Population Ecology Presented By: Dean Thomas

What is population ecology?

A population is an assemblage of individuals of the SAME species inhabiting a given area. A population is an assemblage of individuals of the SAME species inhabiting a given area. Ecology is a field of biology that focuses on the interactions between organisms and their environment Ecology is a field of biology that focuses on the interactions between organisms and their environment So population ecology is the dynamics of a species population and how they interact with their environment So population ecology is the dynamics of a species population and how they interact with their environment

What kinds of things do population ecologists look at? Population Structure Population Structure Population Growth Population Growth

Population Structure Interested in how many individuals make up the population. Interested in how many individuals make up the population. How are the individuals distributed throughout the environment? How are the individuals distributed throughout the environment? Age Structure Age Structure

Types of Distribution Clumped Clumped Uniform Uniform Random Random

Distribution? Clumped.jpg

Distribution? King Penguins on Salisbury Plain – Over 100,000 Penguins! Chap_3/Part_3/SP_King_Penguins.jpg

Distribution? RandomFerns.jpg

What type of distribution pattern do humans show? Why?

Population Growth Growth Rate = the percent change in a population over one year Growth Rate = the percent change in a population over one year Growth rate is affected by Growth rate is affected by ? ? ? ?

Population Growth Growth Rate = the percent change in a population over one year Growth Rate = the percent change in a population over one year Growth rate is affected by Growth rate is affected by Natality (births) Natality (births) Mortality (deaths) Mortality (deaths) Immigration Immigration Emigration Emigration

Growth rate = birth rate – death rate Let’s try an example Let’s try an example A population of 100 rabbits gives birth to 30 rabbits in one year. A population of 100 rabbits gives birth to 30 rabbits in one year. 30 births 30 births 100 adults=.30 * 100% = 30% birth rate 100 adults=.30 * 100% = 30% birth rate If 10 individuals of the 100 rabbits died, what is the death rate? If 10 individuals of the 100 rabbits died, what is the death rate? What is the growth rate of the rabbit population? What is the growth rate of the rabbit population?

What’s going to happen if this continues? Population%20Growth.jpg

If both of these species became endangered, which has a better chance of rebounding?

Can a population grow forever? Animals have the capacity to grow exponentially, but they are limited by resources. Animals have the capacity to grow exponentially, but they are limited by resources. What are the four main resources that limit growth? What are the four main resources that limit growth?

Can a population grow forever? Animals have the capacity to grow exponentially, but they are limited by resources. Animals have the capacity to grow exponentially, but they are limited by resources. What are the four main resources that limit growth? What are the four main resources that limit growth? Food Food Water Water Shelter Shelter Space Space

Carrying Capacity The maximum population that can be supported by an environment The maximum population that can be supported by an environment grolog.gif Question: What would happen if a population grew beyond their carrying capacity?

Carrying Capacity Density-dependent factors Density-dependent factors

Carrying Capacity Density-dependent factors Density-dependent factors Population-limiting factors that increase as population increases in size Population-limiting factors that increase as population increases in size Food supplies Food supplies Risk of disease in crowded areas Risk of disease in crowded areas Increase in toxin concentration caused by increased waste levels Increase in toxin concentration caused by increased waste levels Causes declines in birth or death rates Causes declines in birth or death rates

Carrying Capacity Density-independent factors Density-independent factors Influences on population rates that are not affected by density Influences on population rates that are not affected by density Severe drought Severe drought Cold winter Cold winter Effects could be worse depending on the size of population Effects could be worse depending on the size of population

Age Pyramids Which of the two pyramids show a more rapid growing population? What if (a) was inverted?

Let’s look at population ecology at work! 5.jpg Abby Benson - Abby is studying the population ecology and sex-biased dispersal of thirteen- lined ground squirrels in and out of prairie dog colonies in northern Colorado. Her research is also part of the broader NSF- funded plague project underway in northern Colorado.NSF- funded plague project

How do we estimate populations when we don’t have census data? It’s hard to count every individual and can be very time consuming! It’s hard to count every individual and can be very time consuming! If the critters are mobile, they are probably sneaky and don’t want to be found. Makes your job a little harder. If the critters are mobile, they are probably sneaky and don’t want to be found. Makes your job a little harder.

Examples of population survey techniques Plot sampling (Quadrat sampling) Plot sampling (Quadrat sampling) Estimate density Estimate density Estimate percent cover Estimate percent cover What types of organisms is this method good for? What types of organisms is this method good for? What would it not work for? What would it not work for? AOg/yQIYwuH6g8c/SpellmanEcolab_Stephanie%26Me_plots.jpg

Examples of population survey techniques Mark-Recapture Sampling Mark-Recapture Sampling Capture Capture Mark all that you captured Mark all that you captured Release Release Recapture Recapture Estimate population by the ratio of marked to unmarked Estimate population by the ratio of marked to unmarked

Examples of population survey techniques Mark-Recapture Sampling Mark-Recapture Sampling Equation: N/M = n/R Equation: N/M = n/R N = Estimated Population N = Estimated Population M = Marked individuals M = Marked individuals n = number of individuals in the second sample n = number of individuals in the second sample R = Recaptured individuals R = Recaptured individuals So, N = Mn/R So, N = Mn/R

Examples of population survey techniques Mark-Recapture Sampling Mark-Recapture Sampling An example An example

Mark-Recapture Sampling in Action! Still Creek Fish Trap, Mt. Hood, OR

Can you find the marked fish?

Mark-Recapture Sampling in Action! Still Creek Fish Trap, Mt. Hood, OR

Back to the office to analyze the data!

Link to recent Hudson River plane crash

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Where does population ecology come into play with the dangers of bird strikes? Well, lets be wildlife biologists and take a look!