Ecology Chapter on Population Growth

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Questions and Answers

What is true about clumped population distribution?

  • It is characterized by populations clustering around resources. (correct)
  • It results from strong social interactions between individuals.
  • It occurs in environments with high resource availability.
  • It is the rarest distribution found in nature.

Which equation accurately represents population change?

  • ∆N = (b + i) – (d + e) (correct)
  • ∆N = (b + e) + (d + i)
  • ∆N = (d + e) – (b + i)
  • ∆N = N / (b + e)

What does biotic potential refer to?

  • The actual growth rate under natural conditions.
  • The growth rate limited by environmental factors.
  • The maximum growth rate under ideal conditions. (correct)
  • The minimum population growth rate expected.

Which type of population distribution is least common in nature?

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

What factor is NOT considered in an open population?

<p>Resource availability (A)</p> Signup and view all the answers

Which of the following contributes to uniform distribution in populations?

<p>Direct competition for resources (B)</p> Signup and view all the answers

What does the per capita growth rate formula calculate?

<p>The average growth of an individual in the population. (B)</p> Signup and view all the answers

Which of the following factors influences all open populations?

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

What is meant by the term 'carrying capacity' in ecological studies?

<p>The maximum number of organisms that an ecosystem can support (D)</p> Signup and view all the answers

What does an S-shaped growth curve represent?

<p>Slow initial growth, followed by rapid increase until carrying capacity is reached (C)</p> Signup and view all the answers

Which of the following describes r-selected populations?

<p>Numerous small offspring and early maturation (C)</p> Signup and view all the answers

What type of growth curve is typically associated with species that reproduce quickly?

<p>J-shaped growth curve (D)</p> Signup and view all the answers

Which statement accurately describes density-dependent factors?

<p>They become more effective as population density increases (D)</p> Signup and view all the answers

What characteristic is NOT associated with K-selected populations?

<p>Shorter life spans (A)</p> Signup and view all the answers

What happens when a population exceeds the carrying capacity?

<p>The population may crash and then experience a new growth phase (A)</p> Signup and view all the answers

Which of the following does NOT define the capacity for survival?

<p>The average number of young produced (B)</p> Signup and view all the answers

Flashcards

What are the main types of population distribution patterns?

Population distribution patterns describe how individuals are spaced out in a given area. The three main patterns are clumped, random, and uniform.

What is a "clumped" population distribution?

Clumped distribution, the most common pattern, occurs when individuals are clustered together. This is often due to limited resources or social benefits like predator evasion.

What is a "random" population distribution?

Random distribution, the least common, occurs when individuals are scattered randomly. This happens in homogenous environments where there are no specific attractions or repulsions.

What is a "uniform" population distribution?

Uniform distribution, less common, is characterized by evenly spaced individuals due to competition or territoriality. This pattern creates maximum distance between neighbors.

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What is population density?

Population density is the number of individuals per unit area or volume.

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What are the factors influencing population size?

Population size is determined by four key factors: natality (births), mortality (deaths), immigration (individuals entering), and emigration (individuals leaving).

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What is biotic potential?

Biotic potential refers to the maximum growth rate a population can achieve under ideal conditions. It's limited by environmental resistance.

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What is environmental resistance?

Environmental resistance represents the factors that limit a population's growth, such as competition for resources, predators, and disease.

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Offspring (Maximum per Birth)

The maximum number of offspring an organism can produce per birth. Think of it as the potential for reproduction.

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Capacity for Survival

The likelihood that offspring will survive to reach reproductive age. It's about how well they can make it to adulthood.

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Procreation (Frequency)

The number of times per year an organism reproduces. It's about how often they try to have offspring.

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Maturity (Reproductive)

The age at which an organism becomes sexually mature and capable of reproduction. Think of it as starting to have babies.

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Carrying Capacity

The theoretical limit of a population size that a specific environment can sustain over a long period of time. It's like the maximum number of residents a city can hold comfortably.

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Sigmoidal Growth (S-shaped)

A type of population growth curve characterized by a rapid initial increase followed by a gradual leveling off as the population approaches the carrying capacity. It's like a curve shaped like a stretched-out 'S'.

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J-shaped Growth

A type of population growth curve characterized by a steep, exponential increase followed by a sudden decline. It's like a curve shaped like a 'J'.

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Density-Independent Limiting Factors

Factors that limit population growth that are independent of population density. Think of it as environmental events that impact everyone equally.

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Study Notes

Population Growth

  • Quantitative population measurements are like snapshots in time
  • Ecologists use multiple measurements over long periods to understand population growth
  • Both distribution and growth are important when studying populations and communities

Population Distributions

  • Habitat and lifestyle influence how populations are distributed
  • Population distributions follow three general patterns

Patterns of Distribution

Clumped

  • Most common pattern in nature
  • Occurs when resources are scarce, leading to grouping around resources
  • Used by organisms with cooperative behaviors (like hunting or predator avoidance)

Random

  • Least common distribution pattern
  • Occurs when the environment is homogenous
  • No strong social interactions are present

Uniform

  • Less common than clumped distribution
  • Distance between individuals is maximized due to competition for resources or social interactions (like territoriality)

Population Calculations

  • Density (D) is calculated as individuals (N) divided by area (A) or volume (V)

Population Change

  • Four factors determine population size:

    • Natality (births)
    • Mortality (deaths)
    • Immigration
    • Emigration

  • Population change is calculated as (births + immigration) - (deaths + emigration)

  • Per capita growth rate is calculated as (change in population)/population

Biotic Potential

  • It is the maximum growth rate under ideal conditions
  • Depends on environmental factors
  • Offspring per birth, chances of survival, reproductive rate and maturity age are some relevant factors that influence growth

Carrying Capacity

  • Growth rate increases and then slows down due to resources being limited
  • It is the maximum sustainable population an ecosystem can maintain

Possible Growth Phases

  • Populations can exhibit an S-shaped (logistic) growth curve
  • Population number increases until it reaches the carrying capacity
  • Fluctuations near carrying capacity

J-Curves

  • Represents sudden rapid growth, followed by a sharp decline
  • Occurs when populations quickly outgrow their ecosystem capacity
  • Common in organisms with rapid reproduction (e.g., insects, bacteria).

Limiting Factors

  • Density-independent factors: unaffected by population density
  • Density-dependent factors: affected by population density (often alleviated when density decreases)

K-selected Populations

  • Characteristics:
    • Late maturation
    • Fewer, larger young
    • Longer life spans
    • More parental care
    • Intense competition for resources

r-selected Populations

  • Characteristics:
    • Early maturation
    • Numerous, small young
    • shorter life spans
    • Little parental care
    • Little competition for resources

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Population Dynamics Student Notes PDF

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