EFFECTS OF A KOPJE ON A RODENT COMMUNITY IN TSAVO
WEST NATIONAL PARK, KENYA

Fanson1, B.G., Fanson, K.P.1, and Brown, J.S.2

1Department of Biological Sciences, Purdue University, West Lafayette, IN 47907
2Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL 60607

Kopjes are rock outcroppings that dot the African savannahs. Despite their prevalence, few studies have explored their effects on the biotic community. Here, we investigated how a community of rodents perceive the predation costs on and surrounding a kopje in Tsavo West NP, Kenya. We studied the foraging ecology of four rodents: the unstriped ground squirrel (Xerus rutilus), the bush rat (Aethomys chrysophilus), the common spiny mouse (Acomys cahirinus), and the narrow footed thicket rat (Grammomys dolichurus). By using the technique of giving-up densities (GUDs), we were able to look at predation costs at different spatial scales: microhabitat (cover vs. open) and habitat (kopje vs. savannah). The diurnal ground squirrel showed no difference in perceived predation costs at the habitat scale, but GUDs at the microhabitat scale suggest that squirrels may be employing different spatial use strategies to mitigate different predation pressures when foraging on the kopje than the savannah. The nocturnal bush rat used the savannah habitat exclusively, not allowing for comparison with the kopje habitat. At the microhabitat scale in the savanna, the bush rat showed no difference between cover and open GUDs. The thicket rat and spiny mouse used the kopje almost exclusively, probably due to high predation costs in the savannah (as inferred from trays at the kopje’s edge). On the kopje, GUDs were significantly lower for cover microhabitats than open. Overall, these changes in predation costs appear to strongly affect the habitat selecting behavior of the thicket rat and spiny mouse, but other factors such as background food availability probably are probably at least as influential as predation costs in determining the spatial decisions of the ground squirrel and bush rat in regards to the kopje habitat. We conclude that the kopje alters the landscape of fear in the savanna for at least some rodent species.

Keywords: foraging, kopjes, predation, rodents

EFFECTS OF DETRITAL SUBSIDY ON DIVERSITY OF GROUND-DWELLING SPIDERS AND INSECTS

Riem, J.G.1 and A.L. Rypstra2

1 Department of Zoology, Miami University, Oxford, OH 45056
2 Department of Zoology, Miami University, Hamilton, OH 45011

Productivity is a factor that has been shown to have a strong effect on species diversity in some systems. Terrestrial arthropods have been underrepresented in productivity-diversity studies. In terms of competition theory, productivity can be defined as the flow of energy into resources for which competition is occurring. Spiders are generalist arthropod predators that are limited by prey availability. Previous studies have established that a bottom-up linkage exists between detrital food webs and spider assemblages. We conducted our study in a no-till soy agroecosystem where we manipulated densities of spider prey through detrital additions. This is a cyclical ephemeral ecosystem in which an interaction between the annual recolonization by spiderlings and competition for prey may drive spider diversity. The purpose of our study was to investigate the species diversity and community composition of ground-dwelling spiders in response to an experimentally imposed range of prey densities. We added detritus at four levels (control, low, medium, high) at early and mid-season. We sampled insects and spiders at early, mid-, and late season. Insects were collected on sticky traps, and spiders were collected by destructive sampling of litter and soil. We will present results on densities of key orders of insects as well as effects on spider diversity.

Keywords: Biodiversity, productivity, spiders, insects

RE-EXAMINATION OF CRITICAL TRANSITION TEMPERATURE AND ACTIVATION ENERGY CORRELATING WATER LOSS IN INSECTS WITH HABITAT PREFERENCE

Rellinger, E.J., Ark, J.T., Benoit, J.B. and Yoder, J.A.

