First Annual Graduate Student Symposium

Saturday, March 6, 1999, 8:30 AM - 4:30 PM, B102 CLSL
Organized by the Graduate Students in Ecology and Evolutionary Biology (GEEB)
Sponsored by the Program in Ecology and Evolutionary Biology (PEEB)

Goals   Awards    GEEB Background   Acknowledgments    Schedule   Abstracts    Presenters

All talks are by graduate students studying at the University of Illinois. All participants and attendants are cordially invited to a student-faculty mixer immediately following the talks. The mixer will be held in the PSL Greenhouse Conservatory, 1201 S. Dorner Drive. Refreshments will be provided.

• Goals

1. The symposium is an opportunity for students and faculty to gain exposure to graduate student research in ecology, evolution, and related fields.Participation and attendance is encouraged from anyone working in ecology, evolutionary biology, behavior, conservation, environmental sciences, fisheries and wildlife biology, systematics, biogeography, modeling and other related fields.
   
2. All Ph.D and most Master’s students will give a talk a scientific meeting during the course of their program. The symposium is an opportunity for graduate students to gain experience presenting research ideas/results to peers in a formal setting. Top of page

• Awards

Awards will be given in four categories: 1) Best Overall Talk, 2) Best Talk in Ecology and Natural Resources, 3) Best Talk in Evolution and Systematics, and 4) Best Master’s Talk. Presenters may only win an award in one of the previous categories. Announcement of awards will be made at the faculty-student mixer following the symposium.

Judging Criteria:  The first five questions rate the presenter on the content of the talk, while the last two rate  presentation style. For each category the speaker receives a score of 1-10, for a total possible total of 70. Evaluation forms will be sent to the presenters after the scores have been tallied and awards decided. The judging criteria were established by the symposium committee.  The first five questions rate the presenter on the content of the talk, while the last two rate  presentation style. For each category the speaker receives a score of 1-10, for a total possible total of 70. Evaluation forms will be sent to the presenters after the scores have been tallied and awards decided. The judging criteria were established by the symposium committee.

1. How well was the hypothesis or research question defined? Was the speaker specific in mentioning the central goal of the research at the beginning of the presentation?
2. Was the talk coherent and focused?
3. How appropriate is the design of the study? Were the methods clearly defined in the presentation?
4. Were the conclusions well supported? Was the data analysis and interpretation appropriate and in enough detail so that you could follow the speaker?
5. Was the speaker effective in communicating the significance of this work?
6. How was the speaker’s presentation style (poise, voice, eye contact, pacing of talk, etc.)?
7. Were the audio/visuals effective and appropriate? Top of page

• Graduate Students in Ecology and Evolutionary Biology

The symposium is organized by Graduate Students in Ecology and Evolutionary Biology (GEEB). GEEB is a registered student organization at the University of Illinois at Urbana-Champaign. The fundamental goal of this organization is to coordinate and unify the many graduate students in ecology and evolutionary biology on campus. This includes students that have interests in natural resources, wildlife management, modeling, entomology, conservation biology, and related fields. This organization is affiliated with the new Program in Ecology and Evolutionary Biology (PEEB) that is currently being developed at the University of Illinois at Urbana-Champaign.

Besides the organization of this symposium, other GEEB activities include: 1) Invited speakers to discuss NSF/EPA grant writing skills and issues pertaining to PEEB, 2) Coordination of discussion groups in ecology and evolutionary biology, 3) Development of a collection of funded NSF-dissertation improvement grant applications, 4) Organization of social activities such as parties and happy hours.

For more information please contact one of the following:
    President: Dave Chalcraft, 333-5390, chacraf@life.uiuc.edu
    Vice-President: Jeff Steinmetz, 244-2102, jsteinmetz@life.uiuc.edu
    Treasurer: Jennifer Nesbitt, 333-2235, jjnesbit@life.uiuc.edu
    Secretaries: Jason Knouft, 244-4230, knouft@mail.inhs.uiuc.edu
        and Sunshine Vanbael, 333-2235 , vanbael@students.uiuc.edu  Top of page

