Exam 2 - Lecture Notes Flashcards
Define life table
age-specific mortality schedule of a population
Define cohort life table
an age-specific mortality schedule based on following a cohort throughout life
Define the variables in the life table (x nx lx dx qx)
x = age nx = # alive at age x lx = proportion surviving from start to age x dx = # dying during age interval x to x+1 qx = per capita rate of mortality during age interval x to x+1
Define a Type I survivorship curve
Low mortality for most of life (higher mortality of older organisms)
Example of Type I survivorship pop
Humans
Define a survivorship curve
Per capita rate plotted on a logarithmic scale to make a curve - uses Nx column of life table
Define a Type II survivorship curve
Constant rate of mortality
Example of a Type II survivorship curve
Small mamals
Define Type III survivorship curve
High mortality rates early in life, followed by a lower/constant mortality rate
Examples of Type III survivorship curve
Invertebrates, Song sparrow of BC
Define static life table
calculated from cross section of a population at a specific time, like a snapshot. Easy for humans (census) harder for plants and animals
Example of a static life table
Human females in Canada, 2006 - data taken from a census
Find the age intervals, fill in data, calculate qx
What are the three types of data used for non-human life tables (list)
Survivorship directly observed
Age at death observed
Age structure directly observed
What is surviroship directly observed
Following a single cohort until death to create a cohort life table
Example of surviroship directly observed
Connell’s classic competition experiment following two species of barnacles Chthalamus and Semibalanus
What are the assumptions of age at death observed and what is it
1 - that the pop size is constant through t
2 - birth and death rates for each group are constant
This is a method for creating a non-human life table
Examples of age at death observed (3)
1 - Baboons in Kenya National Park - 274 females ID and aged at death
2 - Murie examined Dall Sheep in National Park Alaska - direct observations and collecting skulls (608) analyzed to create static life table
3 - Human demography data collected from cemetery
Define age structure directly observed and state an assumption
Forming static life tables by determining how many individuals exist at each age. Assume constant age distribution (rare)
Examples of age structure directly observed
1 - fish through otolith and body scales
2 - tree rings through core samples
Define Malthusian parameter
The intrinsic capacity for increase (r) determined by combined effects of both the environment and certain innate qualities of the organism
What are the variables of the malthusian parameter and what do they mean
lx - capacity for increase (proportion surviving to age x)
bx - births (# of female offspring produced per female aged x to x+1, often only females counted)
R0 - net reproductive rate - rate per generation obtained by lx * bx and summing across all groups
Define net reproductive rate (R0)
The rate per generation obtained by multiplying lx and bx and then summing across all groups, which weighs natality against number of survivors per interval
Define R0 values vs 1
R0 = 1, pop replaces itself exactly = stable
R0 < 1, pop decreasing
R0 >1, pop increasing
What did Lotka show that would eventually create a stable age distribution? What is the equation?
That when a pop has constant natality and mortality rates, it would approach a stable age distribution
dN/dt = rN
What is the mean length of generation in terms of r?
r = ( ln R0) / G where G = 1 , r = ln R0
For mean length of generation in terms of r, define significance of r in relation to 0
r = 0, pop stable
r > 0, pop up
r < 0, pop down
Define finite rate of increase (lambda)
net reproductive rate over a certain t interval - long t interval
What is lambda equal to and what does it mean in comparison to 1
lambda = R 0
lambda = 1, stable
lambda > 1, up
lambda <1, down
Define population dispersion
pattern of spacing among individuals within a certain area (NOT DISPERSAL)
List the three main types of dispersion
Clumped Distribution
Random Distribution
Uniform Distribution
Define clumped distribution
A model of dispersion where individuals have a higher probability of being found in some area than in others = pattern
Animal example of clumped distribution
school of fish
Plant example of clumped distribution
Plants, but water in a desert
What is the process of clumped distribution
Attraction b/t individuals or attraction of individuals to a common resource - perhaps more common in areas with spotty resources
Define Uniform Distribution
A model of dispersion where the individuals are regularly spaced = pattern
Example of uniform distribution
Birds on a wire (distance to peck)
What is the process of uniform distribution
Result of antagonistic interactions b/t individuals or local depletion of resources - where individuals repel each other
Define Random distribution
A model of dispersion where the individuals have an equal chance of living anywhere within the area, cannot predict one with knowledge of another
What is the process of random distribution
A result of neutral interactions between individuals and even between them and the environment
What are the types of population growth
Exponential Pop. growth
Logistic Pop. growth
Define exponential pop growth & state what kind of pop appropriate for
Continuous pop growth in an unlimited environment appropriate for a pop w/ overlapping generations - the rate of growth keeps increasing over time
What is the equation for exponential pop growth and define the variables and state if constant
dN/ dt = r(m)N
r(m) = max per capita rate of increase - constant
N = pop size - increases
Example of exponential pop growth
Scots Pine colonizing after a glacial recession - used pollen from lake sediments and grew at exponential rates for 500 yr about 9500 years ago
Define logistic pop growth & state curve shape
As pop size increase, growth rate eventually slows and then ceases as pop size levels off, resulting in a s-shaped curve
Define carrying capacity (K)
The number of individuals of a particular pop that the environment can support
When growth stops, b=d, growth = 0
Equation for logistic pop growth and explain variables
dN/dt = r(m) *N *(1 - N/K)
r(m) = max per capita rate of increase (usually larger than r - realized per capita rate of increase)
(1- N/K) gets smaller until N=K where growth is then 0
In the logistic model, what does realized per capita rate of increase depend on
r= r(m) *(1-N/K) is dependent on the population size
In logistic growth, what is the relationship between r, r(m) and N?