Department of Biology, Wittenberg University, Springfield, OH 45501

Water-proofing cuticular lipids in insects undergo a phase change at a certain temperature, called critical transition temperature (CTT), accompanied by an abrupt, lethal acceleration of water loss. As such, CTT is an effective indicator of habitat preference for a species with regard to temperature tolerance best suited for survival. Identifying CTT has been problematic, leading to misinterpretations about its use, because of improper data analysis and inconsistencies in specimen pretreatment and measuring water loss rates. It was the purpose of this study to evaluate the significance of CTT and standardize how it is determined. The specific amount of energy required for a molecule of water to pass through the lipid boundary between the insect and its surroundings is designated as the activation energy, Ea. Historically, Ea has been calculated from the slope (-Ea/Rgas) over a range of temperatures where ln water loss rate is proportional to reciprocal absolute temperature 1/T (Arrhenius plot) in typical Boltzmann fashion. Where lipids 'melt' at the CTT is reflected by a change in the amount of energy, presumably less, that is needed to cross the boundary as indicated by a steeper slope due to water loss increase. The regression more adequately describes a permeability constant Pc rather than an Ea because low water loss rate indicative of an impermeable barrier does not yield a high Ea. Pc is found using same methods to derive Ea; Pc more appropriately illustrates that water loss increases with temperature. Proper determination of CTT involves using an untransformed plot (rate vs. temperature) with logarithmic values, causing CTT in many previous studies to disappear. Although CTT is absent, Pc permits correlation between insects with a low Pc and presence of a water impermeable barrier, suggesting xeric-adaptation. In conclusion, the regression has been improperly designated as Ea but useful for analysis of water loss, prompting redesignation as Pc. Additionally, CTT, in many previous studies, arises from improper graphical analysis.

Keywords: Insect, activation energy

EFFECTS OF PREDATORS AND HABITAT COMPLEXITY ON FORAGING EFFICIENCY IN A SPECIES OF WOLF SPIDER (Pardosa milvina)

Schmidt, J., DeVito, J., and Rypstra, J.

Zoology Department, University of Miami, Oxford, OH 45056

Structurally complex habitats are important for both species abundance and diversity. Here was a laboratory assessment designed to study the effects of habitat complexity on spider foraging efficiency. The primary study species was Pardosa milvina. We manipulated foraging conditions by adding habitat complexity and predators. Two habitat treatments were used: simple (peat moss) and complex (peat and straw). Three predator treatments were used: Pardosa alone, Pardosa and Hogna together, and Pardosa foraging with other Pardosa. Logistic regression analysis was used to compare the effects of various treatments or prey capture. Both complex habitat and predator additions had negative effects on foraging efficiency. High levels of complexity reduced prey capture by Pardosa. However, when spiders were at high densities, complexity reduced intraguild predation and interference among coexisting spiders. These results suggest that there are costs and benefits to habitat complexity.

Key words: habitat complexity, intraguild, predation, foraging

EFFECTS OF DEER HERBIVORY ON FLORISTIC HETEROGENEITY
AND PLANT INVASIONS IN ILLINOIS

Wachholder, B.E. and Meiners, S.J.

Department of Biological Sciences, Eastern Illinois University, Charleston, IL 61920

Nine deer exclosures and paired control plots were sampled at locations throughout the state of Illinois. A paired-sampled T-test found tree cover significantly lower in control than exclosure plots. Mean cover of herbs and grasses were higher in control plots, while liana, shrub, and total cover were higher in exclosures, though these differences were not significant. Cover of invasive exotic herbs, shrubs, and lianas were compared at sites where they occurred. Mean cover of exotic invasive herbs was higher in control plots than exclosures, but the difference was not significant. Mean cover of the invasive exotic liana Lonicera japonica was significantly higher within exclosures than in control plots. Coefficients of species accumulation were also higher in exclosures at (several) sites. There results suggest (1) deer herbivory may be reducing tree regeneration and floristic heterogeneity throughout Illinois, and (2) deer herbivory inhibits invasion by preferred woody browse species such as Lonicera japonica, and could facilitate invasions by herbaceous species.

AMPHIBIAN COMMUNITY DYNAMICS AT TWO SCALES
OF ANTHROPOGENIC PERTURBATIONS

Walston, L.J.

