Flashcards in Ch 8-9Population Chages & Interactions Deck (31):
Populations of organisms are......
Can assess the health of animals or entire species
The number of organisms
Calculated by dividing the number of organisms (n) by the total area (A) or total volume (V)
Factors that affect population change
1. Natality - # of births
2. Mortality - # of deaths
3. Immigration - "in" move in
4. Emigration - "exit" move out
Describes how quickly a population is increasing or decreasing
Per capita growth rate:
Represents the change in a populations size relative to the initial population size.
Population growth models
-density ~dependent factors
-density ~independent factors
Allows things to enter and leave
Does not allow things to enter or leave
Size increases as a fixed rate per time
Any factor limiting a populations ability to reach it's biotic potential.
Maximum # of offspring a species could produce with unlimited resources
2 types of growth curves that show population growth.
4 phases of growth curves (J-shaped & S-shaped)
1. Lag phase
2. Growth phase
3. Stationary phase
4. Death phase
Influences a population due to its density.
Ex. Disease or predators
Influences a population regardless of density.
Ex. Fire or flood
Interaction between the same species.
Interaction between different species.
Few offspring, more parietal care
Usually larger, longer life span
Elk, elephants, humans
Many offspring, little to no parental care
Usually smaller, short life span.
Predator prey cycles
A relationship in which organisms of two different species live in close, usually physical contact.
One benefits and the other is harmed
One benefits and the other doesn't care
Both organisms benefit
the slow replacement of one community of plants by another.
-Plants take over an area not previously covers by plants.
-due to the lack of nutrients
-Plants take over an area that was pervious lay covers by plants.
-faster due to availability of nutrients.
-first plants to arrive during succession...