Animal Dispersal

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.

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Theimer, an accomplished ecologist.

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.

Interactions between plants and animals are incredibly diverse and complex and span terrestrial, atmospheric and aquatic environments. The last decade has seen the emergence of a vast quantity of data on the subject and there is now a perceived need among both teachers and undergraduate students for a new textbook that incorporates the numerous recent advances made in the field. The book is intended for use by advanced level undergraduate and beginning graduate students, taking related courses in wider ecology degree programmes. Very few books cover this subject and those that do are out of date.

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

An outline of the principles of animal dispersion. The integration of social groups by visible signals. Dispersion in the breeding season: birds. Display characters and natural selection. Fourther consideration of castes in animal societies. Timing and synchronisation. Vertical migration of the plankton. Fluctuations, irruptions and emigrations. Recruitment through reproduction. Socially-induced mortality. Deferment of growth and maturity.