Department of Biological Sciences, Eastern Illinois University, Charleston, IL 61920

Pond-breeding amphibians are important components to wetland ecosystem energy dynamics by consuming primary and secondary production and providing relatively large amounts of biomass to higher trophic levels. Although numerous factors are linked to recent declining amphibian populations, anthropogenic perturbations such as habitat modification and introduced species have had the greatest impacts. I conducted a field experiment at two different scales to examine the effects of these factors on a pond-breeding amphibian community in east-central Illinois. On a temporal scale, I investigated the effects of introduced fish on a native amphibian community and the resilience of the amphibian community after mitigation, via the experimental application of Rotenone. On a spatial scale, I also assessed the influence of the landscape composition surrounding wetlands on amphibian distribution. Landscape composition is critical for amphibians to complete many life-history functions. Therefore, I associated the distribution of amphibians along a terrestrial habitat gradient surrounding breeding ponds, and I examined the additional effects of landscape composition of the terrestrial habitat on the migration orientation of adult and juvenile amphibians. Mitigation of introduced fish did not improve the reproductive success of all amphibian species; only smallmouth salamander recruitment increased following fish removal. However, I observed an increase in species richness and diversity within the community following mitigation, indicating the resilience of pond-breeding amphibian community following restoration. The abundance of amphibians increased with increasing width of the forested terrestrial buffer habitat. Similarly, juvenile dispersal patterns significantly deviated from random expectations in favor larger buffer habitats. My results indicate that management objectives promoting larger buffer habitats around breeding ponds and removal of predator populations are important strategies for maintaining populations of pond-breeding amphibians.

Keywords: Amphibians, Perturbation, Mitigation

ROUND GOBY (NEOGOBIUS MELANOSTOMUS) AND DREISSENID EFFECTS ON YOUNG-OF-THE-YEAR SMALLMOUTH BASS (Micropterus dolomieu)

Winslow, C.J., J.G. Miner, and D.D. Wiegmann

Department of Biological Sciences, Bowling Ggreen State University,
Bowling Green, OH 43403

The Lake Erie community has fluctuated considerably over the past century. Antropogenic pertibations to the system, including the introduction of invasive species, haved played a major role in shifting abundances and species compositioins. The introduction of dreissenids (quaga and zebra mussels), round goby (RG), Bythotrephes, Echinogammarus, and white perch have impacted fish communities through food-web shifts and alterations of the physical environment. The importance of these interactions has led fisheries management to shift from an individual species perspective to the level of the entire fish community. Mesocosms were used to quantify how two particular invasives, dreissenids and RG, indirectly and directly affect the growth and vulnerability of young-of-the-year smallmouth bass (YOYSMB). The impact of these invasives on smallmouth bass is of special concern due to their importance as a game fish in Lake Erie. Dressenids potentially indirectly aid YOYSMB by providing structural complexity which increases invertebrate prey resources. RG, because of their aggressive behavior, probably directly influence YOYSMB by interfering with habitat use (potentially decreasing foraging efficiency and increasing predation risk). Additionally, young RG may indirectly affect the abundance of invertebrates among dressenids because of diet overlap between the two species. Therefore, it becomes important to evaluate how dressenids mediate YOYSMB growth through their influence on food density and to evaluate how RG directly and indirectly affect YOYSMB growth. Treatments within mesocosms (N=54, 0.3·m-2) included varying densities of YOYSMB, dressenids (presence/absence - how mussels mediate competition), and RG (presence/absence), and in these growth, diet, and survivorship of YOYSMB were quantified. In the presence of conspecifics or RG, YOYSMB growth was 66 and 65% lower, respectively, than YOYSMB alone (ANOVA, P=0.013, and Tukey’s LSD, P<0.05). This suggests that intraspecific and interspecific competition are equivalent. Because RG are found at high densities (up to 15·m-2 - unpublished data, C. Knight), the competitive effects of RG on YOYSMB appear to be substantial. Overall, our proposed experiment contributes information on growth of SMB exposed to invasive species and their potential increase in vulnerability to predators, two major factors that contribute to their recruitment into the fishery.

Keywords: invasive species, smallmouth bass, competition, fisheries

COMMUNITY RESPONSE TO RAINFALL DEVIATION
IN A SUCCESSIONAL SYSTEM
 (POSTER PRESENTATION WINNER!)

Yurkonis, K.A. and Meiners, S.J.