• Acknowledgments

Sponsorship:  We thank the Program in Ecology and Evolutionary Biology (PEEB) for their generosity in providing funding and resources for this event.
Logistical Support:  Thanks to all those in GEEB who helped with A/V duties, moderated sessions, helped keep coffee and refreshments stocked during the breaks, and helped set up and serve at the mixer. Thanks to Sabrina Russo and Loni Morse for the program cover design. We also thank Lisa Smith for help in assembling the programs. Thanks to Jana Waite for putting together the web page for this symposium.
Judges: We received more volunteers to serve as judges than we could use. Thanks to all faculty who generously volunteered their time (we know how precious it is). A special thanks to those who actually served as judges:  Carol Augspurger, Plant Biology; Jeff Brawn, INHS, Center for Wildlife Ecology; Carla Cáceres, INHS, Center for Aquatic Ecology;Mark David, Natural Resources and Environmental Sciences; Dave Enstrom, INHS, Center for Biodiversity; Ed Heske, NHS, Center for Wildlife Ecology; Geoff Levin, INHS, Center for Biodiversity; Ken Paige, Ecology, Ethology, and Evolution; Chris Phillips, INHS, Center for Biodiversity; Jen Tank, Natural Resources and Environmental Sciences; Dave Wahl, INHS, Center for Aquatic Ecology; Martin Wikelski Ecology, Ethology, and Evolution
Symposium Committee:  Vivien Braslau, Jason Knouft, Jennifer Nesbitt, Dan Rosenblatt, Sabrina Russo, Jeff Steinmetz, Heather Vance, Barry Williams Top of page

•  Schedule of Talks

• Abstracts

1. Factors determining host range of hymenopteran endoparasitoids used for biological control. 1. Factors determining host range of hymenopteran endoparasitoids used for biological control. Marianne Alleyne, Department of Entomology

    Extensive study of insect immune systems has yielded a better understanding of the interplay between behavioral, cellular, molecular and genetic mechanisms used by insects to defend against invaders. This knowledge should be used to predict how natural enemies (novel and coevolved) utilize potential hosts, which will help us plan the safe deployment of natural enemies for biological control.
    Our experimental system consists of two New World pyralid stalk borers, Diatraea saccharalis and D. grandiosella; one Old World pyralid borer, Ostrinia nubilalis; and three Old World microgastrine braconid parasitoids, Cotesia chilonis, C. flavipes and C. sesamiae. The associations between the Diatraea hosts and the Cotesia parasitoids are novel, as the parasitoids have had long associations with taxonomically different but ecologically similar host genera. O. nubilalis was chosen as an outlier.
    Our experiments on host suitability, host hemocyte counts, chronology of encapsulation, etc., indicate that parasitoids that are taxonomically, behaviorally and ecologically very similar may differ in their ability to utilize a host of the same species. Different species of parasitoids may even use different methods (i.e. venom, polydnavirus, ovarian proteins and teratocytes) at different times after parasitization to counter the host immune response. Although C. flavipes was often encapsulated in these hosts, C. chilonis never was. Conversely, similar hosts differed in their response against invaders. C. sesamiae, for instance, never was encapsulated in D. saccharalis but was commonly encapsulated in D. grandiosella.
    Some encapsulation of the parasitoid does not rule out its potential as a biological control agent. These patterns suggest the host range of these parasitoids will be narrow ¾ due to ecological and physiological factors ¾ thus limiting effects on non-target species. However, the lack of consistent patterns also shows that explicit testing will be needed to determine host ranges.
Keywords: insect, immune system, encapsulation, biological control, physiology.  Top of page  Schedule

2. Growth and physiological differences among walleye stocks. Tracy Galarowicz, Department of Ecology, Ethology, and Evolution

    Walleye (Stizostedion vitreum) populations throughout the country are often maintained by supplemental stockings with different source populations. Different stocks within a species may have genetic and geographical variation resulting in physiological differences that affect growth. We estimated juvenile walleye growth, food consumption, and metabolic rates at different temperatures (5-25 °C) of 5 different stocks from Arkansas (2); Missouri; Wisconsin; and Alberta, Canada, to examine how these physiological differences affect growth. Metabolic rates were correlated with temperature and were higher for the southern stocks at the warmer temperatures. Similarly, food consumption rates increased with temperature, and the southern stocks had higher rates at 25 °C. Conversion efficiencies were lower for the southern stocks at the higher temperatures. However, relative growth (g* g^-1* day^-1) showed few differences between the stocks at all temperatures. These physiological differences, as well other potential differences, have strong implications for conservation of walleye stocks, bioenergetics models, and management of introduced stocks.
Keywords: aquatic ecology, physiology, fish stocks, growth  Top of page  Schedule

3. A Molecular Phylogenetic Study of Leguminosae Subtribe Glycininae and G. max (L.) Merr. Jeongran Lee; Advisor, T. Hymowitz; Department of Crop Sciences

