APES Chapter 4,6,7
Terms
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- demography
- the study of populations
- population dynamics
- the study of population change (growth)
- population
- members of the same species living in the same area
- species
- all individuals capable of interbreeding
- growth rate equation
-
(birthrate)-(death rate)
*doesn't account for immigration/emigration - crude birth, death, growth rates
- those numbers out of 1,000
- age structure
- the proportion of a population in each age class
- total fertility rate (TFR)
- the expected number of children, per woman, per lifetime
- replacement-level fertility
- when TFR equals 2.1
- population momentum
- (lag effect)
- history of human population growth (major booms)
-
1. hunter-gatherers
2. neolithic culture--> agriculture
3. Industrial Revolution
4. the present - what is the approximate world population?
- 6.3 billion (and growing!)
- how do we project future population growth? (3 methods)
-
a. exponential growth
b. doubling time
c. logistic growth curve + carrying capacity - logistic growth curve
- s-shaped curve that portrays a J-curve until the line hits carrying capacity and levels off into an "s." The point of the turn in the "s" is the inflection point
- stages of demographic transition
-
1. high birthrate; high death rate (LDC)
2. high birth; low deathrate (transition)
3. low birthrate; low deathrate (MDC) - environmental effect of people on the environment (equation)
- (impact per person)* (number of people)
- methods of achieving zero population growth
-
a. delay marriage (childbirth)
b. birth control
c. economic rewards/ penalties - population age structure graphs: PYRAMID
- many young ppl, high deathrate, short average lifetime, LDC (ex/ Kenya)
- population age structure graphs: inverted pyramid
- many old people, low deathrate, long average lifetime (ex/ Italy)
- population age structure graphs: column
- birthrate and deathrate are low, many older people, MDC (ex/ USA)
- population age structure graphs: column w/ bulge
- occurs if some event caused a high birth/deathrate for some age groups but not others (ex/ baby boom)
- zero population growth
- the number of births equals the number of deaths and there's no net change (this can't really be accurate though because of lag time)
- maximum lifetime
- the genetically determined possible age to which an individual can live
- life expectancy
- the avg. number of years an individual can expect to live given his present age
- limiting factors
-
SHORT TERM (immediate and temporary--> drought)
INTERMEDIATE-TERM (effects seen after 1 but before 10 yrs --> pesticide use)
LONG TERM (effects not seen until after a decade --> soil erosion) - basic characteristics of ecosystems
- structure, processes (chemical cycling, energy flow), change
- ecological community
- a set of species interacting w/in the ecosystem
- ecological succession
- the process of establishment and development of an ecosystem
- food chains/ food webs
- the linkage of who feeds on whom (the latter being more complex)
- trophic levels
- conists of all those organisms in a food web that are the same number of feeding levels away from the original source of energy --> SUN
- 1st, 2nd, 3rd trophic levels
-
1. producers aka autotrophs
2. consumers (herbivores)aka heterotrophs
3. consumers (carnivores) aka heterotrophs - decomposers/detritivores
- (ex/ bacteria and fungi) feed on wastes and dead organisms on all trophic levels. (detritivores have mouths)
- community-level effect
- when interaction between 2 species leads to changes in the presence or absence of other species or in a large change in abundance of other species
- keystone species
- (ex/ sea otter) has a large effect on its comminity or ecosystem. it's removal or addition to the community leads to major changes in abundances of many other species
- holisitc view
- everything affects everything else. an ecological community is more than the sum of its parts.
- watershed
- a commonly used practical delineation of the boundary of an ecosystem on land. w/in a watershed any drop of rain that reaches the ground flows out in the same stream. topography determines watershed.
- biological diversity
- the number of species in an area, or the number of genetic types
- biological evolution
- refers to change in inherited characteristics of a population from generation to generation. it can result in speciation.
- The 4 processes which lead to evolution
-
1.mutation
2.natural selection
3.genetic drift
4.migration - mutation
- a chemical change in a DNA molecule. this can affect the expressed characteristics when cells or individuals reproduce
- natural selection
- "survival of the fittest"--> those best fitted for survival will be more abundant
- genetic drift
- changes in the frequency of a gene in a population not due to anything but chance
- the 3 qualities of species diversity
-
species richness (total # of species), evennes (the relative abundance of species), and dominance (the most abundant species)
species diversity has to do with the relative chance of seeing a species as opposed to actual numbers - 3 groups classifying life on earth
-
1. eukaryota (animals, plants, fungi, protists--> has nucleus)
2. bacteria
3. archaea (both have no nucleus) - competitive exclusion principle
- 2 species that have exactly the same requirements cannot coexist in the same habitat
- habitat vs. niche
-
habitat=home
niche= profession, role in the environment - symbiosis
- a relationship between 2 organisms that is beneficial to both
- factors that influence diversity
-
latitude + altitude (biogeography)
environmental stress
human involvement
etc - ecological gradient
- the change in abundance of a species over a distance