When in is very small, r approx equals r(m)
As N increase, r will decrease until N=K and then r=0
It is a straight line with r decreasing as N increases
For the logistic model, compare N and K
N < K, r is positive as pop grows
N = K, r = 0 and growth stops
N > K, r is negative and pop declines
What is an example of logistic pop growth lab
Paramecium (Gause) put 20 in a tube and added constant quantity of bacteria each day as food and every 2nd day he washed away waste.
Growth was slow 5 days, rapid 5 days, then leveled off after 10 days
Example of logistic pop growth in the field
Ibex pop following successful reintroduction to switzerland; slow to increase early, mid-30s increase, level off in the 60s and then oscillations around K
What are the assumptions of the logistic model
1 - the rln b/t density and rate of increase is linear
2 - the pop has a stable age distribution initially
3 - the density has been measured in appropriate units
4 - the depressive influence of density on the rate of increase operates instantaneously without any time lags
What is an example of the density being measured in appropriate units for the logistic model?
Flies - model may be adding larger individuals at the start of growth and smaller individuals near the end - maybe it would be more accurate to measure biomass instead of flies
List the types of models of Logistic growth
Deterministic models
Stochastic models
Define deterministic models
A model of logistic growth that, given certain initial conditions, predicts one exact outcome (red line) with a clean, smooth line
Define stochastic models
A model of logistic growth that recognizes that population trends represent outcomes of many individual probabilities, with some observations higher than normal and others lower.
Use given data to create prob masses that represent a range of possible values the pop could follow
Example of stochastic model factors
1 - # of young born per female or # taken by predators
2 - flip a coin to determine # of offspring, h = 1 t = 3
Define competition
two species seek or use the same limited resource to the detriment of both
Ex competition b/t 2
Owl vs red-tailed hawk - both eat same types of things, and the owl even uses the red hawk nest
What kinds of things do plants compete for
Light, water, nutrients, space, or even pollinators
What kinds of things do animals compete for
Water, food, mates (access to mates), or space for safe nesting/roosting
Ex competition in the wild
More than just 2 species - Red-tailed Hawk, Broad-winged Hawk and Great Horned Owl
broad and red are in the same genus, but the broad is smaller
Define resource competition
Utilize common resources that are in short supply. Doesn’t need to be directly, just thru gain and use where all individuals affected equally
Define interference competition
Harm one another in the process even if the resource is not in short supply
Example of interference competition
Wolf and coyote - both nocturnal and both eat small animals
What are the two models of interspecific resource competition
- Lotka - Volterra competition model
2. Tilman’s Competition model
What is the Lotka- Volterra Competition Model
It is an interspecific resource competition model that predicts coexistence of 2 species when, for both species, interspecific competition is weaker than intraspecific competition
Otherwise, one species is predicted to exclude the other
Define species 1 and species 2 of Lotka Volterra and give an example
Species 1 - high utilization rate, 16 individuals supported (wolf)
Species 2 - much less utilization per individual, so 64 supported (coyote)
Give the logistic equations for species 1 and 2 in the Lotka - Volterra model
dN1/dt = r1N1 [( K1 - N1 - alphaN2 )/K1] dN2/dt = r2N2 [K2 - N2 - betaN1)/K2]
What are the competition coefficients of the Lotka volterra model and what does that mean
alphaN2 and betaN1 show the effect on an individual of the species stated in the above, on the pop growth of the opposite species
Competition coefficients compared to 1
alpha > 1, competitive effect of an individual of speccies 2 on the pop growth of species one is GREATER THAN that of an individual of species 1
alpha < 1, the copetitive effect of an individual of species 2 on the pop growth of species 1 is LESS THAN that of an individual of species 1
When will Lotka-Volterra pop growth stop?
