratory analysis. Among naturally and land use caused factors of soil status and of the changing conditions within forest …


Die Gasteromyceten Der Mongolei Und Ihre Bedeutung Für Die Systematik, Chorologie Und Ökologie) = The Mongolian Gasteromycetes And Their Importance For The Systematics, Chorology, And Ecology, Heinrich Dörfelt Jan 2005

Die Gasteromyceten Der Mongolei Und Ihre Bedeutung Für Die Systematik, Chorologie Und Ökologie) = The Mongolian Gasteromycetes And Their Importance For The Systematics, Chorology, And Ecology, Heinrich Dörfelt

Erforschung biologischer Ressourcen der Mongolei / Exploration into the Biological Resources of Mongolia, ISSN 0440-1298

More than fifty species of Gasteromycetes were collected in Mongolia from 1970 to 2002. Five new species in the genera Geastrum, Lycoperdon, Gastrosporium, and Colus were described by Pilát (1972), Kreisel (1975), Dörfelt (1981) and Dörfelt & Bumžaa (1986). The importance of Mongolian Gasteromycetes for few taxonomical, chorological or ecological problems is discussed in this paper, especially for the species Battarraea phalloides, Disciseda arida, D. bovista, D. candida, Gastrosporium asiaticum, Geastrum simplex, G. corollinum (G. recolligens), G. deylii, G. floriforme, G. huneckii, G. hungaricum, G. …


2005 Virginia Wildflower Of The Year: Bloodroot, Sanguinaria Canadensis, W. John Hayden Jan 2005

2005 Virginia Wildflower Of The Year: Bloodroot, Sanguinaria Canadensis, W. John Hayden

Biology Faculty Publications

Bloodroot is an herbaceous perennial that grows from a persistent, branched underground stem or rhizome. Early each spring, while the forest canopy is still bare, each well-developed rhizome tip produces one leaf and one flower stalk. The leaf is kidney-shaped in its overall outline, but it is also divided into a pattern of rounded lobes and sinuses, rendering a complex overall shape. At flowering time, bloodroot leaves form a loose vertically-oriented collar around the flower stalk with the bluish-green lower leaf surface forming the outside of the collar; as the season progresses, the leaves open flat and expand to their …


Circulation, Mixing And The Distribution Of Remineralized Nutrients, Larry P. Atkinson, John Huthnance, Jose L. Blanco Jan 2005

Circulation, Mixing And The Distribution Of Remineralized Nutrients, Larry P. Atkinson, John Huthnance, Jose L. Blanco

CCPO Publications

No abstract provided.


Origin And Evolution Of Large Brains In Toothed Whales, Lori Marino, Daniel W. Mcshea, Mark D. Uhen Dec 2004

Origin And Evolution Of Large Brains In Toothed Whales, Lori Marino, Daniel W. Mcshea, Mark D. Uhen

Veterinary Science and Medicine Collection

Toothed whales (order Cetacea: suborder Odontoceti) are highly encephalized, possessing brains that are significantly larger than expected for their body sizes. In particular, the odontocete superfamily Delphinoidea (dolphins, porpoises, belugas, and narwhals) comprises numerous species with encephalization levels second only to modern humans and greater than all other mammals. Odontocetes have also demonstrated behavioral faculties previously only ascribed to humans and, to some extent, other great apes. How did the large brains of odontocetes evolve? To begin to investigate this question, we quantified and averaged estimates of brain and body size for 36 fossil cetacean species using computed tomography and …


Feasibility Of Mapping Benthic Biotopes In The Hudson River, Nicole P. Maher, Robert M. Cerrato Mar 2004

Feasibility Of Mapping Benthic Biotopes In The Hudson River, Nicole P. Maher, Robert M. Cerrato

School of Marine & Atmospheric Sciences Faculty Publications

Successful management of aquatic resources requires comprehensive maps that identify the spatial distribution and extent of potentially vulnerable habitats and their resident biota (e.g., essential fish habitat). We illustrate a technique that describes submerged landscapes not only in terms of geophysical properties, but also in terms of the resident biotic communities. Biological community distribution was highly correlated with the geophysical provinces initially identified by Bell et al. (2000). However, fewer groups of stations (created mainly by combining provinces) explained almost as much of the variation in benthic community structure and was a better description of the major biotopes in this …


Fascism, Peter Staudenmaier Jan 2004

Fascism, Peter Staudenmaier

History Faculty Research and Publications

No abstract provided.


