Tài liệu ECOLOGY From Individuals to Ecosystems doc

[...]... are the cliffs falling to the sea The numbers indicate the sites from which the grass Agrostis stolonifera was sampled Note that the whole area is only 200 m long (b) A vertical transect across the study 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.)... in a field in North Wales (UK) To determine whether the characteristics of individuals matched local features of their environment, Turkington and Harper (1979) removed plants from marked positions in the field and multiplied them into clones in the common environment of a greenhouse They then transplanted samples from each clone into the place in the sward of vegetation from which it had originally been... radiated from a single trunk: a single ancestral species that invaded the islands from the mainland of Central America The molecular data also provide strong evidence that the warbler finch (Certhidea olivacea) was the first to split off from the founding group and is likely to be the most similar to the original colonist ancestors The entire process of evolutionary divergence of these species appears to have... different things In the first place we can try to explain or understand This is a search for knowledge in the pure scientific tradition In order to do this, however, it is necessary first to describe This, too, adds to our knowledge of the living world Obviously, in order to understand something, we must first have a description of whatever it is that we wish to understand Equally, but less obviously, the... afterwards to have selected the wrong things Ecologists also often try to predict what will happen to an organism, a population, a community or an ecosystem under a particular set of circumstances: and on the basis of these predictions we try to control the situation We try to minimize the effects of locust plagues by predicting when they are likely to occur and taking appropriate action We try to protect... slightly, in size, rate of development, response to temperature, and so on 2 Some, at least, of this variation is heritable In other words, the characteristics of an individual are determined to some extent by its genetic make-up Individuals receive their genes from their ancestors and therefore tend to share their characteristics 3 All populations have the potential to populate the whole earth, and they would... Indeed, molecular techniques make it possible to analyze the time at which the various flightless birds started their evolutionary divergence (Figure 1.12) The tinamous seem to have been the first to diverge and became evolutionarily separate from the rest, the ratites Australasia next split away from the other southern continents, and from the latter, the ancestral stocks of ostriches and rheas were subsequently... trees are still migrating into deglaciated areas, even now This clearly implies that the timespan of an average interglacial period is too short for the attainment of floristic equilibrium (Davis, 1976) Such historical factors will have to be borne in mind when we consider the various patterns in species richness and biodiversity in Chapter 21 ‘History’ may also have an impact ‘history’ on a smaller on much... These problems are as much part of modern ecology as are the prevention of plagues, the protection of crops and the preservation of rare species Our ability to control and exploit ecosystems cannot fail to be improved by an ability to explain and understand And in the search for understanding, we must combine both proximal and ultimate explanations Pure and applied ecology Ecologists are concerned not only... dioxide) toward the east Melanic forms were concentrated toward the east and were completely absent from the unpolluted western parts of England and Wales, northern Scotland and Ireland Notice from the figure, though, that many populations were polymorphic: melanic and nonmelanic forms coexisted Thus, the polymorphism seems to be a result both of environments changing (becoming more polluted) – to this . •• ECOLOGY From Individuals to Ecosystems EIPA01 10/24/05 1:36 PM Page i •••• EIPA01 10/24/05 1:36 PM Page ii •••• ECOLOGY From Individuals to Ecosystems MICHAEL. been freer to attempt to make this fourth edition an up- to- date guide to ecology now (or, at least, when it was written). To this end, the results from around