    The genus Glycine Willd. belongs to the family Leguminosae, subfamily Papilionoideae, tribe Phaseoleae, and subtribe Glycininae. Since Bentham (1837) established the subtribe Glycinae, there has been controversy in delimiting the boundary of the subtribe. Taubert (1894) and Harms (1906) kept Bentham’s treatment (1865) with the addition of a new genus Eminia. Hutchinson (1964) added Diphyllarium, Nogra, and Teyleria in his 4 subtribes. Verdcourt (1970) added 3 more genera suggesting alliance of Eminia, Pseudeminia, Pseudovigna, Sinodolichos, and Pueraria. Lackey (1977) divided the genera into two groups; Glycine group and Shuteria group based on morphological alliance. Many cytogenetical, chemical, and molecular investigations have been conducted on the cultivated soybean, G. max, because of its economic importance. However, the phylogenetic relationship that would provide useful information to other researchers has been poorly investigated within subtribe Glycininae. In this study, I am investigating the phylogenetic relationships among the Glycininae in order to locate the most closely related genus to the soybean. Intron regions of chloroplast DNA rps16 gene of representatives of the Glycininae were selected, amplified, and sequenced automatically for these purposes. Pairwise sequence divergence values ranged from 0% between Teramnus mollis and T. micans to 10.3% between Mastersia assamica and Neonotonia wightii. Parsimony analysis derived from sequences of this region clearly revealed that the genus Teramnus was closely related to Glycine. In addition, the genus Amphicarpaea was included in the clade comprising Glycine and Teramnus.
Keywords: phylogeny, rps16 gene, intron, Leguminosae, Glycininae  Top of page  Schedule

4. Size-Abundance Relationships in a Neotropical Bird Community. Sabrina Russo, Department of Ecology, Ethology, and Evolution

    Body size is a variable that ecologists have long associated with abundance. This association has been used to describe and explain possible determinants of community structure. Although an inverse relationship between body size and abundance has been documented for many animal taxa, this relationship in birds can sometimes be reversed. Some analyses of birds show a negative relationship between abundance and size and others demonstrate a positive or zero relationship, depending on the spatial and taxonomic scales of analysis. In a 97-hectare mature floodplain forest study plot in the Peruvian Amazon, the slope of the logarithmic relationship between overall avian abundance and body size is -0.35. However, preliminary analyses show that within genera, the largest species tends to be the most abundant, especially in frugivores and granivores. For body size to contribute effectively towards the explanation of community structure, we must understand how the relationship between size and abundance changes at different taxonomic and ecological levels of organization within a community.
Keywords: allometry, body size, population abundance, avian community structure, frugivory  Top of page  Schedule

5. Habitat use of sympatric coyotes and red foxes in central Illinois. Todd E. Gosselink, Timothy R. Van Deelen*, Richard E. Warner. Department of Natural Resources and Environmental Sciences, *Illinois Natural History Survey

    Coyotes (Canis latrans) and red foxes (Vulpes vulpes) persist in similar landscapes, presenting interspecific competition between the two canids. We examined the habitat usage of coyotes, rural and urban foxes to assemble relationships between the co-existing canids. Radio-telemetry was used to attain sequential locations the canids which was combined into an ARC/INFO GIS database attained through GPS cover mapping. Availability of cover types for the animals was determined by using the combined home ranges (95% MCP) of the individual animals. Coyotes used tilled cropland and forested areas more than expected (P<0.05), and used rural residential areas less than expected (P<0.05). Conversely, rural foxes used rural residential and abandoned farmsteads areas more than expected (P<0.05),while the no till and till cropland areas were used less than expected (P<0.05). Urban foxes used low density urban areas, grassland, industrial and residential edges more than expected (P<0.05). In comparing coyote and rural fox locations, abandoned farmsteads and tilled cropland had higher percentage of rural fox locations than coyote locations. Forests and no till cropland had higher percentage of coyote locations than rural fox locations. When the habitat composition of the combined home ranges of rural foxes and coyotes were compared, it revealed coyote home ranges containing more forested and rural grassland areas than rural fox home ranges. Rural fox home ranges comprised of more tilled cropland areas than coyote home ranges. Our research suggests that rural foxes are specifically using habitat types which the coyotes are not using as much, allowing for less interactions between the two canids, a possible preference of the fox.
Keywords: red fox, coyote, central Illinois, habitat, urban fox   Top of page  Schedule

6. The Conservation Status of Eastern Populations of Speyeria idalia (Lepidoptera: Nymphalidae) Inferred From mtDNA Sequences. Barry Williams, Department of Ecology, Ethology and Evolution

