Rarefaction Plot Concepts and Analysis

The video tutorial guides students through the process of understanding and creating rarefaction plots. It begins with an introduction to the homework tasks, focusing on sampling and OTU cataloging. The tutorial then explores the relationship between the number of samples and OTUs, using a rarefaction plot as a tool for illustration. An example from a study in French Guiana is used to explain the concept. The video provides detailed steps on how to create a rarefaction plot, including data transformation and graphing. It concludes with plotting samples, analyzing trends, and a review of the content.

What should you have completed before moving on to the homework section?

• Data analysis report

• Rarefaction plot

• OTU catalog and diversity calculation table

• Species identification

What is the relationship between the number of samples and the number of OTUs or species found?

• There is no relationship

• More samples generally lead to finding more OTUs or species

• Fewer samples lead to finding more OTUs or species

• The relationship is always linear

In the example of the rarefaction plot from French Guiana, what does the x-axis represent?

• Number of habitats

• Number of individual small mammals

• Number of samples

• Number of species

What might indicate that there are still more species to find in a rarefaction plot?

• A curve that loops back

• A flat curve

• A steeply rising curve

• A downward curve

What is the purpose of transforming data before creating a rarefaction plot?

• To change the data values

• To simplify the data for graphing

• To make it more complex

• To remove unnecessary data

How do you determine the total number of species in a sample when creating a rarefaction plot?

• By adding new species found in each sample to the cumulative count

• By counting all species in each sample separately

• By averaging the number of species across samples

• By multiplying the number of species by the number of samples

What is the first step in creating your own rarefaction plot?

• Analyzing the data

• Collecting more samples

• Using the Diversity Index calculation

• Drawing the plot

When plotting a rarefaction curve, what does the y-axis typically represent?

• Number of OTUs

• Number of habitats

• Number of species

• Number of samples

What is a key feature of a rarefaction curve?

• It always increases linearly

• It shows a relationship between individuals and species

• It remains constant regardless of sample size

• It decreases as more samples are taken

What are the two types of trends you might see in a rarefaction curve?

• Curved and straight

• Increasing and decreasing

• Flat and steep

• Linear and exponential