Exam 43: Ecological and Evolutionary Consequences of Interactions Within and Among Species

Which pairs of species are participating in mutualistic interactions in which one type of nutrient is exchanged for another?

Given a population of 1,000 T.castaneum individuals,how many individuals of T.freemani would be needed to reduce the per capita growth rate of the T.castaneum population to zero?

Which type of interaction is typically random and brief?

Use the following to answer questions : A biologist examines three species of plants (A,B,C)and finds the patterns shown in the chart below.The effect by a species is the extent to which any individual of that species lowers the per capita growth rate of a given species.The effect on a species is how much the per capita growth rate of a species is affected by a given species.Thus,every individual of species A would lower the growth rate of species C by 0.017;and every individual of species C would lower the growth rate of species A by 0.014. -Based on these observations,should species A and B be able to coexist? Why or why not?

Use the following to answer questions : You have been observing an experimental population of nematodes that is given a set amount of a new food type at a given time.Over time,you notice that the carrying capacity appears to be increasing,as the food can support more individuals. -You notice that the current population consists of nematodes with the same mean body size as ones from generations ago,but with a reduced variance.What type of selection likely has been operating?

Use the following to answer questions : Refer to the graph below showing the grass abundance in plots with and without the presence of kangaroo rats between 1931 and 1945 at the Santa Rita Experimental Range in southern Arizona. -If we assume that the presence of the grasses increases rat reproductive rates,what term would best describe the interaction between rats and grasses in 1945? Why?

Intraspecific competition and herbivory by deer are both factors affecting the population growth rate of a bushy plant.Assume the following variables: the per capita growth rate of the bush is 0.1 when population density is very low;c is the rate per individual plant per meter square by which the population rate decreases due to competition;B is the density of plants per meter square;p is the rate by which individual deer reduce the per capita growth rate of the plant;and D is the number of deer.If G is the growth rate of the plants after accounting for intraspecific competition and predation,what is the equation for G?

Evolutionary "arms races" are usually the result of

Which type of species interaction is least likely to lead to a local extinction of at least one of the species involved?

C.F.Gause based his experimental studies of competition primarily on

Use the following to answer questions : Refer to the figure below showing the population densities of two species of Paramecium grown separately and together. -What is the difference in the carrying capacity of P.caudatum with and without the other species? What type of interaction is the likely explanation for this difference?

Which process is most likely to lead to intraspecific competition being stronger than interspecific competition?

Use the following to answer questions : Refer to the figure below showing a food web in the grasslands of Yellowstone National Park.[Note: Red arrows refer to animals consumed by carnivores;blue arrows correspond to plants consumed by omnivores and herbivores.] -The gray wolf preys on elk,but this is not the only possible way in which it affects elk.How might the removal of the gray wolf affect elk indirectly through a trophic cascade?

A population of birds colonizes an area and eats seeds in that locale.Over the course of evolution,the variability of birds eating seeds has decreased and the birds become more efficient at converting seeds into energy.Likely,______ selection has been operating,and has caused a(n)_______ in the carrying capacity.

A primary consumer

Some pathogens have the least effect on whichever of a set of vulnerable species is the least prevalent.This is an example of _______ advantage.

The American chestnut

Use the following to answer questions : Refer to the graph below showing the grass abundance in plots with and without the presence of kangaroo rats between 1931 and 1945 at the Santa Rita Experimental Range in southern Arizona. -If we assume that the presence of the grasses increases kangaroo rat reproductive rates,what term would best describe the interaction between kangaroo rats and grasses in 1935? Why?

Use the following to answer questions : In Joseph Connell's experiments with barnacles in the intertidal zone,he removed two species from their usual zones (stellate barnacles on the upper levels,rock barnacles on the lower levels)and observed the response of the other species.The results showed that stellate barnacles thrived on both levels in the absence of rock barnacles,whereas the rock barnacles remained only on the lower levels. -The distribution of rock barnacles is restricted by

In Joseph Connell's studies on the effects of competition on the distributions of different barnacle species,the experimental treatment was the _______ of one of the species of barnacle.