Population & Biodiversity Study Guide

Unit 6: Population & Biodiversity STUDY GUIDE
You can write on this sheet or on another sheet of paper. FILL IN THE FOLLOWING BLANKS WITH THE
1. Populations can be described in terms of three things:
a. Population size = number of total individual in a population (all members of the same species living in the
same area)
b. Population density = number of individuals per unit area
Population dispersion = distribution of individuals within a given space: The 3 types of dispersion
are (provide definition & example):
i. Random = random placement; Ex: seen in some plants
ii. Uniform = evenly spaced – helps reduce competition; Ex: sea turtles nesting, cacti in desert
iii. Clumped = small, close groups – helps in defense & reproduction; Ex: herds, packs, flocks
2. Growth rate = change in pop size over time; (B + I) – (D + E)
a. Occurs when new individuals are added by birth or immigration
Or when individuals are lost due to death or emigration
3. Reproductive potential = max number of offspring that an individual can produce
a. High reproductive potential is seen in organisms like: bacteria, insects, rodents, protists, clams, frogs, etc.
4. The two kinds of population growth are:
a. Exponential growth; J-shaped
i. Defined as: rapid, continuous growth
ii. Occurs when there’s plenty of resources, little competition and predation
b. Logistic growth; S - shaped
i. Defined as: rapid growth followed by leveling off at carrying capacity
ii. Occurs when the population levels off at carrying capacity
5. Carrying capacity = maximum number of individuals an ecosystem can support
6. Factors that limit population growth are:
a. Density-dependent factors (related to pop size)
i. Examples: limited resources, disease, predation
b. Density-independent factors (control pop regardless of size)
i. Examples: natural disasters, humans – habitat destruction, pollution, etc.
7. There are 2 kinds of organisms with respect to population growth:
a. r-selected organisms = organisms with high reproductive rate to balance high death rate of offspring
i. Examples: frogs, insects, clams, small mammals
b. k-selected organisms = organisms that have a longer generation time, late sexual maturity, & fewer young
i. Examples: elephants, whales, birds, large mammals, humans
8. Demography = study of human populations
9. Developed countries examples: USA, Canada, Australia, Japan, England, France, Italy, Germany, etc.
a. Have HIGH or LOW birth rate? LOW
10. Developing countries examples: Mexico, China, India, Haiti, Jamaica, Egypt, Peru, etc.
a. Have HIGH or LOW birth rate? HIGH
11. Properties used to predict future population changes:
a. Doubling time = time it takes for a pop growing at a specific rate to double its size
b. Fertility rate = number of babies born each year per 1,000 women; high in developing countries
c. Migration = movement into an area
d. Age structure = distribution of ages in a country
i. Developing countries’ age structure diagrams look like pyramid/ triangle
ii. Developed countries’ age structure diagrams look like rectangles; more even among age classes
Demographic Transition = model that shows the effects of economic and social changes on a population’s birth
and death rates
Current human population ~ 7 billion
a. What affects a country’s population growth:
i. Type of economy
ii. Status of WOMEN
iii. Cultural beliefs such as the importance of sons
iv. Religious beliefs
b. Problems with human population growth include (name at least 5 problems):
i. Resource depletion, esp. nonrenewable resources
ii. Water & air pollution
iii. Loss of farmable land
iv. Loss of biodiversity
v. Diseases
c. Ways governments slow down population growth: advertising, family planning programs, economic
incentives, legal punishments. Ex: China’s One-Child Policy; Thailand’s funny commercials
Biodiversity: Number of species on Earth is estimated to be 10 million; actual number known is 1.7 million
Biodiversity can be studied at three levels:
a. Species diversity = number of different species in an area
b. Ecosystem diversity = variety of habitats, communities, and ecological processes in an ecosystem
c. Genetic diversity = all the different genes contained within the population’s gene pool
Why is biodiversity important? (1) W dependent on healthy ecosystems to ensure balanced nutrient cycles; (2) we
use a variety of organisms for food, clothing, shelter & medicine; (3) bioethics – some believe it’s the moral thing
to do to save organisms; (4) aesthetic value & personal enjoyment
High biodiversity can be found in tropical rain forests, coral reefs, coastal areas, and islands
Biodiversity hotspots = have high numbers of endemic species and are threatened by humans
a. Endemic species = species found only within a limited area
Endangered species = species in immediate danger of extinction
Threatened species = species who’s populations are declining
Threats to biodiversity include:
a. Habitat fragmentation and destruction
b. pollution
c. invasive species – not native to an area and causing problems
d. overharvesting
Solutions to the loss of biodiversity include:
a. Captive breeding programs and zoos
b. Important Law: Endangered Species Act of 1973
c. IUCN stands for: International Union for the Conservation of Nature and Natural Resources
d. CITES stands for: Convention on International Trade in Endangered Species