APES - Unit 3 Population

specialists

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

generalists

larger range of tolerance; broader niche makes them lass prone to extinction and more likely to be invasive; broad food requirements; high adaptability

biotic potential

maximum reproduction rate of a population

K-selected

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

r-selected

“quantity;” many offspring, little to no care; 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 pop. growth rate; more like to be invasive; better suited for rapidly changing environments

K-selected

-low biotic potential = hard for pop. to recover after a disturbance

-high parental care means death of parent = death of offspring

-invasives (usually r) outcompete for resources with high biotic potential and rapid pop. growth

-less likely to adapt and more likely to go extinct

r-selected

-high biotic potential = more rapid pop. recovery after disturbance

-low parental care means death of parent doesn’t impact offspring

-not as impacted by invasive species since their pop. grows quickly (more likely to BE the invasive)

-larger population and faster generation time = higher chance of adaptation and lower chance of extinction

survivorship curve

line that shows survival rate of a cohort (group of same aged individuals) in a population

from birth to death

faster drop in line

what type of line in survivorship curves shows quicker die-off of individuals?

slower drop in line

what type of line in survivorship curves shows longer average lifespan?

Type 1 Survivorship Curve

(mostly 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

Type 1, K-selected

What survivorship curve do mammals and humans fall into? Are they K-selected or r-selected?

Type 2 Survivorship Curve

(in between r and K)

-steadily decreasing survivorship throughout life

Type 2, in between r and K

What survivorship curve do birds typically fall into? Are they K-selected or r-selected?

Type 3 Survivorship Curve

(mostly r-selected)

-High mortality (low survivorship) early in life due to little to no parenting

-few make it to midlife; Slow, steady decline in survivorship in midlife

-Even fewer make it to adulthood; slow decline in survivorship in old age

Type 3, r-selected

What survivorship curve do insects, fish, and plants typically fall into? Are they K-selected or r-selected?

carrying capacity

(k) The maximum number of individuals in a population that an ecosystem can support (based on limiting resources)

**population briefly “overshoots” (k) and then die-off happens**

food, water, habitat (nesting sites, space)

What limiting resources determine the carrying capacity?

overshoot

when a population briefly exceeds carrying capacity (ex: deer breed in fall, give birth all at once in spring; sudden spike in population = ____)

Consequence of overshoot

resource depletion (ex: overgrazing in deer)

die-off

Sharp decrease in population size when resource depletion (overshoot) leads to many individuals dying (ex: many deer starve with too many new fawns feeding in spring)

2. the lynx pop. increases due to increase in food (hare)

In the Predator-Prey Cycle, what happens after 1. the hare pop. increases due to low predator pop.(lynx)?

3. the increasing lynx pop. limits the hare pop.; leads to die-off

What happens after 2. the lynx pop. increases due to increase in food (hare)?

4. hare die-off decreases lynx food source, leading to die-off

what happens after 3. the increasing lynx pop. limits the hare pop.; leads to die-off?

5. hare pop. increase due to low predator pop. (lynx) (back to step 1 beginning of process)

what happen after 4. hare die-off decreases lynx food source, leading to die-off?

size (n)

total number of individuals in a given area at a given time

safer from population decline

what does a lager size population mean?

density

Number of individuals/area (ex: 12 panthers/km²)

high density

higher competition, possibility for disease outbreak, Possibility of 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

50:50

what is the ideal sex ratio for breeding (usually)

die-off or bottleneck effect

what can lead to skewed sex ratio (not enough females) limiting pop. growth?

density dependent factors

factors that influence pop. growth based on size (examples limit pop. growth rate based on their size: aka-small populations don’t experience these factors, large do)

density- dependent factors

the following are examples of what:

• food

• competition for habitat

• water

• light

• disease

density independent factors

factors that influence population growth, independent of their size (it doesn’t matter how big or small a population is natural disasters limit them both)

density-independent factors

the following are examples of what:

• natural disasters (flood, hurricane, tornado, fire)

biotic potential

exponential growth

logistic growth

initial rapid growth, then limiting factors limit population to k

biotic potential

max potential growth rate, with no limiting resources (competition, food, disease, predators) slow growth, and eventually limit population to carrying capacity (k)

population size (calculating population change)

(immigrations + births) - (emigrations + deaths)

age cohorts and growth

groups of similarly aged individuals

prereproductive

0-14

reproductive age

15-44

post reproductive

45+

pre-reproductive

the higher the growth rate, the larger the __________ age group

pre-reproductive

the population is in decline if the reproductive age group is larger than the __________ age group

growth rate

size difference between 0-14 and 15-44 indicates _______

current and future growth

large 0-14 cohort

slight growth/stable

roughly equal 0-14 and 15-44

population decline

larger 15-44

rapid growth

extreme pyramid shape

slow, stable growth

less extreme pyramid

stable, little to no growth

house

declining population

narrowest at base

total fertility rate (TFR)

average number of children, a woman in a population will bear throughout her lifetime

higher TFR

higher birth rate, higher population growth rate (generally)

replacement level fertility

the TFR required to offset deaths in a population and keep population size stable (about 2.1 in developed countries → replaced mom and dad)

