Population Ecology

Question 1

What is ecology?

Answer 1

-Study of how organisms interact with one another in their environment

Question 2

What is natural selection?

Answer 2

• 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

Question 3

Describe populations?

Answer 3

• 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

Question 4

Describe population Range?

Answer 4

• 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

Question 5

What are Metapopulations?

Answer 5

• 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

Question 6

What is Generation time?

Answer 6

• 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)

Question 7

What is age structure?

Answer 7

• Determined by the numbers of individuals in each different age group
• Has critical influence on populations growth rate

Question 8

What is cohort?

Answer 8

-Group of individuals of the same age

Question 9

What is fecundity?

Answer 9

-Number of offspring produced in standard time

Question 10

What is mortality?

Answer 10

-Death rate in standard time

Question 11

What is survivorship?

Answer 11

-Percent of an original population that survives to a given age

Question 12

Describe what effects that amount of offspring that will be produced?

Answer 12

• 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

Question 13

Do populations change is size based on the number of offspring born?

Answer 13

-No, populations normally remain the same side regardless of the number of offspring born

Question 14

What is biotic potential?

Answer 14

• When there are no limits on population growth

- All populations eventually reach some sort of limit imposed by a shortage

Question 15

What is carrying capacity?

Answer 15

-It is the maximum number of individuals that the environment can support

Question 16

What is density-dependent?

Answer 16

• A factor that regulates populations

- They’re factors that affect the population and depend on population size

Question 17

What is density-independent?

Answer 17

• Other factors affect populations regardless of size

ex. natural disasters

Question 18

Describe negative and positive feedback?

Answer 18

• Negative: reduce population size

- Positive: Allee effect, growth rates increase with population size

Question 19

What are density independent effects?

Answer 19

• 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

Question 20

What effects the cost of reproduction?

Answer 20

• When resources are limited the cost of reproduction is high
• Selection will favor individuals that can compete and utilize resources efficiently

Question 21

What are K-selected populations?

Answer 21

-adapted to thrive when population is near its carrying capacity

Question 22

What happens when populations are below carrying capacity?

Answer 22

• Resources are abundant

- Costs of reproduction are low

Question 23

What are r-selected populations?

Answer 23

-Selection favors individuals with the highest reproductive rates

Question 24

How is human population growing?

Answer 24

• Growing exponentially
• Birth and death rate has dropped
• There is a carrying capacity for humans but we continue to grow past it

Question 25

What is an Ecological Footprint?

Answer 25

-Amount of productive land required to support an individual