Podcast
Questions and Answers
What is the primary focus of demography?
What is the primary focus of demography?
How are life tables primarily used in demography?
How are life tables primarily used in demography?
Which of the following accurately defines population density?
Which of the following accurately defines population density?
What effect does population size have on a population's potential for adaptation?
What effect does population size have on a population's potential for adaptation?
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Why is it often impractical to count all individuals in a population?
Why is it often impractical to count all individuals in a population?
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What sampling method is commonly used for studying immobile or small organisms?
What sampling method is commonly used for studying immobile or small organisms?
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How does body size relate to population density according to the observations made?
How does body size relate to population density according to the observations made?
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The term 'demographics' is often incorrectly assumed to refer solely to what?
The term 'demographics' is often incorrectly assumed to refer solely to what?
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What primarily caused the difference in growth rates between the high-density and low-density donkey populations?
What primarily caused the difference in growth rates between the high-density and low-density donkey populations?
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In which population was juvenile mortality higher?
In which population was juvenile mortality higher?
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Which of the following factors is considered density-independent when discussing population mortality?
Which of the following factors is considered density-independent when discussing population mortality?
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What occurred in the low-density plot from 1986 to 1987?
What occurred in the low-density plot from 1986 to 1987?
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How does a dense population recovering from a density-independent cause differ from a sparse population?
How does a dense population recovering from a density-independent cause differ from a sparse population?
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What was the condition of the food that contributed to the juvenile mortality in high-density populations?
What was the condition of the food that contributed to the juvenile mortality in high-density populations?
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Which scenario exemplifies a density-independent population regulation factor?
Which scenario exemplifies a density-independent population regulation factor?
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What did researchers conclude about the numbers of offspring birthed by mothers in different densities?
What did researchers conclude about the numbers of offspring birthed by mothers in different densities?
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What does the carrying capacity, denoted as K, refer to?
What does the carrying capacity, denoted as K, refer to?
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When N equals K in logistic growth, what happens to the population growth rate?
When N equals K in logistic growth, what happens to the population growth rate?
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Which of the following statements best describes logistic growth?
Which of the following statements best describes logistic growth?
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What does the term ‘K - N’ represent in the logistic growth equation?
What does the term ‘K - N’ represent in the logistic growth equation?
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In logistic growth, what effect does intraspecific competition have on population dynamics?
In logistic growth, what effect does intraspecific competition have on population dynamics?
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What is a key characteristic of the initial phase of an S-shaped curve in logistic growth?
What is a key characteristic of the initial phase of an S-shaped curve in logistic growth?
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How does the growth rate behave as a population approaches its carrying capacity?
How does the growth rate behave as a population approaches its carrying capacity?
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Which of the following statements about logistic growth is incorrect?
Which of the following statements about logistic growth is incorrect?
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What is the main purpose of using a quadrat in ecological studies?
What is the main purpose of using a quadrat in ecological studies?
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What is a critical factor in obtaining an accurate population estimate using quadrats?
What is a critical factor in obtaining an accurate population estimate using quadrats?
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In the mark and recapture technique, what factor affects the recapture rate of marked organisms?
In the mark and recapture technique, what factor affects the recapture rate of marked organisms?
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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?
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?
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Which distribution pattern is characterized by individuals being evenly spaced apart?
Which distribution pattern is characterized by individuals being evenly spaced apart?
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Which type of organisms benefits most from using the mark and recapture technique?
Which type of organisms benefits most from using the mark and recapture technique?
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What does a clumped distribution pattern indicate about a population?
What does a clumped distribution pattern indicate about a population?
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What is a potential source of error when estimating population size through quadrat sampling?
What is a potential source of error when estimating population size through quadrat sampling?
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What significant event is believed to have started the extinction of woolly mammoths?
What significant event is believed to have started the extinction of woolly mammoths?
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What factor is suggested to have reduced the range of woolly mammoths significantly over time?
What factor is suggested to have reduced the range of woolly mammoths significantly over time?
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Which island is noted for having a population of woolly mammoths that survived until relatively recent times?
Which island is noted for having a population of woolly mammoths that survived until relatively recent times?
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According to a 2012 study, what is concluded about the extinction of woolly mammoths?
According to a 2012 study, what is concluded about the extinction of woolly mammoths?
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What was the approximate time frame during which humans first hunted woolly mammoths?
What was the approximate time frame during which humans first hunted woolly mammoths?
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What is suggested as a complexity in maintaining stable mammoth populations?
What is suggested as a complexity in maintaining stable mammoth populations?
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Which museum hosts the only stuffed mammoth in the world?
Which museum hosts the only stuffed mammoth in the world?
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What aspect of woolly mammoths is known due to their preserved carcasses found in ice?
What aspect of woolly mammoths is known due to their preserved carcasses found in ice?
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What characterizes K-selected species in terms of their reproductive strategy?
What characterizes K-selected species in terms of their reproductive strategy?
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Which of the following is an example of an r-selected species?
Which of the following is an example of an r-selected species?
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How do K-selected and r-selected species differ in terms of environmental adaptation?
How do K-selected and r-selected species differ in terms of environmental adaptation?
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What is a consequence of unchecked human population growth?
What is a consequence of unchecked human population growth?
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In what way do humans alter their environment compared to other species?
In what way do humans alter their environment compared to other species?
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What is a key relationship between population growth and economic development?
What is a key relationship between population growth and economic development?
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Which of the following correctly describes life history strategies in species?
Which of the following correctly describes life history strategies in species?
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What factor most significantly influences the carrying capacity of an environment?
What factor most significantly influences the carrying capacity of an environment?
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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
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Population size and density are characteristics used to study populations.
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Population size = total number of individuals.
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Population density = number of individuals per unit area.
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Populations can be distributed randomly, in groups or uniformly (e.g. dandelions randomly, oak trees in groups, penguins uniformly).
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Demography is the statistical study of populations over time.
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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.
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Life tables model the probability of age groups dying before the next birthday, mortality rates, and life expectancy.
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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).
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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
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Population growth is regulated by density dependent (e.g., competition, predation, disease) and density independent factors (e.g., weather, natural disasters).
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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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