51 research outputs found

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

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    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

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    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

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

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    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

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    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

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

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    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

    Conservation genetics of Australasian sailfin lizards: Flagship species threatened by coastal development and insufficient protected area coverage

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    a b s t r a c t Despite rampant coastal development throughout Southeast Asia and the Pacific, studies of conservation genetics and ecology of vulnerable, coastal species are rare. Large bodied vertebrates with highly specialized habitat requirements may be at particular risk of extinction due to habitat degradation and fragmentation, especially if these habitats are naturally patchily distributed, marginal, otherwise geographically limited, or associated in space with high human population densities or heavy anthropogenic disturbance. Particularly telling examples of these conservation challenges are large Australasian reptiles with obligate habitat requirements for lowland, coastal and mangrove forests. Plagued by habitat destruction due to high human densities along coastlines, sprawling rural development, and rapidly developing estuarine fisheries industry, coastal forest reptiles are experiencing rapid declines. And yet studies of population biology, genetics, and habitat requirements of species depending on these environments are few. We undertook the present study in order to take a multifaceted approach to understanding a poignant conservation problem. We identify significant evolutionary units for conservation in large-bodied sailfin lizards (genus Hydrosaurus), model suitable habitat in the Philippines from extensive occurrence data and evaluate the efficacy of the current protected area network, and identify the source of hydrosaurs in the illegal pet trade. We determine that the extent of the species' habitat coincident with protected areas is low. Our forensic evaluation of the illegal pet trade in the Philippines determines the existence of a natural population that is at risk of systematic exploitation by traders. Together, this integrative study characterizes a conservation urgency of particular significance: the genetically distinct sailfin lizards of the Bicol faunal region, with suitable habitat virtually unprotected, and clear evidence of heavy exploitation for illegal trade. To the best of our knowledge, our study is the first conservation genetic study to evaluate the potential effectiveness of the protected landscape coverage in the Philippines, a Megadiverse nation and Biodiversity Hotspot

    Paléoenvironnements et adaptations humaines au Dernier Maximum Glaciaire : le cas du Badegoulien

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    Avec l’avancée de nos connaissances sur la variabilité climatique de la dernière période glaciaire en Europe, une meilleure précision des simulations paléoclimatiques et le développement d’algorithmes prédictifs, il est aujourd’hui possible d’aborder sur de nouvelles bases la relation entre environnement et culture au Paléolithique supérieur. Cette étude expose les résultats de l’application de la modélisation de niches éco-culturelles (Eco-Cultural Niche Modeling) au Badegoulien (culture archéologique de la fin du Dernier Maximum Glaciaire). L’application de deux architectures prédictives – Genetic Algorithm for Rule-Set Prediction (GARP) et Maximum Entropy (Maxent) – à partir des données archéologiques, paléoclimatiques et géographiques, nous a permis de reconstituer la niche écologique propre à cette culture. Les résultats obtenus montrent que les deux territoires définis à partir de la circulation des matières premières lithiques au Badegoulien correspondent à des conditions environnementales légèrement distinctes mais qui appartiennent à la même niche écologique.This study details an application of Eco-Cultural Niche Modeling (ECNM) aimed at examining the ecological context of the Badegoulian archaeological culture during the middle and later part of the Last Glacial Maximum in France, using two modeling architectures – the Genetic Algorithm for Rule-Set Prediction (GARP) and Maximum Entropy (Maxent). We reconstructed the ecological niche of the Badegoulian and also assessed whether eco-cultural variability existed within the technocomplex. We identified two broad but distinct territories within the Badegoulian based on lithic raw material circulation and used randomization-based tools to compare the eco-cultural niches estimated for these two territories, taking into account the use or non-use of conditions within the dispersal range of the human populations in question. In order to examine patterns of eco-cultural niche similarity, we used ENMTool’s (Warren et al., 2008 and 2010) niche overlap measures and the associated background similarity test. The overlap measures compare two maps (in this case, the eco-cultural niche reconstructions for the two Badegoulian territories) and measure the similarity between them. The background similarity test then evaluates whether the observed degree of similarity between the two maps is greater than would be expected by chance. We defined a background area for each of the Badegoulian territories based on a generalization of lithic raw material transport within the Badegoulian. This was accomplished by establishing a buffer with a radius of 175 km centered on clusters of recorded archaeological sites within each territory. When creating these buffers, we also kept intact the boundary between the northern and southern territories since there are no known instances of lithic raw material circulation between the two. The predicted geographic range of the ecological niche reconstructed for the Badegoulian technocomplex as a whole covers much of present-day France, extending north into southern Belgium and south into the northern third of the Iberian Peninsula, although the known distribution of the Badegoulian does not extend into either of the two regions. The eco-cultural niche reconstructions for the two lithic raw material circulation networks show an overlap in the southern portion of the present-day region of Poitou-Charentes, the western part of the Limousin region, and southwards along the western margin of the Massif Central. The background similarity tests indicate that these two Badegoulian territories are interpredictive and thus occupy the same ecological niche. However, the northern territory is associated with ecological conditions that are slightly cooler and more humid than those of the southern territory. We propose that the identified Badegoulian lithic raw material circulation networks reflect distinct social territories associated with particular conditions within a single ecological niche. The relationship between these territories and ecological factors has interesting implications, considering that they share a common lithic technology. We argue that the trend towards territoriality observed in the Upper Solutrean (Banks et al., 2009) carries over into the Badegoulian, during which time territories become more distinct, even if the distinction is not readily apparent in terms of stone tool types. This study illustrates the utility of combining ecological niche reconstructions with archaeological data to identify and evaluate diachronic trends in cultural continuity for situations in which such patterns may be missed when the focus is solely on lithic technology and typology.info:eu-repo/semantics/publishedVersio
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