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 Raccoon Activity 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 RED- meat (rodents, amphibians, reptiles, birds, eggs) • 15% of diet PURPLE- berries & fruits • 25% of diet GREEN- plants (leaves, grasses, herbs) • 20% of diet YELLOW- insects (grub, larvae, ants, termites) • 15% 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?