APES Unit 3 Test

Specialists

Specialists

Smaller range of tolerance, or narrower ecological niche makes them more prone to extinction

• Specific food requirements (bamboo)

• Less ability to adapt to new conditions

Generalists

Larger range of tolerance, broader niche makes them less prone to extinction & more likely to be invasive

• Broad food requriements

• High adaptability

K-selected species

• 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 species

• 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 Survivorship Curve

• Mostly K-selected

• 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

  • Ex: most mammals

Type II

• In between r and K

• Steadily decreasing survivorship throughout life

Type III

• Mostly r-selected

• 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

  • Ex: insects, fish, plants

Carrying Capacity (k)

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

  • Food

  • Water

  • Habitat (nesting sites, space)

• 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 ex: overgrazing in deer

• Die-off: sharp decrease in pop. size when resource depletion (overshoot) leads to many individuals dying

  • Ex: many deer starve with too many new fawns feeding in spring

Which diagram of carrying capacity is theoretical? Which is more realistic?

Figure 1 is theoretical, and Figure 2 is more realistic

Describe relative population changes in a predator-prey relationship.

Population fluctuation cycle

1. Prey population increases due to low predator population

2. Predator population increases due to higher prey population

3. Prey population decreases due to higher predator population

4. Predator population decreases from prey die-off

Population size

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

• Larger = safer from population decline

Population density

Number of individuals per unit area

• High density = higher competition, possibility for disease outbreak, possibility of depleting food source

Population distribution

How individuals in pop. 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, the more ideal for breeding (usually)

• Die-off or bottleneck effect can lead to skewed sex ratio (not enough females) limiting pop. growth

Density-Dependent Factors

Factors that influence pop. growth based on size

• Ex: food, competition for habitat, water, light, even disease

• All of these things limit pop. growth based on their size; aka - small pop. don’t experience these, large do

Density-Independent Factors

Factors that influence pop. growth independent of their size

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

• It doesn’t matter how big or small a pop. is, natural disasters limit them both

Biotic potential

Max. potential growth rate, with no limiting resources

• May occur initially, but limiting resources (competition, food, disease, predators) slow growth, & eventually limit pop. to logistic growth, or carrying capacity (k)

  • Exponential growth

Calculating population change

(Immigrations + Births) - (Emigrations + Deaths)

Age Cohorts

Groups of similarly aged individuals

• 0-14 = prereproductive; 15 - 44 = reproductive age; 45 + = post reproductive

• Size difference between 0-14 & 15-44 indicates growth rate

  • Larger 0-14 cohort = current & future growth

  • Roughly equal 0-14 & 15-44 = slight growth/stable

  • Larger 15-44 = pop. decline

Population growth of an extreme pyramid (age structure diagram)?

Rapid growth

Population growth of a moderate pyramid (age structure diagram)?

Slow, stable growth

Population growth of a house-shaped age structure diagram?

Stable, little to no growth

Population growth of an age structure digram that’s narrowest at its 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, higher pop. growth rate (generally)

Replacement Level Fertility

The TFR required to offset deaths in a pop. and keep pop. size stable

• About 2.1 in developed countries (replace mom & dad)

  • 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: health care, clean water, enough food

• 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 for moms &  babies)

  • More reliable food supply

Factors that affect TFR

• Development (Affluence): more developed, or wealthy nations have a lower TFR than less developed nations

  • More educational access for women

  • More econ. opportunity for women

  • Higher access to family planning education & contraceptives

  • Later age of first pregnancy

  • Less need for children to provide income through agricultural labor

• Gov. Policy: can play a huge role in fertility by coercive (forceful) or noncoercive (encouraging) policies

  • Forced or vol. sterilization

  • China’s 1 (now 2) child policy

  • Tax incentives to have fewer children

  • Microcredits or loans to women without children to start businesses

Affluence and TFR

• More access to contraceptives & family planning

• Ed./econ. 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

• 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

  • Ex: synthetic fixation of Nitrogen in 1918 leads to synthetic fertilizer, dramatically increasing food supply

Growth Rate (r)

% increase in a population (usually per year)

Crude Birth Rate & Crude Death Rate (CBR & CDR)

Births & deaths per 1,000 people in a population

Calculating Growth Rate

(CBR - CDR)/10; should always be expressed as a percentage

Rule of 70

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

Factors that increase human population growth

• Higher TFR  → higher birth rate

• High infant mortality rate can drive up TFR (replacement children)

• High immigration level

• Increased access to clean water & healthcare (decrease death rate)

Factors that decrease human population growth

• High death rate

• High infant mortality rate

• Increased development (education & 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

Gross Domestic Product (GDP)

Key economic indicator of standard of living

• Total value of the goods & 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, health care, stable food sources

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 to industrial transition

• Typically very poor (low GDP)

• Typically high death rate & high infant mortality

  • High TFR for replacement children & agricultural labor

Industrializing/developing

• part way through this transition

• Decreasing death rate & IMR

  • Rising GDP

Industrialized/developed

• completed the transition

• Very low DR & IMR

• Very High GDP

• Low TFR

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

• Econ./societal Indicators

  • Low per capita GDP

  • Shorter life-expectancy

  • High infant mortality

  • High TFR

  • Low literacy rate & school life expectancy for girls

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

• Econ./societal Indicators

  • High per capita GDP

  • Long life-expectancy

    • Low infant mortality

  • TFR, near replacement level (2.1)

  • High literacy rate & 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 & career pursuits

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

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

• Econ./Societal Indicators

  • Very high per capita GDP

  • Longest life-expectancy

  • TFR, below  replacement level (2.1)

    • Highest contraceptive use rates