Population Dynamics

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Chapter 10

• Population Dynamics

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Life Tables and Survivorship Curves
Life Tables provide data on age cohorts, number
of survivors, number of deaths, and also
reproductive information Survivorship Curves
indicate the number of surviving individuals over
time
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Constant Survival Rates
Some populations exhibit consistent rates of
mortality through the age of the cohort
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High Early Mortality
Other populations suffer high mortality of young
individuals, while a few survive to old age
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Deevey Survivorship Curves
Type I High old-age mortality Type II Constant
mortality Type III High juvenile mortality
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Regenerating Age Structure
Age structures show the abundance of individuals
at different ages in the population
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Non-Regenerating Age Structure
Some populations do not show evidence of
regeneration
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Varying Age Structures
Some populations exhibit bursts of regeneration
as well as time-periods of low regeneration
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Phlox drummondii Life Table
A population that is increasing in size Ro net
reproductive rate
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Geometric Rate of Increase
A rate of change indicating consistent growth (?)
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Mud Turtle Life Table
A population that is decreasing in size Ro S
lxmx 0.601 Sxlxmx 6.4 T (Sxlxmx)/Ro
10.6 average generation time
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Generation Times
Generation time is correlated with body
size Why?..
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Per Capita Rate of Increase

• The rate of increase in population size relative
  to the size of the population
• r (ln Ro) / T

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Dispersal Range Expansion
As populations grow in size, they seek more area
in which to live Why?.
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Rates of Expansion
Some populations expand at different rates than
others Why?. What does this difference
indicate about the ecological impacts of some
species?.
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Dispersal and Climate Change
As climates change, distributions change, and
populations disperse
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Dispersal and Food Supply
Populations may disperse to follow a food supply
even if their population size does not change
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Summary

• Survivorship Curves
• Age Distributions
• Life Tables Ro, ?, T, r
• Dispersal