Population and Community Ecology Flashcards
What is this a definition for?
Predicts how natural selection should shape the way organisms parcel their resources into making babies
Life history (theory)
Organism reproduces in one event
Semelparity
Organism reproduces throughout their life
Iteroparity
Life history can be p——– (seasonal) or c——— (but may fluctuate)
Pulsed, continuous
Each organism has a limited amount of energy that can allocate for maintenance, survival, growth and reproduction - L—-, 196-
Principle of allocation (Levon 1968)
There are i— individuals and i— generational trade-offs
Intra, inter
Give some examples of intra-individual trade-offs - 6 examples
Reproduction vs survival, reproduction vs growth, current reproduction vs future reproduction, no. of offspring vs size of offspring, no. of offspring vs survival of offspring, reproduction vs conditions
Give some examples of inter-generational trade-offs
Parental survival vs the number of offspring. Parental survival vs offspring condition.
Give an example for each of these survivorship curves:
Type 1
Type 2
Type 3
Humans, Birds, Trees (respectively)
Net reproductive rate = Survivorship * F——- (Look at equations in lecture 1)
Fertility
T/F R0 tells you how fast a population is growing
False (just tells you if it is growing or shrinking)
What is the equation for population growth rate?
= R0^1/T
If a population growth rate was 0.98, then a population would be growing / declining by -% each year
Declining, 2
The fundamental equation for an unstructured population size makes these assumptions:
1. U——- population
2. C—– population
3. Time-i—– around reproduction and survival
4. S——– breeding (birth pulse reproduction)
5. Pre——— census
unstructured, closed, invariant, seasonal, breeding
BIRTHS depends on per-capita f——- rate and offspring s—— rate from one year to the next
fertility, survival
The number of individuals n— year depends on the number of individuals THIS year multiplied by the probability they s—— and the b—- contribution
Survive, birth
Population growth rate is dictated by the symbol l—–
Lambda (review this lecture though. Lecture 2. It’s a big one)
What is the main difference between a structured and a unstructured population model?
- in a structured one,ndividuals starting b—— at a certain age
- Their survival & fertility is considered to be c—— once they reach that age
- The other unstructured assumptions remain
breeding, constant
The l—- in life-cycle diagrams just show us that an individual is staying in that class (ie. that age class)
loops
The structured population model not only tells us the total numner of individuals, but also the p——– of individuals in each class (ie. age / sex/ size / state)
proportion
Z— are included in the matrix projection models to NULLIFY irrelevant values, such as fertility when an individual is not old enough to breed
Zeros
In an MPM, does the state vector or the projection matrix give you the transitions amongst the different states
The projection matrix
In an MPM, what does the state vector give you?
It gives you the abundance of individual in each state
Together, the state vector and the projection matrix give you the p——- g—- r—
population growth rate (PGR)
In the column vector model, you f— the far right column and m—— everything in the column it then fulls in. The zeros do not count so they do not matter
flip, multiply
A growth model has 2 phases. What are they?
- The initial ‘transient’ phase
- The long term constant phase
T/F initial conditions affect long term behaviour
FALSE (they only affect short term behaviour. )
Each age / demographic class eventually settles down to a constant value,. This is known as the S—- P—— S——-
Stable population structure
T/F a computer can calculate stable population behaviour for us
True (we just need the projection matrix)
Do matrix projection models (MPMs) account for population strucure?
Yes
An MPM for stage-strucutre populations (which life stage an organism is in) will generally include:
1. ——-
2. ——
3. ——- rates amongst the states
Fertility, survival, transition
To build a MPM, you must consider:
1. When r——– happens
2. When we c—– the population
reproduction, census
Why are pre-breeding census more common?
