1,147 research outputs found

    A pilot survey of the central colony of the Waved Albatross Phoebastria irrorata on EspaĂąola Island

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    Española Island is the main breeding site of the Waved Albatross Phoebastria irrorata but little is known of the nesting populations other than those at Punta Cevallos and Punta Suárez. In May 2008 we located nesting albatrosses from nearly the top of the island to the south coast (the “Central Colony”), including in areas not previously reported. We found evidence of a strong interaction between the distribution of woody vegetation and nesting albatrosses. Many albatrosses nest in areas too overgrown to fly into, and walk long distances to and from more open take-off and landing points. Tortoises facilitate albatross movement and nesting by creating trails that albatrosses use. The need remains for a comprehensive estimate of albatross population size and distribution that includes both coastal and inland populations

    Stability criteria for the consumption and exchange of essential resources

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    Models of consumer effects on a shared resource environment have helped clarify how the interplay of consumer traits and resource supply impact stable coexistence. Recent models generalize this picture to include the exchange of resources alongside resource competition. These models exemplify the fact that although consumers shape the resource environment, the outcome of consumer interactions is context-dependent: such models can have either stable or unstable equilibria, depending on the resource supply. However, these recent models focus on a simplified version of microbial metabolism where the depletion of resources always leads to consumer growth. Here, we model an arbitrarily large system of consumers governed by Liebig’s law, where species require and deplete multiple resources, but each consumer’s growth rate is only limited by a single one of these resources. Resources that are taken up but not incorporated into new biomass are leaked back into the environment, possibly transformed by intracellular reactions, thereby tying the mismatch between depletion and growth to cross-feeding. For this set of dynamics, we show that feasible equilibria can be either stable or unstable, again depending on the resource environment. We identify special consumption and production networks which protect the community from instability when resources are scarce. Using simulations, we demonstrate that the qualitative stability patterns derived analytically apply to a broader class of network structures and resource inflow profiles, including cases where multiple species coexist on only one externally supplied resource. Our stability criteria bear some resemblance to classic stability results for pairwise interactions, but also demonstrate how environmental context can shape coexistence patterns when resource limitation and exchange are modeled directly

    Parrots and Palms: Analyzing Data to Determine Best Management Strategies and Sustainable Harvest Levels

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    This exercise1 presents a scenario and raw data on a realistic conflict between parrot conservation and palm tree harvest. It requires that students analyze data very comparable to what would be gathered in the field, to: 1) construct a life tables for the palm and parrot, 2) extract vital statistics about both the palm and parrot population from the life tables, 3) estimate maximum sustainable yield for both species, and 4) make a decision about the sustainability of harvest intensity. It illustrates the importance of data analysis skills for conservation

    Evolutionary response to global change: Climate and land use interact to shape color polymorphism in a woodland salamander

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    Evolutionary change has been demonstrated to occur rapidly in human‐modified systems, yet understanding how multiple components of global change interact to affect adaptive evolution remains a critical knowledge gap. Climate change is predicted to impose directional selection on traits to reduce thermal stress, but the strength of directional selection may be mediated by changes in the thermal environment driven by land use. We examined how regional climatic conditions and land use interact to affect genetically based color polymorphism in the eastern red‐backed salamander (Plethodon cinereus). P. cinereus is a woodland salamander with two primary discrete color morphs (striped, unstriped) that have been associated with macroclimatic conditions. Striped individuals are most common in colder regions, but morph frequencies can be variable within climate zones. We used path analysis to analyze morph frequencies among 238,591 individual salamanders across 1,170 sites in North America. Frequency of striped individuals was positively related to forest cover in populations occurring in warmer regions (\u3e7°C annually), a relationship that was weak to nonexistent in populations located in colder regions (≤7°C annually). Our results suggest that directional selection imposed by climate warming at a regional scale may be amplified by forest loss and suppressed by forest persistence, with a mediating effect of land use that varies geographically. Our work highlights how the complex interaction of selection pressures imposed by different components of global change may lead to divergent evolutionary trajectories among populations

    Literature review on the use of action research in higher education

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    This literature review considers the use of action research in higher education. It specifically looks at two areas of higher education activity. The first concerns academic teaching practice and includes a discussion of research and pedagogy practice, and staff development. The second considers student engagement. In both these core features of higher education, action research has proved to be a central approach to the investigation, reflection and improvement of practice. Each of these main foci includes a discussion of the limitations of the literature. The review illustrates the extent and range of uses to have benefited from an action research approach

