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Population Ecology Ch. 52 U109PP
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Not changing fitness of tagged individuals ... Survivorship curves can be classified into three general types. Type I, Type II, and Type III ... – PowerPoint PPT presentation
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Title: Population Ecology Ch. 52 U109PP
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Population Ecology- Ch. 52 U109PP
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Hierarchy of ecology study
biosphere
ecosystems
What are the unique interactions at the
population ecology level that are important to
understand?
communities
populations
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Defining population
- Individuals of the same species that occupy the
same area - Why of the same species?
- How big is an area?
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Attributes of a population
- Population size
- Why is it important to know?
- How can a biologist establish a populations size
(N, number)? - Population density
- Population distribution/dispersion
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One method of population size estimation
- Mark-recapture
- Members of a population are marked and released
back into the population. - The population is later resampled (recaptured).
The number of individuals recaptured that are
tagged and those that are not tagged is used to
generate an estimate of the population size
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Assumptions and caveats of the mark-recapture
technique
- Trap happy
- Trap shy
- Not changing fitness of tagged individuals
- Experimenter dependent how many do you want to
mark and recapture?
How close is the estimate to the real
population size? How close does it need to be?
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Attributes of a population
- Population size
- Population density
- Number of individuals per unit area
- May limit reproduction in low densities may
promote disease spread, aggression, competition
in high densities - Population distribution/dispersion
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Attributes of a population
- Population size
- Population density
- Population distribution/dispersion
- The way individuals in a population are arranged
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Patterns of Dispersion
- Environmental and social factors
- Influence the spacing of individuals in a
population
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- A clumped dispersion
- Is one in which individuals aggregate in patches
- May be influenced by resource availability and
behavior
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- A uniform dispersion
- Is one in which individuals are evenly
distributed - May be influenced by social interactions such as
territoriality
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- A random dispersion
- Is one in which the position of each individual
is independent of other individuals
(c) Random. Dandelions grow from windblown seeds
that land at random and later germinate.
Figure 52.3c
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Demography
- Demography is the study of the vital statistics
of a population - And how they change over time
- Death rates and birth rates
- Are of particular interest to demographers
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Life Tables
- A life table
- Is an age-specific summary of the survival
pattern of a population - Is best constructed by following the fate of a
cohort
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- The life table of Beldings ground squirrels
- Reveals many things about this population
1. Females live longer
2. Death rate relatively constant
Table 52.1
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Survivorship Curves
- A survivorship curve
- Is a graphic way of representing the data in a
life table
Want to buy life insurance?
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- The survivorship curve for Beldings ground
squirrels - Shows that the death rate is relatively constant
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- Survivorship curves can be classified into three
general types - Type I, Type II, and Type III
Late loss
Constant loss
Early loss
Figure 52.5
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Reproductive Rates
- A reproductive table, or fertility schedule
- Is an age-specific summary of the reproductive
rates in a population
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- A reproductive table
- Describes the reproductive patterns of a
population
Who makes babies and when
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- Concept 52.2 Life history traits are products of
natural selection - Life history traits are evolutionary outcomes
- Reflected in the development, physiology, and
behavior of an organism
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