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Ch. 51 - Population Ecology
Freeman - Biological Science 8th Edition
Freeman8th EditionBiological ScienceISBN: 9780138276263Not the one you use?Change textbook
All textbooksFreeman 8th EditionCh. 51 - Population EcologyProblem 13
Chapter 51, Problem 13

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Burmese pythons (Python molurus bivittatus) are constricting snakes that can reach enormous sizes (up to 7 meters in length). They are native to Southeast Asia but were released into southern Florida from the pet trade. Many other snakes occur naturally in this area. Are the introduced pythons a problem?
The data in the graph show the number of pythons that were encountered, not the total number of pythons in the population. Design a mark–recapture experiment to estimate the total population size of pythons, and list at least two assumptions you would be making in your experiment.
Bar graph showing increase in Burmese python encounters in Florida from 2000 to 2020, peaking near 3000 in 2020.

Verified step by step guidance
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Step 1: Understand the mark-recapture method. This technique involves capturing a sample of the population, marking them in a harmless way, and then releasing them back into the environment. After some time, another sample is captured, and the number of marked individuals in this second sample is used to estimate the total population size.
Step 2: Plan the initial capture. Decide on the area and time for capturing a sample of Burmese pythons. Ensure that the method of capture is safe and ethical for the snakes. Once captured, mark each python in a way that does not harm or alter their behavior, such as using a non-toxic paint or a small tag.
Step 3: Release the marked pythons back into their habitat. Allow enough time for them to mix back into the population before conducting the second capture. This period should be long enough to ensure thorough mixing but not so long that the marks fade or the pythons migrate out of the study area.
Step 4: Conduct the second capture. Capture another sample of pythons from the same area. Count how many of these are marked from the first capture. Use the formula for population estimation: \( N = \frac{M \times C}{R} \), where \( N \) is the estimated total population size, \( M \) is the number of marked individuals in the first sample, \( C \) is the total number of individuals captured in the second sample, and \( R \) is the number of marked individuals recaptured.
Step 5: List assumptions. Two key assumptions in this experiment are: (1) The marked pythons have mixed evenly back into the population and have the same chance of being recaptured as unmarked pythons. (2) The marks remain visible and do not affect the pythons' survival or behavior.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Mark-Recapture Method

The mark-recapture method is a technique used in ecology to estimate an animal population's size. It involves capturing a sample of individuals, marking them, and releasing them back into the environment. After some time, another sample is captured, and the number of marked individuals is counted. This data helps estimate the total population using statistical models.
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Assumptions in Mark-Recapture

Several assumptions are crucial for the accuracy of mark-recapture experiments: the marked individuals must mix randomly with the population, marks must not affect the animals' survival or behavior, and the population should remain closed, meaning no significant immigration, emigration, births, or deaths occur during the study period. Violating these assumptions can lead to inaccurate population estimates.
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Ecological Impact of Invasive Species

Invasive species like Burmese pythons can disrupt local ecosystems by preying on native species, competing for resources, and altering habitat structures. Their introduction can lead to declines in native biodiversity and changes in ecosystem functions. Understanding their impact is crucial for managing and mitigating ecological damage in affected areas.
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Related Practice
Textbook Question

Burmese pythons (Python molurus bivittatus) are constricting snakes that can reach enormous sizes (up to 7 meters in length). They are native to Southeast Asia but were released into southern Florida from the pet trade. Many other snakes occur naturally in this area. Are the introduced pythons a problem? Burmese pythons were first found in the wetlands of Everglades National Park in the 1980s, but only rarely. The accompanying graph shows what happened next. Most of the data are derived from chance encounters of pythons on roads and intermittent search effort near roads (pythons are notoriously difficult to find). Despite the variability in search effort, what type of population growth best describes the trend in the data from 2000 to 2020? a. logistic b. exponential c. linear d. logarithmic


Textbook Question

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Burmese pythons (Python molurus bivittatus) are constricting snakes that can reach enormous sizes (up to 7 meters in length). They are native to Southeast Asia but were released into southern Florida from the pet trade. Many other snakes occur naturally in this area. Are the introduced pythons a problem?

Researchers hypothesize that the severe winter of 2010 caused the decline in the number of pythons encountered that year. Is cold weather typically a density-dependent factor or a density-independent factor? Explain the difference.

Textbook Question

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Burmese pythons (Python molurus bivittatus) are constricting snakes that can reach enormous sizes (up to 7 meters in length). They are native to Southeast Asia but were released into southern Florida from the pet trade. Many other snakes occur naturally in this area. Are the introduced pythons a problem?

A life table would help researchers make predictions about python population growth. If you were to track a cohort of pythons over time to construct a detailed life table, what kind of data would you want to collect?

Textbook Question

Burmese pythons (Python molurus bivittatus) are constricting snakes that can reach enormous sizes (up to 7 meters in length). They are native to Southeast Asia but were released into southern Florida from the pet trade. Many other snakes occur naturally in this area. Are the introduced pythons a problem? Pythons are generalist predators, consuming more than 75 species of prey including frogs, mice, rabbits, squirrels, porcupines, raccoons, leopards, deer, monkeys, alligators, and birds ranging from wrens to herons. Some surveys showed the disappearance of some animals, such as rabbits and opossums, from areas with pythons. Do you think food availability limits, or could limit, the carrying capacity of Burmese pythons in the Everglades?

Textbook Question

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Burmese pythons (Python molurus bivittatus) are constricting snakes that can reach enormous sizes (up to 7 meters in length). They are native to Southeast Asia but were released into southern Florida from the pet trade. Many other snakes occur naturally in this area. Are the introduced pythons a problem?

The range of Burmese pythons in Florida is expanding rapidly. List at least one abiotic factor and one biotic factor that might limit the range of pythons.