Mammals Of Carlsbad Caverns National Park, New Mexico, Kenneth N. Geluso, Keith Geluso Jan 2004

Mammals Of Carlsbad Caverns National Park, New Mexico, Kenneth N. Geluso, Keith Geluso

Bulletin of the University of Nebraska State Museum (1924–2023)

Carlsbad Cavern was established as a national park on 14 May 1930, after being designated as a national monument for nearly seven years. The park is located in southeastern New Mexico, and today it encompasses 189.3 km2 (73.1 mi2). Eighty-eight percent of the park lies in the rugged Guadalupe Mountains, while 12% is located on relatively flat land along the base of the mountains. The park contains a variety of habitats ranging from desert scrub at the lowest elevations to coniferous woodlands on the highest summits. Five months after Carlsbad Cavern was declared a national monument, Vernon …


Relationships Between Needle Nitrogen Concentration And Photosynthetic Responses Of Douglas-Fir Seedlings To Elevated Co2 And Temperature, James D. Lewis, Melissa S. Lucash, David M. Olszyk, David T. Tingey Jan 2004

Relationships Between Needle Nitrogen Concentration And Photosynthetic Responses Of Douglas-Fir Seedlings To Elevated Co2 And Temperature, James D. Lewis, Melissa S. Lucash, David M. Olszyk, David T. Tingey

Environmental Science and Management Faculty Publications and Presentations

  • Here we examined correlations between needle nitrogen concentration ([N]) and photosynthetic responses of Douglas-fir (Pseudotsuga menziesii) seedlings to growth in elevated temperatures and atmospheric carbon dioxide concentrations ([CO2]).
  • Seedlings were grown in sunlit, climate-controlled chambers at ambient or ambient+3.5° C and ambient or ambient +180 μmol mol-1 CO2 in a full factorial design. Photosynthetic parameters and needle [N] were measured six times over a 21-month period.
  • Needle [N] varied seasonally, and accounted for 30–50% of the variation in photosynthetic parameters. Across measurement periods, elevated temperature increased needle [N] by 26% and light-saturated …


The Selfish Nature Of Generosity: Harassment And Food Sharing In Primates, Jeffrey R. Stevens Jan 2004

The Selfish Nature Of Generosity: Harassment And Food Sharing In Primates, Jeffrey R. Stevens

Jeffrey Stevens Publications

Animals may share food to gain immediate or delayed fitness benefits. Previous studies of sharing have concentrated on delayed benefits such as reciprocity, trade and punishment. This study tests an alternative model (the harassment or sharing–under–pressure hypothesis) in which a food owner immediately benefits because sharing avoids costly harassment from a beggar. I present an experiment that varies the potential ability of the beggar to harass, and of the owner to defend the food, to examine the effects of harassment on food sharing in two primate species: chimpanzees (Pan troglodytes) and squirrel monkeys (Saimiri boliviensis). For …


A Conceptual Framework For Non-Kin Food Sharing: Timing And Currency Of Benefits, Jeffrey R. Stevens, Ian C. Gilby Jan 2004

A Conceptual Framework For Non-Kin Food Sharing: Timing And Currency Of Benefits, Jeffrey R. Stevens, Ian C. Gilby

Jeffrey Stevens Publications

Many animal species, from arthropods to apes, share food. This paper presents a new framework that categorizes nonkin food sharing according to two axes: (1) the interval between sharing and receiving the benefits of sharing, and (2) the currency units in which benefits accrue to the sharer (especially food versus nonfood). Sharers can obtain immediate benefits from increased foraging efficiency, predation avoidance, mate provisioning, or manipulative mutualism. Reciprocity, trade, status enhancement and group augmentation can delay benefits. When benefits are delayed or when food is exchanged for nonfood benefits, maintaining sharing can become more difficult because animals face discounting and …


The Dynastine Scarab Beetles Of Costa Rica And Panama (Coleoptera: Scarabaeidae: Dynastinae), Brett C. Ratcliffe Dec 2003

The Dynastine Scarab Beetles Of Costa Rica And Panama (Coleoptera: Scarabaeidae: Dynastinae), Brett C. Ratcliffe

Bulletin of the University of Nebraska State Museum (1924–2023)

The 157 species of dynastine scarab beetles that occur in Costa Rica and Panama are comprehensively reviewed. Keys, descriptions, distributions, and notes on biology are provided for all species as well as illustrations and maps. The larvae of Enema endymion, Heterogomphus chevrolati, and Dynastes hercules are described for the first time. Also included are synopses of the higher-level taxa, a glossary, a gazetteer of place names, and a species checklist.

