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BIOL2010 > Myron lectures: 24-31 > Flashcards

Myron lectures: 24-31 Flashcards

1
Q

what is ecology?

A

> the study of the interactions that determine the distribution and abundance of organisms

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2
Q

what is ecological theory?

A

> explanations or ideas that attempt to account for species abundance and distribution (a and d) - these are in effect ‘models’
predict changes in a and d under different conditions

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3
Q

what are some theories surrounding regulating populations?

A

> predation
- top down model
- parasitoids, predators, parasites, pathogens all control the subject organism
resource limitations
- bottom up model
- plants and other food sources regulate the subject animal
Competition
- side to side model
- other organisms control the subject organism
the ecological theatre
- physical factors and climate all effect the habitat of the organism and therefore effect its a and d

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4
Q

what factors control all types of interactions?

A

> the climate influences all controlling mechanisms

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5
Q

why is ecology complex?

A

> the number of species that exist in a given location, the changing environment, makes ecology a difficult discipline
complexity means most ecological data analysis requires statistical approaches

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6
Q

what sort of questions do ecologsts ask?

A 
> where organisms are found? - fluctuates
> when the species may occur
> how many occur
> change in numbers
> WHY??
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7
Q

how do you go about answering the important questions in ecology?

A 
> natural history 
 - observation
 - describe
> quantitative natural history
- count and measure
> experiments involving manipulations of animals, plants or habitats
> comparative approach: test by comparing 'ecology' of a large number of species
> models and modelling
 - predictions
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8
Q

why do we use models in ecology?

A

> to identify what may happen
to identify key processes that need to be studied and data that need to be collected
to bridge the scale gap between experiments and problems
because management requires models

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9
Q

what are some uses for models in ecology?

A

> population management for conservation or exploitation
invasions
pest management
predictions

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10
Q

what determines large scale fluctuations in plant feeding insect abundance?

A

CLIMATE
> affects resources (K)
> affects reproduction and survival (lambda)
> will have a strong influence on seasonal and year to year abundance and distribution

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11
Q

what is a population?

A

> all individuals of a specified species in a given area
OR
the group of potentially interbreeding individuals at a given locality
OR
all members of a local populations that share a single gene pool

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12
Q

what defines an area or locality?

A

> area such that two individuals have equal probability of mating
the behavior of mating is important

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13
Q

how can some populations be defined?

A

> if there is regular exchange of individuals
can tell this via mark and recapture
if there is some sort of barrier to movement between populations
in practise or operationally for research purposes a population is what a researcher chooses to call a population. IE we define the boundaries
must measure the flux across these boundaries

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14
Q

what is a metapopulation?

A

> a population of population with little movement between them

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15
Q

what are two key points about populations?

A

> individuals that make up a population are unique (variable even though one species)
movement and gene flow define the population boundary

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16
Q

how can it be hard to define individuals?

A

> for clonal organisms such as fungi and corals and some plants it is often not possible to clearly define individuals
biomass or size are used instead of individuals

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17
Q

what is scale?

A

> populations can be defined on very different scales
what defines a population is gene flow
plants: pollen flow and seed dispersal
animals: movement-habitat interaction

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18
Q

what are habitat patches?

A

> the vary in:
size or area
shape
location and suitability

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19
Q

what are some properties of populations that can be measured?

A 
> size or number, density
> age structure
> sex ratio
> changes in these
> the contributing processed 
 - B,D,E,I
> with this knowledge over time we can estimate population growth
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20
Q

what are important factors for population growth?

A

> r - intrinsic rate of increase
Ro - net reproductive rate
lambda - multiplication rate

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21
Q

what are population and habitat units?

A 
> sources 
- b>d
- I classical populations
 - B=D
 - I=E
> sinks
- BE
- if I--> 0 then population goes extinct 
> potential sinks B empty habitats 
- B>D
- I=0
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22
Q

what is a habitat?

