Studied by 0 people
specialists
narrow niche
less adaptable because of specialized needs
more likely to become extinct
use a specific set of resources
easily affected by changing conditions
have an advantage when conditions are more constant
generalists
broad niche
adaptable to many environments
less likely to become extinct
use a variety of resources
high range of tolerance
have an advantage when conditions change
K-selected species
quality.
few offspring with heavy parental care to protect them.
high parental care means death of parent = death of offspring
generally fewer reproductive events than r-strategists
ex: most mammals and birds
long lifespans, long time to sexual maturity, low biotic potential, slow population growth rate and slow recovery after disturbances
more likely to be disrupted by environmental change or invasive species.
less likely to adapt, more likely to go extinct
r-selected species
many offspring with little to no parental care
low parental care means death of parent doesn’t equal death of offspring
may reproduce only once, but generally reproduce many times throughout lifespan
ex: insects, fish, plants
shorter lifespan, quick to sexual maturity, high biotic potential, high population growth rate and fast recovery after disturbances
more likely to be invasive, not really effected by other invasive species
better suited for rapidly changing environment conditions
higher chance of adaptation and lower chance of extinction
biotic potential
the maximum reproductive rate of a population in ideal conditions
survivorship curve
a line that displays the relative survival rates of a cohort in a population from birth to maximum age. there are types 1, 2, and 3 curves.
K-selected are usually type 1 or 2
r-selected are usually type 3
cohort
a group of individuals of the same age
type 1 curve
mostly K-selected
high survivorship in early life due to high parental care
high survivorship in mid-life due to large size and defensive behavior
rapid decrease in survivorship in late life with old age
ex: most mammals
type 2 curve
in between r and K
steadily decreasing survivorship throughout life
linear line
type 3 curve
mostly r-selected
high mortality rate/low survivorship early in life due to little to no parental care
few make it to mid-life; slow, steady decline in survivorship in mid-life.
even fewer make it to adulthood or later life; slow decline in survivorship in old age
ex: insects, fish, plants
carrying capacity (k)
the maximum number of individuals in a population that an ecosystem can support based on limiting resources.
food
water
habitat
overshoot
when a population briefly exceeds carrying capacity
ex: deer breed in fall, give birth all at once in spring; sudden spike in population = overshoot
consequence of overshoot
resource depletion leading to die-off
die-off
sharp decrease in population size when resource depletion leads to many individuals dying
size (N)
total number of individuals in a given area at a given time
larger = safer from population decline
Density
number of individuals/area
ex: 12 panthers/km squared
high density = high competition, possibility for disease outbreak or depleting food source
Distribution
how individuals in a population are spaced out compared to each other
random (trees)
uniform (territorial animals)
clumped (herd/group animals)
sex ratio
ratio of males to females. closer to 50:50 is more ideal for breeding (usually)
die-off or bottleneck events can lead to skewed sex ratios, limiting population growth
density dependent factors
influence population growth based on size, like food or space
density independent factors
influence population growth regardless of population size
logistic growth
initial rapid growth, then limiting factors limit the population to K.
population change formula
(immigrations + births) - (emigrations + deaths)
population pyramids / age structure diagrams
left side is male, right side is female
moving outward
lowest = youngest
highest = oldest
extreme pyramid (vast majority at bottom): rapid growth
less extreme pyramid: slow, stable growth
house: stable, little to no growth
narrowest at base: declining population
Total Fertility Rate (TFR)
average number of children a woman in a population will bear throughout her lifetime
higher TFR = higher birth rate, generally higher population growth rate
replacement level fertility
the TFR required to offset deaths in a population and keep size stable.
about 2.1 in developed countries (replace both parents).
higher in less developed countries due to higher infant mortality.
