Ecology and evolutionary biology.
Vice-chair: Clifford Ochs, University of Mississippi
Hunter Henry Executive Room 8
1:30 AVIAN RESPONSES TO PRESCRIBED FIRE AND SELECTIVE HERBICIDES IN INTENSIVELY MANAGED PINE OF MISSISSIPPI
Raymond Iglay (1*), B. D. Leopold (1), L. W. Burger, Jr. (1), and D. A. Miller (2), (1) Mississippi State University, Mississippi State, MS 39762 and (2) Weyerhaeuser Company, Columbus, MS 39704
With limited knowledge on the independent and combined effects of burning and herbicides on avian communities in mid-rotation loblolly pine (Pinus taeda) plantations, it is essential to understand their interactions to enhance silviculture management for sustainable forestry. We investigated long-term effects of prescribed fire and selective herbicides on avian communities in thinned, intensively managed loblolly pine through 2, 3-year burning rotations in Mississippi using 4 treatment regimes (burn, herbicide, burn*herbicide, control). Seventeen of 47 species with > 5 observations/year revealed heterogeneous use of each treatment within nesting guilds with most influence in burn*herbicide and control treatments. Mean total bird abundance and total avian conservation value decreased from one year pre-treatment until one year post second burn when they began to increase with greatest abundance and priority score in burn*herbicide plots. Mean species richness did not significantly differ among treatments across years but increased across all treatments beginning one year post second burn. Avifauna would generally benefit from use of prescribed fire and selective herbicides, particularly species of high conservation concern in the southeast. However, treatment regimes should vary across a landscape to offer a myriad of vegetation types to benefit multiple species and nesting guilds.
1:45 CYTOTOXICITY AND GENOTOXICITY OF BENZO[a]PYRENE AND ITS ENZYMATIC DEGRADATION INTERMEDIATES IN HACAT AND A3 CELLS
Xiaoke Hu*, Yi Zhang, Xueheng Zhao, and Huey-Min Hwang, Jackson State University, Jackson, MS 39217
Benzo[a]pyrene (BaP) is listed as a priority pollutant by the US Environmental Protection Agency. In the present study, BaP was oxidized with a Trametes versicolor laccase that was immobilized on functionalized kaolinite particles, and the cytotoxicity and genotoxicity of BaP and its degradation intermediates were measured in human HaCaT keratinocytes and A3 T lymphocytes. Cytotoxicity was assessed with fluorescein diacetate (FDA) uptake, while the alkaline Comet assay measured the genotoxicity, using tail moment, tail DNA content, and tail length as metrics for quantifying DNA damage. Based on the assumption that the oxidation reaction was first order, the half life ([t.sub.1/2]) for the oxidization of BaP by immobilized laccase was computed to be 58.5 hr. After 87 hr of oxidation, 20 [micro]M of BaP decreased to 9.6 [micro]M. HPLC analysis identified 1,6-benzo[a]pyrene quinone (1,6-BaQ), 3,6-benzo[a]pyrene quinone (3,6-BaQ), and 6,12-benzo[a]pyrene quinone (6,12-BaQ) among the oxidation products. Most treatments of HaCaT cells and A3 lymphocytes with BaP or its quinone intermediates resulted in significant decreases in viability (P<0.05); dose-dependent decreases in cell viability were detected at concentrations of 0.1, 1 and 5 [micro]M. While treatment of HaCaT cells with as little as 0.1 [micro]M 6,12-BaQ caused significant DNA damage, DNA damage was detected in HaCaT cells only with 1 and 5 [micro]M 1,6-BaQ and 3,6-BaQ and 5 [micro]M BaP. In Comet assays conducted with A3 lymphocytes, all three quinone intermediates caused significant increases in tail DNA content at 1 and 5 [micro]M. The results indicate that immobilized laccase is capable of degrading BaP, but several of those biodegradation products caused significant DNA damage in human cells.
2:00 DO ABUNDANCE AND DISTRIBUTION EXPLAIN YEAR-TO-YEAR INCONSISTENCIES IN BIRD-LANDSCAPE RELATIONS?