    The range of the prairie and open land obligate butterfly Speyeria idalia extends from North Dakota and Colorado east to Virginia and Maine where it is associated with its larval host plant Viola sp. Once common throughout its range, populations in the eastern U.S. have been disappearing at an alarming rate with only two colonies known east of Illinois. One colony, found in western Virginia, is estimated to number around 50 individuals while the second is estimated to be in the thousands. The larger of the two colonies is located on an U.S. Army installation in east central Pennsylvania where current land use practices have the potential to destroy the little remaining Speyeria idalia habitat. Several large colonies remaining in the great plains portion of Speyeria idalia's range make protection under the Endangered Species Act of 1973 unlikely. Previous studies have described Speyeria idalia as morphologically uniform throughout its range, however several ecological and behavioral observations suggest that eastern populations may be a distinct subspecies. The purpose of this study is to examine patterns of genetic differentiation among populations of Speyeria idalia from across its range using mtDNA sequences of the cytochrome oxidase I and II genes. Molecular markers may be able to elucidate patterns of historical biogeography that may not be obvious upon visual inspection of morphological characters. MtDNA sequences show that the Pennsylvania population is a distinct evolutionary lineage that has been separated from the western populations for some time. Genetic differentiation of the eastern population is not due to distance effects alone as populations separated by similar distances in the great plains share the same mtDNA haplotype. These data suggest that eastern populations of Speyeria idalia are worthy of subspecific status and therefore protection under the Endangered Species Act.
Keywords: conservation genetics, phylogeography, butterflies, Endangered Species Act  Top of page  Schedule

7. Resistance to plant invasion: factors affecting the success of garlic mustard. Julie Beckstead, Deptartment of Plant Biology

    Garlic mustard (Alliaria petiolata), a biennial herb, is rapidly invading native herbaceous communities of eastern deciduous forests. This study examines which microhabitat factor(s) offer resistance to invasion by limiting resources for garlic mustard’s reproduction and subsequent recruitment. In a central Illinois forest, 1-yr rosettes were transplanted randomly into 100 1 m2 plots. Each microhabitat was characterized by measuring both its abiotic (light, litter cover, and soil nutrients) and biotic (species richness, total plant cover, and species diversity) factors. Site resistance was quantified by the relative success of garlic mustard (total fruit number and subsequent recruitment). Results from a multiple regression showed that abiotic factors, predominantly light availability and soil nitrogen, played a larger role than biotic factors in determining total fruit number. However, high fruit production alone did not ensure recruitment success. Summer light availability was also a key factor in the survival of offspring to 1-yr rosettes. Overall, the regression models explained a relatively small amount of the variance in site resistance; indicating that unexamined factors are operating as well. Light availability and soil nitrogen are the examined factors offering site resistance to invasion by affecting garlic mustard reproduction and its subsequent recruitment. Although this study shows that microhabitats with specific characteristics can resist invasion by garlic mustard, the spatial pattern and relative abundance of these resistant and nonresistant microhabitats may result in a different invasion outcome in the long-term.
Keywords: plant invasion, Alliaria petiolata, microhabitat, community ecology  Top of page  Schedule

8. What stimuli are associated with starvation that modulate rate of honey bee behavioral development?. David J. Schulz, Department of Entomology

    Severe food shortage causes precocious foraging in honey bee colonies, but it is not known how bees perceive starvation conditions. We examined three potential stimuli that may mediate this effect: volatile starvation odors, the absence of food stores in honeycomb, and changes in social interactions due to starvation. No evidence of volatile starvation odors was detected: rate of behavioral development for well-fed individuals exposed to air from a starved colony was similar to bees in a fed colony, but significantly different than bees in a starved colony. No effect of empty honeycombs was detected: rate of behavioral development for well-fed individuals in a starved colony was similar to that of bees in a fed colony, but significantly different than bees in a starved colony. Social interactions were monitored in both starved and well-fed colonies in observation hives. Analyses of social behaviors including trophallaxis, begging, and antennating will be used to determine whether information about starvation is communicated via worker-worker interactions.
Keywords: division of labor, behavioral development, colony integration, starvation, Apis mellifera  Top of page  Schedule

9. Speciation studies in the Percina subgenus Swainia (Percidae: Etheostomatinae). Thomas J. Near, Department of Ecology, Ethology and Evolution

    Hypotheses concerning modes of allopatric speciation make explicit predictions regarding patterns of phylogenetic and biogeographic diversification. This investigation will test allopatric speciation models using phylogenetic and biogeographic information for the subgenus Swainia, a monophyletic group of four described species in the genus Percina. Complete gene sequences of the mitochondrially encoded cytochrome b have been collected from all species of Swainia, including individuals from multiple populations of P. phoxocephala and P. nasuta. Patterns of nucleotide variation were investigated and phylogenetic relationships were estimated using maximum parsimony, maximum likelihood, and distance optimality criteria. Heterogeneity of nucleotide substitution rate was examined using both maximum parsimony relative rate tests and a likelihood ratio test. Inferred phylogenetic relationships, biogeographic patterns, and relative amounts of nucleotide divergence are used to develop hypotheses of speciation in Swainia.
Keywords: darters, speciation, mitochondrial DNA, phylogeny, historical biogeography  Top of page  Schedule

