ch 19 popu n com Flashcards
demogrpahy
- state study of populations
what are Populations characterized by?
size and density
methods to estimate population size
all take samples
Quadrat - metal fence that is placed in random location of population and counts how many
Mark and Recapture = mark indidviduals in the population, put them back, then recapture and count how many of the marked ones are present
describe the Formula for Mark and Recapture
of marked ones in first catch X # of total ones in second catch / # of marked ones in second
what are the three Distribution Patterns
RCU
Random
Clumping
Uniform
Random Distribution Pattern
there is no real pattern as to how these organisms distribute
ex plants, flowers
Clumping Distribution Pattern
organisms surround tightly around a rescoure
ex. herd of sheep around food
Uniform Distribution Pattern
for terrortorial reasons
ex. school of fish
survivorship curve
a graf that shows # of inividuals surviving at each age
name all types of Surviviorship Curves
Type 1 = organisms tend to have longer life spans as they are nurtured very well by parent
ex. humans
Type 2 = life spans are constant, their likely hood to live and die are same
ex. birds
Type 3 = higher chance to live longer as baby tan adult
ex. trees
Exponential Growth Model
- theoretically predicts what populations will grow without taking into account the limitations faced
- usualyl occurs when new species in introduced
- rep by rN
graph shape of Exponential Growth
J shaped
Logistic Growth Model
- better reflects irl
- takes into account the limitations that interfere with grotwth
- there is STRUGGLE FOR EXISTENCE
- more scarce resources become, population plateaus
graph shape of Logistic Gorwth
S shaped
Carrying Capacity
population size of a species capable of being supported by environemtn
limitation of Logistic model
- simplication of irl popu dynamics
- does not take into account different weather conditions or nat disastors
- populations don exist by themselves
Density Dependant Regulation Factor
- growth and mortality rate of popu depends on the density of that popu itself
Density independatn regualtion factor
- when natural disastors occur, chances to live or die are same
the two feeding dynamics between organisms
Predators
Prey
Mechanical Defence Mechanism
- organisms with armour, shels or thorns or toxins to literally not get eaten
ex. turtle shells, porcupine needles
Camouflage
-organisms changing colour to blend environemtn to not get eaten
ex. camelion, walking stick
Mimcry
organisms matching other specices colours to avoid getting eaten
ex. bee lokkni like wasp
Warning Colouration
- organisms with colours to make them look poisionous
ex. some frogs DONT EAT me
Competition Exclusion Principle
2 species cannot coexist if they are competing for the same resources
- one will end up leading the other speices into extinction
- basically surivival of fittest
