Community Ecology Quiz
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Questions and Answers

What type of interaction occurs when two species compete for the same limited resource?

  • Mutualism
  • Exploitation
  • Cooperation
  • Competition (correct)

Which of the following is NOT a type of interspecific interaction?

  • Exploitation
  • Positive interaction
  • Intraspecific competition (correct)
  • Competition

In the context of community ecology, what does interspecific competition result in?

  • Decreased population of one or both species (correct)
  • Increased resources for all species
  • Enhanced reproductive success for both species
  • Ongoing cooperation between species

Which of the following best describes the term 'community' in ecology?

<p>Different species potentially interacting in an area (A)</p> Signup and view all the answers

What is the primary focus of community ecology?

<p>Interactions and relationships among various species (D)</p> Signup and view all the answers

What does the variable $N_0$ represent in community ecology?

<p>Initial population size (C)</p> Signup and view all the answers

Which equation represents the relationship involving births in population ecology?

<p>$N = N_0 + B$ (A)</p> Signup and view all the answers

In which scenario would a discrete model of population growth be appropriate?

<p>Species with distinct breeding seasons (A)</p> Signup and view all the answers

What does the term 'intrinsic rate of increase' refer to?

<p>The maximum rate a population could grow under ideal conditions (A)</p> Signup and view all the answers

Which of the following correctly describes the model involving parental generation?

<p>It relates the progeny to the previous generation's size. (D)</p> Signup and view all the answers

What happens during competitive exclusion?

<p>One species becomes locally extinct due to competition. (A)</p> Signup and view all the answers

What is meant by resource partitioning?

<p>Species adapt to occupy different ecological niches. (D)</p> Signup and view all the answers

What defines the fundamental niche of an organism?

<p>The potential role an organism could occupy under ideal conditions. (D)</p> Signup and view all the answers

What results from character displacement?

<p>Closely related species diversify to reduce competition. (B)</p> Signup and view all the answers

What does the realized niche refer to?

<p>The actual conditions and resources used by an organism. (C)</p> Signup and view all the answers

What is the primary purpose of cryptic coloration in prey species?

<p>To camouflage themselves and avoid predation (A)</p> Signup and view all the answers

What is the difference between Batesian and Mullerian mimicry?

<p>Batesian mimicry involves a non-toxic species that resembles a toxic one, while Mullerian mimicry involves two toxic species resembling each other. (B)</p> Signup and view all the answers

Which of the following statements about mimicry is true?

<p>Mimicry can help both dangerous and non-dangerous species survive. (B)</p> Signup and view all the answers

How does mimicry potentially benefit non-toxic species?

<p>By causing predators to avoid them due to perceived toxicity (D)</p> Signup and view all the answers

What does the term 'advertise bad taste/toxicity' refer to in the context of animal defense strategies?

<p>These animals signal to predators that they are harmful or unpalatable. (C)</p> Signup and view all the answers

What is a characteristic of ectoparasites?

<p>They live outside the host. (D)</p> Signup and view all the answers

Which interaction type benefits both species involved?

<p>Mutualism (C)</p> Signup and view all the answers

What does the Shannon diversity index measure?

<p>Species richness and relative abundance (B)</p> Signup and view all the answers

How do trophic levels relate to energy flow in an ecosystem?

<p>They group organisms that access energy similarly. (A)</p> Signup and view all the answers

What limits the length of food chains in communities?

<p>Energy inefficiency transfer between trophic levels. (A)</p> Signup and view all the answers

Which type of ecological succession is characterized by the growth of a community from bare rock?

<p>Primary succession (D)</p> Signup and view all the answers

In what way can keystone species influence community structure?

<p>By having a disproportionate impact on ecosystem dynamics. (B)</p> Signup and view all the answers

What is an example of a positive interaction where one species benefits without affecting the other?

<p>Commensalism (B)</p> Signup and view all the answers

What type of consumers are tertiary consumers in an ecosystem?

