14. What is a Population Flashcards
Population
Individuals of the same species that co-occur in space and time
Density
Number of individuals per unit area
Distribution
size, shape, and location of area occupied
Other demographic characteristics
age distribution, sex ratios, birth/death rates, immigration/emmigration, rate of growth
Absolute density
number of individuals of a populationo per unit area
ecological density
the number of individials per unit area of SUITABLE HABITAT
Dispersal
PERMANENT movement of individuals (propagules) usually from one population to another
Dispersal
PERMANENT movement of individuals (propagules) usually from one population to another
migration
seasonal movement of individuals from one location to another
6 dispersal methods for seeds
Gravity- large seed size, short dispersal distance
Ballistic- explosive dispersal over short distances
Wind- seeds with appendages, short-long distances
Water- seeds that float, short-long distance
Animals- ingestion/defacation or hooks, short-long distance
Humans- breeding and transportation, short-long distance
Immigration
movement into an area
emmigration
movement out of an area
Functional response
increase/decrease in feeding rate
numerical response
change in density of predator populations in response to prey densities
Reproduction numerical response
time lag between prey population and peak predator population, not synchronized
lag time is needed for predators to produce offspring
Dispersal numerical response
no time lag between peak prey and predator populations, synchronized
No lag time because species are highly mobile and can track prey across a landscape
distribution
the geographic distribution of a species as limited by the physical environment and species niche requirements
3 types of small scale distribution
Random: equal chance of living anywhere
Regular/even: uniformly spaced
Clumped: higherp probability to live in some areas versus others
Neutral interactions
Random distribution
random disturbances, uniform distribution of resources
Antagonistic interactions
Regular distribution
uniform distribution of resources, depetion of resourses
Positive interactions
Clumped distribution
patchy resources, dispersal limitation
Large scale distribution
Area with substatial environmental change, individuals are often clumped
Why arent all species everywhere?
All organisms have limited energy and resources
It takes extra energy to survive and reproduce in regions at the edge of their niche, so they usually dont bother trying to survive extreme conditions
Eastern grey kangaroo niche
tropical forests
Western grey kangaroo niche
temperate woodland and shrubland
Red kangaroo
savanna and desert species (adapted to hot, dry, arid conditions
Africanized honeybee
Hybrid species
Aggressive compared to farm bees
efficient foragers
can create large cononies due to excess food
form massive swarms
Why arent africanized honeybees in Canada
its too cold, unless global warming
DIspersal lag
When a species can expand to newly suitable ranges but have not had time to yet
Metapopulation
a group of subpopulations living in patches connected by an exchange of individuals
only exist when individuals disperse from one population to another, otherwise it is not considered a metapopulation