10. Abundance and nesting success of Acadian flycatchers (Empidonax virescens) in Illinois as a response to fragmentation at different spatial scales, and vegetation structure and composition. Leonardo Chapa, Department of Natural Resources and Environmental Sciences

    Habitat fragmentation has been identified as one of the major threats to wildlife. Corridors (linear features of vegetation that connect forest tracts) have being proposed as a management strategy for fragmented landscapes. Since corridors offer possible advantages, as well as disadvantages, there is controversy among scientists on their usefulness. I censused Acadian Flycatchers and measured their nesting success, 1993-1996. Abundance of Acadian Flycatchers in floodplain forest corridors (n = 19) in the Cache Bioreserve in southern Illinois increased with corridor width (range 100-3000 m), and reached an asymptote at about 500m. Daily nest predation rates (n = 600+) decreased as a negative exponential function of corridor width, but levels of cowbird parasitism were unrelated to corridor width. I am currently investigating how forest fragmentation at multiple spatial scales (within forest, within landscape, and among landscapes) influences abundance and nesting success of Acadian Flycatchers. I will also test the alternative hypothesis that vegetation structure and composition may be the most important factor determining nesting success and populations. I will test this by measuring the concealment of the nest itself, complexity and heterogeneity of vegetation in the area around the nest, and the kind of forest in which the nests are located (tree species diversity, structural complexity). This will be the first study to show that in order to reduce the impact of fragmentation on migratory birds, management strategies should consider the individual effects of multiple scales of fragmentation and that conservation efforts should be focused on large scales.
Key words: forest fragmentation, corridor width, differential spatial scales, neotropical migratory birds, nest predation, brood parasitism  Top of page  Schedule

11.Cost of habitat selection in prairie voles. Y. Kirk Lin, Department of Ecology, Ethology, and Evolution

    The ideal free distribution model of Fretwell and Lucas (1970) assumed that habitat selection was without cost. The cost of habitat selection can be incorporated into the model as the fitness loss while abandoning home range in a habitat and colonizing another habitat. The cost of accepting a new home range in a different habitat should inflate the value of the original habitat to compensate for the fitness lost. In an experimental landscape, we measured the cost of habitat selection in prairie voles using isodar analysis (Morris 1987). This is the first empirical study testing the modified IFD model. The result confirmed cost of habitat selection did inflate the value of the original habitat and produce an isodar with a lower intercept. Furthermore, the costs of habitat selection was negatively density dependent. The mechanisms underlie the costs of habitat selection remain unclear.
Keywords: habitat selection, ideal-free distribution, isodars  Top of page  Schedule

12. The structure and function of trees in a warmer and drier future. Hafiz Maherali, Department of Plant Biology

    Future increases in air temperature resulting from anthropogenic activities will lower humidity and increase the water vapor pressure deficit (VPD) of the atmosphere. Such changes in climate have the potential to alter plant biomass allocation patterns. Established theory predicts that trees decrease their investment in leaves relative to water-conducting tissue in the stem (sapwood) as VPD increases. Using published values for conifers we show that the ratio of leaf / sapwood area (AL/AS) decreases significantly with increasing VPD only in Pinus species and not in Abies, Pseudotsuga, Tsuga and Picea. Water relations data indicate that pines adjust to increasing atmospheric vapor pressure deficit by altering aboveground morphology while non-pine conifers may change the properties of the water-conducting elements. The decrease in AL/AS and an associated shift in biomass allocation from foliage to stems with higher VPD suggests that pines will expend more photosynthate supporting structural mass in the future than their contemporary counterparts. The increased investment in sapwood at the expense of foliage under warmer, drier conditions and the carbon cost of supporting sapwood respiration may offset part of the CO₂ fertilization effect on plant growth.
Key words: biomass allocation, climate change, net primary production, vapor pressure deficit, xylem function  Top of page   Schedule

13. Effects of area and age of habitat patches on nesting success in grasslands. Jeffery W. Walk, Eric L. Kershner, and Richard E. Warner, Department of Natural Resources & Environmental Sciences

    Appropriate design and management of grassland reserves is important to ensuring these areas serve as "source" populations, where a surplus of offspring are produced for immigration and recolonization of neighboring habitats. From 1996 to 1998, we monitored nesting success in grassland birds, primarily dickcissels (Spiza americana) and eastern meadowlarks (Sturnella magna), on managed grasslands 3-120 ha in southeastern Illinois. We found a significant effect of habitat area on attracting certain grassland species (i.e., area sensitivity), but no relationship between area and nesting productivity. Predation within established grasslands (sods >10 years) appears greater compared to younger fields (sods <3 years) of similar size, with evidence this is due to higher snake populations in older habitats; evidence at nest bowls suggests mammals are the important predators on smaller, younger grasslands. Overall, nest success was highly variable among grasslands and among years. Using undisturbed, "short-term" (<5 year), shifting grasslands (similar to production set-aside areas) near large core grassland reserves appears to be a useful technique for increasing productivity of species that invade such habitats quickly.
Keywords: grassland birds, area effects, colonization, predation, agroecosystems  Top of page  Schedule

