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Population
the totality of organisms of the same species occupying the same area at the same time
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Species
group of individuals that can interbreed and produce viable offspring
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Population size
# of individuals in a population
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Density
# of individuals per unit area or volume
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birth rate
the # of individuals added annually to the present population through reproduction per 1000 individuals
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death rate
the # of individuals who die annually per 1000 individuals
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Natural Growth rate
CBR-CDR= P*100= NGR
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Immigration
when new individuals enter and reside within a population
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Emigration
- or out-migration
- happens when individuals leave the population
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Doubling time
- = Total growth rate
- the length of time it will take for a population to double in size
- 70/Growth rate(ln%)
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Clumped type of dispersion
- individuals grouped in clumps
- found in nature
- ex. moss, school of fish
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Uniform pattern of dispersion
- individuals are evenly spaced
- rarely happens in nature
- ex. phytoplankton
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Random type of dispersion
- each individual is independent from the rest
- more rare
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Sex ratio
- # of male relative to # of females
- irrelevant for some organisms
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Operational Sex ratio
ratio of sexually receptive males to sexually receptive females
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productivity is linked to
non pregnant people
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Age distribution
the # of individuals in each stage of its life cycle
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Pre-productive
larvae of insects, fingerling of tilapia, plant seedlings, babies
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Reproductive
sexually mature insects, plants with flowers and fruits, chicks with period
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Post reproductive adults
no longer capable of sexual reproduction such as annual/ biennial plants that have shed their seeds, tilapia that have spawned, women in menopause
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What would happen if there was an increase in:
1. Pre-productive
2. Post reproductive
3. Reproductive
- 1. rapid growth
- 2. decline
- 3. baby boom
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wider base
needs a good support system to take care of young and old
Guatemala, Saudi Arabia
Rapid growth
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US, Aus, Canada
Slow Growth
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Germany, Bulgaria, Sweden
can't support oldies
(-) Growth
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Spain, Austria, Greece
base<-> same
Zero Growth
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lag phase
- low population density
- adjust to the environment, no sexual maturity
- acclimation and adjustment
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What is found on a typical growth curve?
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exponential phase
increase in # of individuals
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plateau phase
competition and survival
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What shape is the growth curve of humans?
J-shaped
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optimal # of individuals that can survive in a specific area over time
Carrying capacity
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What happens when the carrying capacity is exceeded?
- population losses
- availability of resources would decrease
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totality of the factors that would tend to limit the population
all limiting factors
environmental resistance
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What are the two reproductive strategies?
R-strategy
K-strategy
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larger animals which rear offsprings
long life span, give birth to young
limited by?
- K-strategist
- density-dependent factors
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Density dependent factors:
1.
2.
3.
- Density dependent factors:
- 1. competition for resources
- 2. territory
- 3. crowding and stress
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smaller organisms
produce large number of eggs and/ offsprings
quantity over quality
R-strategist
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The population of the r-strategists reaches the carrying capacity. The population is limited by density dependent.
F A L S E
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Density Independent factors:
1.
2.
3.
- 1.climate
- 2.anthropogenic desruction
- 3. natural disasters
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# of survivors:
Type 1 flipped J
Type 2 /
Type 3 pabaliktad na J
- Type 1: Late loss= loss is late @ the cycle
- Type 2: Constant loss= same amt. of loss
- Type 3: Early loss= R strategists
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Total Population Growth
(CBR +Imm) -(CDR+ Em)
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Life expectancy
average # of years an infant is expected to live
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Infant mortality Rate
# of babies of every 1000 born annually that die before reaching ----
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Why are death rates lower in MDC than LDC?
- Nutrition
- Improved Sanitation
- Medical and public health technology
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