When N1=K1-alphaN2 and N2= K2 - betaN1
L.V. growth model graph - equilibrium stable vs unstable
Equilibrium: when the lines cross in a graph
Stable: when vectors are directed towards the point (K1 and K2 are on the INSIDE)
Unstable: when vectors are directed away from the point (K1 and K2 are on the OUTSIDE)
growth model L.V. - how do you know which species “wins”
N1 wins when the N2 isocline is contained within the N1 space (look at axis)
Define Tilman’s growth model
Similar to Lotka-Volterra but with a mechanism - considers a response to 2 essential resources, and the rate of consumption of each
Response to 2 essential resources - what it means to increase or decrease
when either resource is low, pop declines
both are high, pop increases
Zero growth isocline is in the middle
Plant and animal examples of 2 essential resources
plant - H20 and N
animal - calories and Na+
What is the rate of consumption for the tilman model determined by?
It is determined by the slope of consumption vectors
Evidence in the lab of the tilman model - gause
2 species of yeast : the limiting factor was narrowed to [ethyl alcohol] as waste built up
Evidence in the lab of tilman model - bug
two species of grain beetle with limiting factor determined to be environmental T
Define niche
sum of environmental factors that influence the growth, survival, and reproduction of a species (when, where, and how a species makes its living)
Define competitive exclusion
Gause stated that 2 species with identical niches cannot coexist indefinitely
What 2 things does the competitive exclusion principle state about when 2 species compete
1- one species will be a more effective competitor for limited resources
2 - eventually exclude all individuals of the second species
What is a fundamental niche
The physical conditions under which a species might live in the absence of interactions with other species
What is a realized niche
The portion of the fundamental niche that a species actually exploits in the presence of competitors
Example of realized niche
2 species of Barnacles -Chthamalus is smaller and better able to resist desiccation so they live on the higher rocks whereas Balanus is on the lower. But, when Balanus removed, Chthamalus lives everywhere
Define competitive release
Shift in a species niche as a result of competition - converse of competitive exclusion
Define niche overlap
When 2 or more organisms use a portion of the same resource simultaneously, food or habitat
Give an example of niche overlap
feeding positions of 5 warbler species in coniferous forests
Define character displacement
Resulting from directional selection for reduced niche overlap
Define character release
response to removal of a competitor
Example of character release
Grebes, both prey on small fish, so there was a change in bill morphology. When together, red-necked only 40mm and great-crested is 50 but apart both 50
List the two life history strategies
r selection
K selection
Define r selection
A life history strategy that favors a higher population growth rate - strongest in the species often colonizing new or disturbed habitats
Define k selection
A life history strategy that favors more efficient utilization of resources such as food and nutrients - strongest in species with pop near their carrying capacity
Define exploitation
One organism makes its living at the expense of another
Define herbivoes
consume plant material but rarely kill them
define predators
kill and consume other organisms
define parasites
live on the tissues of their hosts, but generally do not kill them
define parasitoids
insect whose larvae consume its host, killing it in the process
define pathogens
include disease, a debilitating condition, in their host
Example in our lab of parasitoid, predator, and herbivore
Gall Fly is herbivore, wasps are the parasitoids, and birds are the predator
Define the parameters of the Lotka-Volterra pop cycle
1 - that the host pop grows at an exponential rate
2 - that the host pop size is limited by its parasites, pathogens or predators
What is the equation for the Lotka-volterra prey pop cycle with variables defined
rate of change = dNh/dt = r(h)N(h) -pN(h)N(p)
r(h)N(h) = exponential growth of the host pop
pN(h)N(p) = deaths due to parasitism or predation
N(h) = # hosts
N(p) = # predators
What is the equation for the Lotka-volterra predator pop cycle with variables defined
rate of change = dNp/dt = cpN(h)N(p)-d(p)N(p)
N(h) = # hosts
N(p) = # of parasites or predators
cpN(h)N(p) = rate at which predators or parasites convert hosts to offspring
pN(h)N(p) = rate at which exploiters destroy host
c = conversion rate into offspring
d(p)N(p) = predator deaths
What are the only two variables in the lotka-volterra predator and prey pop cycle equations?
N(h) and N(p)
What are the two assumptions of the Lotka-Volterra pop cycle
1 - neither the host nor the exploiter are subject to carrying capacities
2- changes in either pop are instantaneously translated into responses in the other pop (unrealistic)
What are the results of the Lotka-Volterra pop cycle
Reciprocal effects on host and exploiter pops with reciprocal oscillations when #s plotted against t
When do you get an elliptical oscillation as the lotka-volterra pop cycle graph?
