Mitch LangeJack Connor

Kelly Goehring

Population Ecologyh

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What is it exactly?

Studying populations in relation to the environment… Environmental influences, on population density, distribution, age

structure, and population size

With more of these guys…

There will be less of these guys

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Population DensityPopulation size can be determined in a number of ways:

Like number of nests, burrows, tracks, or poopAdditions to population occur from :

http://www.scotlandincolour.com/finch/finches-flying01ll.jpg

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Population Size

ImmigrationBirths

Leaving So Soon?

Animals leave because of:

Deaths & Emigration: Movement of animals out of a population

http://www.ect.coop/wp-content/uploads/2010/08/Osprey-Leaving-Nest.jpg

http://laudyms.files.wordpress.com/2010/03/hawk_eating_prey.jpg

Dispersion 3 types:

http://mycozynook.com/36_02aClumpedDispersion-L.jpg

http://bio1903.nicerweb.com/Locked/media/ch53/53_04cRandomDispersion-L.jpg

http://bio1903.nicerweb.com/Locked/media/ch53/53_04bUniformDispersion-L.jpg

• Clumped: Most common, with individuals in separate patches• Uniform: Evenly spaced, with patterns resulting from interactions• Random: Unpredictable Spacing

Demography

Vital Statistics of populations and their change over time Particularly looking at birth rate and death rates Life Table

Age that a person/animal is expected to live to Cohort= group of individuals of same age. Used to follow the fate from birth to

death

Survivorship Curve• Plot to see which data points in a

cohort are still alive

http://bealbio.wikispaces.com/file/view/survivorship.gif/104532503/survivorship.gif

Life History Some species reproduce in a one shot chance called semelparity

If offspring survival rate is low, this is favored Others reproduce in the annual cycle called iteroparity

More favorable when there is dependable environment and might be competition for resources

There are many trade-offs between reproduction and survival: High mortality rates in offspring often exhibit large number of small offspring High predation rates also factor into large numbers of offspring

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Time For Math

Per Capita Rate of Increase is the amount a population goes up over time Deaths>Births is declining population Births>Deaths is growing population Births=Deaths is zero population growth

Intrinsic rate of increase or rmax is when the per capita rate of increase is at its maximum

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Logistic Growth Model

With more population density, each individual has access to fewer resources

The carrying capacity is the max population an environment can support In this model, the per capita rate of increase declines as carrying capacity is

reached The graph of most real populations is like an S shape When the population increases to it there is a lag in time where the population

can resettle

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Things Are Complex

• Density Dependency• Death rate rises as population density rises• Also a birth rate falling with rising density

• Density Independency • Birth rate or death rate does NOT change with population density

Density Dependent

Competition for Resources More population more competition

Territoriality Territory space is what the animals compete for i.e: nesting sites

Health Transmission rate of a disease can wipe out a population

Predation More food captured means lowered population

Toxic Wastes Intrinsic Factors

Physiological effects of things like over-reproduction

http://www.grguy.net/Q2_30Y3399-Cheetah-marking-300.jpg

http://recyclingewaste.files.wordpress.com/2011/09/toxic-waste.jpg

Things Are Still Complex

Population Dynamics Metapopulations

Population Cycles = predictable intervals

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Humans

People Population Growth

1962-no longer y^x Demographic Transition Developed countries: reproduction rates about = replacement level Population growth in Developing countries

http://www.mongabay.com/images/pop.gif

Age Structure

Relative number of individuals at each age

Global Carrying Capacity-Humans

Some say a billion, some say a trillion Ecological Footprint( EF)

Produce all resources, absorb all wastes Ecological Capacity( EC)

Actual resource base of their country U.S. EF= 8.4 ha, EC= 6.2 ha World EF= 1.7 ha

http://sunhomedesign.files.wordpress.com/2009/04/cc-graphic1.gif

Limiting Factors

Space Nonrenewable Resources Renewable Resources Earth’s Capacity to Absorb Wastes