A

> often treated as synonymous with vegetation category or biome, ecosystem type, community, spatial mosaic and foraging patch
places where a species normally lives, often described in terms of physical factors
the resources and conditions present in an area that enable occupancy - including survival and reproduction - by a given organism.
habitat is organism specific. it is the sum of specific resources that are needed by organisms
a place where a species can complete its life cycle

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23
Q

how do you measure habitat?

A

> mapping
physiological ecological approach
observational
experimental

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24
Q

what is a species niche model?

A

> > species niche distribution models the realised niche. they do this by describing the environment in which the species is found - generally in terms of the bioclim variables, and sometimes including non-climatic variables.

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25
Q

what is climax?

A

> describes how the species population responds to environmental variables. SDMs describe the environment, where CLIMAX describes the species.

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26
Q

why are empty habitats important?

A

> if ‘suitable accessible habitat’ s empty then species are limited by other species, either predation and/or inter-specific competition, or
if all habitats are full, the intra-specific competition is likely important
but how suitable are empty habitats

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27
Q

how do you determine if an empty habitat is suitable?

A

> do a transplant experiment.
if transplant successful
- habitat is suitable. Distribution limtied because of access or species fails to recognise area as suitable
transplant not successful
- habitat not suitable either due to other species or due to some other requirement (chemical or physical) not being met

28
Q

why are species absent?

A 
> dispersal?
 - area inaccessible
> Behaviour?
 - habitat selection
> Other species
- predation, competition
> physical and chemical factors?
 - temp, light , moisture, fire, salinity , pH, nutrients
29
Q

what is a resource?

A

> resource life expectancy goes down and the organism using its life expectancy goes up
they are important for habitats because resources combine to give habitats by intersection and union or equivalence and equality

30
Q

what are the different types of habitat/resource boundaries?

A

> contiguous union and disjointed union via movement
disjointed non-union linked by seasonal movement
- count both habitats
- migration needs to be taken into consideration
metapopulation of to habitat patches linked by random movement

31
Q

what do individuals vary in?

A

> age, stage, size, location etc
contributes to likelihood of survival, reproduction and movement
need to be able to get a handle on this to estimate contribution to potential population change - estimate demographics
interested in life-history evolution

32
Q

decribe development

A

> organisms have to grow, develop and survive to the reproduction stage and reproduce for a population to persist in a location

33
Q

unitary vs. modular organisms

A

> most animals are unitary - develop from a zygote through a set of irreversible changes; form is determinate
most plants are modular - growth and differentiation occurs at meristems along roots and shoots. plants are thus repetitive modules. timing and form are complex but predictable. colonial animals also modular

34
Q

what do age and module structure d?

A

> influence potential population change and growth of individual

35
Q

what is the best to measure for demographics? age, stage or size?

A

> age
- usual for mammals and birds
- individuals of the same age are similar
- assumes you can age individuals
- computationally simple
- time step and age step are the same
stage
- life history stage: egg, larva, pupa, imago
- time step and stage duration differ
size
- useful if individuals of same age can be very different
- need to define size classes
- describe growth rate to estimate size class transitions

36
Q

what are the different types of life cycles graphs?

A 
> age structured models
> stage structured models
 - can stay in same age class per time step
> messy life histories: coral colonies
 - can fragment and o back to a smaller class
37
Q

what is important about temperature and development?

A

> for ‘poikilthermic’ (not warm blooded) organisms (insects, plants, frogs etc) development is a function of temperature
how rapidly they progress through their development stages depends on how warm/cool it is

38
Q

what are degree days?

A

> the amount of heat needed by an organism to progress to the next life stage. temp x time

39
Q

what happens to populations that exist in different habitats? (same species?

A

> in a cold environment, only have three generations in the time that a hot environment has 7.
these two populations will have very differnt future potential growth rates, PGR. you can estimate PGR using life tables.

40
Q

what are life tables?

