Communities+ Biomes

Question 1

community=

Answer 1

all of the populations of species living in a particular area at the same time

Question 2

______ b/w populations in a community influence the # of individuals in each population

Answer 2

Interactions

Question 3

t/f

communities range in size from small isolated areas to large open areas

Answer 3

true

Question 4

communities can have distinct or gradual ___

Answer 4

boundaries

Question 5

Why might it be hard to draw boundaries around a community?

Answer 5

because many species move between communities!
eg. many birds migrate in spring and fall

eg. differs with stage of life: amphibians spend larval life in aquatic communities and adult life in terrestrial

Question 6

t/f

communities are characterized the same way biomes are

Answer 6

true!

Question 7

How are terrestrial vs aquatic communities characterized?

Answer 7

terrestrial: vegetation

aquatic: focus on physical characteristics or dominant group of organisms

Question 8

Species composition of a community changes as you move across the landscape. This is called ______ ______

Answer 8

community zonation

w/ change in enviro conditions, some species become better able to survive and compete

Question 9

Give an example of community zonation in the mountains

Answer 9

based on elevation:
- diff species at base of mountain vs middle vs at the peak

the zones in which each species flourishes reflect different tolerance ranges for temp/ moisture. diff abilities to compete

Question 10

Community zonation also occurs in aquatic communities. For example:

Answer 10

kelp forests below intertidal zones, changes as you go higher. In splash zone, hardy species like limpets exist because they can survive desiccation when the tide is out

Question 11

Interdependent communities=

Answer 11

species depend on each other to exist

ie if you take one out, the other can’t survive

Question 12

Independent communities=

Answer 12

the species do not depend on each other to exist

• species live in the same place b/c they have similar adaptations & habitat requirements

Question 13

species richness within communities changes throughout the world. What might affect this?

Answer 13

resources available

diversity of habitat

keystone species

frequency/ magnitude of disturbance

Question 14

The # of species in a community can also be affected by the diversity of the habitat and whether habitats are ____. Why?

Answer 14

connected

diff habitats give diff benefits (eg one for nesting & one for feeding)

communities w/ higher diversity of habitats offer more potential niches & therefore have a higher diversity of species

Question 15

Keystone species=

Answer 15

species that has a disproportionately large effect on its community. Removing a keystone species can cause a community to collapse

Question 16

Give an example of a keystone species

Answer 16

sea stars

• they eat mussels
• if they didn’t, the mussels would take over and decrease the diversity

Question 17

keystone species can affect communities by influencing the structure of a habitat. In this case they’re called _____ _____

Answer 17

ecosystem engineers

Question 18

give an example of an ecosystem engineer

Answer 18

beaver!
- dams block the flow of water = ponds develop
= different community of plants & animals colonizes and persists in the non-flowing water

Question 19

a change in community composition after a disturbance= opportunity for _____

Answer 19

succession

some species are well adapted to this & benefit from disturbances

Question 20

When enviros are rarely disturbed, pops can continue to ____, resources become __(more/less) abundant, & ability to ___ becomes more important

Answer 20

grow

less

compete

Question 21

what level of disturbance yields the highest diversity and why?

Answer 21

medium amount of disturbance

both types of species (adapted & not adapted to disturbance) can persist & total # of species can be higher than it would be at either extreme

Question 22

Intermediate disturbance hypotheis=

Answer 22

more species present in a community that has occasional disturbances than in one with very frequent or rare disturbances

Question 23

when disturbance in a community is low, species richness is ____

Answer 23

low

Question 24

when disturbance in a community is moderate (freq or intensity) species richness is ___

Answer 24

high

Question 25

when disturbances are high, species richness ____

Answer 25

declines

Question 26

What are the 3 factors that influence community organization

Answer 26

body size
trophic status
succession

Question 27

Larger organisms require more ____ and more resources to maintain their size
- they have a ____ metabolic rate per unit mass than smaller organisms

Answer 27

energy
lower

Question 28

larger organisms have greater storage capacity (eg energy stored at fat), and therefore have a greater capacity to:

Answer 28

withstand prolonged stress
eg starvation, dehydration, cold

Question 29

small organisms require ___ resources compared to larger ones. Therefore they can use ___ areas & be more ___ while still maintaining high pop densities’

Answer 29

fewer

smaller

specialized

Question 30

___ organisms can respond to spatial heterogeneity (patchiness)

Answer 30

small

Question 31

carrying capacity is ___ for larger animals

Answer 31

lower

ie can have fewer larger organisms in an area b/c habitat can’t sustain them

Question 32

t/f
The capacity of an area to support many individuals and a diverse community depends on total consumers

Answer 32

false

depends on total primary productivity (plants) b/c of trophic levels

Question 33

primary succession=

Answer 33

all the soil and organic matter have been removed (by glacier/ volcano)

Question 34

secondary succession=

Answer 34

most living organisms are removed but some signal (or seed bank) of previous system remains
eg fire or flood

Question 35

_____ ____ proposed 5 hypotheses of species distribution based on his work with plants

Answer 35

Robert Whittaker

Question 36

t/f

combinations of many of Robert Whittaker’s hypotheses are possible

Answer 36

true

he didn’t realize that: interactions are much more complex than he proposed

Question 37

Biomes=

Answer 37

major communities of plants & animals occurring together at the landscape scale
- tundra, grassland, savanna, etc

Question 38

Biomes are analogous to the ______ concept but at a larger scale

*exam question

Answer 38

community