Scale and ecological and historical determinants of a species' geographic range: The plant parasite Phoradendron californicum Nutt. (Viscaceae)

Geographic ranges of species are fundamental units of study in ecology and evolutionary biology, since they summarize views of how species' populations and individuals are organized in space and time. Here, I assess how abiotic and biotic factors limit and constrain species' geographic range, structure its distributions, and change in importance at multiple spatial and temporal scales. I approach this challenge using models and testable hypothesis frameworks in the context of ecological, geographic, and historical conditions. Concentrating on a single species, the desert mistletoe, Phoradendron californicum, I assess the relative importance of factors associated with dispersal, host-parasite-vector niche overlap, and phylogeographic patterns for cpDNA within a 6 mya timeframe and at local-to-regional geographic extents. Results from a comparison of correlative and process-based modeling approaches at resolutions 1-50 km show that dispersal-related parameters are more relevant at finer resolutions (1-5 km), but that importance of extinction-related parameters did not change with scale. Here, a clearer and more comprehensive mechanistic understanding was derived from the process-based algorithm than can be obtained from correlative approaches. In a range-wide analysis, niche comparisons among parasite, hosts, and dispersers supported the parasite niche hypothesis, but not alternative hypotheses, suggesting that mistletoe infections occur in non-random environmental subsets of host and disperser ecological niches, but that different hosts get infected under similar climatic conditions, basically where their distributions overlap that of the mistletoe. In a study of 40 species, including insects, plants, birds, mammals, and worms distributed across the globe, genetic diversity showed a negative relationship with distance to environmental niche centroid, but no consistent relationship with distance to geographic range center. Finally, P. californicum's cpDNA phylogenetic/phylogeographic relationships were most probable under a model of geologic events related to formation of the Baja California Peninsula and seaways across it in the Pliocene and the Pleistocene; however, fossil record, niche projections to the LGM, and haplotype distribution suggested shifting distributions of host-mistletoe interactions and evidence of host races, which may explain some of the genealogical history of the cpDNA. In sum, the chapters presented here provide robust examples and methodologies applied to estimating the importance and scale at which different sets of abiotic and biotic factors act to structure a species' geographic range

A GIS and object oriented classification application to the problem of scaling ecological patterns and processes

Graduate Student, Ecology and Evolutionary Biology, The University of KansasPlatinum Sponsors * KU Department of Geography * Coca-Cola Gold Sponsors * KU Institute for Policy & Social Research * State of Kansas Data Access and Support Center (DASC) * KU Libraries GIS and Data Services * Wilson & Company Engineers and Architects Silver Sponsors * ASPRS - Central Region * Bartlett & West * C-CHANGE Program (NSF IGERT) * Garmin * Kansas Applied Remote Sensing Program * KansasView * KU Transportation Research Institute * KU Biodiversity Institute Bronze Sponsors * KU Center for Remote Sensing of Ice Sheets (CReSIS) * KU Center for Global & International Studies * KU Environmental Studies Progra

Potential invasion of exotic ambrosia beetles Xyleborus glabratus and Euwallacea sp. in Mexico: A major threat for native and cultivated forest ecosystems

We analyze the invasive potential of two Asian ambrosia beetles, Xyleborus glabratus and Euwallacea sp., into Mexico and the southern United States. The fungal symbionts of these beetles have been responsible for damage to trees of the family Lauraceae, including Persea americana and other noncultivated tree species on both coasts of the United States. We estimate their potential threat using ecological niche modeling and spatial multi-criteria evaluation protocols to incorporate plant and beetle suitabilities as well as forest stress factors across Mexico. Mexico contains higher climatic and habitat suitability for X. glabratus than for Euwallacea sp. Within this country, the neotropical region is most vulnerable to invasion by both of these species. We also identify a corridor of potential invasion for X. glabratus along the Gulf of Mexico coast where most Lauraceae and native Xyleborus species are present; dispersal of either X. glabratus or Euwallacea sp. into this region would likely lead to major disease spread. However, the overall potential damage that these beetles can cause may be a function of how many reproductive hosts and how many other ambrosia beetles are present, as well as of their capacity to disperse. This work can also alert relevant managers and authorities regarding this threat

Process-based and correlative modeling of desert mistletoe distribution: a multiscalar approach