A

> age-specifc summary of the mortality rates operating on a ‘population’
can include reproduction
to construct life tables we need to estimate the number in each age class

41
Q

what is a census?

A

> complete count of all individuals in population
sometimes possible for small, closed populations of very observable ‘things’
- trees in a small patch of forest
- birds on a small island
- koalas in a forest remnant
usually impossible
- bad!!

42
Q

what is the sub-sampling methods?

A 
> quadrats and transects
 - try to census population in a sub-sample of total area
> design issues
 - how many sub-samples?
 - what shape should they be?
 - how should you select them?
43
Q

what is the sampling theory?

A

> how many are there? estimating p
known area, A? known density D, then P=DxA
take n small areas each of area “a”, count or census the number xi in each and estimate density D, D=Exi/n

44
Q

what is the number entering stage?

A

> area under population curve divided by stage duration

> mortality estimates only as good as individual population sample estimates!

45
Q

what are cohort life tables for species with discrete generations?

A

> apply mostly to annual species or species with short lived adults
a cohort life table follows a single cohort of individuals (those born at the same time) from birth to death of the last one

46
Q

cohort tables with life histories that have overlapping generations

A

> many birds corals and trees, mammals
hard to get data as it is difficult to recognise cohorts and follow fates of individuals
easier for sessile organisms

47
Q

how do you quantify life histories?

A

> life tables - mortality and survival with age
fecundity schedules - show how patterns of fecundity change with age
realised versus potential fecundity
problematic in the field

48
Q

what are the columns in life tables?

A

1) stage or age interval, x
2) number of individuals in the ‘population’ at start of each stage or age interval (Nx or ax)
3) Lx: proportion of original cohort alive at start of each stage (lx = Nx/No)
4) dx: proportion or number dying during each stage (x = Nx-Nx+1)
5) qx: stage-specific mortality rate (qx =dx/lx or =dx/Nx) is a measure of the probablility of an individual dying during the stage
6) kx: or killing power reflects the intensity or rate of mortality; can be summed and compared across studies (kx=lnNx+1 - lnNx)

49
Q

what is a fecundity table?

A

> Fx: total number of eggs (offspring) produced during each stage (realised)
mx: the individual fecundity or birth rate per female; mx = Fx/Nx
lxmx: eggs produced per original individual in each stage

50
Q

what is Ro?

A

> basic or net reproduction rate
the mean number of offspring produced per original individual by the death of the last member of cohort
either sum of Fx divided by No (total number of offspring produced by the cohort per original number of individuals) or as the sum of the lxmx (sum of offspring produced per original individual during each stage) adjusted for sex ratio
Ro indicates to what extent a population can increase or decrease.

51
Q

how do you estimate Ro and lambda?

A

> Ro fundamental net per capita rate of increase or NET Reproductive rate
lambda is the multiplication rate per generation
if a population doubles every time interval then lambda = 2
lambda = Nt+1/Nt

52
Q

how do you estimate r?

A

> r=lnRo/T,
the rate at which the population increases in size (changes in population size) per individual per unit time
and T is generation time
for discrete population T=1 and Ro = lambda
or r=ln lambda for organisms with discrete generations (univoltine) - one generation per year.
in populations with overlapping generations r is the intrinsic rate of increase that the population has the potential to achieve IFF lx and mx are stable over time
if this occurs then age structure becomes stable, and the population grows exponentially
rare

53
Q

what happens to population projections on a spreadsheet

A

> for given mortality and fecundity schedules, population settles down to exponential growth
but initial behaviour depends on starting conditions
e.g., starting with juveniles or with reproductive adults

54
Q

what are leslie matrixes?

A

> results (eventually) in exponential growth or decline
reaches a stable age distribution (fixed proportion of individuals in each age class)
can be generalised to stages of differing length (lefkowitz matrix)
- individuals can remain in stages, jump stages and drop to previous stages.

55
Q

what is population dynamics?