May be due to logistical reasons, such as when species have offspring they may hide away more leading to underestimation, and knowing adult populations BEFORE breeding season could help to estimate the number of individuals entering the breeding season
In a post-breeding census, the youngest individuals are - years old, an individual which is j—— but matures next year contributes o——- and we have to discount additions through reproduction by the adult survival rate
juvenile, offspring
In a pre-breeding census, we have to DISCOUNT additions through reproduction by the n——- survival rate
newborn
T/F pre-breeding and post-breeding census have different long-term population growth rates
FALSE (they are THE SAME, only age classes are defined differently)
P——– A—— can use MPMs to produce simulations of how some aspect of demography changing may effect population growth
Pertubation Analysis
Pertibation analysis can be classified by:
i) the type of p——– we are interested in such as population growth
ii) the type of p——- such as a change in survival
property, pertubation
In pertubation analysis, we calculate the g—— of the line at the point on the graph we are interested in. We create a tangent. This gives us the rate of change of l—-
Gradient, lambda / population growth
When we calculate sensisivities we need:
1. The h— level matrix elements (just the elements with the numbers)
2. The l– level matrix parameters which give the ‘formulae’ or relevant parts i guess
- These are displayed in 2 different matrixes. Review lecture 3.
high, low
Definition: Gives you how much a dependent variable will change (ie. population growth) when we alter the independent variable (ie.survival) by a small amount
Sensitivity Analysis
When calculating a paremeter sensitivity which relies on two seperate paramaters (ie. survival and reproduction), we must calculate rates of c—– for both of these parameters and then m—— the effects and s– them to get their total ‘net’ effect.
- See lecture 3.
change, multiply, sum
Calculating parameter sensistivity can hep us deal with many drivers of c—-
Change. Such as climactic variable, species traits and anything to do with demography
Elasticities are needed because different parameters in s———- are on different s—- so cannot be used to show p——— changes in parameters or matrix elements
sensitivities, scales, proportional
Sensitivities only show a—– changes in parameters wheras elasticities show p—— changes which can be compared
- Lecture 3
absolute, proportional
Sensitivity analysis can resolve m—— pathways of effect when more than one thing effects population size
Multiple
Elasticity analysis gives better s——–
sensitivities
CASE STUDY: The desert tortoise is CRITICALLY endangerous due to r——— diseases, pet attacks, h—— loss and competition with livestock for f—.
Take 15 to – years to reproduce.
Respiratory, habitat, food, 20
CASE STUDY: Built an MPM on desert tortoises based around s—, considering survival, r——– and also growth. Used m—-c——-r—— to get data.
size, reproduction, mark-capture-recapture
CASE STUDY: Desert Tortoise. Conclusion was that the survival of —– individuals was the most important.
large
An intervention can help population growth by:
1. Affecting rates with l—- elasticities by a s—- amount.
2. Affecting rates with m——- elasticities by a —– amount
large, small, medium, large
CASE STUDY: Comparing mammal species. Used a t——- (triangular) plot to do this. Works like the Soil Triangle if u know u know xx. Found that f—— was best for ‘faster’ lived species
Ternary, fertility
CASE SUDY: Black-browed albatross.
Live in southern ocean. L—- concern, live for – years, mature at -to 9 years.
Least, 70, 7
CASE STUDY: Black-browed albatross. Considered a– and when they first reproduced and became ‘experienced breeders’. SST was most important c—— variable and transitions (f——) was the most important functional trait but not by much
age, climate, foraging
Problems with how phylogenies used to be derived:
1. Based on h—— and not rigorous scientific analysis
2. Too much reliance on s———- distribution of fossils from where the fossils were in rock and how old the rock does. This doesn’t necessarily make one thing the ancestor of another.
hunches, stratigraphic
What is this a definition of?
A table that lists terminal taxa as rows and the characters (presence of certain features) as columns. Each cell in the matrix is then coded with the character state applicable for each taxon-character combination. Used to calculate cladistic relationships by seeing what features organisms SHAREQ
Character Matrix
Give an example of analaguous characteristics
Wing shape in insects vs birds
Define homoplasy
The independent acquisition of the same trait in unrelated lineages
What is Cole’s paradox?
The fact that iteroparity abounds in nature despite the theoretical prediction that it would be easier to be semelparous as all you’d need to do is increase your offspring number by one.
