Lec 22 (Ecological communities)

Question 1

What is a community?

Answer 1

“an association of
potentially interaction
species inhabiting
some defines area, at
some particular scale,
over some particular
span of time.”

Question 2

Biosphere?
Ecosystem?
Community?
Population?
Individual?

Answer 2

Biosphere: All space occupied by living
things on Earth

Ecosystem: A region containing interacting
abiotic and biotic factors

Community: Population of species that occur
together in the same space and
time

Population: Individuals of the same species
that co-occur in space and time

Individual: Living entities that are genetically
and physically discrete

Question 3

Community structure?

Answer 3

attributes of a community, such as
the number of species or the distribution of individuals among species within the
community

Question 4

Species are described by their diversity, richness, and evenness… what are these?

Answer 4

Species Diversity: a measure of diversity that
increases with species evenness and species
richness

Species Richness (s): the number of species in a
community

Species Evenness: the relative abundance of
species in a community

Question 5

What are the three types of species diversity?

Answer 5

Gamma: diversity within a region or
landscape

Alpha: diversity within a locality within a
region or landscape

Beta: the difference between the diversity of
a region or landscape, and a locality within
the region or landscape

Question 6

An entire forest would be?

What about just a snapshot of a forest?

Answer 6

• Gamma

- Alpha (a subset of gamma)

Question 7

-What is Beta Diversity?

Answer 7

A measure of the diversity
among locations within a
region.

Example: Compare β
between the forest and
field

Question 8

So, there’s a lot of species out there. Almost too
many to count or investigate individually. Because of this, ecologists often study _______ or groups of __________organisms.

Answer 8

• guilds

- similarly functioning

Question 9

Talk about Species Dominance

Answer 9

More often than not, communities include a
“dominant” species, one that is more common
than all others.

Most species in the community will occur in
moderate abundances.

Few species will dominant or be rare.

Question 10

Species Richness vs. Species Evenness

Answer 10

Richness is a measure of the number of different kinds of organisms present in a particular area.

Evenness compares the similarity of the population size of each of the species present.

Question 11

-Why does species evenness matter?

Answer 11

-Leads us to ask why one species is lower than another one

Question 12

Rank Abundance Curve?

Answer 12

-plot of relative abundance of species against their rank in abundance.

assess dominance and diversity in community.

Question 13

What is the Relationship Between Environmental

Complexity and Species Diversity?

Answer 13

In general, the more complex the environment, the greater species diversity.

Question 14

heterogeneous vs homogenous

Answer 14

heterogeneous= complex

Homogenous= simple

Question 15

Few factors that influence
organism, Few niches=?

Many factors that influence organisms and Many niches=?

Answer 15

Homogenous/simple (Alberta plains)

Heterogenous/complex (rainsforest)

Question 16

Paradox of the Plankton… Lakes are?

Answer 16

• Complex
• As you go deeper in water there is less oxygen and temperatures drop (get colder)
• Different seasons cause changes to the water (temp, O2 content) making lakes heterogenous/complex

Question 17

Changes in and differences between
communities are not only indicated by the
number of species and the evenness of those
species, but the species themselves… this is known as
Species composition. What is species composition?

Answer 17

Species composition: the species that occur in a

given community at a given time

Question 18

Why is species composition important?

Answer 18

Shifts in species composition to
non-native species often leads to
changes (usually decreases) in
species richness and evenness

Question 19

What are Biotic Invaders (Non-native species, Invasive Species)

Answer 19

Species that establish a new range in which

they proliferate, spread, and persist to the detriment of the environment.