647 research outputs found

    Negative Biotic Interactions Drive Predictions of Distributions for Species From a Grassland Community

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    Understanding the factors that determine species’ geographic distributions is important for addressing a wide range of biological questions, including where species will be able to maintain populations following environmental change. New methods for modelling species distributions include the effects of biotic interactions alongside more commonly used abiotic variables such as temperature and precipitation; however, it is not clear which types of interspecific relationship contribute to shaping species distributions and should therefore be prioritised in models. Even if some interactions are known to be influential at local spatial scales, there is no guarantee they will have similar impacts at macroecological scales. Here we apply a novel method based on information theory to determine which types of interspecific relationship drive species distributions. Our results show that negative biotic interactions such as competition have the greatest effect on model predictions for species from a California grassland community. This knowledge will help focus data collection and improve model predictions for identifying at-risk species. Furthermore, our methodological approach is applicable to any kind of species distribution model that can be specified with and without interspecific relationships

    Contrasting Ecosystem-Effects of Morphologically Similar Copepods

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    Organisms alter the biotic and abiotic conditions of ecosystems. They can modulate the availability of resources to other species (ecosystem engineering) and shape selection pressures on other organisms (niche construction). Very little is known about how the engineering effects of organisms vary among and within species, and, as a result, the ecosystem consequences of species diversification and phenotypic evolution are poorly understood. Here, using a common gardening experiment, we test whether morphologically similar species and populations of Diaptomidae copepods (Leptodiaptomus ashlandi, Hesperodiaptomus franciscanus, Skistodiaptomus oregonensis) have similar or different effects on the structure and function of freshwater ecosystems. We found that copepod species had contrasting effects on algal biomass, ammonium concentrations, and sedimentation rates, and that copepod populations had contrasting effects on prokaryote abundance, sedimentation rates, and gross primary productivity. The average size of ecosystem-effect contrasts between species was similar to those between populations, and was comparable to those between fish species and populations measured in previous common gardening experiments. Our results suggest that subtle morphological variation among and within species can cause multifarious and divergent ecosystem-effects. We conclude that using morphological trait variation to assess the functional similarity of organisms may underestimate the importance of species and population diversity for ecosystem functioning

    Prospectus, November 23, 1976

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    TRUSTEES MEET: 25% TUITION INCREASE VOTED BY BOARD, NEW HOUR TOTAL $17; PC news in brief: Redford stars in \u27Jeremiah Johnson\u27, Spring Schedule changed, Sociological film today, See Chicago Bulls Nov. 30; Till Nov. 30th: Preregister now; \u27Disaster bus\u27 being fixed, should be ready by Jan.; Persecutor\u27s life changed; Illinois low in educ. support; Onarga application approved; 28% late on stud. loans; Before finals: Withdraw by December 15th; GI Bill: New vet allowances announced; Sign up now to save courses for later; Campus competition: Gunki heads stud. recognition; Library stairs sculpture just hanging around for 2 years; Theta Epsilon meets Dec. 1; Senior university: Sangamon State rep visits today; Care and cooking: There\u27s more to wild game than just hunting it; Flipping the bird...a collection of turkey recipes: First, the real one; Then, some recipes by for turkeys...: ...figure five pounds per person, ...I forgot to say to take the turkey out of the bag, ...watch the expressions of delight as they eat it; Timeless marital problems looked at in Coward play; Artist-in-residence: Wayne Forbes: showing need for people to care; Santa Claus arrives Friday; Theta Epsilon Frat. officers announced; Community Cultural Series: Twain Amer. Humor superb; Fifth Column: False Promises of entertainment; Classifieds; Cobra\u27s Corner: 3 candidates for center: Betka is \u27all-business\u27 vying for starting position; Bears still 1st, \u27Excess\u27 within 3 points; Schedule changed: Cagers open tonite at DuPage; Parkland Basketball Roster; Cobra captains ready; Decker wins final Freddy; Lockers must be renewed; Parkland College 1976-1977 Basketball Schedule; Women\u27s Basketball Schedulehttps://spark.parkland.edu/prospectus_1976/1002/thumbnail.jp
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