Exam 12: Population Growth and Regulation

Consider a biologist who is studying a fish. The biologist conducts an experiment with four treatments in artificial ponds of the same size. In the first treatment he adds 10 fish to each pond. In the second treatment he adds 100 fish to each pond. In the third treatment he adds 10 fish and additional food. In the fourth treatment he adds 100 fish and additional food. At the end of the experiment he finds that female fish in ponds with only 10 fish produce many more eggs than female fish in ponds with 100 fish. However, adding food did not alter the number of eggs each female fish produced. Explain what this experiment tells us about how these fish are affected by density-independent, positive density-dependent, or negative density-dependent factors.

The net reproductive rate refers to

Alpine ibex are a type of wild goat that lives high in the mountains. During winters with heavy snow, Alpine ibex have high mortality rates regardless of the population size. This is an example of

The exponential growth model and the logistic growth model both initially look the same. Explain the difference between the two models. What causes the logistic model to change trajectory?

In the logistic growth model, which term determines how quickly a population will initially grow from low density?

In the logistic growth model, which term determines the maximum number of individuals a population can sustain?

The logistic growth model describes a maximum population size that is

Which of the following statements about the logistic growth model is accurate? I. The per capita rate of population increase declines as population size increases. II. The overall rate of population increase is highest at K/2. III. The overall rate of population growth is negative when N is greater than K/2.

The age structure of a population is often represented by a pyramid. What does an age structure pyramid with a broad base and a narrow top indicate about a population?

What type of survivorship curve describes a species that has a high rate of juvenile mortality but low adult mortality?

According to an exponential growth population model, when the number of births is less than the number of deaths,

The following table for a species of plant that has four life stages was constructed from research done in the 1960s. Age Class (x) Survival Rate Survivorship Fecundity Seed 0.3 1.000 Seedling 0.2 0.300 Small adult 0.1 0.060 20 Large adult 0.006 50 Forty years later, biologists went back to the same site and determined the life table for the population, shown in the following table. On account of changing climatic conditions, seed survival decreased from 30 percent to 10 percent. However, these changing climactic conditions also cause large adults to produce four times as many seeds, so that they now produce 200 seeds. All other variables stay the same. Age Class (x) Survival Rate Survivorship Fecundity Seed 0.1 1.000 Seedling 0.2 0.100 Small adult 0.1 0.020 20 Large adult 0.002 200 Explain whether the change in climate is beneficial or harmful to this plant population based on these tables. Be sure to reference any relevant calculations you should make and explain the relative importance of the decreased seed survival and increased seed production.

The following table shows the survival and fecundity of a flowering plant. Age in Years (x) Survival Rate Survivorship Fecundity 1 0.1 1.0000 2 0.8 0.1000 3 0.8 0.0800 4 0.8 0.0640 10 5 0.0512 20

Which describes the figure of logistic population growth shown in the graph?

Plants are more likely to show which type of survivorship curve?

A disadvantage of static life tables is that

You are a biologist studying deer populations in four parks: Chagrin, Bedford, Bradley, and Brookside. These four parks are all the same size, and they have similar weather. You estimate deer population size in October 2011, before winter comes. Then you estimate the size of the herd the next year, in October 2012. The data are listed in the table: Park October 2011 Population October 2012 Population Chagrin 125 90 Bedford 50 77 Bradley 150 68 Brookside 75 96 Explain whether each of the following statements is supported by the data and why or why not. I. These populations have exponential growth. II. The changes in population size are density dependent. III. All of these populations are below their carrying capacity.

Under positive density dependence, population growth rate

Which reflects density-independent population regulation? I. a winter storm that kills birds with equal probability regardless of bird abundance II. a drought that kills a higher proportion of plants when there are many plants and a smaller proportion when there are fewer plants III. a lethal disease that is more easily transmitted when animals are found in high abundance than in low abundance

Which reflects negative density dependence? I. A fungus infects and kills plants at a higher rate when they are abundant than when they are rare. II. A group of birds has a higher per capita survival rate when it is large than when it is small. III. A large population of deer exhausts local food supplies and has a high risk of death; a small population has plentiful food and low risk of death.