Lecture.25.Population Patterns.KRG.upload rev

Lecture.25.Population Patterns.KRG.upload rev - What is a...

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1 What is a population? How is it different from an individual? 2 Population … Population dynamics : The patterns and processes of change in populations. • A population consists of individuals of a species that interact with one another within a given area at a particular time. • The study of population processes is called demography .
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Populations – Some Attributes Different from an Individual Size – numbers (rarity, commonness) Density – distribution in space (per unit area or volume) Change in size over time (increases/decreases in numbers, range ) Age structure – number of individuals in age cohorts (or aggregate classes) Genetic structure – distribution of genetic variations 4 Sometimes, it isn’t easy deciding who’s who… Trembling aspen – identical ramets Bryozoan – identical zooids Amanita – fruiting bodies Modular organisms
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5 Overall Distributions in Space Range - areal extent of a population or species Encelia - brittlebush 6 5 Overall Distributions in Space Range - areal extent of a population or species Kangaroos - Australia
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7 Ranges expand and contract … Starlings … 120 released in Central Park in 1890/1891 Over 200 million now Range expansion … Introduced Zebra mussels has expanded rapidly…
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Kudzu Former range of American chestnut. In early 1900’s chestnut blight (imported from Asia in nursery stock) has all but eliminated this once dominant tree . Range Contraction … “Chestnuts roasting on an open fire….” In June 2009, a mature American Chestnut was discovered in Farmington, New Hampshire
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How Do Ecologists Study Populations? h
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Lecture.25.Population Patterns.KRG.upload rev - What is a...

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