Are most perennials itero or semelparous
Most perrenials are iteroparous.
When calculating a demographic model for a perennial species, you must consider the individuals which are —- ——- as well as those which have just produced seeds (lecture 5 see equations)
Still around
Why doesn’t Cole’s paradox actually work in reality?
1. Seed s—— CONSTANTLY assumed to be 1.
2. P——– surivival also CONSANTLY assumed to be 1
3. Populations are NOT limited by d—— d——– etc.
survival, perennial, density dependence.
The good news is analysis can account for these things
How must an iteroparous species ‘win’ against a semelparous one?
It’s fertility (seed production) per average lifespan must be HIGHER than the total lifetime seed production for the semeloarous ine.
Perennial production per lifespan must be higher than annual per year production (even though a year is essentially an annuals lifespan)
- See equation in lecture 5
Iteroparity is FAVOURED when:
1. Average adult s——- is high (longevity is good)
2. T——— variation in adult s—— is low (ie. s—— is ALWAYS high)
survival, temporal, survival
What kind of environment are r-selected species expected to evolve in?
A low-density, low competition environment (opposite is true of K-selected species)
Lecture 5:
The L—– g—– model shows us that r is favoured at Low densities (in that period of exponential growth - low N) and K at high densities when a pop is near / at it’s carrying capacity (high N)
logistic growth
What are the characteristics of a K and an r selective species?
R:
Many small offspring
Early reproduction
Small size
Short lived
K:
Few large offspring
Delayed reproduction
Large size
Long-lived
What is the problem with r / K selection theory?
We DO see these kind of species in nature, but selection would have to act on a POPULATION LEVEL
Generation time is hard to calcilate when rates of s——- and r——– VARY with age / a class
selection, reproduction.
Generation time is the average time between a birth of an i—— and their o——. Must be weighted by a–. Survivorship * fertility * age of an individual (lxmx) gives you this weight.
individual, offspring
It is harder to calculate gen time when the class is NOT a– and is something like s— instead. This is as:
1. Individuals can be in multiple s—- throughout their life.
2. Individuals in the SAME state may still have different t——— in life.
MPMs can calciulate this for us
states, trajectories
MPMs can give us:
- G——– time
- Average time of f—- reproduction
- L— expectancy
- S———– curves
generation, first, life, survivorship
What is levin’s principle of allocation?
Each individual has a finite quantity of resources which is can use for all necessary processes.
Understanding how life-histories are structured can help us understand:
1. E——-
2. A——– of a species
3. D———– of a species
evolution, abundance, distribution
The c——— d——— case study took many plant life histories to see if any charecteristics correlated. Ended up with 2 axis:
1. Fast-s— continuum (fast growth & short lived vs slow growth and long lived)
2. R———- strategy (highly reproductive & itero vs poorly & semel)
comparative demographic, slow, reproductive.
- Results showed patterns, such as if you were slow-growing you were unlikely to be short-lived. Can be used to predict life-histories of certain species with insufficient data.
What is r?
r is the intrinsix EXPONENTIAL population growth. It is calculated by subtracting deaths from births
dN/dt = bN-dN = r. What is N in this?
N is the population size. b & d are given in terms of per-capita. dN/dt is the change per unit time
When populations start at a relatively large / small size, they demonstrate exponential growth
small
What is the normal shape for population growth?
The logisitc growth model. Big events can have an impact on populations but nonetheless these populations tend to bounce back.
What is the most common determinant of K?
Energy & Resource limitation.
K is when b ? d
When b = d
What does the equation dN/dt = bN-dN become when you account for the logsitic growth model?
It becomes dN/dt = rN-rN^2 / K. rN would just be exponentual, where as rN SQUARED means that per capita growth DECLINES with density
In early competition experiments, it was found to be hard/ easy to predict the outcomes between species
hard. The Lotka Volterra model can help us tounderstand when competitive exclusion may occur however.
In early experiments on competition, they included r——- u– to show how competition reduced it’s availability
Resource use.