<p>Predators of secondary consumers (A)</p> Signup and view all the answers

Which of the following is a type of disturbance that can impact communities?

<p>Natural events like fires and floods (D)</p> Signup and view all the answers

Which of the following statements about mutualism is true?

<p>Both partners benefit but incur some costs. (D)</p> Signup and view all the answers

What distinguishes primary consumers from other trophic levels?

<p>They consume primary producers. (B)</p> Signup and view all the answers

What is a key benefit of having a highly diverse community?

<p>Greater resilience to disturbances (D)</p> Signup and view all the answers

What role do predators play in maintaining healthy populations?

<p>They help to remove sick and weak individuals from the population. (C)</p> Signup and view all the answers

Which of the following options describes an exploitation relationship?

<p>An interaction where one species is harmed while the other benefits. (B)</p> Signup and view all the answers

How does natural selection relate to predation?

<p>Predation drives significant amounts of evolution via natural selection. (C)</p> Signup and view all the answers

What is one major evolutionary response to predation that prey species exhibit?

<p>Aposematic coloration. (D)</p> Signup and view all the answers

What can be a consequence of predator-prey interactions on population dynamics?

<p>Prevention of overpopulation and overexploitation of resources. (D)</p> Signup and view all the answers

In what way can competition among barnacles affect their realized niche?

<p>It leads to a smaller realized niche due to competitive exclusion. (B)</p> Signup and view all the answers

What is an 'arms race' in the context of predator-prey interactions?

<p>An evolutionary struggle where predators and prey develop adaptations against each other. (B)</p> Signup and view all the answers

Why are predators often perceived negatively despite their ecological benefits?

<p>They are often associated with destruction and harm. (D)</p> Signup and view all the answers

What occurs when two species shift to avoid direct competition?

<p>Resource partitioning (B)</p> Signup and view all the answers

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

<p>The fundamental niche represents potential roles, while the realized niche is the actual role. (C)</p> Signup and view all the answers

What phenomenon occurs when closely related species diversify to minimize competition?

<p>Character displacement (D)</p> Signup and view all the answers

Which of the following best describes the disadvantages for the winner in a competitive interaction?

<p>Risk of self-harm and energy expenditure (D)</p> Signup and view all the answers

What is a potential consequence of competitive exclusion on species diversity?

<p>Reduction of one species leading to diversity loss (B)</p> Signup and view all the answers

What impact does competition have on species trying to access limited resources?

<p>It leads to negative effects on both species involved. (A)</p> Signup and view all the answers

Which statement accurately describes interspecific competition?

<p>It can result in resource partitioning. (C)</p> Signup and view all the answers

In a community, what is the primary resource that species compete for?

<p>Limited resources such as food. (C)</p> Signup and view all the answers

How can intra-specific competition manifest among individuals of the same species?

<p>By fighting over territory. (D)</p> Signup and view all the answers

What distinguishes competition from exploitation in ecological interactions?

<p>Competition occurs over resources, whereas exploitation involves direct consumption. (B)</p> Signup and view all the answers

What does the variable $N_p$ signify in population ecology?

<p>Number of individuals currently in the population (A)</p> Signup and view all the answers

Which equation best describes the model for discrete population growth?

<p>$N_t = N_0 imes (1 + r)^t$ (A)</p> Signup and view all the answers

Which aspect describes intrinsic rate of increase correctly?

<p>Rate of population growth under ideal conditions (A)</p> Signup and view all the answers

What best characterizes continuous population growth in ecological models?

<p>Births and deaths occur at different times throughout the year (C)</p> Signup and view all the answers

In community ecology, what happens when overlapping of discrete and continuous growth occurs?

<p>Populations may face higher competition for resources (B)</p> Signup and view all the answers

What is the primary function of cryptic coloration in prey species?

<p>To blend into the environment and avoid detection (B)</p> Signup and view all the answers

Which type of mimicry involves a harmless species mimicking a harmful one?

