20.1 Population Growth

Question 1

Population density

Answer 1

The number of organisms in a given are or volume

D= (number of organisms)/ (area)

Question 2

Three theoretical distribution patterns for populations

Answer 2

Uniform

Random and clumped

Question 3

What affects population density estimates?

Answer 3

population distribution

Question 4

Random Distribution (3)+ex

Answer 4

Occurs when resources are very abundant and population members do not have to compete with one another or conversely group together for survival.

Individuals or pairs of organisms are distributed throughout a suitable habitat with no identifiable pattern.

Ex: Individual bull moose or female moose with calves sometimes exhibit a random distribution pattern.

Random distribution in nature is rare.

Question 5

Clumped distribution (3)+ex

Answer 5

More common

Members of a population are found in close proximity to each other in various groups within their habitats

Most populations, including humans exhibit a clumped pattern of distribution, congregating in an area where food, water of shelter is most abundant.

Ex: Aspens: they reproduce asexually by sprouting new trees from the roots of older trees, they grow in groves, resulting in their clumped pattern of distribution.

Question 6

Uniform distribution

Answer 6

Individuals are evenly spaced over a defined area

Ex: Artificial populations such as plants growing in orchards or agricultural fields

Question 7

A population’s size directly depends on

Answer 7

how much and how fast it grows

Question 8

4 processes that can change the size of a population:

Answer 8

1. Births
2. Immigration (Movement of individuals into a population) Increase population size
3. Deaths
4. emigration (movement of individuals out of a population) decrease in population size

Question 9

Change in population size equation:

Answer 9

Change in population size= (Births+immigration)-(Deaths+emigration)

Question 10

Discuss immigration and emigration affect on population sizes:

Answer 10

In nature, these processes can result in gene flow between populations, but they often occur in equal amounts or in such low numbers that they are difficult to measure or do not significantly affect the sizes of the populations.

Question 11

Population explosion: (Ex)

Answer 11

A population increase that grows so rapidly that it spreads before it can be contained
- Invasive species

Question 12

Population crash

Answer 12

Population decrease so rapidly

Question 13

Growth Rate (gr)

Answer 13

The change in the number of individuals in a population over a specific time frame

Question 14

Formula for Growth rate+ its usage

Answer 14

gr= (change in number of individuals)/time

• Used to measure increase or decreases in population size over time

Question 15

Per capita growth rate (2)

Answer 15

The rate of change per individual

Like cgr, it can be negative if deaths and emigration outnumber births and immigration

Question 16

Formula for cgr and its usage: (4)

Answer 16

cgr= (Change in number of individuals *final-initial)/ (the original number in the population)

• To compare populations of the same species that are different sizes or live in different habitats
• Multiply by 100 to show the percent the population has grown
• The amount that a population size has changed in relation to its original size

Question 17

Biotic potential (3)

Answer 17

the highest possible per capita growth rate for a population

the maximum amount of offsprings an individual can produce with unlimited resources

• a population growing at its biotic potential would be expected to grow exponentially

Question 18

factors that determine a species biotic potential: (4)

Answer 18

• Number of offsprings per reproductive cycle
• the number of offspring that survive long enough to reproduce
• the age of reproductive maturity and the number of times that the individual reproduce in a life span
• the life span of the individual

Question 19

Exponential growth pattern

Answer 19

a J shaped curve

Question 20

Logistic growth pattern

Answer 20

• S shaped

If growth is limited by resources such as food, the exponential growth of the population begins to slow as competition for those resources increases. The growth of the population eventually slows nearly to zero as the population reaches the carrying capacity (K) for the environment.

Question 21

Carrying capacity (K)

Answer 21

The theoretical maximum population size that the environment can sustain over an extended period of time

The number of individuals in a population that can live in a given environment without depleting the resources they need or harming their habitat or themselves.

Question 22

density dependent factors (3)+ex

Answer 22

biotic

when a population is small and below the carrying capacity of the habitat, density dependent factors do not limit growth

impact increases with the density of the population

-ex: parasite/predators

Question 23

density independent factors

Answer 23

abiotic
- ex: harsh winter/floods/forest fires

limits growth regardless of the size of density

Question 24

Environment resistance

Answer 24

prevents population from growing at its biotic potential and determines the carrying capacity of the habitat.

Question 25

R selected strategies (4)

Answer 25

• reproduce close to biotic potential
• short life span and an early reproductive age
• produce large amount of offsprings that receive little or no parental care
• take advantage of favourable environmental conditions and reproduce quickly

Question 26

K selected strategies

Answer 26

• populations that live close to the carrying capacity of their habitats
• few offsprings per reproductive cycle and one of both parent take care of it