Lecture 21: What is a ecological community

Question 1

How can you distill the complex patterns of nature into one number?

Answer 1

Through the Shannon-Wiener diversity index (H’)

Question 2

What is Pi within the Shannon-Wiener index?

Answer 2

The proportion of the i^th species

Question 3

What is S within the Shannon-Wiener index?

Answer 3

The number of Species in a community.

Question 4

How do you calculate (pi)?

Answer 4

you divide the species number by the total number of species within the population.

Question 5

How do you calculate the H’ value?

Answer 5

You take the sum of pi In pi and multiply it by negative 1

Question 6

What should the value be when you sum up pi?

Answer 6

1

This takes into account the who community (thus equaling 1)

Question 7

How do you calculate species evenness?

Answer 7

Though the use of Pielou’s J

Question 8

Within Pielou’s J, what is In(s)

Answer 8

The total number of species

Question 9

When J = 1

What level of evenness is in the community?

Answer 9

Perfectly even

Question 10

When j = 0

What level of evenness is in the community?

Answer 10

Very uneven

Question 11

What is a Rank Abundance Curve?

Answer 11

Plot of relative abundance of species against their rank in abundance

(another tool to assess weather a species is dominant and to measure diversity)

Question 12

What is rank abundance?

Answer 12

How abundant a species is compared to other species

Question 13

What is Relative Abundance?

Answer 13

% or proportion of community individuals

Question 14

What will a Abundance rating of 1 mean?

Answer 14

Means that they are the most abundant species within the community

Question 15

How of you calculate richness on a Rank Abundance curve?

Answer 15

Where the X-axis value ends determines the amount of species in the community (the richness)

Question 16

What will the slope of a Rank Abundance curve represent?

Answer 16

It represents the evenness of the community.

The steeper the slope the less even you are

Question 17

True or false:

The shallower the slope the greater the evenness

Answer 17

True

Question 18

What is the relationship between environmental complexity and species diversity?

Answer 18

In general, the more complex or heterogeneous

the environment, the greater species diversity.

Question 19

What is included within environmental complexity?

Answer 19

– Vertical structure (trees? no trees?)

– Water movement (current? no current?)

– Nutrient availability

– Light availability…

Question 20

What are the factors included within
(Simple
Homogeneous)?

Answer 20

Few factors that
influence
organisms
• Few niches

Question 21

What are the factors included within (Complex

Heterogeneous)?

Answer 21

-Many factors that influence organisms

• Many niches

Question 22

What is Species Composition?

Answer 22

The species that occur in a given community at a given time.

Question 23

What is the Paradox of the Plankton.

Answer 23

How can there be so many species of plankton living in such a simple environment?

Question 24

How are lakes Heretogenous with life?

Answer 24

They have seasonal cycles of temperature, oxygen, and nutrients that make complex environments for plankton and other microorganisms

Question 25

Changes in and differences between
communities are not only indicated by the
number of species and the evenness of those
species, but the ______________

Answer 25

Species themselves