3.7 Populations in ecosystems

Question 1

What is a population?

Answer 1

Group of organisms of the same species living in the same habitat.

Populations are essential for studying ecology and evolution.

Question 2

Define habitat.

Answer 2

Part of an ecosystem in which particular organisms live.

Habitats can vary greatly in size and conditions.

Question 3

What is a community in ecological terms?

Answer 3

All the populations of different species in the same area at the same time.

Communities are composed of various interacting species.

Question 4

Define ecosystem.

Answer 4

A community and the non-living components of an environment (the biotic and abiotic factors). Ecosystems can range in size from the very small to the very large.

Ecosystems include interactions between living organisms and their environment.

Question 5

What is a niche?

Answer 5

An organism’s role within an ecosystem, including their position in the food web and habitat.

Each species occupies their own niche governed by adaptation to both abiotic and biotic conditions.

Question 6

What does carrying capacity refer to?

Answer 6

The maximum population size an ecosystem can support.

Carrying capacity is influenced by various environmental factors.

Question 7

Define abiotic factors.

Answer 7

Non-living conditions of an ecosystem.

Examples include temperature, light, and soil conditions.

Question 8

What are biotic factors?

Answer 8

Impact of the interactions between organisms.

Biotic factors include competition, predation, and symbiosis.

Question 9

List factors that determine the carrying capacity of a population.

Answer 9

• Abiotic factors
• Biotic factors (interspecific competition and intraspecific competition)

These factors work together to limit population sizes.

Question 10

How do abiotic factors affect population sizes?

Answer 10

Abiotic factors can affect the size of different populations, ranging from temperature to soil conditions.

Organisms are adapted to specific abiotic conditions in their environment.

Question 11

Fill in the blank: The less harsh the abiotic factors (plenty of water and light), the _______.

Answer 11

larger the range of species and the larger the population sizes.

This indicates the importance of favorable conditions in supporting biodiversity.

Question 12

What is a population?

Answer 12

Group of organisms of the same species living in the same habitat.

Populations are essential for studying ecology and evolution.

Question 13

Define habitat.

Answer 13

Part of an ecosystem in which particular organisms live.

Habitats can vary greatly in size and conditions.

Question 14

What is a community in ecological terms?

Answer 14

All the populations of different species in the same area at the same time.

Communities are composed of various interacting species.

Question 15

Define ecosystem.

Answer 15

A community and the non-living components of an environment (the biotic and abiotic factors). Ecosystems can range in size from the very small to the very large.

Ecosystems include interactions between living organisms and their environment.

Question 16

What is a niche?

Answer 16

An organism’s role within an ecosystem, including their position in the food web and habitat.

Each species occupies their own niche governed by adaptation to both abiotic and biotic conditions.

Question 17

What does carrying capacity refer to?

Answer 17

The maximum population size an ecosystem can support.

Carrying capacity is influenced by various environmental factors.

Question 18

Define abiotic factors.

Answer 18

Non-living conditions of an ecosystem.

Examples include temperature, light, and soil conditions.

Question 19

What are biotic factors?

Answer 19

Impact of the interactions between organisms.

Biotic factors include competition, predation, and symbiosis.

Question 20

List factors that determine the carrying capacity of a population.

Answer 20

• Abiotic factors
• Biotic factors (interspecific competition and intraspecific competition)

These factors work together to limit population sizes.

Question 21

How do abiotic factors affect population sizes?

Answer 21

Abiotic factors can affect the size of different populations, ranging from temperature to soil conditions.

Organisms are adapted to specific abiotic conditions in their environment.

Question 22

Fill in the blank: The less harsh the abiotic factors (plenty of water and light), the _______.

Answer 22

larger the range of species and the larger the population sizes.

This indicates the importance of favorable conditions in supporting biodiversity.

Question 23

What are biotic factors?

Answer 23

Interactions between the living components of an ecosystem, such as interspecific and intraspecific competition and predation.

Biotic factors influence the dynamics of populations and ecosystems.

Question 24

Define interspecific competition.

Answer 24

Competition between members of different species for the same limited resource, such as habitat, food, or water.

The individual better adapted to the environment is more likely to succeed in interspecific competition.

Question 25

Define intraspecific competition.

Answer 25

Competition between members of the same species for resources and a mate. ## Footnote The success in intraspecific competition depends on which organism is better adapted to the environment.

Question 26

What role does courtship play in intraspecific competition?