Department of Biological Sciences, Eastern Illinois University, Charleston, IL 61920

Perturbations such as drought, herbivory and fire often influence community structure through shifts in resource availability. Although changing resource levels can affect community structure, the mechanisms by which communities respond to fluctuating resource levels are not well understood. We examined species turnover dynamics to determine the mechanisms behind successional community responses to yearly changes in rainfall. Using long-term data from the Buell-Small Succession Study, we compared species richness and turnover rates to rainfall deviation. Species richness declined in wet and dry years and remained low following wet years. Declines in diversity resulted from decreased community colonization and increased extinction rates during wet and dry years. Species most strongly affected during wet and dry years were rare and infrequent in the community. High turnover of the rare species may be driven by increased competition during extreme events, limitations on establishment sites due to high cover during wet years, and physiological mortality during drought years. These findings are further supported at the population level as ruderal species (annuals, biennials and perennials) were most strongly affected during wet and dry years. Our results suggest that successional systems can have predictable responses to changes in resource availability.

Keywords: Species turnover, drought, resource availability, succession

THE NITROGEN BUDGET OF A NORTHERN HARDWOOD FOREST: ANNUAL REQUIREMENTS AND ATMOSPHERIC INPUTS

Nave, L.E.

Department of Evolution, Ecology, and Organismal Biology,
The Ohio State University, Columbus, OH 43210

I assessed the nitrogen (N) requirement for forest growth across five years (1999-2003) at the University of Michigan Biological Station, an aspen-dominated mixed deciduous forest in northern Lower Michigan. Carbon cycle work at this site has yielded estimates of the carbon (C) mass allocated annually to major forest biomass pools as well as a multi-year dataset of forest biomass C/N ratios. I used annual estimates of C allocated to leaves, coarse and fine roots, fine woody debris, and wood biomass pools, combined with C/N ratios for each, to determine the annual N requirement of this forest. For these five years, the N requirement for growth varied between 59 and 63 kg N ha-1 yr-1. This annual requirement exceeded estimated N mineralization at the site (10-15 kg N ha-1 yr-1), suggesting that atmospheric inputs may make important contributions to this forest’s N nutrition. To test this hypothesis, I collected bulk deposition and throughfall from April to November 2004. During this period, bulk deposition of NH4-N, NO3-N, and organic N totaled 5.4 kg N ha-1, with the forest canopy retaining 2.2 kg N ha-1, principally in the form of NH4-N and organic N. These results suggest that atmospheric N deposition and subsequent retention by the canopy contribute to the annual N requirement of this northern hardwood forest.

Keywords: nitrogen, budget, canopy, throughfall.

BENTHIC ALGAL COMMUNITY STRUCTURE AND BIOACCUMULATION OF MERCURY IN A COASTAL WATERSHED

Novoveska, L.1, Phipps, S.W. 2, and Pederson, C.L.1

1 Department of Biological Sciences, Eastern Illinois University, Charleston, IL 61920
2 Weeks Bay National Estuarine Research Reserve, Fairhope 36532

Largemouth bass in the Fish River watershed of coastal Alabama are known to contain relatively high concentrations of mercury. Monitoring efforts often include description of biotic community structures as well as bioconcentrations of pollutants such as mercury at impacted and reference sites. Benthic microalgal assemblages may be an ideal choice for biological monitoring of anthropogenic stress in stream ecosystems, largely due to their sedentary nature and their ability to bioaccumulate toxic substances. Artificial substrates were deployed at 13 sites in the channel of the Fish River and selected tributaries at different distances from Weeks Bay, a subestuary of Mobile Bay. Principal Components Analysis indicates that 11 sites are homogeneous on a physical and chemical basis, while two sites are somewhat more distinct. This environmental variability is reflected in the diatom assemblages which were found to characterize each site. However, Gomphonema parvulum is cosmopolitan throughout the watershed and therefore is suitable for assessment of mercury contamination. Individual cells of G. parvulum from each site were observed using a Scannning Electron Microscope equipped with an Energy Dispersive X-ray Spectrometer (SEM-EDS) in effort to detect the presence of mercury. Failure to detect mercury via SEM-EDS suggests that the method is insensitive to presence of the element, that G. parvulum does not bioconcentrate mercury, or that aqueous concentrations of mercury within the Fish River watershed are negligible.

