Populations

Question 1

What is a hypothesis?

Answer 1

A hypothesis is a proposed explanation for something that researchers have observed.

Question 2

What is a prediction?

Answer 2

A prediction is a statement of an outcome that should occur if a hypothesis is correct.

Question 3

What is the treatment group?

Answer 3

The treatment group a group that experiences experimental conditions that conform to the mechanism proposed in the hypothesis

Question 4

What is the control group?

Answer 4

The control group a group that represents the normal or no-treatment condition

Question 5

What are controlled conditions?

Answer 5

Aspects of an experimental design that are used in both control group and experimental treatments to eliminate bias among treatments and reduce influence from confounding factors.

Question 6

What is population?

Answer 6

A group of individuals of the same single
species that live in the same region at the same time and interact
with each other via competition, cooperation, and
sexual reproduction

Question 7

What is the outcome variable?

Answer 7

The outcome variable is the quantity relevant to the hypothesis being tested that is measured.

Question 8

What is a time series?

Answer 8

A sequence of data points collected over time to study and analyze population size.

Question 9

What is limiting factors?

Answer 9

In ecology, limiting factors are elements of an environment that restrict the population size or growth of an organism, ultimately determining the habitat’s carrying capacity.

Question 10

What is carrying capacity?

Answer 10

In ecology, carrying capacity is the maximum population size of a given species that an ecosystem can sustain for an unlimited amount of time, based on the availability of essential resources like food, water, and habitat.

Question 11

Exponential or geometric growth occur when ……

Answer 11

a population grows at a certain rate, with no limiting factors

Question 12

What is unlimited growth?

Answer 12

In ecology, “unlimited growth” refers to the hypothetical exponential growth of a population when its habitat provides an unlimited supply of resources, allowing its size to increase at an ever-accelerating rate.

Question 13

The pattern of unlimited growth graph is often shown as a …

Answer 13

This pattern is often shown as a J-shaped curve and occurs only in ideal environments without any limiting factors.

Question 14

Why is unlimited growth graph often useful?

Answer 14

It is a useful concept for understanding how populations would grow in the absence of environmental constraints.

Question 15

We can model unlimited growth using the …..

Answer 15

exponential model or the geometric model.

Question 16

Multiplicative growth is…

Answer 16

The larger the population becomes, the faster it grows

Question 17

Geometric growth involves …

Answer 17

reproduction at (discrete) regular time intervals.

Question 18

𝑁𝑡 for geometric is…

Answer 18

the population size at time t

Question 19

𝑁0 for geometric is..

Answer 19

is the initial population size at time 0

Question 20

λ for geometric is ….

Answer 20

the finite rate of increase

Question 21

t for geometric is …

Answer 21

the number of time intervals

Question 22

The finite rate of increase indicates …, while the magnitude of the finite rate of increase determines…

Answer 22

whether a population is growing, declining, or at equilibrium. how quick a population is growing or declining.

Question 23

No change when in finite rate of increase when…

Answer 23

𝑁𝑡 = 𝑁0

Question 24

𝜆 > 1 →
𝜆 < 1 →
𝜆 = 1 →

Answer 24

growth
decline
equilibrium

Question 25

Larger values of 𝜆 means.... and smaller values of 𝜆 means...

Answer 25

faster growth, slower growth

Question 26

Continuous exponential growth involves ....

Answer 26

continuous reproduction

Question 27

Difference between geometric vs exponential

Answer 27

Geometric is where we need to calculate at a certain time period or at the regular intervals and you look at it in discrete steps (separate breeding seasons like insects ). Exponential on the other hand is where we can calculate growth for any time period and it not like discrete (so like humans, bacteria - continuous reproduction).

Question 28

Population increases by

Answer 28

an exponent 𝑟

Question 29

The instantaneous rate of increase indicates whether a ...

Answer 29

population is growing, declining, or in equilibrium.

Question 30

The magnitude of the instantaneous rate of increase determines ...

Answer 30

how quick a population is growing or declining.

Question 31

Larger values of 𝑟 ➢ Smaller values of 𝑟 ➢

Answer 31

Larger values of 𝑟 ➢faster growth Smaller values of 𝑟 ➢slower growth

Question 32

𝑟 > 0 → 𝑟 < 0 → 𝑟 = 0 →

Answer 32

𝑟 > 0 → growth 𝑟 < 0 → decline 𝑟 = 0 → equilibrium

Question 33

Exponential versus geometric growth, list the similarities

Answer 33

Similarities *no limiting factors * Both involve some rate of increase

Question 34

Exponential versus geometric growth, list the differences

Answer 34

Differences * Geometric growth is discrete, exponential growth is continuous * Geometric growth * “finite” - 𝜆 * Exponential growth * “instantaneous” - 𝑟

Question 35

Can exponential growth continue forever?

Answer 35

Nope, because in reality, resources are limited.

Question 36

Most populations have growth limits! Logistic growth occurs ....

Answer 36

when a population grows at a decreasing rate as it approaches carrying capacity

Question 37

In any given environment, a population typically has ...

Answer 37

a carrying capacity

Question 38

What is carrying capacity determined by?

Answer 38

The resources available in that environment * e.g., food, water, and habitat

Question 39

What is the inflection point on a graph?

Answer 39

The point of the fastest growth after which growth begins to slow down.

Question 40

Population growth is usually constrained by ....

Answer 40

density dependence

Question 41

What is density dependence?

Answer 41

the growth, mortality, or other vital rates of a population are influenced by that population’s density or size OR how crowded a population is, affects how fast it grows, how many die, and other important things for the population.

Question 42

Shortcut to remember density dependence?

Answer 42

“The more crowded, the harder it is to survive and grow.”

Question 43

Why does density dependence often happen?

Answer 43

Often because of biotic factors that limit population growth * e.g., limited resources, predation, and disease.

Question 44

Examples of to why density dependence happens

Answer 44

Limited resources: More animals = less food per animal. Predation: Predators might focus more on areas where prey are crowded. Disease: Illness spreads more easily when individuals are packed close together.

Question 45

Numerous factors can constraint growth, what are some of them?

Answer 45

Biotic Factors * Competition, predation, parasitism and disease Abiotic Factors * Temperature, precipitation, sunlight, pH

Question 46

At higher population densities, there is very often increased intraspecific competition. What is intraspecific competition? Example?

Answer 46

Intraspecific competition is when members WITHIN the same species compete with each other for things they need, like food, water, or space. Example: Many deer in one forest fighting for the same food.

Question 47

Populations grow rapidly at first, but growth is eventually constrained by...

Answer 47

by density dependence.