APES unit 3

specialists

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