The L— V——- model shows i——– competition wheras the l——- g—– model shows i——– competition. In the LV model, N1 shows species one and N2 shows species 2.
Lotka Volterra, interspecific, logistic growth, intraspecific
What does alpha 12 model and what does alpha 21 model.
Alpha 12 models the impact of species 2 on species 1. Alpha21 modles the impact of species 1 on species 2. The larger the value, the bigger the effect (look up equation!! Lecture 7)
Alphaij can be described to measure ecological equivalence. What does this mean?
It shows how many memeber of one species are equivalent to another. In terms of resource use it shows how much an individual of one spcies consumes of a resource in comparison to another.
If aij = 2 then species j would consume twice as much as species i.
Competition coeffiecients (aij) is higher when the niche overlap is lower/higher and there is therefore more/less competition
higher, more
When we change model parameters in the Lotka Volterra model, we assume that - and - are the same.
K and r for both species. These models can then be used to give an alpha value and see if coexistence is possible at varying levels of competition
Can density of a species affect the impact of competition outcomes?
Yes. For example, at a medium density competion may be possible, but at lower or higher ones, this may not be the case.
To solve the competition equation and examine the outcomes (lecture 7) we must find the conditions wherein dN1/dt = –2/–
= DN2/dt = 0 (an equilibrium)
Under these equations we eventually get to see under which value of alpha co-existence can occur (really look at this lecture again lily)
Which equation shows interspecific competition being stronger and which shoes INTRA specific competition being stronger.
1. a12 <1 and a21 <1
2. a12 >1 and a21 > 1a
- Intra is stronger. Stable co-existence possible
- Inter is stronger. Unstable co-existence possible
aij<1 and aji <1 means that c——- co——— can occur, as when the density of species i increases past a certain amount, the effect on itself pushes it back to an e——-. They can/cannot coexist no matter the starting densities
competitive co-existence, equilibirum, can
What does aij>1 and aji>1 result in?
UNSTABLE competitive co-existence. The species may coexist but interspecific comp is more important than intra, so they can only exist at some starting densities. May depend on which species has entered a habitat first. Unlikely to happen in reality as dependent on a stable habitat like tropical rainforest
Ecologists have been troubled as to how in h——- communities, there can be enough n—- for every specoes
hyperdiverse, niches
A limitation of the Lotka Volterra Model is that it assumes species live in a c—— environment
constant
What is equilibrium theory?
Dictates that the balance between losses & gains in a community maintain specie richeness at an overall constant. Implied processes balance diversity.
What is non-equilibirum theory?
States that disturbance and stochastic events prevent an equilibrium from being reached, hence delaying competitive exclusion
What is the intermediate disturbance hypothesis?
States intuitively that too much disturbance will reduce species diversity by destroying communities entirely. Supported my Molino & Sabatier 2001 and Bongers et al. 2009
Does disturbance prevent competitive exclusion?
No, it only delays it in time
What is the neutral theory?
This is a model for diversity wherin all species are identical, so competition takes longer to rin it’s cause. When randomness is added in, species can co-exist for a very long time before just 1 species ‘wins’.
Neutral theory does NOT explain diversity. Why?
- ignores species specific traits
- neglects ecological interactions like predation, mutualism etc.
- ignored evolutionary processes
- does not consider habitat heterogeneity
What two communities does Hubbell’s Neutral Theory involve?
The local community at the specific sites, and then the wider meta-community
In Hubbell’s Neutral theory, the letter J refers to what?
The number of trees (or other individuals) in a community
G– D—— described gap formation and competition to fill that gap left
gap dynamics
We assume there are / are not empty spaces in Hubbell’s Neutral Theory
Are NOT. Every gap left is immediatelly filled.
In the Hubbell theory, what occupies a vacant site is r—– and all species essentially are e—— identical and the same in b—– and d—–.
!!! What is the problem with this??
random, ecologically, births, deaths
- Normally these assumptions are not correct
In Hubbell Theory, species can be —– from a population just by chance
lost
What number of species will you eventually end up with under Hubbell’s Theory?
1 (although they will persist for a long time before this)