14. A Contradiction of Cope’s Rule Using an Extant Continental Biota. 14. A Contradiction of Cope’s Rule Using an Extant Continental Biota. Jason H. Knouft, Department of Ecology, Ethology, and Evolution

    Change in body size within an evolutionary lineage over time has been under investigation since the synthesis of Cope’s Rule, which states that there is a tendency for groups of organisms to evolve larger bodies. Fossil evidence for several taxonomic groups has been examined in relation to this theory and have either supported Cope’s rule or failed to show any pattern in the evolution of size. However, no studies have investigated the evolution of body size within extant, regional groups. Using phylogenetic relationships of extant species, I show that the evolutionary trend for body size in North American fishes contradicts Cope’s Rule: seven (containing ~75% of North American fishes) of nine families exhibit an evolutionary trend toward a decrease in size. I also show that the most diverse families do not display the predicted increase in size variation as the lineage radiates.
Keywords: Cope’s rule, body size, evolution, fish  Top of page  Schedule

15. Phytic acid as a resistance factor against an insect herbivore. Ellen S. Green, Department of Entomology

    The interaction between wild parsnip (Pastinaca sativa), an introduced biennial species, and the parsnip webworm (Depressaria pastinacella), its principal herbivore, is one of very few natural systems in which quantitative estimates have been made of the selective impact of an insect herbivore on the chemistry of its host plant. Previous studies of this system have concentrated on variation in content and composition of furanocoumarins, plant secondary metabolites that serve as resistance factors against the parsnip webworm. The focus of my research is to determine whether variation in the content and composition of plant primary metabolites (protein, vitamins, and minerals), by virtue of their nutritional impact on insects, affects activity in parsnip webworms cytochrome P450 monooxygenases, enzymes utilized to detoxify hostplant furanocoumarins .
    Like most herbivorous insects, the parsnip webworm depends on its foodplant for most of its dietary requirements. It is possible that low nutrient quality of a hostplant may detrimentally affect cytochrome P450 function in this insect and thus compromise its ability to utilize a plant as a food source. In that P450s are heme-based enzymes, it is not unreasonable to suppose that primary metabolites that contain iron or affect iron availability may play a crucial role in maintaining P450 function. One such compound, phytic acid, is an iron chelator found in the developing seeds of P. sativa. Fruits of parsnip plants vary in content of phytic acid, often exceeding 1% fresh weight. In the presence of xanthotoxin, a linear furanocoumarin found in parsnip, phytic acid significantly reduced xanthotoxin metabolism in caterpillar midgut homogenates by 2.5 fold (60%). In addition, relative growth rates, relative consumption rates, and efficiency of conversion rates were all significantly reduced when caterpillars fed on an artificial diet containing phytic acid as compared to controls.
    For oligophagous species, adopting a control strategy based on primary metabolite quality can lead to improved yields, reduced risks of the acquisition of pest resistance, and reduced impacts on nontarget species compared with conventional pesticide treatment.
Keywords: phytic acid, resistance factors, cytochrome P450, Oecophoridae  Top of page  Schedule

16. 16. Tharu Cultures, Pahari Cultures, and Natural Resource Use in the Far Western Tarai Region of Nepal. Bill Hechler, Department of Natural Resources and Environmental Sciences

    The Tarai region of Nepal is the portion of the Gangetic plain lying within Nepal’s southern border. Since the near-eradication of malaria in the 1960s, the Tarai has undergone heavy migration of Nepali-speaking hill Hindus (‘Pahari,’ hill people) into heavily forested areas previously inhabited only by Tharu tribal people. This projects examines the natural resource use patterns of households of each of four populations: Isolated Tharu, Tharu near Pahari, Pahari near Tharu, and Isolated Pahari. Results show that the Tharu and Pahari are quite similar on 10 of the 33 parameters considered. Few (4) of the differences between Tharu and Pahari styles of natural resource use are effects of ethnicity itself. Geographic factors account for 13 of the 23 differing parameters. Acculturation is identified as a factor in 4 of the parameters, and 2 are due to local cultural factors. This suggests that ethnographic studies of natural resource use that fail to consider geography, acculturation, and local cultural factors probably fail to account correctly for most of the actual variation.
Keywords: Tharu, Pahari, agriculture, forestry, Nepal  Top of page  Schedule

17. The potential of Doppler surveillance radars for studying bird movements. Robert H. Diehl, Ronald P. Larkin*; Department of Ecology, Ethology, and Evolution, *Illinois Natural History Survey

