Population Distribution and Abundance

Question 1

Niche

Answer 1

set of all possible environmental conditions that lets the population sustain itself; population profile

Question 2

Fundamental niche

Answer 2

potential / full range of environment conditions which a population can exist in

Question 3

Realized niches

Answer 3

the environmental conditions a species occupies as a result of overlapping/pressure from superior competitors

Question 4

Exclusion Principle

Answer 4

No two species can occupy the same niche indefinitely

Question 5

How does climate influence species distribution? [4]

Answer 5

1. Food production
2. Water supply
3. Habitat
4. Incidence of parasites pathogens and competitors

Question 6

Distribution of individuals on small scales [3]

Answer 6

1. Random - equal chance of being anywhere; uniform distribution of resources
2. Regular - uniformly spaced; individuals avoid one another, resource competition is heavvy
3. Clustered/Aggregated - resources are clumped/patchy

Question 7

Allelopathy

Answer 7

secretion of chemicals to ward off other plants / organisms

Question 8

Distribution of Barncles along an interidal exposure gradient

Answer 8

1. CHTAMALUS STELLATUS
2. BALANUS BALANOIDES

Balanus is more vulnerable to dessication, excluding it from the upper intertidal zone, Chthamalus adults appear to be excluded from lower areas by competition

Balanus > Chthamalus in size of fundamental niche

Question 9

Distribution of Tropical Bee Colonies

Answer 9

Hubbell and Johnson proved that aggressive bee colonies would show regular distribution while non-aggressive species would show random or clumped distributions

Question 10

Distribution of Desert Shrubs

Answer 10

Desert shrubs are NOT regularly spaced BECAUSE of competition.

Phillips and MacMahon: distribution changes from clumped to regular patterns

Clump: germinate at safe sites; not dispersed from parent areas; asexual reproduction

Clump –> Regular: competition between juveniles

Question 11

Plant Distributions along moisture gradients:
Dry upper slope - ?
Midslope - ?
Moist valley bottom - ?

Answer 11

Dry upper slope - TABLE MOUNTAIN PINES
Midslope - RED MAPLES
Moist valley bottom - HEMLOCKS

Question 12

Large Scale Distribution Patterns

Answer 12

1. Gradients - noticeable trend in increasing/decreasing population along a direction
2. Dispersal - movement of individuals either by jump dispersal or range expansion

Question 13

Jump dispersal

Answer 13

Dispersal over unfavoured conditions

Question 14

Range expansion

Answer 14

Dispersal over favoured conditions

Question 15

Dispersal movements overtime

Answer 15

1. Dispersal - movement from place to place
2. Vicariance - split from its parent population by a geographical phenomenon
3. Extinction

Question 16

Why are there Llamas in African and South A. but not in North A.?

Answer 16

• Dispersal of common ancestor in NA to SA and Africa during Pangea
• Vicariance of SA and Africa lands
• Extinction of common ancestor in NA

Question 17

Metapopulations

Answer 17

Group of subpopulations living on patches of habitat connected by an exchange of species e.g. Alpine butterfly and Lesser Kestrels

there is movement of individuals between patches of populations but what happens at one patch does not affect the other

Question 18

Commoness and Rarity [3] factors

Answer 18

1. Geographical range of species
2. Habitat tolerance
3. Local population size

Question 19

Rarity I

Answer 19

Extensive range, broad HT, small population

PEREGRINE FALCON

Question 20

Rarity II

Answer 20

Extensive range, narrow HT, large population

PASSENGER PIGEON

Question 21

Rarity III

Answer 21

Restricted Range, narrow HT, small population