infant mortality rate (IMR)
number of deaths of children under 1 year per 1,000 people in a population
higher in less developed countries due to lack of access to healthcare, clean water, or enough food
higher IMR = higher TFR due to families having replacement children
factors in IMR decline
access to:
clean water
healthcare (hospitals, vaccines, vitamins, supplements)
reliable food supply
development (affluence) affecting TFR
more developed or wealthy nations have a lower TFR than less developed nations
more educational access for women
more economic opportunity for women
higher access to family planning education and contraceptives
later age of first pregnancy
less needs for children to provide income through agricultural labor.
government policy affecting TFR
can play a huge role in fertility by coercive (forceful) for noncoercive (encouraging) policies
forced or voluntary sterilization
china’s 2 child policy
tax incentives to have fewer children
microcredits or loans to women without children to start a business.
malthusian theory
earth has a human carrying capacity, probably based on food production
human population growth happens faster than growth of food production
humans will reach a carrying capacity limited by food
technological environment
humans can alter earth’s carrying capacity with innovation
ex: synthetic nitrogen fixation leading to synthetic fertilizer.
growth rate ( r )
% increase in a population (usually per year)
crude birth and death rate (CBR and CDR)
births and deaths per 1,000 in a population
rule of 70
dividing the number 70 by the population growth rate to get the time it takes for a population to double (in years)
calculating growth rate
(CBR-CDR)/10
factors that increase population growth
higher TFR = higher birth rate
high IMR can drive up TFR (replacement children)
high immigration rates
increased access to clean water, food, and healthcare (decreased death rate).
factors that decrease population growth rate
high death rate
high IMR
increased development
increased education for women
delayed age of first pregnancy
postponement of marriage age
standard of living
what the quality of life is like for people of a country
gross domestic product (GDP)
key economic indicator of standard of living
total value of the goods and services produced
per capita GDP is total GDP/total population
High GDP & life expectancy are both indicators of development & low pop. growth
life expectancy
key health indicator of standard of living
average age a person will live in a given country
increases with access to water, food, and healthcare.
industrialization
the process of economic and social transformation from an agrarian/farming economy to an industrial one.
pre-industrialized/less developed
a country that has not yet made the agrarian to industrial transition
typically very poor (low GDP)
typically high death rate and high infant mortality
high TFR for replacement children and agricultural labor
industrializing/developing
part-way through this transition
decreasing death rate and IMR
rising GDP
industrialized/developed
completed the transition
very low DR and IMR
very high GDP
low TFR
stage 1 - preindustrial
high IMR and high death rate due to lack of access to clean water, stable food supply, and healthcare
high TFR due to lack of access to
education for women
contraceptives / family planning
need for child agricultural labor
little to no growth due to high CBR and CDR balancing each other out
little to no countries in phase 1.
stage 2 - industrializing/developing
modernizations bring access to clean water, healthcare, and stable food supplies
IMR and CDR decline
TFR remains high due to
lack of education for women and contraceptives / family planning
need for child agricultural labor
generational lag (it takes time for education and societal change to spread).
rapid growth due to high CBR and declining CDR
economic / societal indicators
low per capita GDP
shorter life-expectancy
high infant mortality
high TFR
low literacy rate and school life expectancy for girls.
stage 3 - developed/industrialized
modernized economy and society increase family income, so TFR decreases significantly due to
more educational opportunities for women
delayed age of marriage and first child to focus on education / career
access to family planning and contraceptives
slowing growth rate as CBR drops closer to CDR
economic / societal indicators:
high per capita GDP
long life-expectancy
low infant mortality
TFR near replacement level
high literacy rate and school life expectancy for all.
stage 4 - post-industrialized/highly developed
highly modernized countries that are very affluent
TFR declines even further as families become more wealthy and spend even more time on educational and career pursuits
increased wealth and education brings even more prevalent use of family planning and contraception
CBR drops lower than CDR and growth becomes negative
economic / societal indicators:
very high per capita GDP
longest life-expectancy
TFR below replacement level
highest contraceptive use rates
Note 
Flashcard (41)