Keywords: Benthos, Biomonitoring, Mercury.

PERVASIVE RNA EDITING AMONG MITOCHONDRIAL NAD5 TRANSCRIPTS IN HORNWORTS

Branch, T. and Duff, R.J.

Department of Biology, University of Akron, Akron, OH 44325

Hornwort mitochondrial genomes have some of the highest rates of RNA editing among plants. Work to explore the phylogeny of hornworts using mitochondrial genes allowed us to infer divergent frequencies of RNA editing sites among nad5 sequences Comparison of nine partial mitochondrial nad5 genomic and cDNA sequences from diverse taxa of hornworts reveal 113 edited sites in only 1107 nucleotides. No single sample has more than half of these sites though each hornwort taxon has similar total numbers of edited sites with one exception. Leiosporoceros, which represents a potentially sister taxa to all other hornworts, has only eight edited sites. Phylogenetic analyses of hornwort genomic and cDNA sequences reveals that 54 of 84 (64%) of the phylogenetically informative sites within the hornwort clade are edited positions. These sites are shown to play a role in determining the topology of the basal nodes of the hornwort phylogeny. In particular, Leiosporoceros is resolved as sister to the hornworts when edited sites are included in the analyses but when edited sites are removed the support for the Leiospoceros sister topology is lost.

Keywords: Hornworts, RNA editing, nad5

SPECIES-DIAGNOSTIC POLYMERASE CHAIN REACTION ASSAY FOR THE IDENTIFICATION OF Anopheles VECTORS OF HUMAN Plasmodium spp.

Brelsfoard, C.L.1, Fritz, G.N.1, Rodríguez, R.2

1 Department of Biological Sciences, Eastern Illinois University, Charleston, IL 61920
2 Laboratorio de Entomologia Médica, Escuela Técnica de Salud Pública,
Cochabamba, Bolivia

Two multiplex PCR were developed to identify two sets of morphologically similar species of anopheline mosquitoes that are primary and secondary vectors of malaria in South America. Each multiplex PCR incorporates species-specific primers with a single primer that anneals to a conserved region of the rDNA. Species-specific primers were based on interspecific sequence variation in the second internal transcribed spacer (ITS2) of the nuclear ribosomal DNA. One multiplex PCR identifies An. oswaldoi and an undescribed species collected in Bolivia. A second multiplex PCR identifies mosquitoes as belonging to the Albitarsis Complex, which includes An. deanorum, An. albitarsis, An. albitarsis B, and An. marajoara. The resulting amplicon is digested with Bfa-I to identify An. marajoara. Identifications using multiplex PCR are useful for continuing studies on the ecological differentiation and population structure at the level of breeding sites for the aforementioned species (at least at the regional level of Bolivia) in areas where species diversity is high and the ecology is complex.

Keywords: Nyssorhynchus, Anopheles, PCR identification

THE INFLUENCE OF POPULATION STRUCTURE ON HISTORICAL
DEMOGRAPHIC INFERENCE

Busch, J.D.1, McCormick, C.R.1, Waser, P.M.2, and DeWoody, J.A.1

1Department of Forestry and Natural Resources, Purdue University,
W. Lafayette, IN 47907
2Department of Biology, Purdue University, W. Lafayette, IN 47907

When analyzed in the appropriate theoretical framework, molecular genetic data can be used to infer the demographic history of a population. For example, two approaches that can detect recent reductions in population size from microsatellite data are heterozygosity excess (Bottleneck program) and the M-ratio. A key assumption of these models is population closure; new alleles can only arise from mutation and not immigration. In reality, local populations are rarely isolated enough to meet this requirement. Before performing bottleneck analyses, it is essential to determine the extent of a population and thus make informed decisions on which sampling locations should be grouped or analyzed independently. We propose to do this with natural populations of the banner-tailed kangaroo rat (Dipodomys spectabilis) using FST-based approaches and assignment tests. At our study site, the putative population(s) are geographically proximate (<300m) and field studies have detected low levels of dispersal among them. A thorough understanding of population structure is requisite prior to conducting demographic analyses.

