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Questions and Answers

What is the primary focus of demography?

  • The statistical study of populations (correct)
  • The examination of environmental impacts on organisms
  • The study of genetic variations within species
  • The analysis of age distribution in human populations

How are life tables primarily used in demography?

  • To analyze mating patterns
  • To set insurance rates (correct)
  • To measure genetic diversity
  • To predict environmental changes

Which of the following accurately defines population density?

  • The average number of individuals per unit area (correct)
  • The genetic variation within a population
  • The adaptability of a population over time
  • The total number of individuals within a population

What effect does population size have on a population's potential for adaptation?

<p>It affects the amount of genetic variation present. (D)</p> Signup and view all the answers

Why is it often impractical to count all individuals in a population?

<p>Because it is logistically or economically infeasible. (A)</p> Signup and view all the answers

What sampling method is commonly used for studying immobile or small organisms?

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

How does body size relate to population density according to the observations made?

<p>Smaller organisms tend to be more densely distributed. (A)</p> Signup and view all the answers

The term 'demographics' is often incorrectly assumed to refer solely to what?

<p>The study of human populations (C)</p> Signup and view all the answers

What primarily caused the difference in growth rates between the high-density and low-density donkey populations?

<p>Maternal malnutrition due to high density (A)</p> Signup and view all the answers

In which population was juvenile mortality higher?

<p>High-density population (A)</p> Signup and view all the answers

Which of the following factors is considered density-independent when discussing population mortality?

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

What occurred in the low-density plot from 1986 to 1987?

<p>Increase in donkey density (B)</p> Signup and view all the answers

How does a dense population recovering from a density-independent cause differ from a sparse population?

<p>It recovers faster if more individuals are left to reproduce. (C)</p> Signup and view all the answers

What was the condition of the food that contributed to the juvenile mortality in high-density populations?

<p>Scarcity of high-quality food (B)</p> Signup and view all the answers

Which scenario exemplifies a density-independent population regulation factor?

<p>Forest fire reducing deer numbers (B)</p> Signup and view all the answers

What did researchers conclude about the numbers of offspring birthed by mothers in different densities?

<p>Density did not affect the number of offspring. (A)</p> Signup and view all the answers

What does the carrying capacity, denoted as K, refer to?

<p>The maximum population size that an environment can sustain (D)</p> Signup and view all the answers

When N equals K in logistic growth, what happens to the population growth rate?

<p>Growth becomes zero (A)</p> Signup and view all the answers

Which of the following statements best describes logistic growth?

<p>It produces an S-shaped curve representing population changes over time (A)</p> Signup and view all the answers

What does the term ‘K - N’ represent in the logistic growth equation?

<p>The number of individuals that can still be added to the population (B)</p> Signup and view all the answers

In logistic growth, what effect does intraspecific competition have on population dynamics?

<p>It affects the growth rate as resources become limited (C)</p> Signup and view all the answers

What is a key characteristic of the initial phase of an S-shaped curve in logistic growth?

<p>Population grows exponentially due to ample resources (B)</p> Signup and view all the answers

How does the growth rate behave as a population approaches its carrying capacity?

<p>Growth rate begins to decrease (B)</p> Signup and view all the answers

Which of the following statements about logistic growth is incorrect?

<p>Population size remains constant at maximum growth indefinitely (D)</p> Signup and view all the answers

What is the main purpose of using a quadrat in ecological studies?

<p>To count the number of individuals within its boundaries. (A)</p> Signup and view all the answers

What is a critical factor in obtaining an accurate population estimate using quadrats?

<p>The placement of the quadrat must be randomized. (C)</p> Signup and view all the answers

In the mark and recapture technique, what factor affects the recapture rate of marked organisms?

<p>The number of unmarked individuals in the environment. (D)</p> Signup and view all the answers

Using the formula from the mark and recapture method, if 80 mice are marked and the second trapping yields 20 marked out of 100 captured, what is the estimated population size?

<p>400 (A)</p> Signup and view all the answers

Which distribution pattern is characterized by individuals being evenly spaced apart?

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

Which type of organisms benefits most from using the mark and recapture technique?

<p>Small, mobile organisms (A)</p> Signup and view all the answers

What does a clumped distribution pattern indicate about a population?

<p>Individuals group together due to resources or social behavior. (B)</p> Signup and view all the answers

What is a potential source of error when estimating population size through quadrat sampling?

<p>Randomly placing the quadrats in identical locations. (C)</p> Signup and view all the answers

What significant event is believed to have started the extinction of woolly mammoths?

<p>Climate change altering their habitat (B), The arrival of human hunters (D)</p> Signup and view all the answers

What factor is suggested to have reduced the range of woolly mammoths significantly over time?

