SU Biological Sciences Department

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    Monitoring of dung beetle (Scarabaeidae and Geotrupidae) activity along Maryland's Coastal Plain
    (Eagle Hill Institute, 2018-03) Simons, Patrick; Molina, Michael; Hagadorn, Mallory; Price, Dana; Biological Sciences
    Our understanding of how human activities impact insect communities is limited. Dung beetles, well known for the ecosystem services they provide, are faced with many conservation threats, particularly from deforestation and agriculture. Here we used 200-m transects and human-dung—baited pitfall traps to examine dung beetle populations in 7 forests of Maryland's Coastal Plain. We set traps once a month, from May 2014 to April 2015, to determine species presence, abundance, range, and seasonality. We collected 6463 individuals representing 22 species; Janes Island State Park (JISP) had the highest abundance (2705 individuals) and Martinak State Park (MSP) had the highest species richness (19 species). During summer 2015, we examined the succession of dung beetles attracted to bait in JISP and MSP. We set 10 traps once a month (May–August) in each site and collected beetles on days 1, 3, 5, 7, 14, and 21 without dung replacement. In JISP, Onthophagus hecate (Scooped Scarab) was abundant throughout each 21-d period, and accounted for 68% of all beetles collected. In MSP, most specimens were collected by day 5. Here we provide information for conservation of locally rare or uncommon species.
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    Marigold Cell Size and Polyploidy
    (Association for Biology Laboratory Education (ABLE), 2004) Hunter, Kimberly L.; Hunter, Richard B.; Biological Sciences
    Most animals are diploid, having one set of chromosomes from the male and one from the female. Polyploid animals, with the exception of some frogs and fish, are usually aborted or die immediately after birth (Gardner et al., 1991). In contrast, estimates are that about 70% of flowering plants and 90% of ferns contain three or more sets of chromosomes (Masterson, 1994; Pichersky et al., 1990). Chromosomes pair at meiosis, therefore most organisms have even sets of chromosomes, such as tetraploids (4 sets), and hexaploids (6 sets). Those with odd numbers have reduced fertility (triploids for example) and often reproduce vegetatively. Many crop plants are polyploid, including coffee, cotton, potatoes, strawberries, sugar cane, tobacco, wheat and corn. Polyploidy in plants has been investigated since the 1930s to try to understand and perhaps make use of its effects (Stebbins, 1947). The grain crop triticale, for example, is a human-generated hybrid polyploid of wheat (Triticum aestivum) and rye (Secale cereale) formed by scientists containing the complete genomes of both grasses. Plant breeders induce polyploidy to attempt to increase yield, improve qualities like fruit size or vigor, and to adapt crops to particular growing conditions (Dewey, 1980; Zeven, 1980). The seedless watermelon and larger tetraploid grapes are examples. In some instances polyploidy has increased flower, seed or fruit size, increased photosynthetic or respiration rates, or increased tolerance of extreme temperatures, drought or flooding (Tal, 1980). However, there are few consistent effects, the primary one being an increase in cell size (Masterson, 1994; Bennett and Leitch, 1997). We have developed a lab (Hunter et al., 2002) based on polyploidy and cell size, to introduce middle school, high school, and college students to several important subjects in biology, including genetics (chromosomes, meiosis and mitosis, polyploidy), plant anatomy (stomata, air and water exchange, leaf structure) and cell biology (genome size and cell size). It also allows the use of simple math in data analysis and utilizes quantitative measurements rather than simple observations. The lab involves growing marigolds for about one month from seed, and measuring guard cell (surrounding the stomata) sizes and densities. A modified version of the lab was presented at the 2003 ABLE meeting in Las Vegas.
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    Investigating Polyploidy: Using Marigold Stomates & Fingernail Polish
    (National Association of Biology Teachers, 2002-05) Hunter, Kimberly L.; Leone, Rebecca S.; Kohlhepp, Kimberly; Hunter, Richard B.; Biological Sciences
    Hands-on experimentation with polyploidy is a useful approach to connect research with classroom teaching. The following activity uses marigolds to explore the effects of differing chromosome number on plant cell size. Researchers have documented a correlation between plant ploidy and guard cell size, and its correlate, density (Masterson 1994). Guard cells control opening and closing of stomates on the leaf surface.
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    Inter-signal interaction and uncertain information in anuran multimodal signals
    (2011) Taylor, Ryan; Klein, Barrett; Ryan, Michael
    Disentangling the influence of multiple signal components on receivers and elucidating general processes influencing complex signal evolution are difficult tasks. In this study we test mate preferences of female squirrel treefrogs Hyla squirella and female túngara frogs Physalaemus pustulosus for similar combinations of acoustic and visual components of their multimodal courtship signals. In a two-choice playback experiment with squirrel treefrogs, the visual stimulus of a male model significantly increased the attractivness of a relatively unattractive slow call rate. A previous study demonstrated that faster call rates are more attractive to female squirrel treefrogs, and all else being equal, models of male frogs with large body stripes are more attractive. In a similar experiment with female túngara frogs, the visual stimulus of a robotic frog failed to increase the attractiveness of a relatively unattractive call. Females also showed no preference for the distinct stripe on the robot that males commonly bear on their throat. Thus, features of conspicuous signal components such as body stripes are not universally important and signal function is likely to differ even among species with similar ecologies and communication systems. Finally, we discuss the putative information content of anuran signals and suggest that the categorization of redundant versus multiple messages may not be sufficient as a general explanation for the evolution of multimodal signaling. Instead of relying on untested assumptions concerning the information content of signals, we discuss the value of initially collecting comparative empirical data sets related to receiver responses.
