Limiting Factors in an Ecosystem

Several Abiotic Factors Can Limit Population Growth  Limiting factor principle Too much or too little of any abiotic factor can limit or prevent growth of a population, even if all other factors are at or near the optimal range of tolerance Directly relates to:  Carrying Capacity (K) The maximum population of a given species that a particular habitat can sustain indefinitely without being degraded (we will return to this concept in Chapter 5)

Examples of Limiting Factors  Temperature Animals have a “thermal range” in which their bodies work Digestion & Metabolism Reproduction Locomotion (escaping predators) Foraging (finding food)  Space How many organisms can physically occupy an area?  Food Is the environment able to support an infinite number of organisms?

Range of Tolerance for a Population of Organisms INSERT FIGURE 3-10 HERE

Temperature of a Scorpion… even invertebrates have limiting factors

Raccoon Activity  Objectives: Define a major component of habitat Identify a limiting factor Recognize the importance of a suitable habitat and limiting factors  Methods Students will ‘become’ raccoons to look for components of a habitat

 Background: Since raccoons are omnivores and eat a variety of food, each color of paper represents a different food item Everyone will get a paper bag that represents the raccoon’s cache (stash of food hidden by an animal to be used at a later date, i.e. winter) “Food” (paper) will be scattered about in a “forest” (open area) Raccoon Activity

 Procedure:  Raccoons must walk through the forest  (raccoons do not run with their food)  Gather food  Hide it in the cache ONE AT A TIME!!!!  You cannot carry more than one food item at a time  Other raccoons can steal from your cache  Do not announce when you do this, raccoons do not make it known when they are stealing one another’s food! Raccoon Activity

 Here’s the catch: Not all raccoons are healthy… You will be randomly assigned a raccoon ‘history’ and must it out while gathering your food Raccoon Activity

 BROWN- nuts (acorns, walnuts, hickory nuts) 25% of diet  PURPLE- berries & fruits 25% of diet  YELLOW- insects (grub, larvae, ants, termites) 15% of diet  RED- meat (rodents, amphibians, reptiles, birds, eggs) 15% of diet  GREEN- plants (leaves, grasses, herbs) 20% of diet  BLUE- water

Summary  Did all raccoons get enough nutrients to survive?  What are the limiting factors?  How does this affect the survival of each animal?  What does this tell you about carrying capacity?