    In the mid 1990’s, a network of over 160 Doppler radars was established to aid in weather forecasting across the U.S. As a research tool, these radars also happen to be capable monitors of avian movements aloft and often reveal striking patterns of such movement at varying spatial scales. On smaller, local scales, radars demonstrate great potential as a conservation tool by identifying and quantifying the use of stopover habitat for both passerines and waterfowl. On regional or national scales, data combined from several radars have provided a unique perspective of migratory corridor use by waterfowl and should allow us to characterize the broad front of passerine migration, especially as birds confront large geographic barriers such as the Great Lakes or barren terrestrial habitats. These visually appealing radar data also beg application in conservation education. With the increasing popularity of recreational bird watching and with Doppler radar as a trendy and familiar feature of weather forecasts, suitable popular media may be favorable to brief coverage of migratory events. Such outlets may provide a conduit for conservation messages that reach large segments of the public.
Keywords: songbird, waterfowl, migration, radar, scale  Top of page  Schedule

18. Casuarina-infective Frankia is localized near Casuarina cunninghamiana trees in Jamaica. Jeff F. Zimpfer, Department of Natural Resources and Environmental Sciences

    Soil was sampled using a linear, systematic series of 10 x 10 m plots extending from the stems of three Casuarina cunninghamiana trees to a distance of 100 meters. The C. cunninghamiana trees were growing on the windward coastal plain of Jamaica. Soil samples were bioassayed to estimate the number of infective units (I.U.) of the symbiotic diazotroph Frankia cm-3 soil, using native Myrica cerifera and exotic C. cunninghamiana as Frankia traps. M. cerifera is common in Jamaica’s eastern mountains at elevations between 1,000-2,000 m and was not present within 50 km of the study site. C. cunninghamiana is commonly planted in Jamaica, naturalized in coastal areas and found from sea level to 300 m. Casuarina-infective Frankia is localized around its host species. Whereas Myrica-infective Frankia seems to occur saprophitically and independently of host presence throughout this site. Casuarina-infective Frankia occurred only within the first 20 m of the Casuarina stems (1-10 m: 88-19,392 I.U. cm-3 soil, 10-20 m: 0-3,063 I.U. cm-3 soil). However, Myrica-infective Frankia was found in all of the plots (235-11,796 I.U. cm-3 soil). Microsymbiont characterisation from both hosts indicate that Casuarina is nodulated by a different group of Frankia strains in the same taxonomic group as other Casuarina-infective Frankia found outside of Australia. Homogenates of C. cunninhamiana leaves and stems increased the number of I. U.’s of Frankia CjI82 001 inoculated and incubated for three months in an artificial soil. Additionally, leaf and stem homogenates incubated moist with a Jamaican soil counteracted the inhibitory effects of soil inoculum and moisture on Frankia infectivity with incubation. Thus, it seems that C. cunninghamiana is able to favor its specific microsymbiont in the soil.
Keywords: Frankia, Casuarina, Myrica, symbiosis, N-fixation   Top of page  Schedule

19. Biotic interactions in a physically dynamic Arizona stream. Jon D. Hoekstra, Department of Ecology, Ethology, and Evolution

   Argia sabino Garrison, known only from three localities worldwide, is seasonally abundant at Sabino Creek, Arizona. Larvae inhabit pools that provide an aquatic refuge during an annual period of stream drying. To assess potential threats to Argia sabino (hydrological alteration, exotic species) and investigate the species’ larval ecology, a field study was conducted in the spring and summer of 1997. Relationships between several pool habitat factors and adult and larval A. sabino densities were investigated. Early instar larvae of A. sabino were indistinguishable from those of Argia pima. Thus the response variable in larval density analyses was the combined density of these congeners. Densities of A. sabino and A. pima larvae were reduced threefold in pools with fish (Gila intermedia, a native cyprinid) and exotic crayfish (Orconectes virilis). Adult A. sabino densities were also dramatically reduced in the presence of fish and crayfish. Concurrent with studies on Argia larvae, we also studied spatial and temporal patterns in the overall pool benthos (algae, macroinvertebrates). Taken together, our findings suggest that: 1) large consumers (crayfish and fish) strongly regulate all elements of the pool benthos in spring and early summer at Sabino Creek, 2) biotic interactions intensify with physical contraction of pools in late spring and early summer, and 3) the effect of exotic crayfish may be intensified in spring and early summer by juvenile recruitment at this time. Thus, physical dynamics and life history features of dominant species interact to regulate the pool benthos at Sabino Creek. Our findings contradict the general assertion that physical dynamics cancel out biotic interactions in frequently disturbed systems. To the contrary, there is evidence from a wide range of systems that physical changes often lumped together as "disturbances" by ecologists intensify certain classes of interactions and relax others.
Keywords: predation, intermittent stream, exotic species, Odonata, conservation  Top of page  Schedule

