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The Effect Of The Study Region On Gis Models Of Species Geographic Distributions And Estimates Of Niche Evolution; Preliminary Tests With Montane Rodents (Genus Nephelomys) In Venezuela, Ali Raza

Dissertations and Theses

Various niche-based techniques exist to model a species' potential geographic distribution in a Geographic Information Systems (GIS) framework. These models compare the environmental conditions of localities of a species' occurrence versus those of the overall study region. In addition to uses in areas such as macroecology and conservation biology, this approach has been applied recently to studies of niche evolution and historical biogeography. Definition of the study region is critical for all of these applications but has not been addressed previously. Here, I examine the effect of changes in the extent of the study region on potential distribution models of …

Biogeography Of Microorganisms Inhabiting Marine Sponges, Suzy C. Szumowski

Macalester Reviews in Biogeography

Sponge-associated microorganisms are an intriguing system for the consideration of biogeographic patterns due to complications arising from their small size and their symbiotic relationship with sponges. Whether or not microorganisms are capable of exhibiting biogeographic patterns is a topic of heated debate in the literature. Recent studies utilizing new identification techniques have revealed an astonishing amount of diversity and spatiotemporal stability in microorganism communities. Case studies outlined in this paper suggest that some sponge-associated microorganisms represent monophyletic groups that have evolved speciesspecific associations with their hosts. The biogeography of these organisms is receiving increasing attention because they are one of …

Controls On Microbial Community Structure In Thermal Environments: Exploring Bacterial Diversity And The Relative Influence Of Geochemistry And Geography, Kendra Renee Mitchell

Biology ETDs

Community wide molecular surveys have revealed incredible hidden phylogenetic and metabolic diversity in microbial habitats. We have conducted the first microbial survey of Yellowstone National Park thermal environments, sampling 103 communities from across the park and across the range of conditions found. Yellowstone is particularly suited for this type of research because of the large number and wide variety of thermal springs, which are naturally occurring chemostats enabling examination of the factors that control microbes and drive community structure. In addition to samples for molecular microbial analysis, we collected water for extensive geochemical analysis in order to begin to deduce …

From Cells To Coastlines: How Can We Use Physiology To Forecast The Impacts Of Climate Change?, Brian Helmuth

Faculty Publications

The interdisciplinary fields of conservation physiology, macrophysiology, and mechanistic ecological forecasting have recently emerged as means of integrating detailed physiological responses to the broader questions of ecological and evolutionary responses to global climate change. Bridging the gap between large-scale records of weather and climate (as measured by remote sensing platforms, buoys and ground-based weather stations) and the physical world as experienced by organisms (niche-level measurements) requires a mechanistic understanding of how ‘environmental signals’ (parameters such as air, surface and water temperature, food availability, water flow) are translated into signals at the scale of the organism or cell (e.g. body temperature, …

Parallel Shifts In Ecology And Natural Selection In An Island Lizard, Ryan Calsbeek, Wolfgang Buermann, Thomas B. Smith

Dartmouth Scholarship

Natural selection is a potent evolutionary force that shapes phenotypic variation to match ecological conditions. However, we know little about the year-to-year consistency of selection, or how inter-annual variation in ecology shapes adaptive landscapes and ultimately adaptive radiations. Here we combine remote sensing data, field experiments, and a four-year study of natural selection to show that changes in vegetation structure associated with a severe drought altered both habitat use and natural selection in the brown anole, Anolis sagrei.

Results: In natural populations, lizards increased their use of vegetation in wet years and this was correlated with selection on limb length …

Microbial Endemism And Biogeography, Brian P. Hedlund, James T. Staley

Life Sciences Faculty Research

The topic of microbial biogeography is almost 100 years old, however, when confronted with questions about the existence and extent of endemism in the microbial world, many microbiologists respond with opinions and theoretical arguments rather than examples of well-conducted studies. We begin this chapter with an overview of this debate as it applies to free-living prokayotes in part because there are relatively few good microbial biogeography studies. Furthermore, the arguments help to frame microbial biogeography in the larger context of biodiversity in that if endemism is common, then many more species exist.

Beyond Ecology: Bugs Reveal The Deep Roots Of Grassland Ecoregions, K. G.A. Hamilton

Proceedings of the North American Prairie Conferences

Northern grassland faunas that were most affected by glaciation, induced climate shifts include more than 225 endemic phytophagous bugs (leafhoppers and related insects, the Homoptera,Auchenorrhyncha) on Canadian plains, and another 275 in Pacific Northwest intermontane grasslands. These exceptionally rich endemic faunas include many insect,plant associations common to related species of bugs, suggesting adaptation to certain environmental factors that persisted over millions of years despite radical environmental changes induced by glacial advances and retreats. Smaller, but significant, endemic faunas of Homoptera,Auchenorrhyncha in other glaciated areas also reveal patterns of ancient ecological areas. Groups of these grassland,endemic bugs are common to grassland …

Adapting A Floral Biogeography Model To Prairie-Dependent Lepidoptera, Eric H. Metzler, John A. Shuey, Leslie A. Ferge, Richard A, Henderson, Paul Z. Goldstein

Proceedings of the North American Prairie Conferences

Analysis of data collected for a study of prairie dependent Lepidoptera in the northern tallgrass prairies showed four distributional patterns. A logical distributional pattern links species' distribution, i.e. Catocala abbreviatella, to larval host plants. Absence of larval host plant data, which is the case for most species of moths, requires inference based on habitat data of known specimens, i.e. Tarachidia binocula, or in the case of infrequently encountered species, i.e. Crambus murellus, capture data for a limited number of specimens. A fourth distributional pattern, i. e. Atrytone arogos, can be explained by hypotheses which explain the …

Population Structure Of The Gopher Tortise (Gopherus Polyphemus) In Florida, Using Microsatellites, Tonia S. Schwartz

USF Tampa Graduate Theses and Dissertations

Gopher tortoise (Gopherus polyphemus) population sizes have drastically declined in the past 100 years. Much of this decline has been attributed to past human predation, to habitat loss from human development, and potentially to the recently discovered upper respiratory tract disease. An understanding of the genetic structure among populations is critical for the long-term success of relocation and other management strategies. This research focuses on the development of a suite of genetic markers and the answers they provided to questions concerning present day population genetics and its use in management. In addition, this study provides inference on historical …

Mammals Of Iowa: Holocene To The End Of The 20th Century, John B. Bowles, Daryl L. Howell, Richard P. Lampe, Howard P. Whidden

Journal of the Iowa Academy of Science: JIAS

This review of Iowa's mammal fauna at the close of the 20th century summarizes changes in distributional patterns following Euroamerican settlement in the early 1800s. Data from historical records, museum specimens, and presettlement late Holocene fossils indicate presence of 69 resident mammals at that time. Hunting pressures and the conversion of prairie and forest to agricultural fields reduced the populations and ranges of many state mammals, and 14 species were extirpated by 1900. An additional 15 species are either uncommon or rare today, and the Iowa Department of Natural Resources lists four species as endangered, three as threatened and one …

The Dynamics Of Animal Distribution: An Evolutionary/Ecological Model, Charles H. Smith

Faculty/Staff Personal Papers

Investigators have sometimes assumed that the factors underlying animal distribution are too complex to lend themselves to normative modelling. In this work, a model of environment and community interaction is constructed which lends itself to the latter kind of interpretation. It is posed that spatially-varying rates and magnitudes of availability of moisture at given locations act as stresses on the nature of community infrastructure, and secondarily on the rates at which new populations may become integrated into these. Populations are thereby viewed as tending to change range in common directions, though at overall rates remaining peculiar to each. This interpretation …