Biogeographical and ecological processes 2, Lecture 34

Question 1

Case study for change in vegetation linked to topographic change

Answer 1

• Sierra Nevada, Spain
• mountain building region
• large difference between sea level & mountain altitude which are very close

Question 2

Other than availability of environmental resources, what determines species distribution of plants?

Answer 2

ability to tolerate periods and levels of environmental stress

Question 3

Environmental stresses

4

Answer 3

Deficiency of:
- light
- moisture
- nutrients and
- temperature 
(which limits photosynthetic production)

Question 4

Common adaptive strategies to severe stress:
(of vegetation)
5

Answer 4

1. a small hard-leaved perennial habit,
2. conservative use of resources,
3. slow growth and turnover of materials, 
4. sequestration / accumulation of food reserves above and/or below ground.
5. flowering + seed production intermittent but vegetative repro. common

Question 5

Niche concept

Answer 5

presence or absence of a species in a habitat depends on availability of a suitable niche

Question 6

Potential range of a plant species

Answer 6

Range of tolerance to abiotic conditions is the physiological or potential range of a plant

Question 7

Actual range of a plant species

Answer 7

no organism exists in isolation so it’s ecological or actual range depends on suitability of biotic environment as well as the abiotic

Question 8

Biotic interactions can be

4

Answer 8

Direct or indirect
Exclusively or mutually antagonistic
Depressive or beneficial
Preclude or essential

Question 9

Two main types of biotic interactions

Answer 9

Negative and positive

Question 10

Negative biotic interactions

2 types

Answer 10

1. competition, both species suffer

2. herbivory, predation and parasitism, one species benefits at the expense of the other

Question 11

Positive biotic interactions

2 types

Answer 11

1. Mutualism, both species benefit

2. Commensalism, one species is benefitted, other is unaffected

Question 12

Two definitions of competition

Answer 12

Struggle of two or more organisms to exploit same limited resource

Or

When interactions between two or more individuals or populations adversely affects growth, fitness or population size of other

Question 13

Competitive exclusion

Answer 13

“when two species are grown in the same environment one either wholly or partially displaces the other”

Question 14

Why is there limited evidence of competitive exclusion in the field?

Answer 14

existing distributions result from past competition

Question 15

Example of obvious competition in disturbed habits

Answer 15

between crops and weeds

Question 16

Most intense (intra-specific) competition

Answer 16

between young individuals of same species, very similar resource requirements

Question 17

Direct form of competition in plants

Answer 17

Allelopathy

Question 18

Most competition in plants is indirect or direct?

Answer 18

indirect

Question 19

Example of allelopathy

Answer 19

plants exude chemicals which inhibit growth if other species
eg: rhododendrons

Question 20

Chemical inhibition can occur…

Answer 20

between species or between seedlings of the same species

Question 21

Intra and inter - specific competition more complex in plants or animals?
and why?

Answer 21

animals,

more mobile, diverse behaviours etc.

Question 22

Competition for what in animals

3

Answer 22

living space
food
breeding partners

Question 23

Animal competition

Interference

Answer 23

aggression/ territorial behaviour

Question 24

Animal competition

predation

Answer 24

but depresses abundance of food (prey or host)

Question 25

Mutualism

Answer 25

Both species benefit

Question 26

Example of mutualism

lichen

Answer 26

Lichens- associate between a fungus and algae

Question 27

Example of mutualism

nitrogen-fixing bacteria

Answer 27

Symbiotic nitrogen-fixing bacteria living within root nodules of legumes

Question 28

Example of mutualism

mycorrhizal fungi

Answer 28

Mycorrhizal fungi in roots of trees and shrubs

Question 29

Commensalism

Answer 29

one species benefitted, other unaffected