25th Midwest Ecology and Evolution Conference Carbondale Civic Center, Carbondale IL March 11-13 2005 _______________________________________________________________________ POPULATION BIOLOGY / ECOLOGY
RECORD 90 DAY SURVIVAL WITHOUT FOOD AND WATER BY ADULTS OF THE AMERICAN
SPIDER BEETLE, MEZIUMAFFINE
Ark, J.T.1, Benoit, J.B.1, Rellinger, E.J.1, Yoder, J.A.1 and Keeney, G.D.2
1 Department of Biology, Wittenberg University, Springfield, OH 45501
2 Department of Entomology, The Ohio State University, Columbus, OH 43210
Colonies of spider beetles, Meziumaffine and Gibbiumaequinoctiale, have persisted in thelaboratory without being provided water for nearly 7 years. These beetles are named for theirspider-like appearance due to a lack of wings and fusion of the elytra, and are a common storedproduct pest of grain and oats. For M. affine, extreme desiccation resistance was provided by athick cuticle, as indicated by a low permeability constant (Pc = 43kJ/mol), extremely low water loss
rates averaging 0.3%/day, group effects reducing water loss, a low water content and impressivesurvival for 90 days with no food and water in arid air. When exposed to this long-term fastingand water shortage, the beetles entered quiescence, extended periods of physical inactivity asthough dead. Replenishing lost water stores, albeit minimal, was restricted to drinking free waterand confirmed by the observation of liquid uptake from Evans blue-stained water droplets and acritical equilibrium activity (CEA) of 1.00av (av=%RH/100), indicating the spider beetle cannot
balance water loss with gains from atmospheric air below saturation. Adaptation for maximumwater retention, rather than water gain, was also featured by G. aequinoctiale. Water balanceprofile of the beetles was compared to a closely-related beetle, Prostephanustruncatus, havingsimilar mass and surface area, but differing by the presence of wings rather than fused elytra. Incontrast to spider beetles, the winged P. truncatus had a 4-fold reduction in survival time and 5-8xaccelerated water loss rates in comparison to spider beetles. This difference, presumably, isattributed to the fused elytra design feature that acts to keep water from leaving the beetleexternally. Capacity for quiescence in the spider beetles also contributes to enhance waterconservation, and is reminiscent of the diapause syndrome. As such, it seems reasonable tosuggest that spider beetles are uniquely adapted for coping with temperature extremes in additionto being particularly desiccation-hardy, which has promoted their ubiquitous distribution.
Keywords: spider beetles, water balance
LACK OF FUNGAL VECTOR CAPACITY BY TICKS HARBORING AN IMPERFECT FUNGUS,
Benoit, J.B.1, Yoder, J.A.1, Rellinger, E.J.1, Gribbins, K.M.1, and Telford III, S.R.2
1Department of Biology, Wittenberg University, Springfield, OH 45501
2Department of Immunology and Infectious Diseases,
Harvard School of Public Health, Boston, MA 02115
A deuteromycete, Scopulariopsisbrevicaulis, has been recovered internally from two tick speciesin our area, the American dog tick Dermacentorvariabilis and lone star tick Amblyommaamericanum. This fungus is present in all life stages with initial infection occurring maternally asa contaminant of eggs. The fungus benefits from this association by obtaining nutrients andwater from the tick, in turn being born with this fungus sets up a pioneering effect conveying aprotective advantage against secondary fungus attack that benefits the tick. Whether ticks cantransmit this fungus is the subject of this study by analyzing tick saliva and feeding sites andblood from a host. Saliva was collected from larvae, nymphs and adults into glass capillary tubesinserted over the mouthparts and stimulated by pilocarpine. Fungal culturing on potato dextroseagar and methylene blue staining by light microscopy was used to analyze samples. Identification was based on microscopic and macroscopic colony characteristics of excisedsubcultures. Tissue biopsies were also examined for evidence of conidia from ears of animmunologically naïve New Zealand white rabbit, Oryctolaguscuniculus, of sites where S. brevicaulis-positive ticks had attached. Less than 4% of tick saliva (N=300 samples each fromlarvae, nymphs and adults) tested positive for S. brevicaulis with slide preparations viewed bylight microscopy and from subcultures. Of 90 adult feeding sites from the rabbit, only 3 testedpositive for S. brevicaulis, and no fungi (0/400 samples) was detected, microscopic observationand fungal culturing, in rabbit blood. Histochemical analysis of tick feeding sites showed noconidia or hyphae in the peristomal space surrounding the tick’s mouthparts while imbedded inhost skin. Results compared favorably to tissue biopsies where no ticks had fed. We recovered100% of S. brevicaulis from tissue (N=40) that had received intradermal injection of fungalinoculum (200ml samples-1.0 x 107 conidia/ml), which served as confirmation of our technique. With little fungi recovered from tick saliva, blood and tissue biopsies from where ticks had fed, ourconclusion is that these ticks are not competent for transmission of S. brevicaulis by the bloodfeeding route.
