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Lecture 7

ENVS 1200 Lecture 7.docx

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Department
Environmental Studies
Course
ENVS 1200
Professor
Anders Sandberg
Semester
Fall

Description
10/21/2013 6:25:00 AM Demography: study of factors that affect the growth + decline of populations Log: scale of measurement using the log of a physical quantity instead of the quantity itself (y-axis should say log)  IN A LOGARITHIMIC SCALE, A CONSTANT RATE OF mortality is seen as straight line  In a arithmetic scale, a constant rate of mortality is seen as a curved line Lecture 6 1) population dynamics  Patterns of survival  Age structure  Generation time  Dispersal  Population Growth A) Patterns of survival: 3 ways biologist do it  Follow a cohort (table) – a user defined group  Record age of death for large # of individuals (if u can estimate the age of death, u can determine patterns of survival  Use the age distribution to calculate survival (not easy to get age off organisms)  Life tables: are age-specific tables showing the expected mortality rates  B) Age structure  A measure of the relative ages within a population  The larger the population of individuals which are capable of reproducing, the more likely it will be that the population can grow B) Generation time:  the length of time b/w the birth of one generation and the birth of another generation C) Dispersal a. Movements of individuals (usually in the context of young) i. Immigration – dispersal into an area ii. Emigration – dispersal out of an area E) Population Growth: has many different variable  Birth rates, deaths sex ratio, generation time, age structure and dispersal (emigration and immigration)  Per capita: a rate which is proportional to the number of individuals in a population What limits population growth?  Density –dependent factors (most are biotic) o Disease, predation, competition, etc.  Rates of population change: per capita rate of increase =
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