The following new species are described: Cyclocephala alazona, C. enigma, C. labidion, C. marylizae, C. mustacha, C. stockwelli, C. una mas (all Cyclocephalini); Irazua dilicra (Oryctini); Amblyoproctus centroamericanus, Hemiphileurus curoei, …


Book Review Of, Principles Of Terrestrial Ecosystem Ecology., Ruth D. Yanai, Melissa S. Lucash, Phillip Sollins Jun 2003

Book Review Of, Principles Of Terrestrial Ecosystem Ecology., Ruth D. Yanai, Melissa S. Lucash, Phillip Sollins

Environmental Science and Management Faculty Publications and Presentations

Reviews the book "Principles of terrestrial ecosystem ecology" by Francis Stuart Chapin III, Pamela A. Matson, and Harold A. Mooney.


A Research Agenda For Political Personality And Leadership Studies: An Evolutionary Proposal, Aubrey Immelman, Theodore Millon Jun 2003

A Research Agenda For Political Personality And Leadership Studies: An Evolutionary Proposal, Aubrey Immelman, Theodore Millon

Psychology Faculty Publications

Despite major neuroscientific advances in the past two decades and parallel conceptual refinement in evolutionary theory, personality-in-politics inquiry remains adrift, divorced from these broader spheres of scientific knowledge. This paper reviews the neurobiological substrates of three major domains of evolutionary biology and behavioral ecology relevant to political personality assessment and the psychological examination of political leaders; furnishes a context and set of guiding ideas to revitalize the study of the person as biopsychosocial entity in politics; advances a generative theory of personality and political leadership performance; and proposes an agenda for advancing personality-in-politics and leadership inquiry, informed by insights derived …


Reconstructing Cetacean Brain Evolution Using Computed Tomography, Lori Marino, Mark D. Uhen, Nicholas D. Pyenson, Bruno Frohlich May 2003

Reconstructing Cetacean Brain Evolution Using Computed Tomography, Lori Marino, Mark D. Uhen, Nicholas D. Pyenson, Bruno Frohlich

Veterinary Science and Medicine Collection

Until recently, there have been relatively few studies of brain mass and morphology in fossil cetaceans (dolphins, whales, and porpoises) because of difficulty accessing the matrix that fills the endocranial cavity of fossil cetacean skulls. As a result, our knowledge about cetacean brain evolution has been quite limited. By applying the noninvasive technique of computed tomography (CT) to visualize, measure, and reconstruct the endocranial morphology of fossil cetacean skulls, we can gain vastly more information at an unprecedented rate about cetacean brain evolution. Here, we discuss our method and demonstrate it with several examples from our fossil cetacean database. This …


Incorporating Local Knowledge Into Population And Habitat Viability Assessments: Landowners And Tree Kangaroos In Papua New Guinea, Philip J. Nyhus, J Williams, J Borovansky, O Byers, P Miller Jan 2003

Incorporating Local Knowledge Into Population And Habitat Viability Assessments: Landowners And Tree Kangaroos In Papua New Guinea, Philip J. Nyhus, J Williams, J Borovansky, O Byers, P Miller

Faculty Scholarship

No abstract provided.


Dangerous Animals In Captivity: Ex Situ Tiger Conflict And Implication For Private Ownership Of Exotic Animals, Philip J. Nyhus, Ronald L. Tilson, J L. Tomlinson Jan 2003

Dangerous Animals In Captivity: Ex Situ Tiger Conflict And Implication For Private Ownership Of Exotic Animals, Philip J. Nyhus, Ronald L. Tilson, J L. Tomlinson

Faculty Scholarship

The risks associated with tiger attacks on people in the wild are well documented. There may currently be more tigers in captivity than in the wild, but relatively little is known about the risks of injury or death associated with owning and managing captive tigers and other large carnivores. The purpose of this study was to conduct a global assessment of attacks by captive tigers on people, with particular emphasis on cases in the United States. Our analysis of 30 international media sources and additional documents uncovered 59 unique incidents in 1998-2001 in which people were reportedly injured or killed …


