Population Ecology Flashcards
What is ecology?
-Study of how organisms interact with one another in their environment
What is natural selection?
- Can operate to make a population better adapted to the environment
- Leads to evolutionary adaptation to environmental conditions
ex. similar/closely related species that live in different environments evolve differently
Describe populations?
- They’re groups of individuals of the same species in the same place
- There’s three characteristics of population ecology
1. Population range, area throughout which the population occurs
2. Pattern of spacing of individuals
3. How the population changes in size through time
Describe population Range?
- Most species have limited geographic range
ex. Devil’s hole pupfish live in only one spring in southern nevada - Ranges change through time due to environmental changes, dispersal to new ares, and humans expanding and reducing a populations ranges
What are Metapopulations?
- A network of distinct, physically distant, interacting populations
- Occurs in areas in which suitable habitat is patchily distributed and is separated by intervening stretches of unsuitable habitat
ex. there are patches of woods that deer live in
What is Generation time?
- Average interval between the birth of an individual and the birth of its offspring
- Populations with short generations can increase in size more quickly than populations with long generations (larger organisms have larger generation times)
What is age structure?
- Determined by the numbers of individuals in each different age group
- Has critical influence on populations growth rate
What is cohort?
-Group of individuals of the same age
What is fecundity?
-Number of offspring produced in standard time
What is mortality?
-Death rate in standard time
What is survivorship?
-Percent of an original population that survives to a given age
Describe what effects that amount of offspring that will be produced?
- The amount of time an individual lives (lives shorter=produces more offspring, lives longer=produces less offspring)
- Larger offspring have a greater chance of survival
Do populations change is size based on the number of offspring born?
-No, populations normally remain the same side regardless of the number of offspring born
What is biotic potential?
- When there are no limits on population growth
- All populations eventually reach some sort of limit imposed by a shortage
What is carrying capacity?
-It is the maximum number of individuals that the environment can support
What is density-dependent?
- A factor that regulates populations
- They’re factors that affect the population and depend on population size
What is density-independent?
- Other factors affect populations regardless of size
ex. natural disasters
Describe negative and positive feedback?
- Negative: reduce population size
- Positive: Allee effect, growth rates increase with population size
What are density independent effects?
- Rate of growth of a population is limited by something unrelated to the size of the population
- External environment aspects: cold winter, droughts, storms, volcanic eruptions
What effects the cost of reproduction?
- When resources are limited the cost of reproduction is high
- Selection will favor individuals that can compete and utilize resources efficiently
What are K-selected populations?
-adapted to thrive when population is near its carrying capacity
What happens when populations are below carrying capacity?
- Resources are abundant
- Costs of reproduction are low
What are r-selected populations?
-Selection favors individuals with the highest reproductive rates
How is human population growing?
- Growing exponentially
- Birth and death rate has dropped
- There is a carrying capacity for humans but we continue to grow past it
What is an Ecological Footprint?
-Amount of productive land required to support an individual
