Population ecology
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Population Ecology. Chapter 52. Population - group of individuals living in same area at same time. Population density - # of individuals per unit area. Population dispersion - arrangement of population in area. Dispersion patterns happen 3 ways. 1 Clumped dispersion - individuals in groups.

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Population Ecology

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Population ecology

Population Ecology

Chapter 52


Population ecology

  • Population - group of individuals living in same area at same time.

  • Population density - # of individuals per unit area.

  • Population dispersion - arrangement of population in area.


Population ecology

  • Dispersion patterns happen 3 ways.

  • 1Clumped dispersion - individuals in groups.

  • 2Uniform dispersion – individuals evenly spaced out.

  • 3Random dispersion - individuals live regardless of where other individuals live.


Population ecology

CLUMPED


Population ecology

UNIFORM


Population ecology

RANDOM


Population ecology

  • Demography - study of statistics of a population.

  • Life tables - show summary of specific ages of population and survival rates.


Population ecology

  • Survivorship curve - can see how many individuals are alive at specific ages.


Population ecology

  • Reproductive tables - reproductive rates at various ages.

  • Focus only on females and not males in these tables.


Population ecology

  • Life history - traits that affect organism’s schedule of reproduction and survival.

  • 1Big-bang reproduction (produce large number of offspring sometimes followed by the organism’s death)

  • Known as semelparity.


Population ecology

The agave plant


Population ecology

  • 2Repeated reproductive episode - organism produces smaller numbers of offspring.

  • This is also known as iteroparity.


Population ecology

  • Change in population - # of births minus # of deaths during that same time.

  • Equation : N/t = r; r= difference between birth and death rates, N= change in population size, and t= change in time.


Population ecology

  • Limitations on population growth due to resources.

  • K = carrying capacity.

  • Carrying capacity – max # of individuals an area can handle based on resources.


Population ecology

  • Logistic population growth model - incorporates affect of population density on rate of increase.

  • Carrying capacity cannot be exceeded - graph is S-shaped.


Population ecology

Carrying capacity

equals change in

population size


Population ecology

Carrying

capacity

Cannot exceed

carrying capacity


Population ecology

  • Life histories - predict how population will reproduce.

  • 1K-selection - live and reproduce around K.

  • 2r-selection - high rates of reproduction, but live in environments where populations are well below K.


Population ecology

  • 2 factors determine the growth of a population.

  • 1Density-dependent factors increase their effect as density increases (negative feedback)

  • 2Density-independent factors - not affected by density increase.


Population ecology

  • Negative feedback - caused by several different factors.

  • One - resources (force populations to stop reproducing if conditions are crowded)


Population ecology

As # of planted seeds increase,

# reproducing decreases


Population ecology

  • Competition for resources can force decreased reproduction rates.

  • Need to defend space can reduce population size.

  • Predation can decrease the size.


Population ecology

  • Human population has been steadily growing since 1650.

  • Zero transition growth # of births = # of deaths.

  • Only way to steady out population growth.


Population ecology

  • One of the difficulties with population growth is looking at the distribution of ages.

  • The problem is that the carrying capacity of Earth has not been determined.


Population ecology

  • http://www.youtube.com/watch?v=GECJcW2Ifm4


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