Diversity Indices and Community Comparisons

A set of 30 flashcards summarizing key concepts from the lecture on diversity indices, their calculations, and implications for ecological studies.

What is the Shannon Index used for?

To measure biodiversity by considering both the number of species and their evenness.

What does the Simpson Index measure?

The probability that two randomly selected individuals belong to the same species.

What is the effective number of species?

The number of equally-common species required to give a particular value of the diversity index.

What is the equation for the Shannon Index (H)?

H = -∑(pi * log(pi)) where p_i is the proportion of species.

What is the equation for the Simpson Index (D)?

D = 1 - ∑(pi^2) where pi is the proportion of species.

Which community is more diverse, C1 or C2, based on species number?

C2 is more diverse because it has 4 species compared to C1's 3 species.

How is Shannon diversity sensitive?

It is sensitive to the presence of rare species.

In terms of dominant species, which index is most affected?

Simpson diversity is influenced more by frequent species.

What does the Berger-Parker index depend on?

It depends only on the most frequent species.

What does a diversity profile illustrate?

It shows the relationship between diversity values and the scale parameter alpha.

How does the scale parameter α influence diversity indices?

It quantifies how much the measure discounts rare species when calculating diversity.

What type of communities cannot be ranked based on diversity?

Communities whose diversity profiles intersect.

What does the Right Tail Sum (RTS) method evaluate?

The sum of relative abundances of species from a certain point onward.

What is the significance of rare species in diversity ordering?

Rare species can skew diversity indices and affect the ranking of communities.

What does Hill’s diversity represent?

It represents the effective number of species based on Rényi diversity.

What happens to the interpretation of diversity when applying Hill’s diversity?

It tends to converge the curves making it harder to distinguish between communities.

What is the formula for the Hill number Nα?

Nα = e^(Hα) where Hα is the Rényi diversity.

How is the Rényi diversity index articulated?

Hα = ln(∑(p_i^α)) / (1 - α) with 0 ≤ α and α ≠ 1.

For α = 0, what does H0 represent?

H0 = ln(S), which is the logarithm of the number of species.

For α → 1, what does H1 equal?

H1 = H, the Shannon diversity.

What does significant overlap in diversity profiles signify?

Difficulties in ranking communities based on diversity.

In the case study by Tóthmérész & Magura, which type of community is more diverse for rare species?

The native forest is more diverse for rare species.

What are the two main families of diversity ordering methods?

Information-related methods and expected number of species-related methods.

What does the formula H(a) indicate?

It includes different diversity types depending on the parameter a.

What challenges arise with using Hill’s index?

They can push curves closer, making distinguishing between them harder.

In diversity profiles, what does a faster decline indicate?

It indicates a less even community.

What community comparison is highlighted in the course materials?

Community C is more diverse than communities A and B.

What does the generalized entropy measure?

It measures diversity using different scale parameters and their impacts.

Why are diversity indices like Shannon and Simpson important?

They provide metrics for comparing biodiversity levels across different communities.

What implication does the presence of dominant species have on community diversity?

Dominant species may enhance certain diversity indices, obscuring overall diversity trends.

What does an effective number of species help clarify?

It aids in understanding the ecological balance and diversity without being skewed by dominance.

What role does software like R and RStudio play in biodiversity studies?

They are used for statistical analysis and graphical representation of diversity profiles.