A Monographic Revision Of The Genus Platycoelia Dejean (Coleoptera: Scarabaeidae: Rutelinae: Anoplognathini), Andrew B. T. Smith Jan 2003

A Monographic Revision Of The Genus Platycoelia Dejean (Coleoptera: Scarabaeidae: Rutelinae: Anoplognathini), Andrew B. T. Smith

Bulletin of the University of Nebraska State Museum (1924–2023)

This paper presents a taxonomic revision of the genus Platycoelia Dejean (Coleoptera: Scarabaeidae: Rutelinae: Anoplognathini: Platycoeliina). Phylogenetic analyses of all species in the genus were conducted and the biogeography of the genus is discussed. The phylogenetic analysis supports the monophyly of Platycoelia and divides the genus into four major clades. Based on the cladistic analysis, the generic names Callichloris Burmeister, Leucopelaea Bates, and Epicallichloris Gutiérrez are considered synonyms of Platycoelia. Character states supporting monophyletic clades are discussed. Descriptions and keys to all taxa are included.

The genus Platycoelia was revised and now includes 62 species, 19 of which are described …


Bats Of Nevis, Northern Lesser Antilles, Scott C. Pedersen, Hugh H. Genoways, Matthew N. Morton, James W. Johnson, Siân E. Courts Jan 2003

Bats Of Nevis, Northern Lesser Antilles, Scott C. Pedersen, Hugh H. Genoways, Matthew N. Morton, James W. Johnson, Siân E. Courts

University of Nebraska State Museum: Mammalogy Papers

Only one species of bat, Molossus molossus, previously has been documented as occurring on the northern Lesser Antillean island of Nevis. Field research and reviews of existing museum collections have provided documentation based on voucher specimens for an additional seven species occurring on the island — Noctilio leporinus, Brachyphylla cavernarum, Monophyllus plethodon, Ardops nichollsi, Artibeus jamaicensis, Natalus stramineus, and Tadarida brasiliensis. The biological diversity of the chiropteran fauna on Nevis is similar to that found on other islands in the northern Lesser Antilles. Ecologically, this is a simple chiropteran fauna, including one …


Inbreeding, Male Diploidy, And Complementary Sex Determination In The Solitary Wasp Euodynerus Foraminatus, Julie Kozaczka Stahlhut Dec 2002

Inbreeding, Male Diploidy, And Complementary Sex Determination In The Solitary Wasp Euodynerus Foraminatus, Julie Kozaczka Stahlhut

Dissertations

In the insect order Hymenoptera, which includes wasps, bees, and ants, females normally develop from fertilized eggs and are diploid, while males develop from unfertilized eggs and are haploid. Underlying mechanisms of sex determination are more complex and vary among different hymenopteran taxa. One such method is single-locus complementary sex determination, or sl-CSD, in which sex is determined by a single gene locus with many alleles. In species with sl-CSD, diploid individuals that are heterozygous at the sex locus develop as normal females and hemizygous (haploid) individuals as normal males, but diploids homozygous at the sex locus will also develop …


The Importance Of Ethics In Conservation Biology: Let's Be Ethicists Not Ostriches, Marc Bekoff Mar 2002

The Importance Of Ethics In Conservation Biology: Let's Be Ethicists Not Ostriches, Marc Bekoff

Ecology Collection

No abstract provided.


Individual Variation In The Duration Of Territory Occupation By Males Of The Dragonfly Perithemis Tenera (Odonata: Libellulidae), Paul V. Switzer Jan 2002

Individual Variation In The Duration Of Territory Occupation By Males Of The Dragonfly Perithemis Tenera (Odonata: Libellulidae), Paul V. Switzer

Faculty Research & Creative Activity

In the dragonfly Perithemis tenera Say, males defend territories around oviposition sites and defense of a site is critical for reproductive success. This study first demonstrated that individual males varied consistently in how long they defended a particular territory within a day (their “tenure”) and in the quality of the sites they defended. I then investigated a number of factors that may have affected territory tenure and may have led to the observed variation among males. Territory occupations that ended “voluntarily” were significantly longer than those that ended because the male was evicted from his territory. For voluntary desertions, tenure …


Individual Variation In The Duration Of Territory Occupation By Males Of The Dragonfly Perithemis Tenera (Odonata: Libellulidae), Paul Switzer Jan 2002

