Populations Test Flashcards
Birth rate (BR)
(# of births per year/total population) * 100
Death rate (DR)
(# of deaths per year/total population) * 100
zero population growth (ZPG)
Occurs when BR = DR (approximately)
Crude Birth Rate (CBR)
(# of births per year/1000 people) * 100
Crude Death Rate (CDR)
(# of deaths per year/1000 people) * 100
Crude infant mortality rate/child mortality rate
(# of deaths of infants or children/1000 live births) * 100
What does a high infant mortality rate mean?
Countries that are considered “developing” tend to have high infant and child mortality rates because of lack of access to food, clean water, and healthcare. This could be due to lack of financial stability in the country to invest in these resources: climate change, political instability/hostility
Total Fertility Rate (TFR)
estimate of the average number of children that each woman in a population will have throughout their childbearing years
What does TFR reveal about cultural values/expectations of the country?
Women can pursue educational and professional pathways; their roles in society are expanded past the household. This is made possible by expanded access to family planning (contraceptives/birth control).
What does TFR reveal about the socio-economic status of the country?
Low TFRs are found in more developed countries. Children aren’t needed for labor. Stable access to food, medicine, clean water so kids are more likely to survive. You don’t need to replace them in order to have people who help with labor. Young girls are attending school, then growing up and joining the workforce. This pushes back the window in which women normally have kids. They don’t normally have kids starting at 17.
Replacement Level Fertility (RLF)
the fertility rate required for the population to remain a constant size (2.1)
Explain how the TFR of a country can decrease, but the population still experiences growth
immigration
population momentum (once children grow up after 20-30 years they could have children of their own. The TFR is above 2.1. Will grow slowly over time)
Imagine a population with a high proportion of young people due to previously high birth rates. Even if the fertility rate drops, this large group of young individuals will eventually reach reproductive age and start having children themselves. Although each woman has fewer children on average, the sheer number of women in this age group can lead to a substantial number of births. As a result, the population keeps growing for several decades even though fertility rates have stabilized. Eventually, as the age structure balances out (with fewer people being born and more aging out of the reproductive group), the population will stop growing and may even start shrinking if fertility remains at or below replacement.
What does a high RLF mean?
High because people in developing countries need children for labor, and developing countries typically have high child mortality rates so they need to replace the children they had.
Expanding Rapidly Age Structure Diagram
- Developing countries
- high TFR but kids are not making it to adulthood
- RLF rate is also high
- pre-reproductive age is the greatest % of the population
- kids needed for labor or need to be “replaced” unfortunately
- exponential growth
Expanding Slowly Age Structure Diagram
- The pre-reproductive age group still represents the largest portion of the population, just less compared to the pyramid
- This population will grow, just not as quickly as it once did
Stable Age Structure Diagram
- aka the “column” diagram
- the proportions of each age group remain constant over time
- RLF is 2.1, Ex: norway, sweden, finland
Declining Age Structure Diagram
- aka inverted “pyramind”
- post reproductive age group is the largest portion of the population
the pre-reproductive age group is the smallest - the birth rate is well below RLF, Ex: China, Japan
Demographic Transition
We say that countries over a period time go (eventually) through all four stages, but the amount of time spent during each stage is what creates specificity for a country’s demographics
Stage 1: Pre Industrial Age
- BR and DR are very high and around equal to each other
- total population remains low and constant (ZPG)
Stage 2: Transitional
- BR stays high, DR drops dramatically
- Dr drops because of improved access to clean water, food, and health care
- Less people are dying, life expectancy goes up
- Total population increases
Stage 3: Industrial
- BR drops and DR continues to drop at a slower rate
- Total population continues to grow
an expanded role women/young girls play in society (they are going to school or working) - Children are not needed for labor
less children dying - TFR decreases as a result
Stage 4: Post Industrial
- BR and DR at at their lowest points and around equal to one another
- Total population approached ZPG
- Higher proportion of post reproductive age -> less workers and less kids
Exponential Growth (Unrestricted Growth)
“biotic potential” refers to the max reproductive rate of a population in “ideal” conditions. Happens in small bursts.
Logistic Growth (Restricted)
Happens overtime. A population evens out because it reaches carrying capacity due to other factors.
Overshoots in Logistic Growth Curve
Organisms that are thriving continue to reproduce and causes an overshoot. This usually leads to a large drop in population and a drop in carrying capacity. This is because resources become more scarce because of the overshoot so carrying capacity drops. resources can be prey, plants, space
Density-Dependent Factors
- predators
- water
- food
- shelter
- disease
- number of mates
These factors increase or decrease competition
Density-Independent Factors
- climate change
- natural disasters
- anthropogenic (human caused) activities, Ex: deforestation, damming rivers, pollution generated from fossil fuels
K - Selected Species
- Life span: Long
- Time to reproductive maturity: Long
- # of offspring: Few
- Size of offspring: Large
- Parental care: Present
- Population growth rate: Logistically/Slow
- Population Dynamics: Stable, near carrying capacity
- Examples: Large mammals like elephants, humans, kangaroo
R - Selected Species
- Life span: Short
- Time to reproductive maturity: Short
- # of offspring: Many
- Size of offspring: Small
- Parental care: Absent
- Population growth rate: Exponential/Fast
- Population Dynamics: Highly variable
- Examples: Small organism like rats, cockroaches, dandelions
K-selected species tend to exhibit which type of on number of survivors graph?
r-selected species tend to exhibit which type of curve on number of survivors graph?
K-Selected: Type 1 (exponential decay graph upside down)
R-Selected: Type 2 (exponential decay graph)
Generalists
These are species that tend to be advantaged in habitats that are changing. R selected species. Includes invasive species.
Specialists
These are species that tend to be advantaged in habitats that remain constant. Includes endangered species.
Population Density
of people / area
Population Growth Rate (r)
r = (BR - DR) %
Annual Growth Rate (r)
r = (CRB - CDR) * 100
ex: (38/1000 - 12/1000) * 100
if migration info given, then add or subtract it (depending on if more people immigrated or emigrated)
ex: ex: (38/1000 - 12/1000 + 2/1000) * 100
Population Change
(Births + Immigration) - (Deaths + Emigration)
Doubling Time
time in years it takes for a population to double assuming that the growth rate (r) remains constant
dt = 70 / r
keep r as a %
which stage of demographic transition is the expanding rapidly age structure diagram in?
stage 2
pyramid shape
this is because the birth rate stays high and death rate drops so total population increases
which stage of demographic transition is the expanding slowly age structure diagram in?
stage 3
less dramatic pyramid shape
this is because BR drops and DR continues to drop at a slower rate
because of an expanded role women/young girls play in society (they are going to school or working)
children are not needed for labor
less children dying
TFR decreases as a result
which stage of demographic transition is the stable age structure diagram in?
stage 1 and 4
column shape
this is because BR and DR are equal to each other in both of these stages
which stage of demographic transition is the declining age structure diagram in?
stage 5
inverted triangle shape
Not on demographic transitions graph
this is because RLF is below 2.1
Ex: China, Japan
