Worksheet 5 Competition This worksheet is designed to help

Worksheet 5 – Competition

This worksheet is designed to help you:

Understand the differences between intraspecific and interspecific competition.

Determine factors that may drive competition in nature.

Answer/address all of the following questions. In all cases, we require that your work be typed and that you make computer printouts of spreadsheets, graphics, or statistical output.

Provide 2 examples of intraspecific competition and 2 examples of interspecific competition. Cite your sources (16pts). Explain which scenario has more intense competition.

2. Produce a table showing the average number of beans collected by each individual during each foraging experiment (20pts).

An example raw data table is provided below – you are required to make a summary table from this information (hint: do not include raw data, only summary values, in a summary table).

3. Produce a bar graph (or bar graphs) reporting the experiment averages with appropriate error bars for each foraging experiment (16pts).

4. Provide null and alternative hypotheses for each foraging experiment—a total of 5 sets of hypothesis. (6 pts)

(hint: the 5 hypotheses will be (1) intraspecific competition between small beaked birds (experiment A), 2) Intraspecific Competition between large beaked birds (experiment B), (3) interspecific competition for small beans (experiment C), (4) Interspecific competition for large beans (Experiment D), 5) high vs. low density intraspecific competition (average A vs. average E).

5. Perform appropriate statistical tests for each hypothesis (12pts).

(hint: you are attempting to find out if there is a significant differences between two populations – for (i) and (ii) the statistical test will be paired and for (iii) the statistical test will be unpaired)

6. Discuss the results of each statistical test, and explain why you observed these patterns (15pts).

7. Explain how competition—both intraspecific and interspecific—drove the evolution of Darwin’s finches (below) to develop specialized beak shapes? What do the different species compete for, and why are differences in morphology (e.g. bill shape and size) important? (15 pts)

Solution

Interspecific competition: Competition between organisms belonging to two different species is termed intraspecific competition.

Intraspecific competition: Competition between organisms belonging to the same species is termed intraspecific competition.

Factors that may drive competition in nature:

i) Interference: Competition arises when individuals interfere with the physical establishment of other individuals in a habitat. There may be interference related to reproduction and survival.

ii) Resource limitation: Utilization of resorces causes their depletion. This increases competition between organisms for space.

2 examples of intraspecific competition: Pigeons competiting for the same crumb of food. Fight between lions for the same mate is an example of intraspecific competition.

2 examples of interspecific competition: Cayotes and gray wolves competing for prey. Blue monkeys and mangabeys, members of different species, fighting for space is an example of interspecific competition.

Members of the same species have the same needs. Hence, intraspecific competition is more intense as compared to interspecific competition.