<p>Climate change impacting their habitat (D)</p> Signup and view all the answers

Which island is noted for having a population of woolly mammoths that survived until relatively recent times?

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

According to a 2012 study, what is concluded about the extinction of woolly mammoths?

<p>Multiple factors contributed to their extinction. (A)</p> Signup and view all the answers

What was the approximate time frame during which humans first hunted woolly mammoths?

<p>20,000 years ago (D)</p> Signup and view all the answers

What is suggested as a complexity in maintaining stable mammoth populations?

<p>Multiple interacting environmental factors (A)</p> Signup and view all the answers

Which museum hosts the only stuffed mammoth in the world?

<p>Museum of Zoology in St. Petersburg (C)</p> Signup and view all the answers

What aspect of woolly mammoths is known due to their preserved carcasses found in ice?

<p>Their physical characteristics and health conditions (C)</p> Signup and view all the answers

What characterizes K-selected species in terms of their reproductive strategy?

<p>They are adapted to stable environments and produce fewer, larger offspring. (A)</p> Signup and view all the answers

Which of the following is an example of an r-selected species?

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

How do K-selected and r-selected species differ in terms of environmental adaptation?

<p>R-selected species are adapted to unpredictable environments. (C)</p> Signup and view all the answers

What is a consequence of unchecked human population growth?

<p>Negative impacts on other species and ecosystems. (C)</p> Signup and view all the answers

In what way do humans alter their environment compared to other species?

<p>They increase the carrying capacity of their environment. (C)</p> Signup and view all the answers

What is a key relationship between population growth and economic development?

<p>Higher economic development typically corresponds with lower population growth rates. (A)</p> Signup and view all the answers

Which of the following correctly describes life history strategies in species?

<p>They can evolve independently, leading to unique combinations. (D)</p> Signup and view all the answers

What factor most significantly influences the carrying capacity of an environment?

<p>Human interventions and resource utilization. (C)</p> Signup and view all the answers

Flashcards

Demography

The statistical study of populations, including tools to describe and analyze population changes.

Population Size

The total number of individuals in a population.

Population Density

The number of individuals per unit area.

Life table

A table that details life expectancy of individuals in a population.

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Population Sampling

Studying a portion of a population to learn about the whole.

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Quadrat

A sampling method used for immobile or slow-moving organisms.

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Inverse Relationship (Body Size & Population Density)

Larger organisms tend to have lower population densities than smaller organisms.

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Accuracy of Population Size Estimation

Directly counting all individuals is the most accurate method, but not always feasible.

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Mark and Recapture

A method to estimate population size by marking and recapturing individuals, and noting the marked individuals within the new capture.

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Random Distribution

Individuals scattered randomly within a habitat.

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Clumped Distribution

Individuals grouped together within a habitat.

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Uniform Distribution

Individuals spaced out evenly within a habitat.

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Population Size Estimation

Using mathematical models to approximate the total number of individuals in a population.

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Species Distribution Pattern

How individuals of a species are arranged within their habitat at a given time.

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Carrying Capacity (K)

The maximum population size that a particular environment can sustain.

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Logistic Growth

Population growth that slows as resources become scarce, eventually leveling off at the carrying capacity.

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Exponential Growth

Population growth that occurs when there are unlimited resources, resulting in a rapid increase in the population.

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S-shaped curve

Graphical representation of logistic growth, showing initial exponential growth that slows down and levels off at the carrying capacity.

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Intraspecific Competition

Competition among individuals within the same species for resources.

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Overshoot

When a growing population briefly exceeds its carrying capacity

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Population Fluctuation

Variations in population size around the carrying capacity.

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Logistic Growth Equation

A mathematical formula that describes population growth, considering the carrying capacity.

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Density-dependent factors

Factors that influence population growth based on the population density. For example, competition for resources, disease spread, and predation are density-dependent factors.

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Density-independent factors

Factors that affect population growth regardless of population density. Examples include weather, natural disasters, and pollution.

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Juvenile mortality

The death of young individuals in a population before reaching adulthood.

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Maternal malnutrition

A lack of adequate nutrition in the mother, which can negatively impact the health and survival of offspring.

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Age-specific mortality

The death rate of individuals within specific age groups in a population.

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Population recovery

The process of a population rebounding after a decline, often due to factors such as reduced mortality or increased birth rates.

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How do density-dependent and independent factors interact?

Density-dependent and independent factors can influence each other and shape population dynamics. For example, a harsh winter (density-independent) can impact a dense population more severely due to competition for resources (density-dependent).

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What's the impact of a mother's nutrition on offspring?