• higher in less developed countries due to higher infant mortality

infant mortality rate (IMR)

number of deaths of children under 1 year per 1000 people in a population

• higher in less developed countries due to lack of access to health care, clean water, enough food

• higher ___ = higher TFR, due to families having replacement children

2

if a population in a developed country is stable, TFR is closest to __

3

if a population in a developed country has a positive growth rate above zero, the TFR is closest to __

1

if a population growth in a country is negative and population size is decreasing, TFR is closest to __

2.5

developing countries usually have a higher replacement level fertility like ___ or above

factors in IMR decline

the following are factors to what:

• access to clean water

• More reliable food supply

• access to healthcare (Hospitals, vaccines, vitamins and supplements for moms and babies)

development (affluence)

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

• more educational access for women

• More economic opportunities for women

• higher access to family planning education and contraceptives

• Later age of first pregnancy

• Less need for children to provide income through Agricultural labor

government policy

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

affluence and TFR

• More access to contraceptives and family planning

• education/economic opportunities require time, leaving less for raising children

• lower IMR = lower TFR

Female Education and TFR

• more education = Fewer unplanned pregnancies

• more education = more job opportunities for women (alternative to marrying young)

Malthusian Theory (what Malthus theorized)

• Earth has a human caring capacity, probably based on food production

• Human population growth is happening faster than growth of food production

• humans will reach a carrying capacity limited by food

the haber-bosch process

what process allowed humans to increase food population?

through technological innovation (ex: synthetic fixation of nitrogen in 1918 leads to synthetic fertilizer, Dramatically increasing food supply

how can humans alter earths carrying capacity?

growth rate (r )

% increase in a population (usually per year) (ex: a _____ of 5% for a population of 100 means they grow to 105)

crude birth rate and crude death rate (CBR and CDR)

births and deaths per 1000 people in a population

global population growth rate (calculating growth rate (r ))

_______ = [CBR-CDR] / 10

rule of 70

The time it takes (in years) For a population to double is equal to 70 divided by the growth rate

doubling time

______ = 70 / % growth rate

factors that increase population growth

the following factors are what:

• higher TFR → higher birth rate

• higher IMR can drive up TFR (replacement children)

• High immigration level

• increase access to clean water and healthcare (decrease death rate)

factors that decrease population growth rate

the following factors are what:

• 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 the quality of life is like for people of a country based

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

life expectancy

Key health indicator of standard of living

• average age a person will live to in a given country

• increases with access to clean water, healthcare, stable food sources

high GDP and life expectancy

indicators of development and low population growth

industrialization

The process of economic and social transition from an agrarian (farming) Economy to an industrial one (manufacturing based)

pre-industrialized / less developed

• A country that has not yet made the agrarian moves 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

• partway through this transition

• Decreasing death rate and IMR

• rising GDP

industrialized / developed

• completed the transition

• Very low death rate and IMR

• Very high GDP

• Low TFR

• Most likely to fall under stage three or four of the demographic transition model

stage 1 - pre-industrial

• 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 and contraceptives/family planning

• need for child agricultural labor

• Little to no growth due to high CBR and CDR Balancing each other out

• (ex: virtually no country is in phase 1)

stage 2 industrializing / developing

• modernizations bring access to clean water, healthcare, stable food supply (IMR and CDR decline)

• TFR remains high due to lack of education for women and contraceptives/family planning, Need for child agricultural labor, Generational lab (takes time for ed. and societal changes to spread)

• Rapid growth, due to high CBR and declining CDR

• this is where most of the world’s population is currently

economic/societal indicators of stage 2 - industrializing / developing

the following are what:

• 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 increased family income, so T4 decline 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 for stage 3 - developed/industrislized

the following are what:

• High per capita GDP

• Long life expectancy

• Low infant mortality

• TFR, near replacement level (2.1)

• 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 (pop. decline)

economic/societal indicators of stage 4 -

post-industrialized/highly developed

the following are what:

• Very high per capita GDP

• Longest life expectancy

• TFR, below replacement level (2.1)

• Highest contraceptive use rates

virtually no country is in phase 1 ( Africa?)

which countries are in stage 1 - preindustrial

where most of the world’s population is currently

which countries are in stage 2 - industrializing/developing?

United States, Canada, and much of Europe

which countries are in stage 3 - developed/industrialized?

United Kingdom, Germany, Italy, and Japan

which countries are in stage 4 - post industrialized / highly developed?