Samuel Riffell (1*) and Kevin Gutzwiller (2), (1) Mississippi State University, Mississippi State, MS 39762 and (2) Baylor University, Waco, TX 76798
Modeling bird-landscape relations is a commonly-used method for identifying and describing relationships between birds (or other animals) and large-scale habitat features. However, modeled relations for a particular species are often inconsistent from yr-to-yr (i.e., specific landscape features are important some years, but not others). The causes of inter-annual inconsistency have not been identified. We predicted more consistent bird-landscape relations for (1) species with high abundance and/or wide distributions; (2) species with smaller fluctuations in abundance and distribution; and (3) species with positive regional population trends. We built logistic (presence-absence) bird-landscape models for 72 species of birds in the Appalachian Mountains and calculated model consistency over a 5-year period. Before testing our predictions, we adjusted model consistency for effects of model selection uncertainty and model complexity, and these factors explained a large proportion of the variation in model consistency. Model consistency increased slightly with species' abundance, but we found no evidence that population fluctuations or regional trends influenced model consistency. Thus, management decisions and descriptions of landscape relations for species with low abundance should be based on as many different years of data as possible. However, we show that uncertainty involved in the model selection process contributes heavily to inter-annual model consistency. Our results highlight the need for continued research about improving model selection techniques and reducing methodological sources of model selection uncertainty.
2:30 FERAL HOGS IN MISSISSIPPI: HABITAT SELECTION AND SURVIVAL
Clay Hayes*, Samuel Riffell, Richard B. Minnis, and Brad D. Holder, Mississippi State University, Mississippi State, MS 39762
Feral hogs have the potential to negatively impact native wildlife and sensitive plant communities, and they have steadily increased their range since their introduction into North America. We examined home range, habitat use, and survival of feral hogs in central Mississippi from April 2005 through April 2006 using radio telemetry. Habitats with dense vegetation were very important in home range placement (2nd order habitat selection) with selection favoring seasonally-flooded old fields, followed by old fields and managed openings, during the dry season. During the wet season, old field habitats were still preferentially-selected followed by agricultural fields, but flooded old fields were not preferentially-selected. For 3rd order habitat selection (within the home range), hogs preferentially used old field and managed openings during the dry season. All habitat types were used randomly within home ranges during the wet season. Seasonal differences in survival were also apparent as the best approximating model was a reduced 2-season model with seasonal survival rates for the dry and wet seasons being 80.8% and 41.4%, respectively. Sex and initial weight did not affect survival. The major cause of mortality was hunting (12 of 15 deaths). Seasonal differences in habitat selection and were apparently caused flooding of preferred habitats, food availability and hunting pressure. Future management activities should focus on hunting hogs and protecting key habitats at sensitive times of the year.
2:45 PARASITISM OF SABAL MINOR BY CARYOBRUCHUS GLEDITSIAE IS INTRODUCED IN MISSISSIPPI.
Robert Hamilton*, Chaz Seyfarth, April Jones, Constance Washington, and Chasity Kent, Mississippi College, Clinton, MS 39058
Caryobruchusgleditsiae, the palm seed Bruchid weevil, infects monocot plants throughout the southeast. We observed the infestation of Sabal minor (dwarf palmetto) in plants in Boyle, Mississippi. The weevil lays eggs on developing seeds. Upon hatching, weevil larvae burrow into the seed and consume the seed. We observed over 90% seed mortality on plants in Boyle, MS. We surveyed other populations of S. minor in Mississippi. None of the natural populations showed any indication of infection. One other cultivated population was infected. Infestations appear to be imported. We recommend that the inflorescences of cultivated S. minor be removed to prevent the spread of C. gleditsiae in Mississippi, particularly the spread into natural populations, where infestations could be devastating.
3:00 THE EFFECT OF NUTRIENT LEVELS ON GENDER EXPRESSION IN GAMETOPHYTES OF CERATOPTERIS RICHARDII.
Robert Hamilton*, Heather Kelly, and Gary L. Williams, Mississippi College, Clinton, MS 39058
Ceratopteris richardii, Horned Fern, occurs in southern Louisiana and southern Alabama. Gametophytes of this species possess two distinct morphologies; large hermaphrodite and a small male. The small male morphology develops only in the presence of other gametophytes in vitro. The appearance of small males in multispore cultures in vitro is called the antheridiogen response. C. richardii gametophytes were cultured in a full nutrient medium, 1/10,000, 1/100,000, 1/1,000,000 and zero nutrient on standard agar plates. Gametophytes grew to sexual maturity on all plates within 13 days of inoculation onto plates. A reduction in gametophyte size and a reduction in the expression of the male gender were observed as nutrient levels declined. The antheridiogen response may be a response that only occurs in high quality (high nutrient) microhabitats.
