value (Figure 5). Use this table to answer the two questions
below.
a Which species has the most impact on the community if
removed? Why? Explain what you did and why you
reached this conclusion. Be sure to explain your result
with both the rank abundance curve and the Simpson’s
Diversity Index.
b Which species has the least impact on the community if
removed? Why? Explain what you did and why you
reached this conclusion. Be sure to explain your result
with both the rank abundance curve and the Simpson’s
Diversity Index.
6. Why do ecologists use both diversity indices and rank abundance curves when interpreting their data?
Notes for Instructors on This Exercise
We used this exercise in conjunction with activities where students went outside, counted species, and created species accumulation curves—often plants but more recently Pokémon (Drew
et al., 2017). In class, we presented community ecology data,
and in small groups students determined how to assess the community (e.g., soil type, species diversity, species richness, species
abundance).
The evaluation questions should be adjusted for the level of
students and type of class. Some questions are designed to test critical thinking; for example, in Question 5b students may decide that
the removal of a low-abundance species always has a small effect.
However, if that species happened to be a predator, that could have
a large long-term cascading effect on the community diversity, but
only a small initial effect.
Figure 3. Simpson’s Diversity Index was calculated using the table in part (A). Then, once the correct numbers were obtained,
we slowly led the students through the calculation of the Index itself in part (B).
Figure 4. This interactive element, supporting Question 4, allowed students to create their own data and see both the rank
abundance curve and the calculated Simpson’s Diversity Index.