Individual Variation In The Duration Of Territory Occupation By Males Of The Dragonfly Perithemis Tenera (Odonata: Libellulidae), Paul Switzer

Faculty Research & Creative Activity

In the dragonfly Perithemis tenera Say, males defend territories around oviposition sites and defense of a site is critical for reproductive success. This study first demonstrated that individual males varied consistently in how long they defended a particular territory within a day (their “tenure”) and in the quality of the sites they defended. I then investigated a number of factors that may have affected territory tenure and may have led to the observed variation among males. Territory occupations that ended “voluntarily” were significantly longer than those that ended because the male was evicted from his territory. For voluntary desertions, tenure …


Compensation For Herbivory In Wild Sunflower: Response To Simulated Damage By The Head-Clipping Weevil, Diana Pilson, Karin L. Decker Jan 2002

Compensation For Herbivory In Wild Sunflower: Response To Simulated Damage By The Head-Clipping Weevil, Diana Pilson, Karin L. Decker

Diana Pilson Publications

Herbivore damage is generally detrimental to plant fitness, and the evolutionary response of plant populations to damage can involve either increased resistance or increased tolerance. While characters that contribute to resistance, such as secondary chemicals and trichomes, are relatively well understood, characters that contribute to a plant’s ability to tolerate damage have received much less attention. Using Helianthus annuus (wild sunflower) and simulated damage of Haplorhynchites aeneus (head-clipping weevil) as a model system, we examined morphological characters and developmental processes that contribute to compensatory ability. We performed a factorial experiment that included three levels of damage (none, the first two, …


Stomatal Responses Of Douglas-Fir Seedlings To Elevated Carbon Dioxide And Temperature During The Third And Fourth Years Of Exposure, James D. Lewis, Melissa S. Lucash, David M. Olszyk, David T. Tingey Jan 2002

Stomatal Responses Of Douglas-Fir Seedlings To Elevated Carbon Dioxide And Temperature During The Third And Fourth Years Of Exposure, James D. Lewis, Melissa S. Lucash, David M. Olszyk, David T. Tingey

Environmental Science and Management Faculty Publications and Presentations

Two major components of climate change, increasing atmospheric [CO2] and increasing temperature, may substantially alter the effects of water availability to plants through effects on the rate of water loss from leaves. We examined the interactive effects of elevated [CO2] and temperature on seasonal patterns of stomatal conductance (gs), transpiration (E) and instantaneous transpiration efficiency (ITE) in Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) seedlings. Seedlings were grown in sunlit chambers at either ambient CO2 (AC) or ambient + 180 µmol mol-1 CO2 (EC), and at ambient temperature (AT) or ambient + 3.5° …


Discounting And Reciprocity In An Iterated Prisoner’S Dilemma, David W. Stephens, Colleen M. Mclinn, Jeffrey R. Stevens Jan 2002

Discounting And Reciprocity In An Iterated Prisoner’S Dilemma, David W. Stephens, Colleen M. Mclinn, Jeffrey R. Stevens

Jeffrey Stevens Publications

The Iterated Prisoner’s Dilemma (IPD) is a central paradigm in the study of animal cooperation. According to the IPD framework, repeated play (repetition) and reciprocity combine to maintain a cooperative equilibrium. However, experimental studies with animals suggest that cooperative behavior in IPDs is unstable, and some have suggested that strong preferences for immediate benefits (that is, temporal discounting) might explain the fragility of cooperative equilibria. We studied the effects of discounting and strategic reciprocity on cooperation in captive blue jays. Our results demonstrate an interaction between discounting and reciprocity. Blue jays show high stable levels of cooperation in treatments with …


Vascular Flora Of Van Horn Woods, Plainfield Township, Will County, Il, Joseph Traina Oct 2001

Vascular Flora Of Van Horn Woods, Plainfield Township, Will County, Il, Joseph Traina

Faculty Publications & Research

The vascular flora at Van Horn Woods Park was surveyed during the 1998-2000 growing seasons. This park is a 30 hectare site located in Plainfield Township, Will County, Illi- nois (SE1/4 S27 T36N R9E). A total of 246 taxa, representing 160 genera and 67 fami- lies, were identified within or immediately adjacent to the park. Seventy-one percent of these taxa were native. Four taxa were collected and submitted to the Morton Arboretum as new county records for Will County. The quality of this site as a natural area was also assessed using quantitative methods based on floral composition and diversity. …