Population Growth and Resource Availability

Question 1

what limits population growth?

Answer 1

population growth is limited by environmental factors, especially by the available resources and space

Question 2

can resource availability and the total resource base be depleted?

Answer 2

yes, resource availability and the total resource base are limited and finite over all scales of time

Question 3

when does population growth accelerate?

Answer 3

when the resources needed by a population for growth are abundant

Question 4

what happens when the resources needed by a population for growth are abundant?

Answer 4

population growth usually accelerates

Question 5

what happens when the resource base of a population shrinks?

Answer 5

the increased potential for unequal distribution of resources will ultimately result in increased mortality, decreased fecundity, or both, resulting in population growth declining to, or below, carrying capacity

Question 6

what is fecundity?

Answer 6

the ability to produce an abundance of offspring or new growth; fertility

Question 7

what are the population characteristics?

Answer 7

size, density, distribution, sex ratio, density-dependent growth factors, density-independent growth factors

Question 8

what is population size?

Answer 8

the total number of individuals in a given area at a time

Question 9

what does a larger population size protect against?

Answer 9

a larger population is safer from population decline

Question 10

what is population density?

Answer 10

the number of individual per unit of area

Question 11

what is an example of population density?

Answer 11

12 panthers/km^2

Question 12

what are the risks of a high population density?

Answer 12

higher competition, higher possibility for disease outbreak, higher possibility of depleting food source

Question 13

what is population distribution?

Answer 13

how individuals in a population are spaced out compared to each other

Question 14

what are the three types of population distribution?

Answer 14

random (trees)
uniform (territorial animals)
clumped (herd/group animals)

Question 15

what is sex ratio in a population?

Answer 15

the ratio of males to females

Question 16

what is the ideal sex ratio? why?

Answer 16

the closer the sex ratio is to 50:50, usually the more ideal for breeding

Question 17

what are some causes of a skewed sex ratio?

Answer 17

die-off or a bottleneck event

Question 18

what is the effect of a skewed sex ratio?

Answer 18

having not enough females in a population limits population growth

Question 19

what are density-dependent growth factors?

Answer 19

factors that influence population growth based on the size of the population

Question 20

what are density-independent growth factors?

Answer 20

factors that influence population growth independent of the size of the population

Question 21

what are some examples of density-dependent factors? why are they density-dependent?

Answer 21

disease, competition for food, habitat, water, light
all of these things limit population growth based on their size (a small population doesn’t experience these things, but a large population does)

Question 22

what are some examples of density-independent factors? why are the density-independent?

Answer 22

natural disasters (flood, hurricane, tornado, fire)
it doesn’t matter how big or small a population is, natural disasters limit them both

Question 23

what is an example of food being a density dependent factor?

Answer 23

if twice as much food is added to a dish of two species of bacteria, both species’ carrying capacity increased by twice the amount
(food is also a limiting resource)

Question 24

what is biotic potential?

Answer 24

maximum potential growth rate, with no limiting resources

Question 25

what type of growth is biotic potential?

Answer 25

exponential growth bc there are initially no limiting resources

Question 26

what is logistic growth?

Answer 26

initial rapid growth, then limiting factors (competition) limit population to K

Question 27

what is the formula for calculating population size?

Answer 27

population size = (immigrations + births) - (emigration + deaths)

Question 28

what inputs increase population size?

Answer 28

immigrations and births

Question 29

what outputs decrease population size?

Answer 29

emigration and deaths