A mother's nutritional status can significantly affect her offspring's survival and growth. Malnutrition can lead to increased juvenile mortality and lower reproductive success.

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K-selected species

Species adapted to stable environments, producing fewer but larger offspring with high parental investment. They tend to live close to their carrying capacity.

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r-selected species

Species thriving in unstable environments. They produce many small offspring with minimal parental care, relying on rapid reproduction and dispersal.

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Human carrying capacity

The maximum population size that the Earth can sustain, taking into account resource availability and environmental impact.

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Human impact on carrying capacity

Humans have increased their environment's carrying capacity through technology and resource management, but often at the cost of other species.

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Age structure

The proportion of individuals in different age groups within a population.

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Economic development & population growth

Countries with higher economic development often have slower population growth due to factors like education and access to healthcare.

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Unchecked population growth

A situation where population growth continues without limits, potentially leading to resource scarcity, environmental damage, and social challenges.

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Woolly Mammoth Extinction

The disappearance of woolly mammoths around 10,000 years ago, likely due to a combination of climate change and human hunting.

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Wrangel Island Mammoth Population

A group of woolly mammoths that survived on Wrangel Island in the Arctic until around 1700 BC, isolated from human contact.

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Climate Change Impact on Woolly Mammoths

Climate change reduced woolly mammoths' habitat significantly, shrinking their range from 3 million square miles to 310,000 square miles.

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Human Hunting and Extinction

Humans hunted woolly mammoths, contributing to their decline, as evidenced by kill sites.

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Migration of Hunters and Extinction

The migration of human hunters across the Bering Strait to North America during the last ice age played a significant role in the woolly mammoth's extinction.

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Multiple Factors in Extinction

No single factor was solely responsible for the woolly mammoth's extinction, but a combination of climate change, habitat loss, and human hunting led to their downfall.

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Woolly Mammoth Adaptation

Woolly mammoths evolved adaptations like thick fur and a layer of fat to survive cold climates.

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Population Dynamics

The study of how populations change over time, considering factors like births, deaths, and migrations.

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Study Notes

Population and Community Ecology

  • Asian carp are invasive species disrupting ecological community structure, threatening native species.
  • Asian carp are a group of species, (silver, black, grass, and bighead carp), farmed and consumed in China for over 1,000 years.
  • They are considered a dangerous invasive species in the US.
  • Invasive species, such as Asian carp, kudzu vine, predatory snakehead fish, and zebra mussels, impact populations and natural/human disturbances.

Population Demographics and Dynamics

  • Population size and density are characteristics used to study populations.

  • Population size = total number of individuals.

  • Population density = number of individuals per unit area.

  • Populations can be distributed randomly, in groups or uniformly (e.g. dandelions randomly, oak trees in groups, penguins uniformly).

  • Demography is the statistical study of populations over time.

  • Life tables detail the life expectancy of individuals within a population, and were initially developed for insurance rates - today it applies to various living populations.

  • Life tables model the probability of age groups dying before the next birthday, mortality rates, and life expectancy.

  • Survivorship curves graph survivorship over time (Type I, II, III).

    • Type I: low mortality early/mid life, high in older individuals (e.g., humans)
    • Type II: relatively constant mortality throughout lifespan (e.g., birds)
    • Type III: high mortality early-life, low mortality in later life (e.g. trees).

  • Sampling methods (such as quadrats or mark-recapture) are used to measure population size and density in large areas due to logistical constraints.

    • Mark-recapture: marking, releasing, recapture, and calculation methods for mobile organisms.

Population Growth and Regulation

  • Exponential growth describes populations increasing without limits.
  • Logistic growth describes populations increasing with limits, approaching a carrying capacity (K).
  • Carrying capacity is the maximum population size a particular environment can sustain.
  • Populations may exceed the carrying capacity, and death rates increase, resulting in a return toward the carrying capacity.
  • Intraspecific competition (between members of same species) intensifies with increasing population density and scarce resources.
  • Density-dependent regulation: population density affects growth rate and mortality (e.g. predation, disease).
  • Density-independent regulation: population density does not affect growth and mortality (e.g. natural disasters).
  • Intraspecific competition: (within same species)
  • Population density affects mortality rate.
  • Resource availability, weather and natural disasters also influence density-independent population regulation

Population Dynamics and Regulation

  • Population growth is regulated by density dependent (e.g., competition, predation, disease) and density independent factors (e.g., weather, natural disasters).

  • Human activities impact carrying capacities and resources

The Human Population

  • Human population growth is exponential.
  • Humans modify their environment to have higher carrying capacities.
  • Population growth is related to economic development.
  • Unchecked human population growth has long-term implications.

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