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Questions and Answers
What describes the 'intrinsic rate of increase' in a population?
What describes the 'intrinsic rate of increase' in a population?
What shape does the population growth curve take under fixed conditions in a lab experiment?
What shape does the population growth curve take under fixed conditions in a lab experiment?
Which organism is mentioned as having a simple logistic curve due to its reproductive method?
Which organism is mentioned as having a simple logistic curve due to its reproductive method?
What is the primary limit on the population of Drosophila in a lab setting?
What is the primary limit on the population of Drosophila in a lab setting?
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What phenomenon occurs when a population temporarily exceeds its carrying capacity?
What phenomenon occurs when a population temporarily exceeds its carrying capacity?
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Which factor can cause the young of a species to experience higher mortality rates despite initially having sufficient food?
Which factor can cause the young of a species to experience higher mortality rates despite initially having sufficient food?
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Which statement accurately characterizes the carrying capacity?
Which statement accurately characterizes the carrying capacity?
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During which process do yeast cells produce ethanol that can be harmful to them?
During which process do yeast cells produce ethanol that can be harmful to them?
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What is the term for the maximum number of individuals of a population that may be supported by environmental conditions?
What is the term for the maximum number of individuals of a population that may be supported by environmental conditions?
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What role do limiting factors play in an ecosystem?
What role do limiting factors play in an ecosystem?
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What happens when reindeer populations are introduced without predators?
What happens when reindeer populations are introduced without predators?
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Which factor does not typically control wild populations according to the information?
Which factor does not typically control wild populations according to the information?
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In what scenario is mass starvation observed in wild populations?
In what scenario is mass starvation observed in wild populations?
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Which statement accurately describes the logistic curve in wild populations?
Which statement accurately describes the logistic curve in wild populations?
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What primarily affects the cormorant populations on different islands?
What primarily affects the cormorant populations on different islands?
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What common occurrence happens to bird populations in various temperate regions during cold winters?
What common occurrence happens to bird populations in various temperate regions during cold winters?
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In which situation would populations of ibex not stabilize even after hunting is banned?
In which situation would populations of ibex not stabilize even after hunting is banned?
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What is a potential result of a population explosion followed by mass starvation?
What is a potential result of a population explosion followed by mass starvation?
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Study Notes
Population Growth 2
- Population growth under ideal conditions (unlimited space and food) increases geometrically.
- Real-world conditions are not ideal, limiting factors affect growth.
- In a laboratory setting, environments are often fixed, leading to logistic growth ("S" curve).
- The carrying capacity is the maximum population size that a given environment can support.
- The logistic growth model demonstrates that populations level off when resources become limited.
- Geometric growth is represented by the equation Nt = N0λt, where Nt is the population size at time t, N0 is the initial population size, and λ is the per capita rate of increase.
- Exponential growth is represented by the equation Nt = N0ert, where Nt is the population size at time t, N0 is the initial population size, r is the per capita rate of increase, and t is time.
- Logistic growth can be modeled by the equation dN/dt = rN(1 – N/K), where N is the population size, r is the per capita rate of increase, and K is the carrying capacity.
Logistic Curves in Lab Experiments
- The Drosophila (fruit fly) population is limited by the yeast it consumes, as yeast reproduce at a consistent rate.
- Yeast populations also follow a logistic curve.
- High ethanol concentrations are toxic to young yeast, allowing only older yeast to survive.
- Simple logistic growth models assume unchanging environmental conditions and no stage structures (like larvae).
Overshoot
- Populations may temporarily exceed carrying capacity (overshoot), especially in organisms with distinct life stages.
- This overshoot occurs when young organisms use a different food source compared to adults and the adults cause a food scarcity and die-off.
Wild Populations
- Stable carrying capacity doesn't often occur in nature.
- Instead, populations often fluctuate due to factors beyond starvation.
- Predation, parasitism, and disease are crucial factors influencing wild population sizes.
- Examples of reindeer on islands and Daphnia in a Canadian lake illustrate population crashes and recoveries rather than stable carrying capacity.
Climate
- Extreme climate events can greatly impact populations, such as cold winters for birds and Ibex in Switzerland.
- These populations do not always have a stable carrying capacity.
- Irregular population sizes may be due to the weather or climate and its impact.
Lack of Nesting Sites
- Some populations have limited carrying capacities due to insufficient nesting sites, impacting their growth and abundance.
- Cormorants on the Great Lakes, for example, are affected by the amount of nesting sites
Rainfall
- Water availability affects carrying capacity in different ways across various locations.
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Description
This quiz explores population growth models, comparing geometric and logistic growth in real-world scenarios. It discusses ideal conditions, carrying capacity, and the mathematical equations that represent these growth patterns. Test your knowledge on how populations behave under different environmental constraints.