When you plot host #s to exploiter #s
Example in the lab of Lotka-Volterra pop cycle
Gause - predator = aquatic protazoan Didinium; prey = paramecium
Grow together - both extinct
Sediment added to bottom - predators ate all available/non-hiding prey then go extinct, prey pop then increase
Only maintain oscillations if periodically added (immigration) individuals of both pops (no refuges)
What are the two components of predation?
functional response
numerical response
Define functional response
response of an average predator to the abundance of prey - whether an individual predator eats more prey when they are abundant
Define numerical response
response of a predator pop to a change in prey density - whether the density of prey will change as prey numbers increase
Example of functional response
Lynx exhibit Type II and cannot eat above certain level, fixed by handling time
Example of numerical response
Lynx #s increase as hare #s increase - lag effects and prey response to form a counterclockwise spiral shape
Where is the largest biomass of plants consumed by herbivores?
In the grasslands at 30-50% of all consumption
List the four hypothesis of plant defense
1 - Optimal Defense Hypothesis
2 - Resource Availability Hypothesis
3 - Plant Stress Hypothesis
4 - Plant Vigor Hypothesis
Define the optimal defense hypothesis
Defenses maximize individual fitness but there is a high cost - supported by the apparent plant theory
What is the plant apparency theory
States that the type and amount of defense varies with the vulnerability of the tissue and that some plants have quantitative defenses (tannins and resins) whereas others have qualitative defenses
What is an apparent plant
An apparent plant is easily found and usually contains quantitative defense compounds - tannins and resins
What is an unapparent plant
An unapparent plant is not easily found and usually contains qualitative defenses - general poisons
What is the problem with the plant apparency theory
Telling if a plant is apparent or not
What is the resource availability hypothesis
Plants with more resources available will be able to grow faster
Define slow growing plant
A plant that stands to lose more to herbivores (difficult to replace) and thus invest more in defense compounds
Example slow growing plant
tree
define fast-growing plant
stand to lose less to herbivores (tissues easily replaced) invest less in defense compounds
example fast-growing plant
Grasses
What is the prediction of the resource availability hypothesis
the higher the growth rate, the lower the investment in defenses
Define inducible defenses
When plants activate chemical defenses only when attacked (induced by herbivore) - most valuble tissues well defended
Example of inducible defenses
Ascophyllum snails induced tannins in basil shoots in two weeks
What are two things herbivores do to be not helpless
evolve enzymes to detoxify plant chemicals and alter their life cycle to avoid plant chemicals
What is the plant stress hypothesis
Abiotically stressed plants become optimal for herbivory, increased nitrogen yet reduced water
what is the plant vigor hypothesis
Herbivores attack vigorously growing plants rather than stressed plants
what is an example of the plant vigor hypothesis
Moose browse young growing green shoots of birch trees and seems to be immune to plant defense chemicals
Is herbivory detrimental?
Not all herbivory is detrimental - grazing on grasses can be positive
Define mutualism
interactions between individuals of different species that benefit both
define facultative mutualism
species that can live without their mutualistic partner
define obligate mutualism
species that cannot live without their mutualistic partner
Plants and mychorrhizal fungi example
fungi provides plants with greater access to phosphorus, copper, zinc and N
Plants provide fungi with carbohydrates
What are the two types of mycorrihizal fungi
Arbuscular mycorrhizal fungi (AMF)
Ectomycorrhizae (ECM)
What three things arbuscular mycorrhizal fungi (AMF) produces
1- arbuscules - sites of exchange b/t plant and fungi
2- hyphae - special fungal filaments efficient water uptake
3- vesicles - fungal E storage organs in root cortex cells
What is ectomycorrhizae
the fungus forms a mantle around the roots and a net-like structure around root cells
What is the relationship between ants and the swollan-thorn acacia
The acacia provides the ants with: shelter, food, beltian bodies (leaflet tips with concentrated oils and protein), and foliar nectaries (sugar and liquie)
Acacia benefits by having its shoots growing faster when they are present and having less predators
What is diffuse mutualism
Involving more than one species, as in some pollinators and others
What is an example of diffuse mutualis
Coniferous trees, mycorrhizae, and voles in the pacific northwest
Tree depends on fungi for nutrient uptake (obligate)
Fungi depends on coniferous for E in carbo form (obligate)
Fungi has facultative rln with voles bc they eat the fruiting bodies
Coniferous has facultative with voles bc they will spread spores in fecal pellets to new trees