<p>Batesian mimicry (A)</p> Signup and view all the answers

Which statement best describes Mullerian mimicry?

<p>It involves two harmful species that look similar, enhancing mutual protection (D)</p> Signup and view all the answers

What does the phrase 'advertise bad taste/toxicity' signify in animal defense mechanisms?

<p>It warns potential predators to avoid consumption (B)</p> Signup and view all the answers

How does mimicry benefit non-toxic species in the wild?

<p>By deceiving predators into avoiding them (C)</p> Signup and view all the answers

Which of the following statements best describes herbivory?

<p>It involves feeding on plants without necessarily being fatal. (D)</p> Signup and view all the answers

What is one primary role of chemical defenses in plants against herbivores?

<p>To deter herbivores through toxins or bitter compounds. (D)</p> Signup and view all the answers

Which of the following best exemplifies morphological defenses in plants?

<p>The presence of thorns, spines, or hairs on plants. (B)</p> Signup and view all the answers

What can be a result of the evolutionary arms race between plants and herbivores?

<p>A stunning degree of natural selection shaping adaptations. (B)</p> Signup and view all the answers

Which of the following is NOT an example of a plant defense mechanism?

<p>Changing environment through nutrient depletion. (A)</p> Signup and view all the answers

What characterizes endoparasites in comparison to ectoparasites?

<p>They usually develop more complex life cycles. (A)</p> Signup and view all the answers

What is one of the main functions of a keystone species in an ecological community?

<p>They enhance the structure and resilience of the community. (A)</p> Signup and view all the answers

In a food web, which term best describes the role of primary producers?

<p>They convert sunlight into usable energy. (B)</p> Signup and view all the answers

What is a characteristic feature of mutualistic interactions?

<p>Both species derive some level of benefit. (C)</p> Signup and view all the answers

What type of succession takes place when a community is regrowing after a disturbance that left the soil intact?

<p>Secondary succession (B)</p> Signup and view all the answers

What does the term 'species richness' refer to in an ecological community?

<p>The number of different species present in a community. (A)</p> Signup and view all the answers

Which of the following accurately describes the effect of disturbances on communities?

<p>They can create opportunities for ecological succession. (B)</p> Signup and view all the answers

Which statement best describes the relationship between trophic levels and energy transfer in an ecosystem?

<p>Energy diminishes as it moves up trophic levels due to inefficiencies. (A)</p> Signup and view all the answers

What defines a community's 'relative abundance'?

<p>The proportion of different species in a community. (B)</p> Signup and view all the answers

What is an example of a disturbance that could impact an ecological community?

<p>Human activities like deforestation (C)</p> Signup and view all the answers

How does the Shannon diversity index (H) function in community ecology?

<p>It assesses species diversity based on richness and evenness. (D)</p> Signup and view all the answers

What is the primary role of fungi in lichen partnerships?

<p>To supply structural support and moisture retention. (A)</p> Signup and view all the answers

Flashcards

Exponential Growth

Population growth where the rate of increase is proportional to the current population size.

Discrete Growth

Population growth in distinct time steps, like yearly.

Intrinsic Growth Rate (r)

The potential per-capita rate of increase of a population under ideal conditions.

Initial Population (No)

The starting number of individuals in a population, at a given moment.

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Population Change (ΔN)

The difference in size between two consecutive generations within a discrete time frame.

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Community Ecology

The study of how different species interact within a shared environment.

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Interspecific Interactions

Relationships between different species that can be competitive, exploitative, or positive.

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Competition (-/-)

When two or more species struggle for the same limited resource, like food, shelter, or mates, leading to a negative impact for both.

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Intraspecific Competition

Competition within the same species, like two birds fighting over a nesting site.

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Resource Limitation

The limited availability of essential resources, such as food, water, or space, that can drive competition between species.

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Competitive Exclusion

When two species compete for the same limited resource, one species will be out-competed and eliminated from the area, leading to local extinction.

