AP Environmental Science Unit 3

Specialists: Smaller range of tolerance, or narrower ecological niche makes them more to (blank)

extinction

Characteristics of a specialist species

Specific food requirements (bamboo)

Less ability to adapt to new conditions

Generalists: Larger range of tolerance, broader niche makes them less (blank)

prone to extinction & more likely to be invasive

Characteristics of a generalist species

Broad food req.

High adaptability

K-selected - “quality” characteristics

few offspring, heavy parental care to protect them

Generally have fewer 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 env. change or invasives

R-selected - “quantity” characteristics

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 likely to be invasive

Better suited for rapidly changing env. conditions

Survivorship Curve

line that shows survival rate of a cohort (group of same-aged individuals) in a pop. from birth to death

Faster drop in line =

quicker die-off of individuals

Slower drop in line =

longer avg. lifespan

Type I (mostly K-selected) characteristics

High survivorship early in life due to high parental care

High survivorship in mid life due to large size & defensive behavior

Rapid decrease in survivorship in late life as old age sets in

Type II (in between r & K) characteristics

Steadily decreasing survivorship throughout life

Type III (mostly r-selected) characteristics

High mortality (low survivorship) 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

Pop. briefly “overshoots” (k) and then (blank)

die-off happens

Highest pop. size an ecosystem can support based on limiting resources:

Some examples are (blank)

Food

Water

Habitat (nesting sites, space)

Consequence of overshoot:

resource depletion

Die-off:

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

Size (N):

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

larger pop. size = safer from (blank)

pop. decline

Density:

# of individuals/area

High density = higher competition, possibility for (blank)

disease outbreak, possibility of depleting food source

Distribution:

how individuals in pop. are spaced out compared to each other

ratio of males to females. Closer to 50:50, the more ideal for (blank)

breeding

Density-Dependent Factors:

factors that influence pop. growth based on size

Density-Independent Factors:

factors that influence pop. growth independent of their size

Biotic Potential = max. potential (blank)

growth rate, with no limiting resources

Population Change equation

(immigrations + births) - (emigrations + deaths)

Larger 0-14 cohort

Roughly equal 0-14 & 15-44

Larger 15-44

• current and future growth rate

• slight growth rate/stable

• pop. decline

Extreme Pyramid shape

rapid growth

Less extreme pyramid

slow, stable growth

House

stable, little to no growth

Narrowest @ base

declining pop.

The replacement level fertility for developed countries

About 2.1 in developed countries

Malthusian theory

• Earth has a human carrying 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

Technological Advancement

• Humans can alter earth’s carrying capacity with tech. Innovation

Calculate growth ratee

CBR- CDR/10

Stage 1 - Preindustrial

High IMR & high death rate due to lack of access to clean water, stable food supply, and healthcare

High TFR due to lack of access to:

• Ed. for women

• Contraceptives/family planning

• Need for child agricultural labor

Little to no growth due to high CBR & CDR balancing each other out

Stage 2 - Industrializing/Developing

Modernizations brings access to clean water, healthcare, stable food supply

IMR & CDR decline

TFR remains high due to

• Lack of ed. for women & contraceptives/family planning

• Need for child agricultural labor

• Generational lag ( takes time for ed. & societal change to spread

Rapid growth, due to high CBR and declining CDR

Stage 3 - Developed/Industrialized

Modernized economy and society increase family income, so TFR declines significantly due to

• More ed. opportunities for women

• Delayed age of marriage & first child to focus on ed./career

• Access to family planning & contraceptives

Slowing growth rate as CBR drops closer to CDR

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 & career pursuits

• Increased wealth & education brings even more prevalent use of family planning & contraception

CBR drops lower that CDR & growth becomes negative(pop. decline)