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Book
Plant Strategies and the Dynamics and Structure of Plant Communities. (MPB-26), Volume 26
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ISBN: 0691209596 Year: 1988 Publisher: Princeton, N.J. : Baltimore, Md. : Princeton University Press, Project MUSE,

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Although ecologists have long considered morphology and life history to be important determinants of the distribution, abundance, and dynamics of plants in nature, this book contains the first theory to predict explicitly both the evolution of plant traits and the effects of these traits on plant community structure and dynamics. David Tilman focuses on the universal requirement of terrestrial plants for both below-ground and above-ground resources. The physical separation of these resources means that plants face an unavoidable tradeoff. To obtain a higher proportion of one resource, a plant must allocate more of its growth to the structures involved in its acquisition, and thus necessarily obtain a lower proportion of another resource. Professor Tilman presents a simple theory that includes this constraint and tradeoff, and uses the theory to explore the evolution of plant life histories and morphologies along productivity and disturbance gradients. The book shows that relative growth rate, which is predicted to be strongly influenced by a plant's proportional allocation to leaves, is a major determinant of the transient dynamics of competition. These dynamics may explain the differences between successions on poor versus rich soils and suggest that most field experiments performed to date have been of too short a duration to allow unambiguous interpretation of their results.


Article
Utilisation of a physically-enriched environment by laboratory mice: age and gender differences.
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Year: 2004

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A variety of recent rodent studies have suggested the use of an enriched environment as a strategy to increase the welfare of captive animals. However, a number of standard procedures of environmental enrichment are applied without taking into account the etho-ecological, species-specific, needs of laboratory animals. The aim of the present study was to evaluate the age and sex differences in the utilisation of a physically-enriched environment, consisting of four differently-shaped plastic compartments: a central chamber, a circle, a running wheel and a tower. These compartments are characterised by features (e.g. size, lightness, presence of food, opportunity to perform physical activity) of eco-ethological relevance for the mouse, the most common laboratory species. Presence and activity in each cage compartment during 5 consecutive days were assessed in juvenile (35 days old) and adult (90 days old) CD-1 mice of both sexes. Mice explored all the compartments, spending most of the time in the central chamber and making an extensive use of the running wheel. Juveniles of both sexes and adult males showed a prominent occupation of the central chamber, where food and sawdust were located, and they widely used it to sleep, suggesting that food availability might be a relevant factor in driving their choice of the resting location. Conversely, adult females displayed a more complex utilisation profile and preferentially stayed in the tower while inactive, suggesting that safety needs, that the covered structure of this compartment probably cater for, may be more relevant for them than availability of food and water resource. These findings indicate that in laboratory mice the features of an enriched environment are differentially relevant according to age and sex and, thus, may exert a different impact on their psycho-physical welfare. (C) 2004 Elsevier B.V. All rights reserved

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