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Resource Partitioning

Species avoid direct competition by specializing on different resources, their active times, or behaviors.

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Fundamental Niche

The full range of resources and conditions a species can potentially utilize or tolerate.

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Realized Niche

The actual range of resources and conditions a species uses in a particular environment, after considering interactions with other species.

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Character Displacement

When closely related species evolve distinct traits (physical or behavioral) to reduce competition, often as a result of sympatric speciation.

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Predation

A relationship where one organism (the predator) hunts and consumes another organism (the prey).

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Predation Timing

Predators can hunt at different times of the day (day/night) to avoid competition or exploit prey vulnerability.

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Exploitation (+/-)

A relationship where one species benefits by consuming another species, often leading to harm for the consumed species.

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Predation's Impact on Evolution

Predation drives natural selection, leading to the evolution of adaptations in both predators and prey.

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Predation Benefits

Predation can benefit ecosystems by removing weak individuals, preventing overpopulation, and promoting biodiversity.

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Aposematic Coloration

Bright, contrasting colors or patterns used by animals to warn predators of their toxicity or defense mechanisms.

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Cryptic Coloration

A type of camouflage where an animal's coloring helps it blend into its surroundings, making it harder for predators to spot them.

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Mimicry

An evolutionary adaptation where one species evolves to resemble another species, often for protection or to gain an advantage.

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Batesian Mimicry

A type of mimicry where a harmless species mimics a dangerous or poisonous species, gaining protection from predators.

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Mullerian Mimicry

A type of mimicry where two or more poisonous or dangerous species evolve to resemble each other, benefiting both by increasing the chances of predators learning to avoid them.

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Parasitism

A relationship where one organism (parasite) benefits by feeding off another organism (host) while keeping the host alive.

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Ectoparasites

Parasites that live on the outside of their host.

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Endoparasites

Parasites that live inside their host.

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Mutualism

A relationship where both interacting species benefit.

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Commensalism

A relationship where one species benefits and the other is neither harmed nor helped.

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Species Diversity

The variety of organisms in a community.

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Species Richness

The number of different species in a community.

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Relative Abundance

The proportion of each species in a community.

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Food Web

A visual representation of feeding relationships between trophic levels.

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Trophic Level

A grouping of organisms that obtain energy at the same number of steps away from the original source (the sun).

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Primary Producers

Autotrophs (plants and algae) that produce their own food through photosynthesis.

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Primary Consumers

Herbivores that eat primary producers.

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Keystone Species

A species that has a disproportionately large impact on the structure and function of a community.

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Ecosystem Engineer

A species that significantly modifies the physical environment around them.

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Disturbance

An event that changes a community by removing organisms and/or altering resource availability.

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What is exponential growth?

A pattern of population growth where the rate of increase is proportional to the current population size. It's like a snowball rolling downhill, getting bigger and faster.

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What is a community?

A group of different species living together in a specific area, interacting with each other and their environment.

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Positive Interactions

Relationships where at least one species benefits, and neither is harmed.

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Herbivory

A type of feeding relationship where an organism consumes plants, often without killing them. This feeding can have a significant impact on the evolution of both the plant and the herbivore.

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Plant Defenses

Plants have developed various strategies to protect themselves from herbivores. These adaptations can be chemical, physical, or both.

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Chemical Defenses

Some plants produce toxic or bitter compounds to deter herbivores. Examples include caffeine, strychnine, and opiates.

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Morphological Defenses

Plants can also have physical features that make them difficult to eat for herbivores. These include thorns, spines, hairs, and tough, indigestible compounds.

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Evolutionary Arms Race

The constant back-and-forth adaptation between herbivores and plants, as each species evolves to overcome the other's defenses. This process leads to a remarkable diversity of adaptations in both groups.

