4.1.1 Demographic significance Confined populations grow more rapidly than populations from which dispersal is permitted (Lidicker, 1975; Krebs, 1979; Tamarin et at., 1984), and demography in island populations where dispersal is restricted differs greatly from nearby mainland populations (Lidicker, 1973; Tamarin, 1977, 1978; Gliwicz, 1980), clearly demonstrating the demographic signi ficance of dispersal. The prevalence of dispersal in rapidly expanding populations is held to be the best evidence for presaturation dispersal. Because dispersal reduces the growth rate of source populations, it is generally believed that emigration is not balanced by immigration, and that mortality of emigrants occurs as a result of movement into a 'sink' of unfavourable habitat. If such dispersal is age- or sex-biased, the demo graphy of the population is markedly affected, as a consequence of differ ences in mortality in the dispersive sex or age class. Habitat heterogeneity consequently underlies this interpretation of dispersal and its demographic consequences, although the spatial variability of environments is rarely assessed in dispersal studies.

A unique, interdisciplinary and up-to-date treatment exploring human migration and its role in creating novel ecosystems over the long term.

Fresh concepts in the study of seed dispersal are spurring a host of exciting new questions, new answers to old questions, new methods and approaches, and a reinvigoration of the field.Seed Dispersal: Theory and its Application in a Changing World presents both recent advances and reviews of current knowledge demonstrating the vigour and vibrancy of the field. It provides new perspectives and directions at a time when efforts to meet growing environmental challenges threatening natural systems are of utmost importance.

Provides an overview of the fast expanding field of dispersal ecology. The causes, mechanisms, and consequences of dispersal at the individual, population, species, and community levels are all considered.

Our knowledge of the structure and dispersal of "Plants, seeds and currents" in the Westindies tropical fruits and seeds is very limited up to the and Azores. Van der Pijl with his extensive know present day, though richness of species and variety ledge of tropical plants offers a great selection of of forms is overwhelming in the tropical forests. detailed information on the subject" Principles of Morphology of tropical fruits and seeds has always dispersal in higher plants" (1972, and earlier pa of botanists from many pers). The author who has earned most merits in attracted the curiosity countries and information may be obtained from the field of seed and fruit predation, chemical defenses of plants, and animal-plant interactions is books and publications concerned with taxonomy. Ulbrich's "Biologie der Friichte und Samen" Janzen. He and his collaborators have thrown new of tropical fruits and seeds (1928) gives examples light on this subject. Nonetheless, a large unknown and their dispersal methods. The two volumes by field still remains ahead of us, especially regarding Van der Roosmalen (1977) dealing with the de a detailed knowledge of fruit and seed dispersal of scription of tropical plants were of utmost value to tropical plant species. me, as the area considered, Surinam, is close to The great opportunity for my own studies was Venezuelan Guiana and because both regions have the fruit and seed collection of Dr.

This advanced textbook is the first to explore the consequences of plant dispersal for population and community dynamics, spatial patterns, and evolution. It successfully integrates a rapidly expanding body of theoretical and empirical research. · The first comprehensive treatment of plant dispersal set within a population framework · Examines both the processes and consequence of dispersal · Spans the entire range of research, from natural history and collection of empirical data to modeling and evolutionary theory · Provides a clear and simple explanation of mathematical concepts

A wide variety of plants, ranging in size from forest floor herbs to giant canopy trees, rely on animals to disperse their seeds. Typical values of the proportion of tropical vascular plants that produce fleshy fruits and have animal-dispersed seeds range from 50-90%, depending on habitat. In this section, the authors discuss this mutualism from the plant's perspective. Herrera begins by challenging the notion that plant traits traditionally interpreted as being the product of fruit-frugivore coevolution really are the outcome of a response-counter-response kind of evolutionary process. He uses examples of congeneric plants living in very different biotic and abiotic environments and whose fossilizable characteristics have not changed over long periods of time to argue that there exists little or no basis for assuming that gradualistic change and environmental tracking characterizes the interactions between plants and their vertebrate seed dispersers. A common theme that runs through the papers by Herrera, Denslow et at. , and Stiles and White is the importance of the 'fruiting environment' (i. e. the spatial relationships of conspecific and non-conspecific fruiting plants) on rates of fruit removal and patterns of seed rain. Herrera and Denslow et at. point out that this environment is largely outside the control of individual plant species and, as a result, closely coevolved interactions between vertebrates and plants are unlikely to evolve.