    Morphometrics Parallel Genetics in a Newly Discovered and Endangered Taxon of GalĂĄpagos Tortoise

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    GalĂĄpagos tortoises represent the only surviving lineage of giant tortoises that exhibit two different types of shell morphology. The taxonomy of GalĂĄpagos tortoises was initially based mainly on diagnostic morphological characters of the shell, but has been clarified by molecular studies indicating that most islands harbor monophyletic lineages, with the exception of Isabela and Santa Cruz. On Santa Cruz there is strong genetic differentiation between the two tortoise populations (Cerro Fatal and La Reserva) exhibiting domed shell morphology. Here we integrate nuclear microsatellite and mitochondrial data with statistical analyses of shell shape morphology to evaluate whether the genetic distinction and variability of the two domed tortoise populations is paralleled by differences in shell shape. Based on our results, morphometric analyses support the genetic distinction of the two populations and also reveal that the level of genetic variation is associated with morphological shell shape variation in both populations. The Cerro Fatal population possesses lower levels of morphological and genetic variation compared to the La Reserva population. Because the turtle shell is a complex heritable trait, our results suggest that, for the Cerro Fatal population, non-neutral loci have probably experienced a parallel decrease in variability as that observed for the genetic data

    Decoherent Histories Quantum Mechanics with One 'Real' Fine-Grained History

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    Decoherent histories quantum theory is reformulated with the assumption that there is one "real" fine-grained history, specified in a preferred complete set of sum-over-histories variables. This real history is described by embedding it in an ensemble of comparable imagined fine-grained histories, not unlike the familiar ensemble of statistical mechanics. These histories are assigned extended probabilities, which can sometimes be negative or greater than one. As we will show, this construction implies that the real history is not completely accessible to experimental or other observational discovery. However, sufficiently and appropriately coarse-grained sets of alternative histories have standard probabilities providing information about the real fine-grained history that can be compared with observation. We recover the probabilities of decoherent histories quantum mechanics for sets of histories that are recorded and therefore decohere. Quantum mechanics can be viewed as a classical stochastic theory of histories with extended probabilities and a well-defined notion of reality common to all decoherent sets of alternative coarse-grained histories.Comment: 11 pages, one figure, expanded discussion and acknowledgment

    The significance of motivation in student-centred learning : a reflective case study

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    The theoretical underpinnings of student-centred learning suggest motivation to be an integral component. However, lack of clarification of what is involved in motivation in education often results in unchallenged assumptions that fail to recognise that what motivates some students may alienate others. This case study, using socio-cognitive motivational theory to analyse previously collected data, derives three fuzzy propositions which, collectively, suggest that motivation interacts with the whole cycle of episodes in the teachinglearning process. It argues that the development of the higherlevel cognitive competencies that are implied by the term, student-centred learning, must integrate motivational constructs such as goal orientation, volition, interest and attributions into pedagogical practices

    Giant GalĂĄpagos tortoises; molecular genetic analyses identify a trans-island hybrid in a repatriation program of an endangered taxon

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    BACKGROUND: Giant GalĂĄpagos tortoises on the island of EspaĂąola have been the focus of an intensive captive breeding-repatriation programme for over 35 years that saved the taxon from extinction. However, analysis of 118 samples from released individuals indicated that the bias sex ratio and large variance in reproductive success among the 15 breeders has severely reduced the effective population size (N(e)). RESULTS: We report here that an analysis of an additional 473 captive-bred tortoises released back to the island reveals an individual (E1465) that exhibits nuclear microsatellite alleles not found in any of the 15 breeders. Statistical analyses incorporating genotypes of 304 field-sampled individuals from all populations on the major islands indicate that E1465 is most probably a hybrid between an EspaĂąola female tortoise and a male from the island of PinzĂłn, likely present on EspaĂąola due to human transport. CONCLUSION: Removal of E1465 as well as its father and possible (half-)siblings is warranted to prevent further contamination within this taxon of particular conservation significance. Despite this detected single contamination, it is highly noteworthy to emphasize the success of this repatriation program conducted over nearly 40 years and involving release of over 2000 captive-bred tortoises that now reproduce in situ. The incorporation of molecular genetic analysis of the program is providing guidance that will aid in monitoring the genetic integrity of this ambitious effort to restore a unique linage of a spectacular animal
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