Answer 26

Courtship rituals are linked to competition for a mate, where fitter individuals may perform better rituals to attract mates. ## Footnote Fitter individuals may have more energy and better physical condition, such as fur or feathers, to succeed in courtship.

Question 27

What is represented in a predator-prey dynamics graph?

Answer 27

The interaction between predator and prey populations over time, showing fluctuations in their sizes. ## Footnote Typically, there are more prey than predators, and changes in prey population size precede changes in predator population size.

Question 28

True or False: In predator-prey dynamics, predator population size always changes before prey population size.

Answer 28

False. ## Footnote The prey population size changes first, followed by a lag period before the predator population changes.

Question 29

What is the general pattern observed in predator-prey population sizes?

Answer 29

Both predator and prey populations fluctuate, with prey populations typically larger than predator populations. ## Footnote This pattern is consistent across different species.

Question 30

Fill in the blank: Interspecific competition involves members of _______ species competing for the same resources.

Answer 30

[different] ## Footnote This competition can occur in various ecosystems and affects species interactions.

Question 31

Fill in the blank: Intraspecific competition involves members of _______ species competing for resources.

Answer 31

[the same] ## Footnote This type of competition can influence evolutionary adaptations within a species.

Question 32

What is the purpose of sampling in ecology?

Answer 32

To measure the impact of changing environments and to protect plants and animals

Question 33

Why is it impractical to count every individual in a population?

Answer 33

It would be too time-consuming and inaccurate

Question 34

What is a key requirement for sampling to provide an accurate estimate?

Answer 34

Many samples (30+ ideally) should be taken and sampling should be random to avoid bias

Question 35

What method should be used to sample slow-moving or non-motile organisms?

Answer 35

Sample using a quadrat

Question 36

What is a quadrat typically sized at?

Answer 36

0.5m x 0.5m

Question 37

How can a random sample area be created?

Answer 37

Using two 20m tape measures at right angles to create a gridded area

Question 38

What tool can be used to generate random coordinates for sampling?

Answer 38

A random number generator, such as a calculator

Question 39

What should be counted or estimated when using a quadrat?

Answer 39

The number of the species being sampled or a percentage cover

Question 40

How many times should sampling be repeated to provide a representative estimate?

Answer 40

At least 30 times

Question 41

Fill in the blank: To avoid bias in sampling, it should be _______.

Answer 41

random

Question 42

True or False: A quadrat can be gridded or open.

Answer 42

True

Question 43

What method should be used to sample motile organisms?

Answer 43

Sample using the mark-release-recapture method

Question 44

What type of sampling is used for uneven distribution?

Answer 44

Line transect

Question 45

What is meant by 'representative estimate' in ecological sampling?

Answer 45

An estimate that accurately reflects the actual population size

Question 46

What is the main goal of estimating population size in ecology?

Answer 46

To understand and manage ecosystems effectively

Question 47

What is the mark-release-recapture method used for?

Answer 47

Estimating populations of motile organisms ## Footnote This method accounts for organisms that can move out of a quadrat.

Question 48

What must the markings used in the mark-release-recapture method be?

Answer 48

Non-toxic, all-weather resistant, and not impact reproduction or predation ## Footnote Ensures that marked individuals can survive and reproduce normally.

Question 49

What ethical considerations must be taken into account in the mark-release-recapture method?

Answer 49

No long-term harm and not increased risk of predation ## Footnote Ethical trapping and marking practices are crucial for animal welfare.

Question 50

What assumptions does the mark-release-recapture method make?

Answer 50

* Marked individuals distribute evenly in the population * No migration, births, or deaths during the study ## Footnote These assumptions are vital for accurate population estimates.

Question 51

List the steps in the mark-release-recapture method.

Answer 51

* Capture initial sample * Mark and release individuals * Allow time for random dispersion * Capture second sample * Record total captured and recaptured * Estimate population size ## Footnote Repeating the process increases reliability of results.

Question 52

Fill in the blank: The estimated total population is calculated using the formula: Estimated total population = _______.

Answer 52

number of organisms initially caught X number of organisms in second sample / number of marked organisms recaptured ## Footnote This formula allows for estimation based on captured samples.

Question 53

In the example provided, how many butterflies were initially caught and marked?

Answer 53

20 butterflies ## Footnote This initial sample is critical for the subsequent calculations.

Question 54

What was the total number of butterflies caught in the second sample?

Answer 54

22 butterflies ## Footnote This number is used along with recaptured marked individuals for estimating population.

Question 55

How many marked butterflies were recaptured in the second sample?