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Study Notes

Community Ecology

  • Community: a collection of different species, living and potentially interacting in a specific area
  • Interspecific interactions: interactions between different species
  • Intraspecific interactions: interactions within the same species

Exponential Growth

  • Discrete with overlap: new births added to previous generation; parents reproduce
  • Discrete with no overlap: new births after parental generation dies
  • Continuous: no time separation between generations
    • Exponential Growth equation: Nt = N0ert
      • Nt = population size at time t
      • N0 = initial population size
      • r = intrinsic rate of increase
      • t = time

Competition (-/-)

  • Two or more species compete for the same limited resource(s) -- food, shelter, territory, etc.
  • Competitive exclusion: one species is outcompeted and becomes locally extinct
  • Resource partitioning: species shift to avoid direct competition

Competition Continued

  • Fundamental niche: the ideal space an organism can occupy based on its needs, resources and adaptations
  • Realized niche: the actual space an organism occupies due to competition and other limiting factors
  • Character displacement: closely related species diverge to avoid direct competition
    • can lead to new species
  • Species diversify to avoid competition

Exploitation (+/-)

  • Relationship where one species consumes some or all of another
  • Predation, herbivory, and parasitism
  • Impacts of predators
    • Removing sick or weak individuals
    • Preventing overpopulation
    • Maintains healthy population

Predation Effects

  • Aposematic coloration: warning colors to advertise bad taste or toxicity
  • Cryptic coloration: camouflaging to hide from predators
  • Mimicry: resembling another species
    • Batesian mimicry: harmless species resembles a harmful species
    • Müllerian mimicry: two or more harmful species resemble one another

Herbivory

  • Feeding on plants; doesn't always need to kill the plant
  • Results in natural selection among plants due to evolutionary arms races
  • Plants defend themselves against herbivores through chemical or morphological adaptations
  • Chemical defenses: toxins, bitter compounds (e.g., caffeine, strychnine, opiates)
  • Morphological defenses: thorns, spines, hairs, difficult to digest compounds (e.g., silica in plants can shred animal guts)

Parasitism

  • Feeding on a host while it remains alive
  • Ectoparasites: live outside host
  • Endoparasites: live inside host
  • Impacts of parasites
    • Often leads to adaptations for complex life cycles and multiple hosts
    • Often leads to significant physical adaptations
    • Impacts food chains

Positive Interactions (+/+ or +/0)

  • Mutualism (+/+): both species benefit from interaction
  • Commensalism (+/0): one species benefits, the other is unaffected

Community Structure

  • Species diversity: the variety of organisms making up a community
    • Species richness: the number of different species
    • Relative abundance: proportions of different species
  • Shannon diversity index (H): a measure of diversity; a higher value indicates a more diverse community

Community Roles

  • Food web: visual representation of feeding relationships
  • Trophic level: grouping of organisms that access energy at the same number of steps from the original energy source (sun)

Trophic levels

  • Primary producers (autotrophs)
  • Primary Consumers (herbivores)
  • Secondary Consumers (predators that eat herbivores)
  • Tertiary Consumers (predators that eat secondary consumers)
  • Quaternary Consumers (predators that eat tertiary consumers)

Limits to Food Chain Length

  • Inefficient energy transfer between trophic levels limits the number of steps/levels in a food chain
  • Fewer carnivores than herbivores at higher trophic levels
  • Expressed as a comparison of biomass (total mass of all organisms)

Community Control

  • Keystone species/ecosystem engineers have disproportionate impacts
  • Community complexity: resilient communities tolerate invasive species and removals better than less diverse communities

Disturbance and Succession

  • Disturbance: events that change communities by removing organisms or altering resource availability
    • Fires, floods, droughts
  • Succession: recovery process following disturbance
    • Primary succession: from scratch
    • Secondary succession: re-growing community

Disturbance Isn't Necessarily Bad

  • Intermediate Disturbance Hypothesis: moderate disturbances lead to more diversity

Other Factors Influencing Communities

  • Humans: biomes/productivity, size, isolation
  • Pathogens: can heavily impact community composition
  • Island equilibrium model: island size, isolation control immigration and extinction rates

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