Ecology Exam 2 Questions

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78 Terms

1
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What is the density-dependent growth model?

It describes how population growth rates are influenced by population density.

2
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What equation represents unrestricted growth?

dN/dt = rN.

3
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Define 'Carrying Capacity' (K).

The maximum population size that the environment can sustain.

4
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What occurs at the carrying capacity, K?

Population growth rate (r) becomes zero.

5
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What is the intrinsic growth rate represented by in equations?

r.

6
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How does a continuous-limited environment differ from a continuous-unlimited environment?

Continuous-limited takes into account carrying capacity, while continuous-unlimited does not.

7
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What does the term 'logistic growth' refer to?

Population growth that initially is exponential but slows as the population reaches carrying capacity.

8
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What impact does density-dependent competition have on population growth?

It can limit resources, decreasing growth rate as population density increases.

9
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What is a life table?

A table that shows the survival and reproductive rates of individuals of different ages in a population.

10
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What is meant by net reproductive rate (R0)?

The expected number of offspring produced by an average female over her lifetime.

11
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Define 'generation time' (T).

The average period between the birth of an individual and the birth of its offspring.

12
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What does λ represent in population studies?

The finite rate of population increase; λ > 1 means growing, λ = 1 stable, λ < 1 declining.

13
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What is the significance of the inflection point in population growth?

It is where the rate of population growth is at its maximum.

14
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What assumptions are made in logistic growth models?

No immigration/emigration, constant environmental conditions, no time lags, and linear relationships between birth and death rates.

15
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What is the difference between 'r' and 'K' selection?

'r' selection prioritizes high growth rates in unstable environments, while 'K' selection focuses on stable environments near carrying capacity.

16
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What is the role of predators in ecological systems?

They can control prey populations, affecting the structure and dynamics of communities.

17
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Define exploitative competition.

When one species limits the availability of resources for another species.

18
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What is interference competition?

Direct interaction between species, such as fighting or chemical warfare, influencing resource availability.

19
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What is Gause's Competitive Exclusion Principle?

Two species competing for the same resource cannot coexist indefinitely.

20
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What does the Lotka-Volterra model describe?

The interactions between predator and prey populations.

21
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What are 'Zero Net Growth Isoclines' (ZNGIs)?

The resource levels at which a species neither increases nor decreases in population.

22
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How does apparent competition differ from true competition?

It occurs when two species indirectly affect each other's population through a shared predator.

23
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What is meant by bottom-up control in ecosystems?

When primary producers limit the population sizes of higher trophic levels.

24
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What is a keystone species?

A species that has a disproportionate impact on its environment relative to its abundance.

25
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What are traits of mutualisms?

Interactions where both species benefit, ranging from facultative to obligate relationships.

26
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Define amenity value of biodiversity.

The intrinsic value that biodiversity provides in maintaining ecosystem functions.

27
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What is the significance of interactions in community ecology?

They explain how species coexist, impact population dynamics, and affect community structure.

28
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Explain the term 'trophic cascade.'

An ecological phenomenon triggered by the addition or removal of top predators.

29
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What is direct effect in interspecific interactions?

When two species interact without involving intermediate species.

30
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Describe indirect effects in ecological interactions.

When interactions between two species involve one or more intermediate species.

31
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What are dominant species in an ecological community?

Species that are most abundant or have the highest biomass.

32
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How do food webs differ from food chains?

Food webs depict multiple feeding relationships and energy flows, while chains depict a single linear path.

33
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What role do microbes play in ecosystems?

They help decompose organic matter and recycle nutrients.

34
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What is resource partitioning?

The division of limited resources by species to help avoid competition.

35
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Explain the concept of community structure.

The composition and organization of species within an ecological community.

36
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What effect do invasive species have on local ecosystems?

They can disrupt local species interactions and dynamics, often leading to declines of native species.

37
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How do stable isotopes help in ecological studies?

They provide information about diet and trophic levels based on the carbon and nitrogen ratios.

38
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What is mutualism?

A type of interaction where both species derive benefit from the relationship.

39
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What defines a community in ecology?

An assemblage of populations of different species in a specific area that interact.

