Question

data analysis: interspecific competition
the principle of competitive exclusion states that two species competing for the same limited resource cannot both have thriving populations. in order to survive, interspecific competition (competition between species) results. if one species has even a slight advantage for survival, it will outcompete the other species and eventually dominate. an example of this principle can be seen in the graphs below, which illustrate the populations of two species of aquatic single - celled microorganisms: paramecium aurelia and paramecium caudatum. in each experiment documented below, the organisms were provided with fresh water and a steady flow of food.
often, interspecific competition does not result in one species dying. in a recent study, ornithologists observed the common nightingale and the thrush nightingale. both of these species were originally found in brushy areas on the wooded edge of prairies. after a few months, the common nightingales were found mostly in the dry, warmer areas of the prairie while the thrush nightingales were found mostly in the cooler wooded portions of the habitat.
discussion questions:

1. look at graph (a). what do you notice about the growth of p. aurelia during days 0 - 5 as opposed to days 5 - 15?
2. what accounts for the differences in growth during these 2 periods?
3. what resources were limited in this experiment?
4. describe what happened in graph (c). give specifics for the first 2 days and the last 14 days.
5. explain the difference in the nightingale habitats from the beginning of the study until the end.

Explanation:

Question 1

Step1: Analyze graph (a) for days 0 - 5

In days 0 - 5, the population of P. aurelia shows exponential - like growth. The population size increases rapidly as the organisms have access to abundant resources initially.

Step2: Analyze graph (a) for days 5 - 15

In days 5 - 15, the growth rate slows down and the population approaches a carrying - capacity. Resources start to become limiting, causing the growth to level off.

Question 2

Step1: Consider initial conditions

In the first 5 days, resources (food, space) are abundant, allowing for rapid growth (exponential phase).

Step2: Consider later conditions

In days 5 - 15, resources become scarce. Competition for food and space increases, leading to a decrease in the growth rate and a leveling off of the population (logistic phase).

Question 3

Step1: Recall experiment details

The experiment provides fresh water and a steady flow of food. However, space in the experimental container is limited. Also, as the population grows, there may be competition for oxygen and other dissolved substances in the water, which can act as limiting resources. So, space and potentially oxygen/dissolved substances are the limited resources.

Question 4

Step1: Analyze first 2 days of graph (c)

In the first 2 days, both species (presumably P. aurelia and P. caudatum) show some growth. They have access to sufficient resources in the early stage of the experiment.

Step2: Analyze last 14 days of graph (c)

In the last 14 days, P. aurelia continues to grow and eventually dominates, while the growth of P. caudatum is suppressed. This shows the principle of competitive exclusion, where P. aurelia out - competes P. caudatum for the limited resources.

Question 5

Step1: Recall initial habitat of Nightingales

Initially, both the Common Nightingale and the Thrush Nightingale were found in brushy areas on the wooded edge of prairies.

Step2: Recall final habitat of Nightingales

After a few months, the Common Nightingales were mostly in the dry, warmer areas of the prairie, while the Thrush Nightingales were found mostly in the cooler wooded portions of the habitat. This indicates that through interspecific competition, the two species have partitioned the habitat to reduce competition for resources.

Answer:

1. In days 0 - 5, P. aurelia has rapid growth; in days 5 - 15, growth slows and approaches carrying - capacity.
2. In the first 5 days, resources are abundant; in days 5 - 15, resources become limiting.
3. Space and potentially oxygen/dissolved substances.
4. In the first 2 days, both species grow; in the last 14 days, P. aurelia dominates and P. caudatum is suppressed.
5. Initially, both in wooded - edge prairie areas; later, Common Nightingales in dry, warm areas and Thrush Nightingales in cooler wooded areas to reduce competition.