Because factors affecting distributional areas of species change as scale (extent and grain) changes, different environmental and biological factors must be integrated across geographic ranges at different resolutions, to understand fully the patterns and processes underlying species' ranges. We expected climate factors to be more important at coarse resolutions and biotic factors at finer resolutions. We used data on occurrence of a parasitic plant (Phoradendron californicum), restricted to parts of the Sonoran and Mojave deserts, to analyze how climate and mobility factors explain its distributional area. We developed analyses at five spatial resolutions (1, 5, 10, 20, 50 km) within the distributional area of the disperser species, and compared ecological niche models from three commonly used correlative methods with a process-based model that estimates colonization and extinction rates in a metapopulation framework. Correlative models improved when layers associated with hosts and disperser were used as predictors, in comparison with models based on climate only; however, they tended to overfit to data as more layers were added. Dispersal-related parameters were more relevant at finer resolutions (1–5 km), but importance of extinction-related parameters did not change with scale. We observed greater coincidence between correlative and process-based models when based only on dimensions of the abiotic niche (i.e., climate), but a clearer and more comprehensive mechanistic understanding was derived from the process-based algorithm

Caracterización Ecológica en Múltiples Escalas de Sayornis saya y S. phoebe y su Zona de Contacto en las Grandes Planicies

We assessed interspecific ecological relationships between Say's (Sayornis saya) and Eastern (S. phoebe) phoebes at three scales by developing ecological niche models at two spatial extents and comparing the models' predictions with data from local-scale surveys. The two species' habitats differed in several environmental attributes, primarily precipitation, temperature, and vegetation indices, at both extents. Local-scale surveys between -97° and -101° longitude revealed a steep gradation in ratios of occurrences Say's to the Eastern Phoebe, increasing from east to west. Local-scale occurrences coincided with results of ecological niche models at the extent of both the continent and contact zone, except for Eastern Phoebe occurrences and vegetation indices at both extents. Say's Phoebes nested in open country with sparse or no surrounding woodland, whereas Eastern Phoebe nests were primarily along woodland streams but also at seven sites in more open country where Say's Phoebes had nested previously. At the contact-zone extent, the niche space of the Eastern Phoebe was embedded more into that of Say's Phoebe than the converse. Although niche models at the contact-zone extent indicated some potential for contact, competition between these two species for nest sites is probably less important in limiting distributions than are autoecological characteristics

ENVIRONMENTAL CORRELATION STRUCTURE AND ECOLOGICAL NICHE MODEL PROJECTIONS

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Environmental Correlation Structure and Ecological Niche Model Projections

This is the published version

Ecological niche modeling of the rare bee Promelitta alboclypeata reveals possible cryptic differentiation across northern Africa and Arabia (Hymenoptera: Melittidae)

International audienceAbstractThe scarcely collected bee Promelitta alboclypeata with known occurrence across northern Africa and the Arabian Peninsula is a typical example of the bee family Melittidae which encompasses a good number of species with sparse or disjunct distributions and particular flower preferences. Using records for 16 localities, we estimated ecological niche models for P. alboclypeata in Maxent on four sets of occurrences, to represent the disparity of the known records, most of them known from the western section of the range. Our estimates show a predicted area for the species in the northern section of the geographic extent assumed accessible to the species (mainly north Africa and the Arabian Peninsula), signaling feasible regions to survey for the presence of the species; possible ecological niche differentiation between the western and eastern populations is also signaled by the models

Human cytomegalovirus US28 facilitates cell-to-cell viral dissemination

Human cytomegalovirus (HCMV) encodes a number of viral proteins with homology to cellular G protein-coupled receptors (GPCRs). These viral GPCRs, including US27, US28, UL33, and UL78, have been ascribed numerous functions during infection, including activating diverse cellular pathways, binding to immunomodulatory chemokines, and impacting virus dissemination. To investigate the role of US28 during virus infection, two variants of the clinical isolate TB40/E were generated: TB40/E-US28(YFP) expressing a C-terminal yellow fluorescent protein tag, and TB40/E-FLAG(YFP) in which a FLAG-YFP cassette replaces the US28 coding region. The TB40/E-US28(YFP) protein localized as large perinuclear fluorescent structures at late times post-infection in fibroblasts, endothelial, and epithelial cells. Interestingly, US28(YFP) is a non-glycosylated membrane protein throughout the course of infection. US28 appears to impact cell-to-cell spread of virus, as the ΔUS28 virus (TB40/E-FLAG(YFP)) generated a log-greater yield of extracellular progeny whose spread could be significantly neutralized in fibroblasts. Most strikingly, in epithelial cells, where dissemination of virus occurs exclusively by the cell-to-cell route, TB40/E-FLAG(YFP) (ΔUS28) displayed a significant growth defect. The data demonstrates that HCMV US28 may contribute at a late stage of the viral life cycle to cell-to-cell dissemination of virus