Podcast
Questions and Answers
What is the main trade-off mentioned in the text regarding life history patterns?
What is the main trade-off mentioned in the text regarding life history patterns?
Which selection, as described in the text, favors high population growth rate and reproduction?
Which selection, as described in the text, favors high population growth rate and reproduction?
What happens when reproduction starts or increases according to the text?
What happens when reproduction starts or increases according to the text?
Which method to estimate mortality rates involves monitoring a group of born organisms each year?
Which method to estimate mortality rates involves monitoring a group of born organisms each year?
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In which scenario is K selection favored?
In which scenario is K selection favored?
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Which of the following is NOT a characteristic of density-dependent factors?
Which of the following is NOT a characteristic of density-dependent factors?
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What is the primary difference between exploitative competition and interference competition?
What is the primary difference between exploitative competition and interference competition?
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Which of the following is NOT a component that can be estimated using a life table combined with a fecundity schedule?
Which of the following is NOT a component that can be estimated using a life table combined with a fecundity schedule?
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In the context of life history strategies, what is the primary difference between an iteroparous life cycle and a semelparous life cycle?
In the context of life history strategies, what is the primary difference between an iteroparous life cycle and a semelparous life cycle?
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What is the primary purpose of a survivorship curve?
What is the primary purpose of a survivorship curve?
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Which of the following statements about birth rate and fecundity schedule is TRUE?
Which of the following statements about birth rate and fecundity schedule is TRUE?
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Study Notes
Life History Patterns
- In any life history, there is a limited total amount of energy available to an organism, leading to trade-offs between growth and reproduction.
- Reproduction may slow or stop growth as resources are diverted.
R and K Selection
- R selection favors high population growth rate and reproduction, prominent in species colonizing new habitats.
- K selection favors efficient resource use and survival, prominent when species grow under crowded conditions.
Methods to Estimate Mortality Rates
- Cohort life table: monitor a group of born organisms and look at the amount that died each year.
- Static life table: record the age of death of a large number of individuals.
- Age distribution: take a sample of individuals and determine the age composition.
Population Dynamics
- Populations are in continuous flux.
- Survivorship curves summarize the pattern of survival in a population.
- Life tables list the survivorship and mortality in populations.
Life Table Analysis
- Combining a life table with a fecundity schedule can estimate:
- Net reproductive rate (R0)
- Geometric rate of increase
- Generation time
- Per capita rate of increase
Population Regulation
- Environment influences population growth by affecting birth and death rates.
- Density-dependent factors:
- Affected by population density
- Often biotic factors (competition, predation, disease)
- Density-independent factors:
- Not affected by population density
- Often abiotic factors (floods, extreme temperatures)
Competition
- Exploitative competition: animals from the same group compete against each other for food.
- Interference competition: organisms from the same family share their food (also territorial behavior).
Life History Variation
- The pattern of growth and reproduction over the lifetime of an organism.
- Result of an evolutionary process: selection on traits that promote survival and reproduction.
- Two types of life cycles:
- Iteroparous life cycle: multiple reproduction times in a life cycle (e.g., humans).
- Semelparous life cycle: only one reproduction time in a life cycle (e.g., salmon).
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Description
Test your knowledge on population dynamics, survivorship curves, and life tables used to estimate various population parameters like net reproductive rate and generation time. Understand the relationship between fecundity schedules and birth rates.
