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APES Chapter 4,6,7


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the study of populations
population dynamics
the study of population change (growth)
members of the same species living in the same area
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
(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.
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
2.natural selection
3.genetic drift
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
niche= profession, role in the environment
a relationship between 2 organisms that is beneficial to both
factors that influence diversity
latitude + altitude (biogeography)
environmental stress
human involvement
ecological gradient
the change in abundance of a species over a distance

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