Answer 55

9 marked butterflies ## Footnote This number is essential for calculating the estimated total population.

Question 56

Using the example, what is the estimated total population of butterflies?

Answer 56

49 butterflies ## Footnote Calculation: (20 x 22) / 9 = 48.89, rounded to 49.

Question 57

What is succession in ecology?

Answer 57

Succession is the change in an ecological community over time. ## Footnote This process involves the gradual replacement of one community by another.

Question 58

What is primary succession?

Answer 58

A primary succession starts with a pioneer species colonising bare rock or sand. ## Footnote This occurs in lifeless areas where soil has not yet formed.

Question 59

What are pioneer species?

Answer 59

Pioneer species, such as lichen, are adapted to survive in harsh abiotic factors. ## Footnote They initiate the process of soil formation through their death and decomposition.

Question 60

What role do pioneer species play in primary succession?

Answer 60

They change the abiotic factors to become less harsh and form a thin layer of soil, humus. ## Footnote This allows for the survival of mosses and smaller plants.

Question 61

What is humus?

Answer 61

Humus is the organic component of soil formed by the decomposition of plant and animal matter. ## Footnote It enriches the soil, improving its nutrient content.

Question 62

How does biodiversity relate to succession?

Answer 62

Changes that organisms produce in their abiotic environment can result in a less hostile environment and increases biodiversity. ## Footnote Biodiversity refers to the variety of life in a particular habitat.

Question 63

What characterizes the climax community?

Answer 63

The final stage in a succession is known as the climax community, and this is dominated by trees. ## Footnote Climax communities are stable and mature ecosystems.

Question 64

What happens to existing species as new species colonize during succession?

Answer 64

Each existing species is outcompeted by a new species colonising. ## Footnote This dynamic can lead to significant changes in the community structure.

Question 65

Fill in the blank: The first stage of succession is characterized by _______.

Answer 65

pioneer species

Question 66

True or False: Primary succession can occur in an area where soil already exists.

Answer 66

False ## Footnote Primary succession occurs in areas without soil, unlike secondary succession.

Question 67

What are two types of succession?

Answer 67

* Primary succession * Secondary succession

Question 68

What is secondary succession?

Answer 68

A process where disruption occurs and plants are destroyed, but succession starts again with existing soil.

Question 69

What is a seral stage?

Answer 69

A stage in succession.

Question 70

What does species richness refer to?

Answer 70

The number of different species in a given area.

Question 71

Define biodiversity.

Answer 71

The variety of life in a particular habitat or ecosystem.

Question 72

What is the importance of conservation of habitats?

Answer 72

To prevent loss of food and space for organisms, which can lead to extinction.

Question 73

How can succession be managed?

Answer 73

By maintaining earlier stages in succession and preventing a climax community.

Question 74

What is the result of managing succession?

Answer 74

A greater variety of habitats and a greater range of species.

Question 75

True or False: Human activity can lead to habitat destruction.

Answer 75

True

Question 76

What conflict must be managed to maintain sustainability?

Answer 76

The conflict between human needs and conservation.

Question 77

Fill in the blank: The process of _______ occurs as species richness and the number of organisms increase.

Answer 77

succession

Question 78

What happens to food webs as larger plant species and animals colonize an area?

Answer 78

They become more complex.

Question 79

What can be done with forests to balance human needs and conservation?

Answer 79

Forests can be coppiced to provide timber while allowing trees to survive.

Question 80

What determines the carrying capacity of a population in an ecosystem?

Answer 80

Different effects of abiotic factors and biotic factors ## Footnote Abiotic factors include non-living elements like temperature and light, while biotic factors refer to living components like species interactions.

Question 81

How can population size be estimated?

Answer 81

Using random sampling with quadrats, belt transects with quadrats, and mark-release-recapture ## Footnote These methods help ecologists assess population sizes in various habitats.

Question 82

What is succession in the context of ecosystems?

Answer 82

The change in a community over time ## Footnote Succession can be primary or secondary, depending on the starting conditions.

Question 83

What links abiotic factors to photosynthesis and respiration?

Answer 83

Light energy for LDR and temperature for LIR and respiration ## Footnote LDR stands for Light Dependent Reactions, and LIR stands for Light Independent Reactions.

Question 84

What does succession link to in terms of ecosystem processes?

Answer 84

Nutrient cycles, biodiversity, and index of diversity ## Footnote Biodiversity refers to the variety of life in a particular habitat, and the index of diversity is a measure of that variety.