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Salamander Spots: Patterned or Not?

Instructional Level: High School

Lesson Plan: Spotted Salamander Symbiosis (5E Instructional Strategies)

Driving Question(s):

How is a changing climate related to fragile ecosystems like vernal pools and how does that relationship impact biodiversity and, in particular, the spotted salamander?

Climate changes affect both the vernal pool and the spotted salamander in different ways. A warming climate may mean less winter precipitation which leads to smaller vernal pools. A warmer climate will stimulate earlier migration dates for the salamander with smaller available habitat for reproduction.

LESSON PLAN STANDARDS:

Exploration

Students will observe images of spot patterns present on images of spotted salamanders. Students will classify these patterns as alternate, opposite, or random. Note: After examining the actual images of salamanders, students may develop additional spot pattern classifications.

Students will state a hypothesis for the spot pattern observed in terms of a null and alternate hypothesis. Students will test data using Hardy-Weinberg and/or Chi Square.

Objectives

Students will:

  1. Observe images of spot patterns present on spotted salamanders.
  2. Classify these patterns as alternate, opposite, or random.
  3. State a hypothesis for the spot pattern observed in terms of a null and alternate hypothesis.

Lesson Materials

  • Internet connection and laptop or personal device
  • Images and video of spotted salamander masses from migration events
  • Spotted or Not (Interactive Lesson)
  • Data Table of spot patterns created by students or teacher

Procedures

Preparation

  • Students should have a grasp of Mendelian and non-Mendelian genetics.
  • This activity is most appropriate for students with a background in Algebra II, although general level classes can complete the lesson by comparing the ratios of individuals possessing each spot pattern.
  • Background information for the concepts used in this lesson can be found in the “References” section below.

Part I – Observation and Hypothesis

  1. Explain that in this vernal pool there is a single population of spotted salamanders but they congregate randomly into several mating groups. Show Video 1 of spotted salamanders. Teacher asks students to focus on the array of spots seen along the back of the salamanders. After viewing Video 1 a few times to understand the group, develop a hypothesis about the spot patterns.
  2. Use the interactive images to assist students in identification of spot patterns.
  3. After the hypothesis is developed, freeze the video at a clear view. Students make the observations: N = total number of individuals in the frozen view, count and record the number of alternate, opposite, and random spot patterns. Provide students the data table for recording spot patterns.
  4. Proceed to Video 2. Repeat the process of viewing, complete a new data table, freeze, count, and record.
  5. Proceed to Video 3. Repeat the process of viewing, complete a new data table, freeze, count, and record.
  6. Calculate the spot arrangement ratios for each mating mass. Consider each mating mass ratio: Does there appear to be a preference for any one pattern with each group?
  7. Collate all three data sets and calculate spot arrangement ratios for the entire population of spotted salamanders in this vernal pool.

Part II – Data Collection

  1. Students view a selection of video clips of spotted salamander mating masses within a single population. They are asked if there is a pattern that can be discerned. Students may need to be guided to classifying spot patterns as alternate, opposite, or random. View Video 1. Movement makes it difficult to count individuals and discern their spot patterns. Pause video where most salamanders are visible. Count individuals visible (N). Observe spots for pattern or not. Create data table with salamander numbers (1,2,3…) and choice of pattern (alternate, opposite, random).
  2. Students return to the paused video to classify the frequency of spot patterns in this mating mass image.
  3. Teacher concludes this session by asking if one spot pattern seems to be prevalent? Is there a pattern that is less common? Can the spot pattern be quantified into a rough ratio?
  4. Proceed to Video 2. Repeat the process of viewing, complete a new data table, freeze, count, and record.
  5. Proceed to Video 3. Repeat the process of viewing, complete a new data table, freeze, count, and record.
  6. Calculate the spot arrangement ratios for each mating mass. Consider each mating mass ratio: Does there appear to be a preference for any one pattern with each group?
  7. Collate all three data sets and calculate spot arrangement ratios for the entire population of spotted salamanders in this vernal pool.
  8. Teacher reviews patterns of genetic inheritance. Based upon the visual evidence, does the pattern of spots seem to follow a pattern of inheritance? Which pattern seems to best fit the data?
  9. Teacher introduces the idea of the Chi-Squared test. Are spot patterns controlled by genetics? Does the inheritance follow a simple dominant recessive pattern? Is the occurrence of spot patterns seen random?

Part III – Evaluation

  • Have students revisit their original hypotheses.
  • Have them write a conclusion document that either confirms or refutes their hypotheses based on their data table and analysis. Have them include all statistical analyses used (total each type, ratio of spot patterns, Chi-squared test).

Note: Conclusion should discuss whether the number of individuals viewed can be considered indicative of the entire spotted salamander population or just for the population that utilizes this particular vernal pool.

Standards

HS-LS3-3 Analyzing and Interpreting Data

Analyzing data in 9-12 builds on K-8 experiences and progresses to introducing more detailed statistical analysis, the comparison of data sets for consistency, and the use of models to generate and analyze data.

  • Apply concepts of statistics and probability (including determining function fits to data, slope, intercept, and correlation coefficient for linear fits) to scientific and engineering questions and problems, using digital tools when feasible.

HS-LS4-3 Analyzing and Interpreting Data

Analyzing data in 9–12 builds on K–8 experiences and progresses to introducing more detailed statistical analysis, the comparison of data sets for consistency, and the use of models to generate and analyze data.

  • Apply concepts of statistics and probability (including determining function fits to data, slope, intercept, and correlation coefficient for linear fits) to scientific and engineering questions and problems, using digital tools when feasible.

HS-LS4-4 Constructing Explanations and Designing Solutions

Constructing explanations and designing solutions in 9–12 builds on K–8 experiences and progresses to explanations and designs that are supported by multiple and independent student-generated sources of evidence consistent with scientific ideas, principles, and theories.

  • Construct an explanation based on valid and reliable evidence obtained from a variety of sources (including students’ own investigations, models, theories, simulations, peer review) and the assumption that theories and laws that describe the natural world operate today as they did in the past and will continue to do so in the future.

References

5E For This Lesson Plan

The Blue Crab: Callinectes Sapidus

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