20. Effect of variation in algal diet on life-history response of larval green treefrogs. 20. Effect of variation in algal diet on life-history response of larval green treefrogs. Vivien Braslau, Department of Natural Resources and Environmental Sciences, University of Illinois and Savannah River Ecology Laboratory

    A field experiment was conducted to determine the growth response of the green treefrog, Hyla cinerea, when raised on several types of dominant algae of the littoral zone. The central hypothesis of this research was that tadpole growth and metamorphic responses depend upon the type of dominant algae that tadpoles consume. Tadpoles that consumed the blue-green alga Chroococcus had a faster growth rate and a larger mass at metamorphosis when compared to tadpoles that consumed the other natural food treatments. Also, across all treatments, growth rate was not significantly correlated to mass at metamorphosis. The food that provided fast growth did not always result in the highest mass for metamorphosing tadpoles. This suggests that there may be essential substances in food that are important for mass retention at transformation. Comparisons of these results to the predictions of the Wilbur-Collins model of amphibian metamorphosis indicate that natural populations may not follow predictions of the model. Experiments that only manipulate food levels may not mimic the complexity of food interactions in the natural environment, suggesting that the differential effects of food quality on tadpole performance should be incorporated into life-history models.
Keywords: blue-green algae, periphyton, tadpole, pond, field experiment  Top of page  Schedule

 21. Fine root turnover and belowground carbon storage in a model loblolly pine ecosystem exposed to elevated CO₂ and temperature. Kate George, Department of Plant Biology

    Increases in fine root production and microbial biomass under elevated CO₂ could increase belowground carbon storage, whereas increased respiration from elevated temperatures could reduce this rate of storage. To test this hypothesis we grew loblolly pine in growth chambers maintaining two temperature levels ("low" 15-25^oC and "high" 20-30^oC), and two CO₂ concentrations ("ambient" 360 and "elevated" 700 ppm). Seedlings grew into a volume of soil which allowed the roots to grow unrestricted. After the plants were five months old, soil cores were taken at four intervals over an eight-month period for analysis of root and microbial biomass. Fine root biomass was greatest in elevated CO₂ (when compared to ambient concentrations) and high temperature treatments (p = 0.05) in later time intervals. There was no effect of the treatments on microbial biomass, which decreased consistently over the sampling period (p < 0.01). A significant interaction of soil respiration with CO₂ and temperature (p = 0.01) resulted in lower respiration rates in the elevated CO₂ treatment compared to the ambient treatment in "high" temperatures, and vice versa in the "low" temperature treatment. Therefore there was greater carbon storage belowground through stimulation of fine root growth in elevated CO₂, which was not reduced by increased respiration rates in the high temperature treatment.
Keywords: carbon budget, climate change, decomposition, mortality, production  Top of page  Schedule

 22. Elevational and Life Zone Variation in the Abundance and Diversity of Seed-Harvesting Leaf Litter Ants (Hymenoptera: Formicidae) in Costa Rica. Duane D. McKenna, Department of Entomology

    To better understand how predation on seeds of tropical forest plants by ants might vary with elevation, I sampled leaf litter arthropods at 17 sites between 1000 and 1700 meters in elevation on the Pacific and Caribbean Slopes of the Cordillera de Tilaran in Northwest Costa Rica. Samples consisted of .25m² of leaf litter from which invertebrates were extracted by sieving and then sorting under a dissecting microscope. I recovered a total of 475 ants representing at least 75 morphospecies in 18 genera of at least four subfamilies. Many other arthropods were also collected. Total ant abundance as well as species richness declined in the samples as elevation increased. Surprisingly, I recovered only nine ants in three genera known to include seed-harvesters (Atta, Pheidole, and Solenopsis), all from the Pacific Slope. "Cafeteria-style" seed offerings in several montane forest types further demonstrated the relative infrequency of seed-harvesting ants in these forests. These findings contrast strongly with those from lowland sites studied by other investigators where densities of seed-harvesting ants were near 100 per m². It is possible, but unlikely, that my study methods missed significant numbers of twig-nesting Pheidole and Solenopsis species that may have been seed-harvesters. Though based on relatively few samples these results suggest that ants may be far less important seed harvesters in the montane forests of the Cordillera de Tilaran than in warm transition premontane wet tropical forests (and other lowland tropical rain forest types). As a result, the dynamics of montane forest seed banks may be much more heavily influenced by rodents and other sources of seed harvesting than lowland rain forests.
Keywords: leaf-litter, ants, seed-harvesting, arthropods, Costa Rica   Top of page  Schedule

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Updated 02/12/99