Biol 208 Lab 1: Niche and Competition Game PDF

# Lab 1: Niche and Competition Game ## Overview - Participate in a game to simulate resource partitioning and how competition puts limits on realized niches. - Participate in a group discussion related to the simulation. ## Objectives - Perform a simulation of competition. - Describe the differe...

# Lab 1: Niche and Competition Game ## Overview - Participate in a game to simulate resource partitioning and how competition puts limits on realized niches. - Participate in a group discussion related to the simulation. ## Objectives - Perform a simulation of competition. - Describe the difference between fundamental and realized niches. - Explain the potential outcomes of competition. - Construct scientific hypotheses with mechanism and directionality. - Distinguish between a hypothesis and a prediction. - Interpret values for niche breadth and niche overlap and use them to predict how species will interact under resource limitation. ## Connections to the lecture material: - What is a niche? - What is the difference between fundamental and realized niches? - What are the potential outcomes of competition? ## Each lab in Biology 208 has: - An associated pre-lab quiz and other supplemental activities/resources on the eClass page. - Pre-lab quizzes are due prior to entering the lab each week. ## Fundamental and Realized Niche - **Fundamental niche:** the total range of physical conditions in which an organism could theoretically survive, in the absence of any interactions with other species. - **Realized niche:** the portion of the fundamental niche that is actually occupied. ### Figure 1-1. Comparison of the fundamental vs. realized niche sizes using three environmental factors - **Fundamental niche** considers the environment as if there are no other species present. ## Competitive Exclusion - When two species compete for a critical resource, one of the species may eventually eliminate the other from the habitat where their distributions overlap. - This principle is termed **competitive exclusion**. ### Outcomes of Competitive Exclusion: - One species replaces another throughout the entire geographic range of the competitively inferior species, resulting in its extinction. - One species eliminates another from part of its range, resulting in a non-overlapping (allopatric) distribution. - Both species remain in an overlapping (sympatric) distribution, but the competitively superior species forces the less efficient or less aggressive species to abandon use of the limited resource and replace it with an alternative. ## The Chi-Square (x²) Goodness of Fit test - This test is used with count/enumeration data to determine if your observations match the expected number of observations, or if there is a statistically significant preference for one of the categories over the other(s). #### Formula: $x^2 = \sum_{i=1}^{N} \frac{(O_i - E_i)^2}{E_i}$ where: - $O_i$ is the observed number in one category - $E_i$ is the expected number - **Degrees of freedom:** the number of categories minus one. ## 1-4 NICHE AND COMPETITION GAME ### Hypotheses and Predictions - A hypothesis is one possible explanation for an observed phenomenon. - A scientific hypothesis must meet certain requirements: - testable - simple - robust - **Directionality:** refers to whether you think your variables interact positively or negatively (e.g. higher, lower, more less, increased, decreased etc.) - **Mechanism:** is a biological explanation for what drives the proposed relationship between your two variables. #### Example: **Hypothesis:** "Global warming extends the range of deciduous species by creating more habitats with moderate temperatures." - **Directionality:** extends - **Mechanism:** creating more habitats with moderate temperatures - A prediction is what you expect to see IF the hypothesis is true. - A single hypothesis can lead to many different predictions. #### Example: **Hypothesis:** "Global warming extends the range of deciduous species by creating more habitats with moderate temperatures." **Predictions:** - The range limits of vine maple will currently be farther north compared to historical ranges. - Germination rates of alder seeds are positively related to annual average temperature. - Trembling aspen seedlings incubated at 30 degrees Celsius will exhibit a faster growth rate than seedlings incubated at 20 degrees Celsius.