From Individuals to Ecosystems 4th Edition - Chapter 21 ppsx

... PM Page 607 •• 21. 1 Introduction Why the number of species varies from place to place, and from time to time, are questions that present themselves not only to ecologists but to anybody who observes ... scale: macroecology Chapter 21 Patterns in Species Richness EIPC21 10/24/05 2:19 PM Page 602 614 CHAPTER 21 different types of habitat. However, MacArthur and Wilson (19...

Ngày tải lên: 06/07/2014, 13:20

... post-emergence activity. The phenol derivatives, particularly the nitrophenols such as 2-methyl-4,6-dinitrophenol, are contact chemicals with broad- spectrum toxicity extending beyond plants to ... We cannot con- tinue to use the same pesticides if increasing numbers of pests become resistant to them. We cannot (if we wish to have fish to eat in future) continue to remove fish fr...

Ngày tải lên: 06/07/2014, 13:20

... water too deep for photosynthesis to be appreciable or even to take place at all, but it derives its energy base from dead phytoplankton, bacteria, animals and feces that sink from the autotrophic ... the normal photosynthetic chan- nels, and it overflows into destructive photo-oxidation reactions. The more nutrient-rich a water body is, the shallower its euphotic zone is likely to b...

Ngày tải lên: 06/07/2014, 13:20

... 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...

Ngày tải lên: 06/07/2014, 13:20

... 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...

Ngày tải lên: 06/07/2014, 13:20

... 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...

Ngày tải lên: 06/07/2014, 13:20

... 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...

Ngày tải lên: 06/07/2014, 13:20

... 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...

Ngày tải lên: 06/07/2014, 13:20

... (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...

Ngày tải lên: 06/07/2014, 13:20

... 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 210 0 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 dat...

Ngày tải lên: 06/07/2014, 13:20