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Lecture 27

BIO SCI 94 Lecture Notes - Lecture 27: Survivorship Curve, Population Ecology, Biotic ComponentPremium

Biological Sciences
Course Code
Brad Hughes

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Population-group of individuals, same species, area,time
Population ecology- study how/why number of individuals in population change
over time
Range- geographic distribution of different species
Abiotic,biotic factors determine range
Range constant flux; abiotic, biotic factor change over time
Distribution and Abundance
Population density- number of individuals per unit area- varies throughout range
Individual’s arrangement in population
Random- if position of individuals independent from each other
Clumped- if habitat quality patchy or organisms social
Uniform- negative interactions→ space individuals evenly
Metapopulation- populations connected by migration
Number of individuals in population depends on- birth, death, immigration,
Birth, immigration→ populations grow
Individuals enter population from another population→ immigration occurs
Death, emigrations → populations decline
Individuals leave population for another→ emigration
Demography - study of factors that determine size and structure of populations
Make predictions of future of populations→ biologist need
Number of individuals of each age
Probability individuals of different ages will survive to following year
Number of offspring produced by females of different ages
Need to know- number of individuals of different ages immigrate/emigrate each
Average time between mother’s first offspring and her daughter’s first
Survivorship- key component of life table
Proportion of offspring produced that survive to particular age
Create graph called survivorship curve→ recognize general patterns in
survivorship, make comparisons among populations or species
Three types of survivorship curves
Type I curve- survivorship throughout life high, most individuals reach
maximum lifespan
Example: humans
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