2.1 Population, Reproduction, and Demography

reproductive strategies

logistic growth

• follows an S curve

reproductive strategies

• k-selected species/k-strategists: populations that tend to stabilize over time near carrying capacity and maximize survival
    * eg. elephant, oak tree
• r-selected species/r-strategists: populations that have a high biotic potential who invest their energy into producing lots of offspring in a short time, maximizing reproduction
    * eg. cockroach, dandelion
• survivorship: the percentage of a cohort that survives at certain ages
    * can be recorded in life tables and survivorship curves

demography

development

• more developed country (MDC): a country with a higher GDP per capita
• less developed country (LDC): a country with a lower GDP per capita

demography

• demography: the study of statistics such as births, deaths, income, or the incidence of disease, which illustrate the changing structure of human populations
• natality: the production of new individuals by birth
• birth rate: the number of live births per 1000 people in a population per year
• life expectancy: the probable number of years of survival for an individual of a given age
    * often calculated at birth
    * good estimate of the overall life quality of a country
• infant mortality rate (IMR): the number of deaths of infants under one year old per year per 1,000 live births
    * people tend to have more children when they don’t think their kids will live to adulthood
    * high IMR → high fertility rate

demographic transition model

• demographic transition: falling death and birth rates due to improved living conditions that come with economic development

age structure

• total fertility rate (TFR): the number of children born to an average woman in a population during her entire reproductive life
• replacement fertility rate (RFR): the number of births at which the population is simply replacing itself
    * more developed countries, ~2.1 per couple (over 2 because children die)
• total fertility rates are decreasing globally, but are mostly still about replacement fertility rates
• age structure: the proportion of the population at each age level
    * helps develop our understanding of the number/percentage of male and female people in the pre-reproductive, reproductive, and post-reproductive ages
    * represented through population pyramids
• population momentum explains why a population will continue to grow even if the fertility rate declines

solving the population problem

the infamous overpopulation bet

• Stanford biologist Paul Ehrlich predicted that millions of people would starve to death as the population increased faster than the food supply
    * drew from Thomas Malthus’ idea that population growth would outpace food supply
    * 1968 book “the population bomb”
• Julian Simon found no historic correlation between increased population and decreased standards of living — he found the opposite
    * believed in human ingenuity

solutions to overpopulation

• ecological footprint: a figure that expresses the impact that a person or population has on the environment
    * often measured in terms of land and water needed to provide resources and dispose of waste

overpopulation vs. overconsumption

• reducing world population growth
    * birth → population (N) → death
      * decrease natality, not mortality
    * reduction of poverty
    * improvement of the status of women
      * women are largely in charge of childcare and domestic work
      * women work 2/3 of all hours worked globally but receive 1/10 of the pay
      * women own a small fraction of the world’s property
        * women can’t own land or property in some countries
      * women constitute 2/3 of the illiterate population
      * women receive less health care and often die of pregnancy-related health issues
    * encouragement of family planning