Keywords: Fungi, tick, transmission, Scopulariopsis
EFFECTS OF CURRENT VELOCITY AND PARTICLE SIZE ON CRAYFISH (ORCONECTES
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 ofspecies. Flood events vary in duration, frequency, and intensity with diverse effects on loticcommunities. The use of refugia (e.g., substrate) by invertebrates may be important forincreasing the likelihood of survival during high flow. Movement to potential refugia becomesrisky as velocities increase and the range of velocities that benthic invertebrates can withstand isvariable. 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 onmonolayers of small pebbles (16-32 mm), large pebbles (32-64 mm), and small cobble (64-128mm) across a range of current velocities. Water velocity was increased by 0.1 m/s incrementsfrom 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 ofparticle size, small crayfish held their position at higher velocities (up to 1.5 m/s) than largecrayfish (up to 0.9 m/s) and were also less active. Particle size effects only occurred with smallcrayfish, 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 seekrefuge and avoid being swept into the drift.
Keywords: Orconectes propinquus, crayfish, flooding, substrate
TRANSMISSION OF FUNGAL ENDOPHYTES IN SEEDS OF FESTUCA OBTUSA
Department of Biological Sciences, Eastern Illinois University, Charleston, IL 61920
Many plants have mutualistic associations with fungal endophytes. Studies of these relationshipshave shown that these associations provide a selective advantage for plants which can bepassed on to future generations. Festuca obtusa is a cool season grass that is commonlyinfected by fungal endophytes that correspond to asexual forms belonging to the genusNeotyphodium (Fungi Imperfecti). This project was designed to ascertain: 1) the percentage oftransmission of endophytes from infected tillers to seeds; 2) whether differing periods of coldstratification improve seed germination; and, 3) the percentage of infection in seedlings. Seeds ofF. obtusa collected in summer 2003 were subsequently divided into four lots: 1) one lot was usedas a control for detection of fungal endophytes in seeds; 2) one lot was germinated and grownwithout cold stratification; 3) one lot was germinated and grown after six weeks of coldstratification; 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, thepercentage of seed germination increased with longer periods of cold stratification, and 100% ofthe seedlings were infected with the fungal endophyte.
Keywords: Festuca, endophytes, mutualistic associations
DETERMINING THE ECOLOGICAL REQUIREMENTS OF FRESHWATER TURTLES
Department of Biological Sciences, Bowling Green State University,
Freshwater turtle populations have been experiencing significant declines in population size anddistribution over the past several decades. They are susceptible to fragmentation because oftheir long life span, which allows poor recruitment to go unnoticed, delayed age to sexualmaturity, variable and often poor reproductive success. Freshwater turtles are an important partof 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 freshwaterturtles, 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 turtlesmay 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 ofshade, 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 factorsfor painted turtle habitat. The results also suggested that painted turtles prefer areas that arelarger, appear to be more heterogeneous and have less motor vehicle traffic. Current research isunderway to complement this study by investigating the ecological requirements of a rarefreshwater turtle, the spotted turtle, Clemmys guttata. This mark-recapture study will collectindividual specific data. A blood sample will also be collected to determine effective dispersal. Several individuals will be equipped with a radio transmitting device. Finally, GeographicalInformation Systems and a spatially-explicit population model will be utilized to evaluate this dataon 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 thoughtime and to evaluate different management plans and their potential outcomes. These studieswill provide critically needed baseline data that will improve our understanding of the threatsfacing 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
DePauw University, 500 Anderson Street, Greencastle, Indiana 46235
Abandoned limestone quarries offer valuable opportunities to study primary succession. Speciesthat establish first in a quarry are of particular interest because they may show morphologicaland/or physiological adaptations to extreme environmental conditions at a small geographicscale. In order to identify local adaptations allowing a species to endure primary successionalconditions, variation within the species must be documented. We compared two populations ofApocynum cannabinum, one in an early successional area in the quarry basin and one in a latersuccessional area in a nearby wet meadow. Population density, proportion of floweringindividuals, number of umbels, and number of fruits were sampled. We also quantified on themicrosite conditions of the plants, and determined water content of the soil. Microsite type andwater content varied significantly between the sites, indicating that abiotic environments mayimpose 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 forgermination and/or vegetative spread of this species may be rare in the quarry bottom relative tothe wet meadow. We also found that the population of A. cannabinum in the wet meadow wasmore robust overall, with a larger population density, more flowering individuals, more umbels perarea, and more fruits per area. Plants in the quarry roadside were more likely to flower than inthe quarry bottom; however, we found that the number of umbels and number of fruits perflowering individual did not differ between the two sites. These data show that some individualsare able to reproduce successfully in the harsh quarry basin. The barrier for the reproduction inthe 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 fruitproduction in that population, despite less stressful abiotic conditions.
