Population and Community Dynamics

Question 1

Population:

Answer 1

Consists of all the members of a species that occupy a particular area at the same time.

Question 2

Species:

Answer 2

A group of organisms that has the potential to interbreed in nature to produce viable, fertile offspring.

Question 3

Evolution:

Answer 3

The change in the frequency of genes in a population’s gene pool from generation to generation.

Question 4

Gene pool:

Answer 4

The total of all the genes in all the population members simultaneously.

Question 5

The Hardy-Weinberg Principle:

Answer 5

Used to quantify an unchanging gene pool. The law states that the frequencies of alleles in a population’s gene pool remain constant over generations if all other factors remain constant.

Question 6

Genetic equilibrium:

Answer 6

Stability of a population’s gene pool.

Question 7

How does a population evolve?

Answer 7

If equilibrium is upset.

Question 8

Conditions of the Hardy-Weinberg Principle:

Answer 8

The population is large, mating is random, no mutations occur, no migration occurs, and no natural selection occurs.

Question 9

Microevolution:

Answer 9

A change in the gene pool of a population over successive generations.

Question 10

Gene flow:

Answer 10

Movement of alleles from one population to another through the movement of individuals or gametes.

Question 11

Genetic Drift:

Answer 11

Change in the gene pool of a population resulting from chance.

Question 12

Founder Effect:

Answer 12

Genetic drift that results when a small number of individuals separate from their original population and find a new population.

Question 13

Bottleneck effect:

Answer 13

A dramatic temporary event which leads to a reduction in population size, usually resulting in a significant genetic drift.

Question 14

Factors that increase population size:

Answer 14

Natality and immigration.

Question 15

Factors that decrease population size:

Answer 15

Mortality and emigration.

Question 16

Exponential growth:

Answer 16

Population size increases by a fixed rate per unit of time with unlimited resources. The closes population’s only limit is biotic potential. J-curve.

Question 17

Logistic growth:

Answer 17

Growth will level off as the population size reaches a carrying capacity. These are characteristics of an open population.

Question 18

Density-Dependent Factors:

Answer 18

Factors that influence a population at a certain density.

Question 19

Density-Independent Factors:

Answer 19

Factors that have the same influence on a population at any density.

Question 20

What examples are there of density-dependent factors?

Answer 20

Intraspecific competition, predation, disease, and interbreeding.

Question 21

Intraspecific competition:

Answer 21

Competition between the same species; within a population.

Question 22

What examples are there of density-independent factors?

Answer 22

Weather and insecticides.

Question 23

K-selected organisms:

Answer 23

S-curve associated, larger organisms, adapted to living at a population at or near carrying capacity.

Question 24

r-selected organisms:

Answer 24

J-curve associated, small organisms, adapted to increase population size rapidly.

Question 25

Estrous Cycle:

Answer 25

The shorter the time between cycles of sexual receptivity, the greater the biotic potential.

Question 26

Mate availability:

Answer 26

The more readily available mates in a population, the greater the biotic potential.

Question 27

Litter/clutch size:

Answer 27

The larger the litter/clutch size, the greater the biotic potential.

Question 28

Fecundity:

Answer 28

The average number of offspring produced per female. The greater the fecundity of a species, the greater the biotic potential.

Question 29

Age of onset of sexual maturity:

Answer 29

The earlier that sexual maturation occurs, the greater the biotic potential.

Question 30

Gender ratio:

Answer 30

The more females there are, the greater the biotic potential.

Question 31

Interspecies:

Answer 31

What occurs in a community (between species).

Question 32

Symbiosis:

Answer 32

A close relationship between members of different species.

Question 33

Mutualism:

Answer 33

Both species benefit from the association. I.e. Bees and pollinated flowers.

Question 34

Commensalism:

Answer 34

One species benefits while the other neither benefits nor is harmed. Ie. Barnacles on a whale.

Question 35

Parasitism:

Answer 35

One species, the parasite, benefits at the expense of the host. Ie. Tapeworms in the human body.

Question 36

Plant defences against herbivores:

Answer 36

Thorns, microscopic crystals in their tissues, spines or hooks on leaves, and harmful chemicals.

Question 37

Animal defences against predation:

Answer 37

Camouflage, deceptive coloration, mechanical or chemical defence mechanisms, and mimicry.

Question 38

Succession:

Answer 38

The sequence of identifiable ecological stages or communities occurring over time in progress from bare rock to a climax community.

Question 39

Primary Succession:

Answer 39

The initial colonization of a barren habitat by pioneer species. Soil is produced during this stage.

Question 40

Secondary Succession:

Answer 40

Re-building of an area that once supported many organisms.

Question 41

Climax Community:

Answer 41

The stage in ecological succession that is stable and self-supporting. There is more production of organic material than use.