Biology Chapter 4: Population Dynamics
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Questions and Answers

What formula do we use to calculate population density?

Total number of individuals/unit area

Some characteristics that all populations have include?

Population density, growth rate, dispersion

How do populations tend to be dispersed?

Randomly, uniformly, and in clumps

Populations also tend to stabilize near the?

<p>Carrying capacity of their environment</p> Signup and view all the answers

Factors that limit populations are either?

<p>Both A and B</p> Signup and view all the answers

Earthquake-related tsunami is considered density independent?

<p>True</p> Signup and view all the answers

Intense competition for a food source is density dependent?

<p>True</p> Signup and view all the answers

Influenza epidemic is a density independent factor?

<p>False</p> Signup and view all the answers

Flooding due to a hurricane is a density independent factor?

<p>True</p> Signup and view all the answers

What do population-limiting factors do?

<p>Keep a population from increasing indefinitely</p> Signup and view all the answers

Density-independent factors include parasites and disease?

<p>False</p> Signup and view all the answers

On Isle Royale, the population of moose decreased as the population of wolves decreased?

<p>False</p> Signup and view all the answers

Competition can occur within a species or between two different species?

<p>True</p> Signup and view all the answers

What type of growth is demonstrated by exponential growth?

<p>Exponential growth</p> Signup and view all the answers

What type of growth does logistic growth refer to?

<p>Logistic growth</p> Signup and view all the answers

A mouse is an example of an?

<p>r-strategist</p> Signup and view all the answers

A spider is an example of an?

<p>r-strategist</p> Signup and view all the answers

A human is an example of an?

<p>k-strategist</p> Signup and view all the answers

An elephant is an example of an?

<p>k-strategist</p> Signup and view all the answers

Population sampling proportion example?

<p>number with tags in last catch/total number in last catch = number tagged fish (or other animal) in first catch/population</p> Signup and view all the answers

Why are the units in a population density calculation squared and not cubed?

<p>There are only two dimensions, length and width</p> Signup and view all the answers

Area of a rectangular object?

<p>length x width</p> Signup and view all the answers

Main idea of this section is?

<p>Populations of species are described by density, spatial distribution, and growth rate</p> Signup and view all the answers

What are the characteristics of populations and how they are distributed?

<p>Populations are groups of the same species in the same area and characteristics of populations include density, distribution, and growth rate</p> Signup and view all the answers

What are the differences between density-independent and density-dependent limiting factors?

<p>Density-independent does not depend on the number of members in a population and density-dependent does depend on the number of members in a population</p> Signup and view all the answers

How does carrying capacity affect reproductive rates?

Signup and view all the answers

Population density?

<p>The number of organisms per unit area</p> Signup and view all the answers

Dispersion?

<p>Is the spacing pattern of a population and its pattern is primarily driven by resources such as food</p> Signup and view all the answers

What is a species' range?

<p>Its distribution across the environment</p> Signup and view all the answers

Why might a species not be able to expand its population range?

<p>Because it cannot survive the abiotic conditions found in the expanded region</p> Signup and view all the answers

Limiting factors?

<p>Are biotic or abiotic forces that keep populations from increasing indefinitely</p> Signup and view all the answers

Limiting factors are either?

<p>Density-independent or density-dependent</p> Signup and view all the answers

Density-independent factor?

<p>Any factor in the environment that does not depend on the number of members in a population per unit area</p> Signup and view all the answers

Density-independent factors are?

<p>Abiotic</p> Signup and view all the answers

Examples of density independent factors include?

<p>Weather events, fire, human alterations of the landscape, and air, land, and water pollution</p> Signup and view all the answers

Density-dependent factor?

<p>Any factor in the environment that depends on the number of members in a population per unit area</p> Signup and view all the answers

Density-dependent factors are?

<p>Biotic</p> Signup and view all the answers

Examples of density dependent factors include?

<p>Predation, disease, competition, and parasites</p> Signup and view all the answers

Population growth rate (PGR)?

<p>Explains how fast a given population grows</p> Signup and view all the answers

Natality?

<p>Birthrate of a population in a given year</p> Signup and view all the answers

Emigration?

<p>Number of individuals moving away from a population</p> Signup and view all the answers

Immigration?

<p>Number of individuals moving into a population</p> Signup and view all the answers

Exponential growth model?

<p>Occurs when growth rate is proportional to population size and all populations grow exponentially until they encounter a limiting factor</p> Signup and view all the answers

Logistic growth model?

<p>Occurs when a population's growth slows or stops following exponential growth and a population stops increasing when the number of births &lt; number of deaths, or when emigration &gt; immigration</p> Signup and view all the answers

Carrying capacity?

<p>Is the maximum number of individuals in a species that an environment can support</p> Signup and view all the answers

Species vary in the number of births per?

<p>Reproduction cycle, age that reproduction begins, and in the life span</p> Signup and view all the answers

Plants and animals are placed into groups based on their?

<p>Reproductive factors</p> Signup and view all the answers

R-strategy?

<p>Rate strategy, adapted for fluctuating environment, generally small, short life span, many offspring, and expend little energy to raise young</p> Signup and view all the answers

K-strategy?

<p>Carrying-capacity strategy, adapted to stable environment, generally large, long life span, few offspring, and invest more energy into nurturing young</p> Signup and view all the answers

Study Notes

Population Density and Dynamics

  • Population density is defined as the total number of individuals per unit area.
  • Populations possess characteristics such as density, growth rate, and dispersion patterns.
  • Dispersion can occur in three main forms: randomly, uniformly, and in clumps.

Carrying Capacity and Growth Factors

  • Populations stabilize near the carrying capacity of their environment, which is the maximum number of individuals that can be supported.
  • Limiting factors that restrict population growth are categorized as density-dependent or density-independent.
  • Density-dependent factors, such as intense food competition, epidemics, and changes in predator numbers, rely on the population size.
  • Density-independent factors, like natural disasters and environmental changes (e.g., tsunamis, hurricanes), are not influenced by population density.

Types of Population Growth

  • Exponential growth occurs when growth rate is proportional to population size before encountering limiting factors.
  • Logistic growth follows exponential growth and occurs when population growth slows or stops due to factors like a higher death rate than birth rate or emigration exceeding immigration.

Population Strategies

  • Species exhibit different reproductive strategies: r-strategists (e.g., mice, spiders) produce many offspring with little investment in their care, while K-strategists (e.g., humans, elephants) have fewer offspring and invest more energy in nurturing them.

Population Characteristics and Dynamics

  • Population growth rate (PGR) quantifies how fast a population grows and is influenced by natality (birthrate), immigration, and emigration.
  • The area of a population can be calculated using length x width, relevant in determining density measures.
  • Species' range refers to their distribution in an environment, which can be limited by abiotic conditions impacting survival.

Limiting Factors and Their Role

  • Limiting factors can be biotic (living factors), like disease and competition, or abiotic (non-living factors), such as weather, pollution, and habitat alterations.
  • Factors influencing population dynamics play a crucial role in maintaining ecological balance and preventing indefinite population increases.

Key Definitions

  • Natality: Birthrate of a population within a specific timeframe.
  • Emigration: The act of individuals moving away from a population.
  • Immigration: The act of individuals moving into a population.
  • Carrying capacity: The threshold population size an environment can sustain.

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Description

This quiz covers key concepts from Chapter 4, Section 1 on population dynamics. It includes definitions and formulas related to population density, characteristics of populations, and dispersion patterns. Test your understanding of how populations interact with their environments.

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