Keywords: demographic history, genetic structure, bottleneck, kangaroo rat

EFFECTS OF CURRENT VELOCITY AND PARTICLE SIZE ON CRAYFISH (Orconectes propinquus) ACTIVITY

Clark, J.M. and Kershner, M.W.

Department of Biological Sciences, Kent State University, Kent, OH 44242

In streams, flooding can play a dominant role in the spatial distribution and relative abundance of species. Flood events vary in duration, frequency, and intensity with diverse effects on lotic communities. The use of refugia (e.g., substrate) by invertebrates may be important for increasing the likelihood of survival during high flow. Movement to potential refugia becomes risky as velocities increase and the range of velocities that benthic invertebrates can withstand is variable. In this study, activity time and slip velocities of small [carapace length (CL)=10-20 mm] and large (CL=20-30 mm) Orconectes propinquus were measured in an artificial flume on monolayers of small pebbles (16-32 mm), large pebbles (32-64 mm), and small cobble (64-128 mm) across a range of current velocities. Water velocity was increased by 0.1 m/s increments from 0.1-1.5 m/s at 5-minute intervals or until the crayfish slipped off of the substrate. In general, as current velocity increased, the probability of slipping increased for all crayfish. Regardless of particle size, small crayfish held their position at higher velocities (up to 1.5 m/s) than large crayfish (up to 0.9 m/s) and were also less active. Particle size effects only occurred with small crayfish, which had higher slip velocities on small cobble than other substrate treatments. Essentially, interstitial spaces in small cobble were large enough to allow small crayfish to seek refuge and avoid being swept into the drift.

Keywords: Orconectes propinquus, crayfish, flooding, substrate

TRANSMISSION OF FUNGAL ENDOPHYTES IN SEEDS OF Festuca obtusa

Cummings, J.A and A.S. Methven

Department of Biological Sciences, Eastern Illinois University, Charleston, IL 61920

Many plants have mutualistic associations with fungal endophytes. Studies of these relationships have shown that these associations provide a selective advantage for plants which can be passed on to future generations. Festuca obtusa is a cool season grass that is commonly infected by fungal endophytes that correspond to asexual forms belonging to the genus Neotyphodium (Fungi Imperfecti). This project was designed to ascertain: 1) the percentage of transmission of endophytes from infected tillers to seeds; 2) whether differing periods of cold stratification improve seed germination; and, 3) the percentage of infection in seedlings. Seeds of F. obtusa collected in summer 2003 were subsequently divided into four lots: 1) one lot was used as a control for detection of fungal endophytes in seeds; 2) one lot was germinated and grown without cold stratification; 3) one lot was germinated and grown after six weeks of cold stratification; and 4) one lot was germinated and grown after twelve weeks of cold stratification. Seedlings were subsequently grown for six to eight weeks, harvested, and inspected for infection. Fungal endophytes were found in 100% of the seeds collected from infected tillers, the percentage of seed germination increased with longer periods of cold stratification, and 100% of the seedlings were infected with the fungal endophyte.

Keywords: Festuca, endophytes, mutualistic associations

DETERMINING THE ECOLOGICAL REQUIREMENTS OF FRESHWATER TURTLES

Harms, H.M., and Root, K.V.

Department of Biological Sciences, Bowling Green State University,
Bowling Green, OH 43403

Freshwater turtle populations have been experiencing significant declines in population size and distribution over the past several decades. They are susceptible to fragmentation because of their long life span, which allows poor recruitment to go unnoticed, delayed age to sexual maturity, variable and often poor reproductive success. Freshwater turtles are an important part of the ecosystem, as they act as scavengers, provide a dispersal mechanism for plants, contribute to environmental diversity, and have the potential to contribute significant biomass. The study, conducted in the summer of 2003, investigated the habitat requirements of freshwater turtles, using painted turtles, Chrysemys picta, as a model organism. I (1) used a GIS program, ArcView, to locate local ponds surrounding Bowling Green, Ohio where pond and marsh turtles may be found in a fragmented setting; (2) performed a survey of painted turtles; and (3) measured a suite of environmental variables particular to that area (e.g., area, pH, amount of shade, etc.). This study demonstrated that the amount of shade and vegetation around a pond, the amount of debris in the water and the amount of other wildlife in the area are important factors for painted turtle habitat. The results also suggested that painted turtles prefer areas that are larger, appear to be more heterogeneous and have less motor vehicle traffic. Current research is underway to complement this study by investigating the ecological requirements of a rare freshwater turtle, the spotted turtle, Clemmys guttata. This mark-recapture study will collect individual specific data. A blood sample will also be collected to determine effective dispersal. Several individuals will be equipped with a radio transmitting device. Finally, Geographical Information Systems and a spatially-explicit population model will be utilized to evaluate this data on a landscape scale and to determine which variables are most critical to freshwater turtle population viability. A predictive model will be developed to evaluate population viability though time and to evaluate different management plans and their potential outcomes. These studies will provide critically needed baseline data that will improve our understanding of the threats facing freshwater turtles and suggest management recommendations for their conservation.