Keywords: Primary succession, Apocynum cannabinum, local adaptation
AGE SPECIFIC SURVIVORSHIP OF DROSOPHILA MOJAVENSIS
Department of Biological Sciences, University of Arkansas, Fayetteville, AR 72701
Multiple mechanisms have been implicated in causing senescence in different species making ageneral understanding of the evolution of aging patterns unclear. Ecological determinants ofaging are probably best studied, especially age specific mortality, but these types of studies havebeen rare in Drosophila given the poor understanding of the ecology of most species in thisgenus. Drosophila mojavensis uses two principal host cacti, agria cactus, Stenocereusgummosus, 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 asuite of fitness components including adult longevity under stress conditions due to the host shiftfrom agria cactus in Baja California to organ pipe cactus in mainland Mexico. Thus, differences inlongevity, 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 forthe study of senescence because the flies can be reared on their natural substrates in thelaboratory. In this study we analyzed survivorship and rates of mortality in flies from a mainlandpopulation grown on two host cacti and laboratory food during their life cycle. Three-day adultcohorts were sorted by sex and housed in cages in groups of 400 individuals. They were fed withthe same food they were exposed to as larvae plus 4% atmospheric ethanol. Dead flies werecounted daily. PROC LIFETEST in SAS was used to estimate both mortality rates and meanlongevity. There was a significance difference among groups using both Log-Rank and Wilcoxontests. 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 agriaand organ pipe tissues compared with lab food differ in their chemical composition, and thereforeinfluence different levels of larval and adult nutrition. To the extent that these substratesinfluence age specific survivorship in adults is not well understood. Future studies are plannedwith additional populations and characterization of gene expression profiles with age using DNAmicroarrays.
Keywords: Drosophila, aging, cactus
POPULATION ECOLOGY OF THE JEFFERSON SALAMANDER, AMBYSTOMA
Department of Biological Sciences, Eastern Illinois University, Charleston, IL 61920
Amphibian populations utilizing small isolated wetlands are often small in size, have little to nocontact with other populations, and are susceptible to stochastic extinction processes. Thepersistence of such populations can only be ascertained by obtaining data that allow theprediction of the population’s growth, trajectory, and capacity to achieve a sustainable size. TheJefferson salamander, Ambystoma jeffersonianum, is a state-threatened species, occurring atfewer than 15 ponds within Illinois. Individuals at a pond in the east-central part of the state arecaptured using a drift fence-pitfall trap array, then sexed, measured for SVL, and marked using aunique combination of toe clips. Also obtained are the number of egg masses, averagepercentage of successfully hatched eggs, and number of juveniles leaving the pond. All data isthen entered into a life history table and used to develop a population model. Informationobtained from the model will be used to determine which life history stage is critical to the survivalof the population, and it will allow management efforts to focus on mechanisms that are mostlikely to cause declines.
Keywords: isolated wetlands, life history stage, life history table, population model,
GEOGRAPHIC VARIATION IN COURTSHIP SONGS AMONG MAINLAND AND BAJACALIFORNIA POPULATIONS OF Drosophila mojavensis
Over, K., de Oliveira, C.C., and Etges, W.J
EFFECTS OF HABITAT FRAGMENTATION ON ECHINACEA ANGUSTIFOLIA POLLINATOR
Institute for Plant Conservation, Chicago Botanic Garden, Glencoe, IL 60022
To examine the effects of habitat fragmentation on the abundance and diversity of pollinatorsvisiting a common prairie purple coneflower (Echinacea angustifolia), we observed and collectedinsect visitors on 254 flowering Echinacea plants in 20 prairie remnants in western Minnesota. We visited each site 3-4 times during the flowering season, and observed 5 randomly selectedplants during each visit. We characterized the spatial pattern of flowering conspecifics at both thepopulation level (i.e. population size) and the individual level (i.e. distance to the nth nearestneighbor for n=1 through 31). Population size ranged from 3 to 4500, and distance to the firstnearest neighbor ranged from 0.1 m to 127 m. We estimated seed set by weighing a subset ofseeds from each observed plant. Echinacea appears to be pollinated primarily by variety of nativebees, with 8 genera of bees from 4 different families (Halicitidae, Anthophoridae, Andrenidae,Megachilidae) represented in our collections. Overall bee visitation was low, with 203 visitsobserved during 139 hours and 40 minutes of observation. After accounting for temporal variationin visitation rates, we were unable to detect any clear relationship between the frequency of beevisitation and Echinacea population size, or between the frequency of bee visitation and theisolation of individual Echinacea plants. Likewise, we found no significant relationship betweenestimated seed set and population size. However, there appears to be a significant negativerelationship between seed set and the isolation of individuals, at least at some spatial scales. Observed rates of pollinator visitation and estimates of seed set were not significantly correlated. We discuss the role of pollinator scarcity and other factors in limiting reproductive success infragmented landscapes.
