K- and r-selected species
What is the main difference between K- and r-selected species?
K-selected populations grow slowly toward carrying capacity, r-selected populations grow quickly and overshoot carrying capacity
What are the three types of survivorship curves?
Type I, II, and III
A rapidly growing population that exceeds carrying capacity may be characterized by which type of growth?
Exponential
What information can be derived from an age structure diagram?
Population size of males and females within various age cohorts
What are the four stages of the demographic transition model?
preindustrial (slow growth), industrializing (rapid growth), industrialized (stable growth), postindustrial (declining growth)
Give an example of an r-selected species and explain why it fits into this category.
plants, insects, frogs, etc. These are all organisms that lay many eggs, have low early survivorship, and their populations grow quickly
Which type of survivorship curve is typically associated with K-selected species?
Type I
What is the difference between exponential and logistic growth?
Exponential is rapid and exceeds carrying capacity, logistic is steady/slow and approaches carrying capacity
What type of growth is represented by a pyramid shape age structure diagram?
Rapid growth
Describe the characteristics of stage 2 in the DTM
high birth rates, declining death rates, due to improved sanitation and economic development
Describe how environmental conditions influence whether a species is K-selected or r-selected.
Unstable conditions contribute to r-selection, while stable conditions contribute to K-selection
What does a Type II survivorship curve represent?
An organism whose survivorship rates are constant throughout life, for example a bird
Describe a scenario where exponential growth might occur
At the beginning of a population or when resources are unlimited
What socioeconomic factors may contribute to a pyramid shape age structure diagram?
low access to contraception, developing economy, low survivorship
Describe the characteristics of stage 4 in the DTM
death rates higher than birth rates, population begins to decline, people live long lives, smaller workforce
How do K-selected species contribute to ecosystem stability?
Stable environments, such as climax communities in ecological succession, are often composed of K-selected species
Explain how survivorship curves can inform conservation strategies
Survivorship curves can be used to predict future population sizes and therefore develop strategies to increase population numbers
Explain the concept of overshoot and die-off
Overshoot is when a population exceeds its carrying capacity and die off is the result of exceeding capacity when resources become limited and organisms die
What implications does an inverted age structure diagram have for a population?
The population is declining, suggesting labor shortages and impacts to economic growth
propose a solution that a government may implement to slow its population growth
improved education, more jobs, access to contraceptives, incentives for smaller families
Discuss how the K- and r-selected species strategies (reproduction, maturity, lifespan, clutch size) affect their population dynamics.
K: small clutch sizes, late maturity, long lifespans, high parental care all contribute to steady population growth
r: large clutch sizes, early maturity, short lifespans, and no parental care all contribute to fast rates of reproduction and rapid growth
How can changes in environmental factors alter survivorship curves over time?
Environmental changes like pollution can decrease survivorship and thus push a Type I curve toward Type II or III. On the other hand, improvements in the environment can shift a Type III curve toward Type II or I.
Discuss how human activities can impact natural population growth models
Pollution may slow growth due to decreased survivorship while environmental conservation may increase growth due to increased survivorship
Compare and contrast the age structure diagrams of developed and developing countries
developed countries tend to have rectangular/inverted diagrams (stable/no growth) while developing countries tend to have pyramid shape (rapid growth)
Discuss how the demographic transition model can be applied to predict future population trends
Most countries tend to go through the same stages, so the DTM can be used to predict the next steps for a country