Keywords: Turtle, Ecology, Conservation, Model

EXAMINING THE POTENTIAL FOR LOCAL ADAPTATION OF Apocynum cannabinum (HEMP DOGBANE) POPULATIONS AT AN ABANDONED LIMESTONE QUARRY

Helm, B.R. and Dudle, D.A.

DePauw University, 500 Anderson Street, Greencastle, Indiana 46235

Abandoned limestone quarries offer valuable opportunities to study primary succession. Species that establish first in a quarry are of particular interest because they may show morphological and/or physiological adaptations to extreme environmental conditions at a small geographic scale. In order to identify local adaptations allowing a species to endure primary successional conditions, variation within the species must be documented. We compared two populations of Apocynum cannabinum, one in an early successional area in the quarry basin and one in a later successional area in a nearby wet meadow. Population density, proportion of flowering individuals, number of umbels, and number of fruits were sampled. We also quantified on the microsite conditions of the plants, and determined water content of the soil. Microsite type and water content varied significantly between the sites, indicating that abiotic environments may impose divergent selective pressures on the two populations. The patchy distribution of the A. cannabinum population at the quarry bottom indicates that microsite or soil conditions suitable for germination and/or vegetative spread of this species may be rare in the quarry bottom relative to the wet meadow. We also found that the population of A. cannabinum in the wet meadow was more robust overall, with a larger population density, more flowering individuals, more umbels per area, and more fruits per area. Plants in the quarry roadside were more likely to flower than in the quarry bottom; however, we found that the number of umbels and number of fruits per flowering individual did not differ between the two sites. These data show that some individuals are able to reproduce successfully in the harsh quarry basin. The barrier for the reproduction in the quarry bottom seems to be in their ability to flower, which may be related to drought tolerance. Perhaps intense competition at the wet meadow prevents higher levels of flower and fruit production in that population, despite less stressful abiotic conditions.

Keywords: Primary succession, Apocynum cannabinum, local adaptation

AGE SPECIFIC SURVIVORSHIP OF Drosophila mojavensis
REARED ON DIFFERENT HOST CACTI

Jaureguy, L. and Etges, W.J.

Department of Biological Sciences, University of Arkansas, Fayetteville, AR 72701

Multiple mechanisms have been implicated in causing senescence in different species making a general understanding of the evolution of aging patterns unclear. Ecological determinants of aging are probably best studied, especially age specific mortality, but these types of studies have been rare in Drosophila given the poor understanding of the ecology of most species in this genus. Drosophila mojavensis uses two principal host cacti, agria cactus, Stenocereus gummosus, in Baja California and organ pipe cactus, S. thurberi, in Sonora and Sinaloa, Mexico and southern Arizona. Populations of D. mojavensis have undergone evolutionary changes in a suite of fitness components including adult longevity under stress conditions due to the host shift from agria cactus in Baja California to organ pipe cactus in mainland Mexico. Thus, differences in longevity, and possibly rates of senescence, are directly related to host cactus use. Therefore, the ecology and evolutionary history of D. mojavensis makes this species a very useful model for the study of senescence because the flies can be reared on their natural substrates in the laboratory. In this study we analyzed survivorship and rates of mortality in flies from a mainland population grown on two host cacti and laboratory food during their life cycle. Three-day adult cohorts were sorted by sex and housed in cages in groups of 400 individuals. They were fed with the same food they were exposed to as larvae plus 4% atmospheric ethanol. Dead flies were counted daily. PROC LIFETEST in SAS was used to estimate both mortality rates and mean longevity. There was a significance difference among groups using both Log-Rank and Wilcoxon tests. Lab food females exhibited the highest longevity, whereas agria females the lowest. Mortality rates of organ pipe females were lower than all the other treatments. Fermenting agria and organ pipe tissues compared with lab food differ in their chemical composition, and therefore influence different levels of larval and adult nutrition. To the extent that these substrates influence age specific survivorship in adults is not well understood. Future studies are planned with additional populations and characterization of gene expression profiles with age using DNA microarrays.