Key words: Echinacea angustifolia, pollination, habitat fragmentation, bees
PHENOTYPIC PLASTICITY IN MIMULUS RINGENS:
A STUDY OF DROUGHT TOLERANCE AND INDUCED HERBIVORE RESISTANCE
1 Department of Biology, University of Evansville, Evansville, IN 47714
2 Department of Environmental Sciences, University of Virginia, Charlottesville, VA 22904
Phenotypic plasticity allows an organism of a given genotype to alter its phenotype dependentupon the environment, within genetic constraints. Plasticity is believed to have a genetic basis,and so could be acted upon by selection. Inbreeding can cause inbreeding depression, whendeleterious alleles become fixed in a line of organisms. Because plasticity is a way of fine tuningan organism’s phenotype to better suit its environment, mutations affecting plasticity genes wouldbe likely to reduce fitness in some environments, though not in all, and would not necessarilycause the death of the organism. In a study at the Blandy Experimental Farm (VA), I examinedtwo aspects of phenotypic plasticity in Mimulus ringens – drought tolerance and inducedherbivore resistance –and how they are affected by inbreeding. I found no significant effect ofinbreeding on drought tolerance, though there was a marginally significant effect of watertreatment on date of first flower. Induced resistance was found to cause a reallocation cost inplants induced at a small size, with induced plants growing less than controls. A marginal effectof breeding*induction was found, with self plants showing the greatest growth lag. However,selfed plants still outperformed outbred plants, growing as much as outbred when induced, andgrowing more when uninduced. No reallocation costs were found for flower number or date offirst flower. Induced resistance was not found to slow herbivore (cotton aphids) population
growth. However, induced resistance may increase fitness in cases of herbivory by otherherbivores. Further studies are needed.
Keywords: Mimulus ringens, plasticity, inbreeding, herbivory
ASSESSMENT OF THE CUTICULAR HYDROCARBONS INVOLVED IN MATE-CHOICE
WITHIN AND BETWEEN TWO POPULATIONS OF Drosophila mojavensis
Department of Biological Sciences, University of Arkansas, Fayetteville, AR 72701
Understanding the physiological mechanisms involved in mate-choice behaviors in closelyrelated, yet isolated populations can lead to a greater understanding of the processes that drivespeciation. It remains unclear whether the mechanisms that cause premating reproductiveisolation between populations or species are an extension of mate-choice systems governingindividual mating decisions within populations. Two allopatric populations of Drosophilamojavensis from Baja California, Mexico and mainland Arizona exhibit a degree of prematingreproductive isolation and are considered possible nascent species. Male cuticular hydrocarbonshave been shown to be one of the major factors determining success of courtship attempts inmany Drosophila species including D. mojavensis. Baja California and mainland populationsexhibit characteristic differences in hydrocarbon composition, and are thus particularly usefulmodels in which to explore the relationships between mate-recognition cues, sexual selection andreproductive isolation. Mating trials within and between the populations were conducted and thecuticular hydrocarbons of each male individual were characterized and quantified. Hydrocarbonprofiles were examined to determine the contribution of each component to mating success withineach population. The results were then compared to determine if the hydrocarbons thatdetermine mating success within a population are the same as those that determine successbetween populations.
Keywords:Drosophila mojavensis, hydrocarbons, mate-choice, reproductive isolation
NEST PARAMETERS OF ALLIGATOR SNAPPING TURTLES (MACROCHELYS TEMMINCKII)
AT BLACK BAYOU LAKE NATIONAL WILDLIFE REFUGE IN NORTHEAST LOUISIANA
Department of Biology, University of Louisiana, Monroe, LA 71209.
The Alligator Snapping Turtle(Macrochelys temminckii) is a predominantly aquatic turtle, withfemales exiting the water only to lay eggs. Oviposition takes place over approximately two weeksbetween the months of April and June. Nest surveys of a population of M. temminckii have beenconducted intermittently since 1997. In 2004, monitoring became more regular and intensive. Inthis preliminary study, a total of 22 intact or partially intact nests were found between 1997 and2004 (9 intact, 13 partially intact). Clutch size averaged 33.4 eggs (N = 9, range 28-44). Meanegg weight for 21 clutches was 31.26 g, with mean egg length and width of 38.4 and 36.8 mm,respectively (N = 20). In 2004, 12 nests were found along a railroad embankment abutting thelake and two along a wooded, old-field margin. The fourteen ovipositional sites were an averageof 8.28 m from the water’s edge, a slope of 12.9° above the horizon, and with 43 percent canopycover.
Keywords: Macrochelys temminckii, Nest ecology, Reproduction
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