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AbstractA probability model is presented to determine the age structure of a fish population from length-frequency data. It is shown that when the age-length key is available, maximum-likelihood estimates of the age structure can be obtained. When the key is not available, approximate estimates of the age structure can be obtained. The model is used for determination of the age structure of populations of channel catfish and white crappie. Practical applications of the model to impact assessment are discussed. Authors: Adams, S MPublication Date: Sat Jan 01 00:00:00 EST 1977Research Org.: Oak Ridge National Lab., TN (USA)OSTI Identifier: 7312272Report Number(s): CONF-770501-2 Citation Formats
Please see Document Availability for additional information on obtaining the full-text document. Library patrons may search WorldCat to identify libraries that hold this conference proceeding. This is a preview. Log in through your library. Abstract Long-term studies of plant populations are reviewed, and their dynamics summarized in three categories. Many short-lived plants have ephemeral, pulsed dynamics lasting only a single generation, with recruitment determined almost entirely by germination biology and by the frequency and intensity of disturbance. Such populations are not amenable to traditional population models. At the other extreme, some long-lived plants have such protracted tenancy of their microsites that it is impossible to establish what pattern of dynamics (if any) their populations exhibit. A relatively small number of species show what we would traditionally regard as population dynamics at a given point in space (i.e. reasonably predictable trajectories that can be modelled by Nt+1 = f(Nt)). A major difficulty in generalizing about plant dynamics is that the majority of species are successional; their recruitment depends upon the death, through senescence or disturbance, of the dominant plants. Where we do have data spanning several generations, it is clear that: (i) the populations are regulated by density dependent processes; (ii) in contrast to some animal populations, numbers appear to vary less from year to year in places where mean density is higher, and less from place to place in years when mean density is high than when density is low; (iii) few, if any, plant populations show persistent cyclic or chaotic dynamics, but (iv) there are several robust generalizations that stem from the immobility and phenotypic plasticity of plants (the law of constant yield; self-thinning rules, etc.). These generalizations are analysed in the context of simple theoretical models of plant dynamics, and the patterns observed in long-term studies are compared with similar data from animal populations. Two important shortcomings of traditional plant demography are emphasized; (i) the dearth of simple manipulative experiments on such issues as seed limitation, and (ii) the tendency to locate study plots around existing mature individuals (the omission of `empty quadrats' may introduce serious bias into the estimation of plant recruitment rates). Journal Information From the beginning of its history the Royal Society has devoted much attention to the publication of communications by its Fellows and others. Within three years from the granting of the first Charter, Henry Oldenburg, the first Secretary, began publishing Philosophical Transactions in March 1665 and it has continued ever since. From 1887 onward, beginning with volume 178, the Transactions have been divided into two series: Series A, (Mathematics and Physical sciences) and Series B, (Biology). Transactions are published monthly and now include papers presented at Discussion Meetings as well as specific themes and reviews. Publisher Information The Royal Society is a self-governing Fellowship of many of the world's most distinguished scientists drawn from all areas of science, engineering and medicine, and is the oldest scientific academy in continuous existence. The Society’s fundamental purpose, reflected in its founding Charters of the 1660s, is to recognise, promote, and support excellence in science and to encourage the development and use of science for the benefit of humanity. The Society has played a part in some of the most fundamental, significant, and life-changing discoveries in scientific history and Royal Society scientists continue to make outstanding contributions to science in many research areas. Rights & Usage This item is part of a JSTOR Collection. How does age structure affect population growth?Countries with lower median age tend to have higher population growth rates. Lower-income countries tend to have a lower median age. This is because they have a 'younger' population overall: high fertility rates across these countries mean they have larger populations of young children and adolescents.
What is likely to be true of a population with an age structure that is pyramid shaped?A broad base and sharply tapering sides (a true pyramid shape) reflects high fertility rates and high mortality rates in younger age groups.
Which animal represents a population displaying a Type 1 survivorship pattern?Humans are an example of a population shown on a Type 1 survivorship curve. Humans have low numbers of offspring per individual and care for these offspring until reproductive age.
How does age structure help us predict population growth?The age structure is closely related to the birth rate, death rate and migration of a population. In the region with high birth rate, the proportion of children tends to be higher, whereas in the region with low birth and death rate, the percentage of elderly population tends to be higher.
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This age structure diagram for a population of white oaks shows that the population is
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