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Corresponding Patterns (corresponding + pattern)
Selected AbstractsReconstructing asymmetrical reproductive character displacement in a periodical cicada contact zoneJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 3 2006JOHN R. COOLEY Abstract Selection against costly reproductive interactions can lead to reproductive character displacement (RCD). We use information from patterns of displacement and inferences about predisplacement character states to investigate causes of RCD in periodical cicadas. The 13-year periodical cicada Magicicada neotredecim exhibits RCD and strong reproductive isolation in sympatry with a closely related 13-year species, Magicicada tredecim. Displacement is asymmetrical, because no corresponding pattern of character displacement exists within M. tredecim. Results from playback and hybridization experiments strongly suggest that sexual interactions between members of these species were possible at initial contact. Given these patterns, we evaluate potential sources of selection for displacement. One possible source is ,acoustical interference', or mate-location inefficiencies caused by the presence of heterospecifics. Acoustical interference combined with the species-specificity of song pitch and preference appears to predict the observed asymmetrical pattern of RCD in Magicicada. However, acoustical interference does not appear to be a complete explanation for displacement in Magicicada, because our experiments suggest a significant potential for direct sexual interactions between these species before displacement. Another possible source of selection for displacement is hybrid failure. We evaluate the attractiveness of inferred hybrid mating signals, and we examine the viability of hybrid eggs. Neither of these shows strong evidence of hybrid inferiority. We conclude by presenting a model of hybrid failure related to life cycle differences in Magicicada. [source] Understanding and modeling basin hydrology: interpreting the hydrogeological signatureHYDROLOGICAL PROCESSES, Issue 7 2005R. E. Beighley Abstract Basin landscapes possess an identifiable spatial structure, fashioned by climate, geology and land use, that affects their hydrologic response. This structure defines a basin's hydrogeological signature and corresponding patterns of runoff and stream chemistry. Interpreting this signature expresses a fundamental understanding of basin hydrology in terms of the dominant hydrologic components: surface, interflow and groundwater runoff. Using spatial analysis techniques, spatially distributed watershed characteristics and measurements of rainfall and runoff, we present an approach for modelling basin hydrology that integrates hydrogeological interpretation and hydrologic response unit concepts, applicable to both new and existing rainfall-runoff models. The benefits of our modelling approach are a clearly defined distribution of dominant runoff form and behaviour, which is useful for interpreting functions of runoff in the recruitment and transport of sediment and other contaminants, and limited over-parameterization. Our methods are illustrated in a case study focused on four watersheds (24 to 50 km2) draining the southern coast of California for the period October 1988 though to September 2002. Based on our hydrogeological interpretation, we present a new rainfall-runoff model developed to simulate both surface and subsurface runoff, where surface runoff is from either urban or rural surfaces and subsurface runoff is either interflow from steep shallow soils or groundwater from bedrock and coarse-textured fan deposits. Our assertions and model results are supported using streamflow data from seven US Geological Survey stream gauges and measured stream silica concentrations from two Santa Barbara Channel,Long Term Ecological Research Project sampling sites. Copyright © 2004 John Wiley & Sons, Ltd. [source] Geographic patterns of diversity in streams are predicted by a multivariate model of disturbance and productivityJOURNAL OF ECOLOGY, Issue 3 2006BRADLEY J. CARDINALE Summary 1Univariate explanations of biodiversity have often failed to account for broad-scale patterns in species richness. As a result, increased attention has been paid to the development and testing of more synthetic multivariate hypotheses. One class of multivariate hypotheses, founded in successional diversity theory, predict that species richness is jointly influenced by periodic disturbances that create new niche opportunities in space or time, and the production of community biomass that speeds displacement of inferior by superior competitors. 2While the joint response of diversity to disturbance and productivity has gained support from theoretical and small-scale experimental studies, evidence that corresponding patterns of biodiversity occur broadly across natural systems is scarce. 3Using a data set that employed standardized methods to sample 85 streams throughout the mid-Atlantic United States of America, we show that biogeographical patterns of primary producer diversity in stream ecosystems are consistent with the predictions of a multivariate model that incorporates disturbance frequency and community biomass production as independent variables. Periphyton species richness is a concave-down function of disturbance frequency (mean no. floods year,1) and of biomass production (µg of biomass accrual cm,2 day,1), and an increasing function of their interaction. 4Changes in richness across the disturbance × productivity response surface can be related to several predicted life-history traits of the dominant species. 5Our findings complement prior studies by showing that multivariate models which consider interactive effects of community production and ecosystem disturbance are, in fact, candidate explanations of much broader patterns of richness in natural systems. Because multivariate models predict synergistic effects of ecological variables on species diversity, human activities , which are simultaneously altering both the disturbance regime and productivity of streams , could be influencing biodiversity more than previously anticipated. [source] Characteristics of the delta formation resulting from sediment deposition in Lake Nasser, Egypt: Approach to tracing lake delta formationLAKES & RESERVOIRS: RESEARCH AND MANAGEMENT, Issue 2 2002M. S. El-Manadely Abstract A major problem encountered by managers of large reservoirs, such as Lake Nasser (located in the south of Egypt), is the continuous deposition of sediments, resulting in a bed-level increase, a decrease in lake capacity, and the creation of a new delta that might eventually hinder navigation. To investigate the sedimentation problem in Lake Nasser, a series of surveyed cross-sections were reviewed and samples of suspended sediment and bed material collected. These sets of data were analysed to investigate the progress of the delta formation, the change in its properties in all directions and the corresponding patterns of suspended and deposited sediment particles. Results showed that deposited sediments, characterized by a variable pattern of particle composition, are building up at the lake entrance. Although the expansion of the delta is multidirectional, its accelerated advance towards the High Aswan Dam would depend on the frequent occurrence of high floods following extended drought periods. Based on the calculated deposited sediment volume in Lake Nasser during the period 1964,1998, the lifetime of the dead storage zone allocated for sediment deposition (31 × 109 m3) is estimated at a minimum of 310 years. [source] | ||||||||||