Morphological correlates of community structure in North American waterfowl

I consider relationships between functional feeding morphology and feeding ecology within a guild of dabbling ducks (Anas spp.) which co-occur year round. This waterfowl guild contains three .core. species with typical bill morphologies and four .peripheral. species which vary from the typical morphology in bill length and width or interlamellar spacing. Nearest neighbors in morphological space tend to have high ecological (dietary) overlap; i.e., similarity in morphology corresponds to similarity in ecology. Moreover, by employing Monte Carlo techniques, correlations between morphology and ecology are shown to be weaker during winter than summer, implying that species overcompensate. during winter and reduce dietary overlap even more than would be expected by similarities in bill morphology alone. Additionally, I examine morphological variation among populations of North American mallards (A. platyrhynchos) to test Roughgarden.s (1974) predictions regarding relationships between intraspecific morphological variation and interspecific competition. Specifically, morphological variation should decrease with either an increase in number of competing species or a decrease in available resources. Although populations show expected trends in bill morphology with sex (males have larger bills than females) and latitude (Bergmann.s rule), I am able to demonstrate only a weak trend in females in relationship between morphological variation and intensity of interspecific competition. Examinations of relationships between morphology and ecology should be considered during that time of year when ecological .' crunches' occur, as this should be when selection for different morphologies and feeding strategies occurs, although species may utilize other mechanisms (e.g., foraging behavior, habitat selection) which could mediate resource partitioning to a greater degree than would be expected solely by morphological differences

Sustainability of Global Golden Inland Waterways

Sustainable inland waterways should meet the needs of navigation without compromising the health of riverine ecosystems. Here we propose a hierarchical model to describe sustainable development of the Golden Inland Waterways (GIWs) which are characterized by great bearing capacity and transport need. Based on datasets from 66 large rivers (basin area > 100,000 km2) worldwide, we identify 34 GIWs, mostly distributed in Asia, Europe, North America, and South America, typically following a three-stage development path from the initial, through to the developing and on to the developed stage. For most GIWs, the exploitation ratio, defined as the ratio of actual to idealized bearing capacity, should be less than 80% due to ecological considerations. Combined with the indices of regional development, GIWs exploitation, and riverine ecosystem, we reveal the global diversity and evolution of GIWs' sustainability from 2015 to 2050, which highlights the importance of river-specific strategies for waterway exploitation worldwide