Population Ecology Flashcards
group of individuals of single species inhabiting specific area
population
physical environmental conditions that allow individuals of species to survive and reproduce
habitat
ability of environmental conditions to support reproductio and survival
habitat quality
habitat quality
- habitat area/volume
- resource concentration
- time
habitat quality = ?
organisms acquire many resources
large population = ?
high survival + reproduction
Characteristics of a population
- distribution
- density
- abundance
- physical environment limits geographic distribution of species
- organisms can only compensate so much for environmental variation
distribution limits
arrangement of individuals of a population within a particular space
distribution
different types of distribution
- random distribution
- uniform distribution
- clumped distribution
organisms are spread throughout the area without an overall pattern
random distribution
organisms are distributed over an area
uniform distribution
organisms are concentrated in an area
clumped distribution
Three reasons for clumped distribution
- patchy distribution of physical and chemical condition suitable for growth
- some parts offer more protection
- dispersal of seeds, larvae and other representative forms of each generation is limited
brought by severe competition and positive antagonism among individuals
uniform distribution
number of individuals in a populatoin
size
size can be stated as
kind - place - time - number
Factors affecting size of population
- natality
- mortality
- immigration
- emigration
number of species that are born
natality
two types of natality
- maximum natality
- ecological natality
absolute or theoretical production of new individual under ideal condition
maximum natality
population incrase under actual or environmental condition
ecological natality
number of species that die
mortality
two types of mortality
- minimum mortality
- ecological mortality
loss of individual under ideal condition
minimum mortality
loss of individual under given environmental condition
ecological mortality
number of species that entered the land
immigration
number of species that leave the land
emigration
number of individuals of a species living in a particular area of that population
density
factors affecting density of a population
- resources
- diseases and parasites
- competition
- predation
there are a range of __ and __ factors that affect population density
- human
- natural
Physical Factors that affect population density
- Relief (shape and height of land)
- Resources
- Climate
relief in high density
low land which is flat
relief in low density
high land that is mountainous
resources in high density
areas rich in resources
resources in low density
areas with few resources tend to be sparesly populated
climate in high density
areas with temperate climates tend to be densely populatied due to enough rain and heat to grow crops
climate in low density
areas with extrene climates of hot and cold tend to be sparsely populated
Human Factors that affect population density
- political
- social
- economic
political in high density
high population with stable governments
political in low density
low population in unstable countries
social in high density
want to live closer to each other for security
social in low density
other groups of people prefer to be isolated
economic in high density
good job opportunities particularly in large cities
economic in low density
limited job opportunities
number of offspring that could theoretically exist if all offsprings survived and produced young
biotic potenital
biotic potential depends on:
- number of offspring produced at given time
- frequency of reproduction
- reproductive life cycle of organism
Why is biotic potential not reach by population?
- environmental resistance
- carrying capacity
collection of environmental factors that reduces the growth rate of a population
environmental resistance
number of individuals in a particular population that the environment can support over an indefinite period of time in terms of food, space, and shelter
carrying capacity
size of population is affected by
- environmental resistance
- biotic potential
- carrying capacity
Factors influencing population growth
- density dependent limiting factor
- density independent limiting factor
- directly associated with living things
- factors that depends on the size of population
density dependent limiting factors
influences the population regardless of the density
density independent factors
examples of density dependent limiting factors
- effect of competition
- predators
- diseases
- availability of space and food
examples of density independent factors
- changes in weather
- temperature
- daily and seasonal variations of sunlight
- amount of available air
- water and soil condition
- slope of the environment
Two types of population growth
- logistic growth
- exponential growth
have period of rapid population growth, goes through a number of phases and eventually stops or slows down
logistic growth
population growth is extremely rapid and at a constant rate
exponential growth
logistic growth
- increase density of populatio and increase in competition
- mortality increases, birth rate decreases
Logistic growth formula
population growth rate = (max. net reproduction per individ.) (no. of individ.) (portion of unexploited resources)
exponential growth
maximum growth rate of population achieving biotic potential
Exponential growth formula
population growth rate = (birth-deaths) (no. of individ.)
Life cycle
- prereproductive period (juvenile period)
- reproductive period
- postreproductive period
depend on age composition and specific growth rates due to reproduction of competent age group
over-all population growth
chart showing the age and sex distribution of the population in a given time
age pyramid
Three Types of pyramid
- pyramid with broad base
- bell shaped polygon
- urn shaped
large percentage of young individuals
pyramid with broad base
moderate proportion of young to old
bell shaped polygon
- low percentage of young individual
- senile or declining population
urn shaped
Types of population pyramid
- stable pyramid
- stationary pyramid
- expansive pyramid
- constrictive pyramid
population pyramid showing an unchanging pattern of fertility and mortality
stable pyramid
- population pyramis typical of countries with low fertility and low mortality
- very similar to constrictive pyramid
stationary pyramid
- population pyramid showing a broad base
- indicate high proportion of childre, rapid rate of population growth, low proportion of older people
expansive pyramid
- population pyramid showing lower numbers of percentages of younger people
- country will have a greying population which means that people are generally older, as the country has long life expectancy, low death rate, low birth rate
constrictive pyramid
recording of births and deaths among individuals of different ages
life table
record of fate of group of newborn individuals until the last one dies
cohort life table
death schedule of the organism taken as the sample for study
survivorship
Three general types of survivorship curves
- type 1 populations
- type 2 populations
- type 3 populations
high survivorship until some age, then high mortality
type 1 populations
type 1 populations examples
- humans in developed countries
- animals in zoo
fairly constant death rate at all ages
type 2 populations
type 2 populations examples
- rodents
- adult birds
- certain turtle species
low survivorship early in life
type 3 populations
type 3 populations examples
- fishes
- seeds
- marine larvae