A

> change in the abundance and distribution of a species over time
animal and plant populations show a wide range of dynamic ‘behaviours’ in both time and space
important for measuring outbreaks

56
Q

compare fluctuations in Ni

A

> N1,N2…,Ni…..Nt
log range (LR) = ln(max(N1,Nt))-ln(min(N1,Nt))
Ri = Ni+1/Ni = the multiplication rate or some similar measure of growth rate
and the variances
growth rate determines how quickly a population changes

57
Q

is there a pattern of spatial variation in abundance over a species geographic range?

A

> most dense in the middle of the climatic range, then gets thinner to the edges of the habitat, but this can change with changing climate.

58
Q

what is regulation?

A

> regulation or a regulator that speeds up or slows down with population size around an equilibrium (often equated with k, or carrying capacity)
since K varies (note this may be a different concept for k) we get regulation that reduces the range of population fluctuations (i.e., the variance in N)

59
Q

what is the regulation belief based on?

A

> crude evidence, impressions or short data sets that suggest population levels change little from year to year. (this evidence is little more than a mean level of abundance which is often confused with k. is the variance bounded?)
logic, given the potential for species to increase ‘something’ must prevent them from: a) increasing indefinitely and/ or b) over exploiting their habitat and/ or c) going so low as to go extinct.
HOWEVER populations do go extinct and they do over exploit habitats during outbreaks, and the potential for increase does not have to be realised, which may or may not have anything to do with population density

60
Q

how do we interpret changes in abundance?

A

> either fluctuations in Nt are around some characteristic level, that is extinctions and outbreaks are rare?
OR
do populations persist? with outbreaks and localised extinctions from time to time?

61
Q

what happens if we accept populations are regulated around equilibrium?

A

> what could achieve this? which biotic factors could have a density dependent effect on:
Death and Emigration
Birth and Immigration
regulation is almost always believed to be due to intra-specific competition and or natural enemies
Death (four ps)
Births (size ‘competition)
if this is the general model for a species population ecology then it ha many implications for population dynamics, life history strategies and even speciation (r and k selection?)

62
Q

what views do populations that hold regulation follow?

A

1) population size determined by equilibrium level which is set at or below the carrying capacity, k
2) density dependence (DD) acts on all population densities, to varying degrees
3) DD factors are intra-specific competition and natural enemies (four Ps)
4) resource limitations infrequent
5) extinctions are rare

63
Q

what is the evidence for no DD?

A

> real populations appear to exist without DD
extinctions do occur
resource limitations also occurs
BUT apparently life tables are too crude to detect DD which must be present! data too short and subject to perturbation and stochastic effects

64
Q

what are the problems with regulation emphasis?

A

> density dependence is infrequent
rare species and local extinctions?
many other ecological factors are important
no common ecological influence across species
ignores specific relationships and biology

65
Q

what are some alernatives to regulation

A

> That population density of insects ‘regulated’ primarily by effects of weather or climate - so called density independent factor
approach population dynamics by looking at all the components of the environment that affects survival and reproduction of individuals - in fact the reject the notion of regulation
spatial heterogenity - difficulty in finding resources
intraspecifc competiton
abiotic factors limit herbivore numbers
different shade of green (N, Toxins etc.)
carrying capacity is expressed as the capacity of resources available, not the mean density of the pop.

66
Q

what is the resource limitation model?

A

1) ultimate population size determined by a ceiling set by L (=resources, not N)
2) density dependence, only sometime in some populations and only at narrow high range densities
3) density dependence is by intraspecific competition
4) resource limitation frequent, at least locally
5) extinction frequent, at least locally

67
Q

what is the general model for resource limitation

A

> to include all factors that affect deaths and births, both quantity and quality of resources (e.g., nitrogen) and weather
envisage many independent factors each with a positive or negative effect on b and or b
as we increase the number of factors from 1 to k then variance of Ni stabilises because r will be 0!

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