From Individuals to Ecosystems 4th Edition - Chapter 11 ppt

... they would seem to constitute a high-quality food resource. But they are not reingested by Chironomus larvae, mainly because they are too large and too tough for its mouth- parts to deal with. ... of 111 g can only develop if there is 10 g of nitrogen and 1 g of phosphorus available. Terrestrial plant material has much higher ratios, ranging from 19 to 315 : 1 for C : N and from...

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... area showing the gradual change from pasture to cliff conditions. (c) The mean length of stolons produced in the experimental garden from samples taken from the transect. (From Aston & Bradshaw, 1966.) the ... evolutionary history. All species are absent from almost everywhere, and we consider next, in Chapter 2, the ways in which environmental conditions vary from place...

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... sometimes to pupae, and then to adults; plants pass from seeds to seedlings to photosynthesizing adults; and so on. The different stages are likely to be influenced by different factors and to have ... population to describe a group of individuals of one species under investigation. What actually constitutes a popula- tion, though, will vary from species to species and f...

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... importance of these factors as determinants of the year -to- year fluctuations in mortality. For instance, we can easily imagine a factor that repeatedly takes a significant toll from a popu- lation, but ... October) from four large predator- reduction sites ( ᭹) and four control sites (7) in western Finland. Predator reduction occurred only over the summer and vole densities tended to re...

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... sampled from diverse localities in northern USA and Canada, and were tested for freezing tolerance and ability to acclimate to cold. Individuals from the most freeze-tolerant population (from ... environ- mental conditions because water tends to move into organisms from the environment and this needs to be resisted. In marine habitats, the majority of organisms are isotonic...

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... dioxide The CO 2 used in photosynthesis is obtained almost entirely from the atmo- sphere, where its concentration has risen from approximately 280 µll −1 in 1750 to about 370 µll −1 today and is still ... feedback from elevated CO 2 concentrations to plant growth, to microbial activity and back to plant growth. The arrows between descriptors indicate causation; the black arrow...

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... therefore trajectories that follow a cohort through time. This is indicated by arrows, pointing from many small, young individuals (bottom right) to fewer, larger, older individuals (top left). Mean ... small population sizes: A to B, B to C) and is small close to the carrying capacity (I to J, J to K), but is large at intermediate densities (E to F). The result is an ‘S...

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... (Murton et al., 1966). Individuals may also gain from living in groups if this helps to locate food, give warning of predators or if it pays for individuals to join forces in fighting off a predator ... attracting individuals to disperse towards one another and forces provoking individuals to disperse away from one another. As we shall see in a later chapter, such compromi...

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... which grows from 1900 to 3000 m. But as colder weather sets in, they travel to lower elevations and from October to May they feed primarily on Bashania fargesii, which grows from 1000 to 2100 m. ... in twelve 5-year age classes through dis- crete 5-year time steps. Values for age-specific survivorship and density-dependent reproductive rates were derived from a thorough data...

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... In plants, for example, this may result from height differences, with one species able to completely over-top another and preempt access to light (Freckleton & Watkinson, 2001). In a similar ... performance was due to improved access to pre- ferred nest sites and consequent decreased losses of nestlings to predators. In the case of virginia’s warblers, but not orange- crowned...

Ngày tải lên: 06/07/2014, 13:20