Please Do Now: What was our definition of a limiting factor? AIM: SWBAT differentiate between density dependent and density independent limiting factors Please Do Now: What was our definition of a limiting factor?

Agenda Do Now Density Dependent vs. Independent Notes Experimental Design Finish Food Inc.

Limiting factors Limiting factors keep the organisms or populations from growing larger They are important in the study of population ecology Only 1 at a time for any given organism or population Often result in adaptations because of their strong influence on selection

What is the difference between Density Dependent/Independent Limiting Factors? Limiting Factors are either density dependent, or density independent Density dependent are those whose severity increases with the size/density of the population Density independent will affect all organisms and populations equally, regardless of their density/size The difference is important because they affect the way populations grow differently

Density Dependent Limiting Factors Size/Population goes up, so does the severity of limiting factor This could be the result of competition for biotic or abiotic resources, or because it is easier for things to do harm to limit populations when they are dense

Density Dependent

Density Dependent

Density Dependent

Density Dependent

Density Dependent

Density Independent Limiting Factors Those factors that will limit the growth of a population or organism that are unrelated to how many organisms exist They are generally abiotic or human in origin

Density independent

Density independent

Density independent

Density independent Human Impacts

Experimental Design Scientists know that colorful petals on flowers help attract animal pollinators. You are interested in determining whether or not the scent of the flower plays a role in attracting the pollinators as well. There are a number of ways you could come up with to test this problems, but you only need one. HYPOTHESIS: INDEPENDENT VARIABLE: DEPENDENT VARIABLE: CONTROLS: BRIEF DESCRIPTION OF EXPERIMENT:

Graphing Now using the space below, graph the results you anticipate for the experiment you describe above. Make sure your experimental design matches the graph you produce.

Concerned with the safety standards of the meat packing industry, you want to determine if there is a relationship between the average number of meat-containing meals one consumes per week and the number of times one experiences food-poisoning like symptoms. You have the resources to conduct hundreds of surveys of people’s diets and their stomach health.   HYPOTHESIS: __________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ INDEPENDENT VARIABLE: ____________________________________________________ DEPENDENT VARIABLE: ______________________________________________________ CONTROLS: __________________________________________________________________ BRIEF DESCRIPTION OF EXPERIMENT: _________________________________________ __________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

Density Independent or dependent? Tomatoes are Anne’s favorite food. Last year, Anne decided to plant her own tomato garden. She wanted a large crop, so she planted many plants in her small garden. At first the plants thrived, but after one month, Anne noticed that they had stopped growing and looked unhealthy. The few tomatoes that her garden produced were small and sour. Anne’s neighbor grew only two tomato plants, but harvested many more tomatoes than Anne. From her experience, Anne learned that overcrowding was a limiting factor in the growth of her tomatoes. Was overcrowding a density-independent or density-dependent limiting factor? Explain your answer.

Density Independent or dependent? Some ocean birds, such as gannets, breed on remote, rocky islands where they are safe from predators. Many gannets flock to these islands each year to build nests. Because the islands are small, only a certain number of birds can nest and reproduce. Is space on the island a density-independent or density-dependent limiting factor? Explain your answer.

Density Independent or dependent?   The trout stream Carlos visits on his annual “catch-and-release” fishing trip always provides him with a plentiful catch. Carlos uses a “fly” lure instead of a worm because young flies are the trout’s main food source. Trout especially like flies called midges and stoneflies, and always prefer to eat the ones that are the most plentiful. For example, when the midge population is high and the stonefly population is low, the trout eat midges and ignore stoneflies. Is the eating pattern of trout density-independent or density-dependent? Explain your answer.

Density Independent or dependent? Thrips are small insects that feed on apple blossoms. They can be a serious pest to apple growers. In recent years, a severe drought hit apple orchards in the state of New York. Because of the drought, most apple trees did not blossom. The thrip population declined sharply because their food source disappeared. Was the drought a density-independent or density-dependent limiting factor? Explain your answer.

Density Independent or dependent? This year, Anne was excited about planting another tomato garden. On a warm day in late March, she carefully set out her tomato seedlings. Two weeks later, the weather turned cold. A frost killed most of the seedlings, and Anne had to plant new ones. Frost was obviously a limiting factor in the growth of Anne’s tomatoes. Was frost a density-independent or density-dependent limiting factor? Explain your answer.

Density Independent or dependent? Alberto is visiting his aunt’s farm. He notices that the number of ticks are different in two adjacent pastures. One pasture is used for grazing dairy cows while the other pasture is used to grow hay. Alberto finds many ticks in the pasture with the dairy cows and almost none in the hay pasture. Is the tick population density-dependent or density-independent? Explain your answer.