Article Abstract:
The physiology of life history trade-offs in animals is discussed. Conceptual issues associated with physiological aspects of trade-offs are discussed and recent advances in the research in the area are described focusing on study of four model systems, Drosophila, birds, lizard, and wing polymorphic insects. Among the most significant recent advances is the incorporation of genetics in physiological studies of trade-offs. Others are development of more sophisticated models of resource acquisition and allocation, a shift to more integrated, multidisciplinary studies of intraspecific trade-offs, the first detailed investigations of the endocrine regulation of life history trade-offs, and integration of investigations of nutrient input with nutrient allocation.
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Article Abstract:
Research into streams in the urban landscape is reviewed with focus on physical, chemical, and biological/ecological effects of urbanization, one at a time. Increase in the amount of impervious surface cover in urban catchments with change in the hydrology/geomorphology of streams is the most consistent/pervasive effect seen. Runoff and discharges bring greater nutrient-loading, and more metals, pesticides and other contaminants in streams. Declines in richness of fish, invertebrate and algal communities result. Study of disturbance may lead to more effective landscape management.
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Article Abstract:
Relationships between variation in local species diversity and gradients of productivity, the regional-scale phenomena of boundary constraints, oxygen availability, sediment heterogeneity, hydrodynamic regimes and catastrophic physical disturbance are discussed. A conceptual model of how these interdependent environmental factors shape regional-scale variation in local diversity is presented. Environmental influences on regional deep-sea species diversity is discussed.
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