Exam 3 Content Flashcards
what is a population?
interbreeding group of organisms of the same species in the same area
what is Exponential growth?
Unrestricted growth, which rate depends on the number of individuals in the population
All populations can do this but cannot be maintained due to resource limitations
how is discrete exponential growth calculated?
N = NoRo^t
Ro = net reproductive rate
Number of females produced per current female
No = initial population size
N = population size
T = time
in what population/breeders do discrete exponential growth occur?
Non-overlapping breeders
Discrete breeders
Ex) Moth breeds once and dies
Ro = 1.9 No = 600
N = (600)(1.9)^2
N = 2166
what is Continuous exponential growth?
Breeding can go on all the time
Has overlap of generations
how is continuous exponential growth calculated?
ΔN/Δt = (rate)N
Δ = number of individuals per unit time
N = number of individuals
r = intrinsic rate of increase
N = Noe^rt
Ex) Head lice
r = 0.028/day
N = 1000 adult life
ΔN/Δt = (0.028)(1000) = 28/day
N = Noe^rt
N = 1000e^(.028)(5)
when should each formula for exponential growth be used?
N = NoRo^t predicts population size (non-overlapping)
ΔN/Δt = rate predicts growth rate (overlapping)
N = Noe^rt predicts population size (overlapping)
what is Logistic Growth?
Restricted growth
How is logistic growth calculated?
Carrying capacity of the environment (K)
Max population size
Population size vs time → S-shaped curve
ΔN/Δt = rN(K-N/K)
Example: Population size is low
K-N^r0/K → K/K
Example: Population size is average
N = K
K-N/K = 0 → ΔN/Δt = 0
No growth
what is Population Regulation?
this limits population growth
what are Density Independent Factors?
Not influenced by population size
Individual population size does not matter
abiotic factors
what are abiotic factors?
examples:
Climate
Fire
Floods
Hurricanes
Tornadoes
what are Density Dependent Factors?
The effect depends on population size
Instenifive as population size increase
Prediction
Disease
Competition
Crowding stress
Newly introduced species can increase population size rapidly when in the new environment there is no predators, competition, and parasites
what is Demography?
Study of vital statistics that affect population growth
how is demography calculated/measured?
Nfuture = No + B - D + I - E
No = current
B = birth rate
D = death rate
I = immigration rate
E = emigration rate
what is Survivorship?
Primary measure for assessing population dynamics
Mirror image of mortality
Assess it by lx
Proportion of original cohort (individuals produced at the same time) surviving to age x
when does survivorship vary?
- Among species
Humans survive longer than dogs - Between sexes in a species
Females live longer than males - Environmental conditions
Developed vs developing countries
what is a Type 1 Survivorship curve?
occurs in K-selected organisms
Low mortality until old age
Produce few offspring
Examples: Elephants, humans (developed countries), rotifers, etc.
what is a type 2 survivorship curve?
Constant mortality throughout life
Examples: Lizards, songbirds, seagulls, etc.
what is a Type 3 Survivorship curve?
occurs in r-selected organisms
High juvenile mortality
Few survive to adulthood
Examples: Insects, oysters, etc
what is Fecundity?
an organism’s reproductive capacity
what is age-specific fecundity and how is it measured?
Age-specific fecundity = mx = # of daughters/female at age x
The highest birth rate in humans is 20
Only measure females because females determine the population size
what is a life table?
Summarize populations demographic parameter
Calculate Ro = net reproductive rate
Ro = Σlxmx
what is age distribution?
Graphical representation of the proportion of the population at each age class
Can influence population growth
Can tell you if the population is growing or not growing
The female side is always fatter than the male side because females live longer
what are Life History Strategies?
All the characteristics that affect survival and reproduction
Natural selections should produce organisms that produce the highest r (intrinsic rate of increase)
Copies of your genes make it to the next gene pool
Depends on the environmental conditions
what is r-Selected Strategy?
Opportunistic life history
Form a continuum
Geared towards rapid life cycle completion in an unpredictable environment
Tramps → high r value
Reproduce early and often
Density independent
Exploit resources rapidly and disperse offspring everyone
Even if it costs them their life
what is a K-selected strategy?
Equilibrial life history
Competing for resources in a stable environment
Population size in near carrying capacity (K)
Quality not quantity of kids
Few, well provisioned kids
Density dependent
Lots of other oransgism like them
Compete
Take care of their young to compete among others
Climax forest
what are the parameters of r-selected strategy?
Survivorship Curve - Type 3
Life Span - Short
# of offspring - High
# of lifetime reproductive events - Once (semelparous)
Environment - Variable
General strategy - Productivity
what are the parameters of K-selected strategy?
of offspring - few
Survivorship Curve - Type 1 and 2
Life Span - Long
# of lifetime reproductive events - Several (iteroparous)
Environment - Stable
General strategy - Efficiency
what is Demographic transition?
A demographic device that explains the relationship between population growth and development
Why doesn’t birth rate drop as fast as death rate?
Historical view - that you need lots of children
Labor on a farm
Desire to increase your numbers compared to other countries or tribes
Many children = prestige (for males)
Lack of birth control (availability or knowledge)
what are the 7 challenges of human population growth?
- Agricultural productivity
Uneven food distribution - Dependency on non-renewable resources (fossil fuels)
Increases CO2 in the atmosphere) - Loss of biodiversity
The rate of deforestation is very high
Species are disappearing rapidly - Accumulation of pollutants
9 million premature deaths attribute to this - Water stress
1.2 billion people experience water stress
Water scarcity - Desertification
Good soil is limited and we are losing it
Takes away cropland - Climate change
The greatest impact on people who are least responsible for it
Most vulnerable to health issues
Ecological interactions with species A and B?
-
Predation
+
-
Parasitism
+
-
Mutualism
+
+
Comencilism
+
O
Amentulism
-
O
which ecological interactions are often clustered under the term symbiosis?
Parasitism, Mutualism, and Comencilism
what is a Niche?
range of abiotic and biotic conditions in which an organism can survive and reproduce (conditions they can live in)
what is a fundamental niche?
all the resources an organism can theoretically use (can use all of these resources if there are no other organisms around)
what is a realized niche?
portion of the fundamental niche that is actually utilized
what is the Competitive exclusion principle?
Limit to the amount of niche overlap that will allow 2 species to coexist → niches cannot be identical