Keywords: Drosophila, aging, cactus

POPULATION ECOLOGY OF THE JEFFERSON SALAMANDER, Ambystoma jeffersonianum, IN ILLINOIS

Klueh, S.

Department of Biological Sciences, Eastern Illinois University, Charleston, IL 61920

Amphibian populations utilizing small isolated wetlands are often small in size, have little to no contact with other populations, and are susceptible to stochastic extinction processes. The persistence of such populations can only be ascertained by obtaining data that allow the prediction of the population’s growth, trajectory, and capacity to achieve a sustainable size. The Jefferson salamander, Ambystoma jeffersonianum, is a state-threatened species, occurring at fewer than 15 ponds within Illinois. Individuals at a pond in the east-central part of the state are captured using a drift fence-pitfall trap array, then sexed, measured for SVL, and marked using a unique combination of toe clips. Also obtained are the number of egg masses, average percentage of successfully hatched eggs, and number of juveniles leaving the pond. All data is then entered into a life history table and used to develop a population model. Information obtained from the model will be used to determine which life history stage is critical to the survival of the population, and it will allow management efforts to focus on mechanisms that are most likely to cause declines.

Keywords: isolated wetlands, life history stage, life history table, population model,

GEOGRAPHIC VARIATION IN COURTSHIP SONGS AMONG MAINLAND AND BAJA CALIFORNIA POPULATIONS OF Drosophila mojavensis

Over, K., de Oliveira, C.C., and Etges, W.J.

Department of Biological Sciences, University of Arkansas, Fayetteville, AR 72701

In Drosophila, male courtship songs confer species-specificity and are implicated as isolating mechanisms between closely related species. Differences in courtship songs are linked to female preference and play a role in sexual isolation between species. The species-distinguishing characteristic parameters of Drosophila songs include inter-pulse interval (IPI), burst duration, inter-burst duration, number of pulses per burst, sine song frequency and intra-burst frequency. IPI has been found to be an important parameter in female receptivity to conspecific males. Drosophila mojavensis, a member of the repleta group, is a cactophilic fly endemic to the Sonoran and Mojave Deserts, and adjacent regions. Male courtship songs of D. mojavensis contain intermittent bursts of pulses that can be characterized as “short” and “long” songs. The goals of the present work were to investigate geographic variation in courtship song characteristics between D. mojavensis populations from Baja California and Mainland Mexico and their role in premating isolation between these populations. In the present study, courtship song analyses were performed with thirteen geographically isolated populations of D. mojavensis (five from mainland and eight from Baja), as well as in F1 and F2 hybrids. Parentals, F1 reciprocals, and F2 reciprocals were recorded in order to detect possible maternal effect, sex linkage, and possible dominance effects. All song variables were subjected to ANCOVA to access the effects of temperature. Least square population means (LSM) were plotted to visualize the degree of geographic variation in the courtship song parameters. Also, all crosses were subjected to ANCOVA. The results show that there is a significant difference among populations for mean IPI (F=18.93, P < 0.0001), with Baja populations having a significantly longer IPI. LSM for mean burst duration were significantly longer in mainland population than those from Baja (LSM 0.307 > 0.239 ms, P<0.0001). Significant differences in courtship song components were found between Baja and mainland populations of D. mojavensis suggesting that courtship songs have evolved along with other behavioral components of sexual isolation including cuticular hydrocarbons and the degree of female discrimination in mate choice.

Keywords: courtship song, Drosophila mojavensis, sexual isolation, reproductive isolation