Species
Why is it difficult to determine how many species exist on Earth?
There is no consensus on the number of species nor is there a database used globally to record each species.
Do populations increase as exponential or linear growth?
Exponential Growth
At what point on a graph does the J Curve level off and start to appear as an S Curve?
Carrying Capacity
What is the term for the predicted length of survival for a population?
Life Expectancy
What pressure is placed on a population to change a J Curve into an S Curve?
Limiting Factors
Rank endangered, threatened, & extinct from largest population to smallest population.
Threatened, Endangered, Extinct
What are the two types of limiting factors? Give an example of each.
- Density-Dependent Factors: Biotic Factors, Example: Disease, Predators, Competition
- Density-Independent Factors: Abiotic Factors, Example: Temperature, Weather, Climatic Changes
Name one example of a K Strategist and one example of an R Strategist.
- K Strategists: Humans & Large Mammals, Small Mammals, (most) Reptiles, Birds
- R Strategists: Fish, Insects, Invertebrates, Bacteria, Trees/Plants
What is the difference between natality and mortality?
Natality is the birth rate (new births) for a population, and mortality is the death rate (number of deaths) for a population.
View the image on the board. What is happening to the population at Point A?
The population is experiencing exponential growth.
Give an example of how one of the four types of environmental isolation can lead to speciation.
Answers will vary. Answer must include an example of behavioral, mechanical, temporal, or geographic isolation.
View the image on the board. What is this chart called and what does it show?
It is called a "Population Pyramid" or "Age Structure Diagram." It shows a current snapshot of a population, including the males and females in each age group.
List 3 characteristics of K Strategists and 3 characteristics of R Strategists.
K Strategists:
- Large organism size
- High energy/offspring expended
- Few offspring produced
- Long parental care
- Long life expectancy
- Type 1 or 2 survivorship curve
R Strategists:
- Small organism size
- Low energy/offspring expended
- Many offspring produced
- Little parental care
- Short life expectancy
- Type 3 survivorship curve
What is carrying capacity?
Carrying capacity is the maximum population size an environment can sustainably support long-term without degrading its resource base.
View the image on the board. What is happening to the population at Point B?
The population has reached its carrying capacity due to the presence of limiting factors.
Name the 4 types of speciation (environmental isolation) & briefly describe each.
- Behavioral: Different mating/courtship
- Mechanical: Different reproductive anatomy
- Temporal: Mate at different times
- Geographic: Separation by geographic barriers
What happens if a population exceeds the carrying capacity?
The mortality rate will increase, and there will be more deaths than births.
Using a whiteboard, draw Type 1, Type 2, and Type 3 survivorship curves.
- Type 1 should be a convex line.
- Type 2 should be a linear line.
- Type 3 should be a concave line.
What is the difference between fecundity and fertility?
Fecundity is the ability for a population to reproduce (the biological capacity of an organism to produce offspring under optimal conditions/theoretical capacity), and fertility is the actual number of offspring produced (heavily influenced by environmental factors/measurable output).
Explain the difference between exponential growth and linear growth.
- Exponential growth increases at a constant rate (doubling).
- Linear growth increases at a constant amount.
What is the Principle of Competitive Exclusion?
Two species cannot exist in the same niche and both thrive.
Describe what a population pyramid would look like if it showed an expanding population.
It would look like a classic pyramid with the base larger than the top as there would be many young individuals (more births and young individuals than any other age group).
What do the X-axis and Y-axis represent on a survivorship curve?
- X-axis: Time
- Y-axis: % of organisms surviving
Do mice or humans have greater biotic potential? Why?
Mice have a significantly greater biotic potential than humans because they are R Strategists that reproduce rapidly, reach sexual maturity in weeks, have short gestation periods, and produce large, frequent litters. This allows mouse populations to explode exponentially under optimal conditions, whereas humans have low biotic potential.
Using a whiteboard, sketch a graph to show exponential growth, logistic growth, and linear growth.
- Exponential growth should appear as a "J Curve."
- Logistic growth should appear as an "S Curve."
- Linear growth should appear as a straight line increasing at a constant amount over time.