DensityDependent Limiting Factors Activity Get yourself into 6

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Density-Dependent Limiting Factors

Density-Dependent Limiting Factors

Activity � Get yourself into 6 groups of 4 -5 students per group �

Activity � Get yourself into 6 groups of 4 -5 students per group � Once you find your group, sit at a table � You have 30 seconds

Activity! � Food Station ◦ You will have one piece of “food” to share

Activity! � Food Station ◦ You will have one piece of “food” to share equally between you and your group members ◦ 3 stations to go to A, B, C-Rotate through them all ◦ Make notes on your worksheet � Shelter ◦ ◦ ◦ Station On the ground you will see 3 “shelters” You must stay in the “shelter” for 3 minutes If you are loud, you’re out NO SHOVING! You will be out if you shove anyone Rotate through all 3 stations Make notes on your worksheet

So what in the world is a densitydependent limiting factor? ?

So what in the world is a densitydependent limiting factor? ?

Competition � Crowded populations mean the individuals have to compete for food, water, space,

Competition � Crowded populations mean the individuals have to compete for food, water, space, sunlight, or anything else necessary for survival and reproduction � Some may have enough to survive, but can’t raise offspring � Some may die of starvation � The more individuals in an area, the faster resources are used up � Could be between individuals of the same or different species

Predation � Predator-prey relationships tend to fluctuate (go up and down) � If there

Predation � Predator-prey relationships tend to fluctuate (go up and down) � If there is a lot of prey, the predator can eat more, increasing the number of predators � If the prey decreases too much in population, there won’t be enough food for predators and so the population of predators decreases

Herbivory (Predation of Plants) � Plant and herbivore populations fluctuate just like the predator

Herbivory (Predation of Plants) � Plant and herbivore populations fluctuate just like the predator and prey populations

Parasitism and Disease � Parasites and disease causing organisms feed at the expense of

Parasitism and Disease � Parasites and disease causing organisms feed at the expense of the host � This can weaken or kill the host � The larger the population the easier it is for the parasite or disease to travel through hosts

Stress from Overcrowding � Some species will fight amongst each other if they are

Stress from Overcrowding � Some species will fight amongst each other if they are overcrowded � This fighting can cause stress leaving individuals susceptible to disease � In a few species, overcrowding can cause females to neglect or kill their own offspring

Word Splash �Organize the following words into 3 categories ◦ Density Dependent ◦ Density

Word Splash �Organize the following words into 3 categories ◦ Density Dependent ◦ Density Independent ◦ I’m not sure

�A hurricane � Famine � A disease kills half of the population � A

�A hurricane � Famine � A disease kills half of the population � A forest is cleared by a logging company � The plants that one species really likes has only grown half as much as usual � An early frost kills cherry trees � There is an unusually large population of wolves that eat a lot of rabbits � Territorial lions start fighting each other for habitat space � The weather has been unusually dry so the watering hole has dried up

So what did your densityindependent factors have in common?

So what did your densityindependent factors have in common?

Density-Independent Limiting Factors

Density-Independent Limiting Factors

So what is it? �A factor that affects all populations in similar ways, no

So what is it? �A factor that affects all populations in similar ways, no matter the population size or density �It includes things like: �Hurricanes �Droughts �Floods �Natural Disasters

Wait a second…is it really density dependent? � So what would happen after a

Wait a second…is it really density dependent? � So what would happen after a drought? ◦ No water so species will compete for the water � WAIT A SECOND MS. JOHNSON! YOU’VE TRICKED US!

�Sometimes a density dependent factor can lead to a density independent limiting factor like

�Sometimes a density dependent factor can lead to a density independent limiting factor like competition �What do you think? ?

Thinking back to logistic growth… � We said that something happens to stop populations

Thinking back to logistic growth… � We said that something happens to stop populations from growing. � How do density-independent and dependent factors play into this?

Carrying Capacity � These limiting factors contribute to what is called carrying capacity �

Carrying Capacity � These limiting factors contribute to what is called carrying capacity � Defined as: the maximum number of individuals of a species an environment can support

On a graph…

On a graph…

Exit Ticket �On a sheet of paper, write a paragraph explaining whether or not

Exit Ticket �On a sheet of paper, write a paragraph explaining whether or not you think that density independent factors should be considered separate from density dependent factors. �Explain your answer using information from today.