3:15 COMPARATIVE POPULATION DYNAMICS OF PEROMYSCUS LEUCOPUS IN NORTH AMERICA: A SPATIAL GRADIENT OF CLIMATE, ACORN PRODUCTION, AND DENSITY DEPENDENCE
Guiming Wang (1*), Jerry O. Wolff (2), Stephen H. Vessey (3), Norman A. Slade (4), Jack W. Witham (5), Joseph F. Merritt (6), and Malcolm L. Hunter, Jr. (7), (1) Mississippi State University, Mississippi State, MS 39762, (2) University of Memphis, Memphis, TN 38152, (3) Bowling Green State University, Bowling Green, OH 43403, (4) University of Kansas, Lawrence, KS 66045, (5) University of Maine, Arrowsic, ME 04530, (6) Ligonier, PA 15658, (7) University of Maine, Orono, ME 04469
Temporal variation in population size is regulated by density dependent feedbacks and exogenous forces. Accumulating evidence has emerged that temporal and spatial variation in climate and resources can modify the strength of density dependence in animal populations. We analyzed eight long-term time series estimates of Peromyscus leucopus abundance from Kansas, Ohio, Pennsylvania, Virginia, Vermont, and Maine, USA, using the Kalman filter and spectral analysis. Model-averaged estimates of the strength of direct density dependence increased from south to north; and the strength of delayed density dependence increased from west to east and from south to north. Longer, colder winter and more variable climate in northerly latitudes might result in stronger density dependence in mouse populations. P. leucopus populations show more pronounced cyclicity from west to east, and the spatial gradient of cyclicity parallels the increased presence and dominance of red oaks (Quercus rubra) among the eight study sites. Furthermore, variable coefficient models link acorn production to the strength of delayed density dependence in P. leucopus populations of Maine: increased acorn crops reduce the strength of direct and delayed density dependence. An acorn failure occurring after peak densities of mice might intensify delayed density dependence and result in a mouse population crash after about a 2-year delay. Our results suggest that in seed-eating Peromyscus, cyclicity is regulated from the bottom up.
3:30 Divisional Business Meeting
6:00 Divisional Poster Session
Location: Bost Auditorium North
Posters may be set up between 4:00p and 4:30p
CAMPUS LANDSCAPING CAN BE MORE ENVIRONMENTALLY SOUND
Alston Parker and Wendy Garrison*, University of Mississippi, University, MS 38677
Landscaping on the campus of The University of Mississippi, while aesthetically pleasing to some, may have unintended ecological consequences. The objective of this study was to see if a more environmentally friendly landscaping approach would be feasible in selected areas of campus. The campus turf management crew typically mows and applies the herbicides Barricade (pre-emergent grasses), MSMA (grasses), Princep (broadleaf and grasses) and Trimec 992 (broadleaf). Runoff flows to the Yocona River via drains. A roped off 300[m.sup.2] plot, designated as the Biology Study Area was not mown or sprayed beginning in April 2006 and continuing throughout Fall 2006. We catalogued dicots (broadleaves) appearing as volunteers from August through October 2006. Each week plants were photographed and identified. Native showy and attractive dicot volunteers included: Chamaecrista fasciculata, Eupatorium capillifolium, Helenium amarum, and Solidago sp.; Native volunteers appropriate as groundcover: Diodia virginiana, Euphorbia maculata; Native volunteers not suitable for landscaping: Ambrosia artemisiifolia (ragweed). The non native invasive but showy Ipomoea purpurea (tall morning glory) also appeared. Pollinators (Coleoptera) identified in the Biology Study Area were absent from a control maintained campus lawn plot. We conclude that for some areas, selective weeding and mowing should be considered as alternatives to herbicide application, but that some maintenance would still be required. Acknowledgements: Gloria Kellum, Jeffery McManus
SOCIAL BEHAVIOR OF SMILISCA BAUDINII
Crystie Baker* and Aimee T. Lee, University of Southern Mississippi, Hattiesburg, MS 39406
Smilisca baudinii, the Common Mexican Treefrog, ranges from the southernmost tip of Texas south to Costa Rica in Central America. Smilisca baudinii is prevalent within its range, especially in populated areas, justifying its common name. When faced with human contact, this frog's behavior is different from other species the researcher has encountered in that it does not jump away or act threatened when handled. The researcher has been unable to locate any extensive research on the behavior of this species. Most of the research found included only physical characteristics and locations in which it had been found. The only type of behavior comments found referenced their breeding habits. The purpose of this project was to contribute to the knowledge of the behavior of this species. The researcher accomplished this by performing experiments to record and compare the frogs' reactions to humans, other animals, and inanimate objects. Using a controlled environment, the researcher placed the frogs in a pre-built testing area and allowed an acclimation period between trials. The variables (the researcher's hand, another person's hand, a figurine, and a fat-tailed gecko) were then introduced and their reactions were recorded. Results indicated that the most common reaction was to not react at all. The reactions varied among all four stimuli which may suggest different reactions between living and nonliving objects and may further suggest different reactions between humans and other animals.
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|Publication:||Journal of the Mississippi Academy of Sciences|
|Date:||Jan 1, 2007|
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