APES unit 3 (populations)

specialist

specialist

smaller range of tolerance, or narrower ecological niche makes them more prone to extinction (specific food requirements, less ability to adapt to new conditions)

generalist

larger range of tolerance, broader niche makes them less prone to extinction and more likely to be invasive (broad food requirements, high adaptablility)

k-selected (quality)

few offspring, heavy parental care to protect them; generally have fewer reproductive events than r-strategist; long lifespan, long time to sexual maturity=low biotic potential=slow pop. growth rate; more likely to be disrupted by environmental changes (ex: most mammals, birds)

r-selected (quantity)

many offspring, little to no care; may reproduce only once, but generally reproduce many times throughout lifespan; shorter lifespan, quick to sexual maturity=high biotic potential=high pop. growth rate; more likely to be invasive; better suited for rapidly changing environmental conditions

biotic potential

the maximum rate at which a population could increase under ideal conditions

survivorship curve

line that shows the survival rate of a cohort in a pop. from birth to death

cohort

group of same-age individuals

faster drop in survivorship curve line

quicker die-off of individuals

slower drop in survivorship curve line

longer average lifespan

type I (mosty K-selected)

high survivorship early in life due to high parental care; high survivorship in midlife due to large size and defensive behavior; rapid decrease in survivorship in late life as old age sets in (ex: most mammals)

type II (in between R and K)

steadily decreasing survivorship throughout life

type III (mostly r-selected)

high mortality early in life due to little to no parental care; few make it to midlife; slow, steady decline in survivorship in mid life; even fewer make it to adulthood - slow decline in survivorship in old age (ex:insects, fish, plants)

carrying capacity (k)

the max number of individuals in a pop. that an ecosystem can support (based on limiting resources like food, water and habitat)

overshoot

when a pop. briefly exceeds carrying capacity

die-off

sharp decrease in pop. size when resource depletion (overshoot) leads to many individuals dying

size (n)

total number of individuals in a given area at a given time (larger=safer from pop. decline)

density

number of individuals/area (higher density=higher competition, possibility for disease outbreak, possibility of depletion food source)

distribution

how individuals in a pop. are spaced out compared to each other (random, uniform or clumped)

sex ratio

ratio of males to females, closer to 50:50, the more ideal for breeding (usually); die-off or bottleneck effect can lead to skewed sex ratio, limiting pop. growth

density-dependent factors

factors that influence pop. growth based on size

examples of density dependent factors

food, competition for habitat, water, light, disease, predation, ect.

density-independent factors

factors that influence pop. growth independent of their size

examples of density-independent factors

natural disasters (flood, hurricane, tornado, fire), migration habits, seasonal temp. changes, ect.

exponential growth

biotic potential, growth without limits

logistic growth

initial rapid growth, then limiting factors limit pop. to k

calculating pop. change

pop. size = initial pop. + (immigrations + births) - (emigrations + deaths)

age cohorts

groups of similarly aged individuals

prereproductive

0-14 year olds

reproductive age

15-44 year olds

post reproductive

45+ year olds

larger prereproductive cohort

current and future growth

roughly equal prereproductive and reproductive cohorts

slight growth/stable

larger reproductive age

pop. decline

extreme pyramid shape

rapid growth

less extreme pyramid

slow, stable growth

house

stable, little to no growth

narrowest at base

declining pop.

total fertility rate (TFR)

average number of children a woman in a pop. will bear throughout her lifetime (higher TFR=higher birth rate=higher pop. growth rate)

replacement level fertility

the TFR required to offset deaths in a pop. and keep pop. size stable (about 2.1 in developed countries to replace the mom and dad)

infant mortality rate (IMR)

number of deaths of children under 1 year per 1,000 people in a pop. (higher in less developed countries due to lack of access to healthcare, clean water, enough food, ect.)

higher IMR=

higher TFR, due to families having replacement children

factors in IMR decline

access to clean water, access to healthcare (hospitals, vaccines, vitamins, supplements, ect.), more reliable food supply, ect.

development (affluence)

more developed, or wealthy nations have a lower TFR than less developed nations

examples of development (affluence)

more educational access for women, more economical opportunity for women, higher access to family planning education and contraceptives, later age of first pregnancy, less need for children to work

government policy

can play a huge role in fertility by coercive (forceful) or noncoercive (encouraging) policies

examples of government policies

forced or voluntary sterilization, china's 1 (now 2) child policy, tax incentives to have fewer children, microcredits or loans to women without children to start businesses

Malthusian theory

earth has a human carrying capacity, probably based on food production; human pop. growth is happening faster than growth of food production

technological advancement

humans can alter earth's carrying capacity with technology innovation

growth rate (r)

% increase in a pop. (usually per year)

crude birth rate (CBR)

births per 1,000 people in a pop.

crude death rate (CDR)

deaths per 1,000 people in a pop.

calculating growth rate (r)

(CBR-CDR)/10

doubling time (rule of 70)

the time it takes (in years) for a pop. to double is equal to 70/r (growth rate)

factors that increase pop. growth rate

higher TFR=higher birth rate; high infant mortality rate can drive up TFR (replacement children); high immigration level; increased access to clean water and healthcare (decreased death rate)

factors that decrease pop. growth rate

high death rate; high infant mortality rate; increased development (education and affluence); increased education for women; delayed age of first child; postponement of marriage age

standard of living

what quality of life is like for people of a country

life expectancy

key health indicator of standard of living

gross domestic product (GDP)

key economic indicator of standard of living

industrialization

the process of economic and social transition from an agrarian (farming) economy to an industrial one (manufacturing basesd)

pre-industrialized/less developed

a country that has not yet made the agrarian to industrial transition, typically very poor/ low GDP

industrializing/ developing

part way through the transition from agrarian to industrial transition, decreasing death rate and IMR, rising GDP

industrialized/developed

completed the transition from agrarian to industrial, very low death rate and IMR, very high GDP, low TFR