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    Incorporating molecular genetics into remote expedition fieldwork
    (2014) Bunting, Shelby; Burnett, Emily; Hunter, Richard; Field, Richard; Hunter, Kimberly
    Conservation expedition groups that use volunteer researchers are widespread in the United Kingdom and are growing in popularity around the world. These expeditions operate in regions of high biodiversity to study and protect the endemic species of these areas. New products have now made it possible to conduct molecular analyses in the field. We tested this in a volunteer-based conservation expedition to an area of tropical montane rainforest and cloud forest in Cusuco National Park, Honduras. Specifically, we (1) tested and modified recommended protocols for use of the new molecular techniques on a wide range of plant and animal species in the field, (2) tested the ability of novice volunteers to successfully use these techniques after minimal introductory training, and (3) used the novel techniques to conduct a small-scale population genetic study of Liquidambar styraciflua L. while on expedition. We found the techniques to be effective on all plant and animal species tested, with some modification of manufacturers' protocols. We also found that novice student volunteers were able to learn the required theory and protocols for the new technology, collect reliable data, and perform basic genetic analyses in a week-long DNA field sampling course. Finally, the Liquidambar case study demonstrated that genetic analyses can be successfully completed in primitive field conditions. These findings have exciting implications for work that can be done in remote locations, often areas of the greatest conservation significance.
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    Understanding the roles of polyploidy and the environment on nordihydroguaiaretic acid variation in Larrea tridentata
    (2014) Zuravnsky, Kristin Nicole; Hunter, Kimberly; Biological Sciences
    Nordihydroguaiaretic acid (NDGA) is the principal compound in the resinous leaf coating of Larrea tridentata (Creosote bush), the dominant shrub of North American deserts. L. tridentata exists as three polyploid races: diploid (2X = 26), tetraploid (4X = 52), and hexaploid (6X = 78). The distributions of these ploidy levels are strongly associated with the three major deserts of the region where diploids primarily reside in the cooler, wetter Chihuahuan desert, tetraploids in the Sonoran desert, and hexaploids in the hot, dry Mojave desert. NDGA is a secondary metabolite of creosote bush that functions to protect plants from biotic and abiotic stressors such as extreme drought, harmful UV radiation, and herbivory. Here, I investigated the role of polyploidy and environmental variables on the production of NDGA by quantifying concentrations from field and greenhouse-grown polyploids. Citizen scientists were utilized to facilitate simultaneous sampling across the entire distributional range of this species, for one full year. Under natural conditions, shrubs produced significantly higher NDGA concentrations than when removed from the harsh desert environment. In field and greenhouse treatments, hexaploids exhibited higher NDGA concentrations than diploids or tetraploids.Within the diploid cytotype, I documented environmental influences on NDGA concentration based on comparisons between a field site experiencing Severe drought, a watered field site, and greenhouse-grown diploids. Principal components analysis revealed that NDGA response to environmental variables successfully predicts the current ploidy distribution of this species. These observations highlight the complexity of plant-environment-genotype interactions and suggest that evolution in production of secondary metabolites may be driven by long-term changes in environmental conditions, and potentially influence species distribution regimes.
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    Altering growth rates and nutritional qualities of microalgal feedstock with symbiotic bacteria
    (2015) Kelly, Stephen M.; Holland, Mark A.; Biological Sciences
    The cultivation of microalgae has many commercial purposes; it is integral in the farming of marine animals such as finfish, shrimp, and bivalves through its use as feedstock, and it has potential for use in renewable energy sources as a biofuel. Pink pigmented facultatively methylotrophic bacteria (PPFM) are known to live symbiotically on plants, feeding off of metabolic wastes and producing growth regulators and nutrients vital for plant development. These bacteria have also been isolated from algae and water samples. One strain of vitamin B12 over-producing PPFM has been previously isolated by our lab, and past research has indicated that co-culturing microalgae with PPFM can increase algal growth rates. Our research investigated the possibility of altering the growth rates and nutritional qualities of microalgae through the use of PPFM by conducting algae growth experiments and nutritional analysis. Microalgal species commonly used as feedstock for industrial bivalve aquaculture were supplemented with vitamin B12 over-producing PPFM. A significant difference in growth between PPFM supplemented and non-supplemented algal cultures was not seen consistently, while preliminary nutritional quality testing showed an increase in amino acid and lipid content for PPFM supplemented algal cultures over non-supplemented cultures.