40
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What is the role of decomposers in the ecosystem?

They break down dead organic matter, recycling nutrients back into the ecosystem.

41
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Explain the concept of a guild in ecology.

A group of species in a community that exploit the same resources in a similar manner.

42
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What are foundational species?

Species that have a strong role in structuring a community.

43
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What contributes to the diversity of an ecosystem?

The variety of species and their interactions within the community.

44
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What are density-dependent growth models?

Models that consider factors affecting population growth related to population density.

45
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What does the Logistic Equation assume regarding immigration/emigration?

It assumes no immigration or emigration occurs.

dP/dt = rP(1 - P/K), models population growth where 'P' is the population size, 'r' is the intrinsic growth rate, and 'K' is the carrying capacity.

46
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What characterizes r-selected species?

They maximize intrinsic growth rate, have low carrying capacity, and prioritize quantity over quality in offspring.

47
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What is a key strategy of K-selected species?

They invest in parental care, have a lower birth rate, and maintain populations near carrying capacity.

48
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Define Fecundity.

The number of offspring produced per reproductive event.

49
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How do death/mortality rates and fecundity vary?

They vary with age, within and across species.

50
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What can age-tables be used for?

To calculate accurate growth rates and population sizes.

51
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What does Generation Time (T) represent?

The average age at which a female gives birth to offspring.

52
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What occurs if a matrix for population remains constant over time?

The percentage of organisms at different life stages will remain constant.

53
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What is exploitation in ecological terms?

Interaction where one species benefits at the expense of another, such as parasitism.

54
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What is the role of predators in ecosystems?

They limit prey abundance through consumption.

55
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How can human intervention affect unchecked non-native species?

It can help control their growth when they lack natural predators.

56
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Define predator-prey dynamic cycling.

Oscillations in predator and prey populations that can occur over time.

57
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What happens to prey populations when predator populations increase?

Prey populations typically decrease due to increased predation.

58
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What is the R* model in competition?

It indicates the resource concentration level at which consumers maintain no net growth.

59
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What happens when two species cannot coexist due to competition?

The species with the lowest R* value for a resource will outcompete the other.

60
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What are diatoms and how do they affect the ecosystem?

Silica-using algae that grow until carrying capacity (K) of silica is reached.

61
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What is the significance of resource supply points in competition?

They represent stable resource levels when inputs and losses are balanced.

62
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Describe the concept of zero net growth isocline.

The resource level where a species' population remains stable.

63
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What is competitive exclusion?

The principle that two species competing for the same resource cannot coexist indefinitely.

64
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What is character displacement?

Differentiation of similar species to minimize competition in overlapping niches.

65
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What is mutualism?

A symbiotic relationship where both species benefit.

66
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What is commensalism?

A relationship where one species benefits and the other is unaffected.

67
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Name an example of facultative mutualism.

Where species can survive without their mutualistic partners.

68
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What are keystone species?

Species that have a disproportionately large effect on their environment.

69
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What do food webs illustrate?

The complex interactions of different species in an ecosystem beyond just food chains.

70
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What are the main methods of determining food webs?

Observational studies, gut content analysis, and stable isotope analysis.

71
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What is a trophic cascade?

An indirect effect in an ecosystem where changes in one population affect multiple other populations.

72
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What implications do disturbances have on predator-prey dynamics?

They can lead to population declines or shifts in community structure.

73
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What is the significance of parasites in food webs?

They are crucial for maintaining healthy ecosystems and biodiversity.

74
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What type of species are often found to outcompete others in regards to resource availability?

Species that can utilize resources more efficiently than their competitors.

75
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What does an increase in primary production lead to in food chains?

It stimulates growth and stability in various trophic levels.

76
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Define apparent competition.

A scenario where two species negatively affect each other indirectly through a shared predator.

77
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What is the impact of resource overlap between two competing species?

It can lead to diminished resources for one or both species, facilitating competitive outcomes.

78
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What is the difference between a fundamental niche and a realized niche?

A fundamental niche is the potential ecological role a species could occupy, while a realized niche is the actual role it plays, considering competition and other factors.