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Exam study > Animal Ecology > Flashcards

Animal Ecology Flashcards

1
Q

Ecology

A

The scientific study of the interactions that determine the distribution and abundance of organisms

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2
Q

Levels of interactions

A
  • Between individuals
  • Individuals and their environment
  • Species
  • Species and their environment
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3
Q

interactions between species and their environment

A
  • interspecific competition
  • resource partitioning
  • predation
  • facilitation
  • dispersal
  • migration
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4
Q

Interactions between individuals and their environment

A
  • behavioural ecology
  • intraspecific competition
  • basic physiological responses
  • life history responses
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5
Q

Abundance

A

number of individuals (designated by N)

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6
Q

What does abundance depend on?

A
  • Interactions with their environment
  • Interactions with your own species
  • Interactions with competing species
  • Interactions with predators
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7
Q

Properties of communities

A
  • diversity
  • trophic structure (food webs)
  • organisation (biological and physical processes)
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8
Q

Why do ecologists care about experimental design?

A
  • Allows correct interpretation of results of surveys and experiments
  • Avoids confounding factors
  • Ensures appropriate level of generality (or specificity) is assigned
  • Makes the statistical analysis easier
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9
Q

Population

A

Group of individuals of same species occupying a defined place at a particular time

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10
Q

Fecundity (natality)

A
  • Number of offspring added to population in a given time (B)
  • Number of offspring per female per unit time (b)
  • Potential reproductive output = fecundity
  • Actual reproductive output = fertility
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11
Q

Mortality

A
  • Deaths in the population in a given time (D)
  • Deaths per individual per unit time (d)
  • Potential longevity = maximum attainable lifespan
  • Realized longevity = actual lifespan
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12
Q

Fundamental concepts of population ecology

A
  • populations tend to grow exponentially
  • populations show self-limitation
  • consumer-resource interactions tend to be oscillatory
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13
Q

why use instantaneous rate

A
  • Better reflects how biological system operate
  • Has more intuitive values
  • mathematically easier to handle – when instantaneous rate is 0 there is no change, when positive it is increasing and when negative it is decreasing
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14
Q

carrying capacity (K)

A
  • Number of individuals that can be maintained indefinitely in the population
  • Number of individuals that available resources can sustain
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15
Q

how does competition affect r?

A
  • increased competition results in fewer resources per capita
  • birth rate and death rate decrease
  • r decreases
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16
Q

factors that affect b and d

A
  • size
  • sex
  • life stage
  • age
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17
Q

cohort life table

A

involve tracking a group of individuals from early life and determining their rate of survival

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18
Q

static life table

A

based on data collected from individuals in a population at one time either from dead individuals or individuals based on an age estimator of some sort

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19
Q

difficulties in getting cohort data

A
  • Tracking animals over time is laborious, often impossible
  • Some animals live longer than the researchers who study them, and even more live longer than research funding cycles
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20
Q

type 1 survivorship curve

A

high infant survival rates and increased mortality later in life

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21
Q

type 2 survivorship curve

A

characterised by constant mortality throughout life

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22
Q

type 3 survivorship curve

A

characterised by higher mortality rates in young, with only some individuals surviving to breeding or older ages

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23
Q

life cycle graphs

A
  • circles for age groups (nodes)
  • lines are for survival and reproduction (verticies)
  • all transitions must have the same time value
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24
Q

life history

A

Schedule of birth, reproduction and death of an individual

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25
Q

life history relationships

A
  • r (rate of increase) is inversely related to generation time
  • generation time is directly related to size, therefore r is inversely related to size
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26
Q

life history patterns

A
  • small size =
  • higher metabolic rate
  • faster growth
  • higher r values
  • short generation time
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27
Q

r/K selection theory

A
  • r selected = grow fast but die sooner
  • suggests trade-offs have taken place among growth and reproduction
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28
Q

problem with r/K selection theory

A
  • Many species possess traits of both r and K selected species
  • E.g. sea turtles – live for many years, and yet produce massive numbers of eggs at a time, with limited parental care
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29
Q

new focus on life history

A

A shift to age-specific life history theory, also referred to as demographic or optimality theory

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30
Q

important life history parameters

A
  • Age that reproduction begins
  • Age that reproduction ends
  • Age of maximum reproductive output
  • Together, these determine the total reproductive output of an individual
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31
Q

life history trade-offs

A
  • age at first reproduction (earlier reproduction but lower adult survival)
  • reproductive effort (higher quality offspring but lower adult survival)
  • reproductive frequency (iteroparous vs semelparous breeding)
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32
Q

Iteroparous breeding

A
  • common for K selected species
  • species that breed more than once, investing significant energy in their offspring each time, such as through child-rearing
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33
Q

Semelparous breeding

A
  • common for r selected species
  • breeding only once, generally producing many offspring in one event with a low energy invested in each individual offspring
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34
Q

reproductive strategy when environment is unpredictable

A

selection favours adult survival over offspring survival and an iteroparous or bet-hedging strategy

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35
Q

reproductive strategy when environmental is stable

A

offspring survival can be higher than adult survival and semelparity is favoured

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36
Q

how predation influences life history traits (guppys)

A
  • Different predation regimes in stream led to a shift in offspring size and a change in reproduction allocation
  • Proved a change in life history traits according to the costs and benefits of reproductive strategy
  • Where predators prefer mature fish, guppies devote a high percentage of body weight to reproduction, have shorter inter-brood intervals and mature at a smaller size
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37
Q

reproductive senescence

A
  • defines the upper limit of reproductive lifespan
  • Grandmother theory – can look after your children’s children
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38
Q

What life history factors protect against extinction risk?

A
  • Large populations
  • Short generation time
  • Early age at first reproduction
  • Fast growth
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39
Q

sustainable harvesting more likely to succeed when life history includes:

A
  • Rapid development
  • Early AFR
  • High fecundity
  • Low body mass
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40
Q

density independent growth

A
  • population growing without constraint
  • exponential growth
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41
Q

density dependent growth

A
  • The regulation of the size of a population by factors that are controlled by the size of the population
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42
Q

allee effects

A

Any mechanism that can lead to a positive relationship between a component of individual fitness and either the numbers or densities of conspecifics

43
Q

example of allee effect

A
  • Predator dilution
  • Antipredator vigilance and predator defense
  • Cooperative breeding
  • Modification of the local environment
  • Reduction in deleterious effects of inbreeding
44
Q

example of allee effect (species)

A
  • wild dogs
  • critical group size required to successfully hunt, raise young and defend resources from competition
45
Q

sustainable harvesting

A

Harvesting of a wild population that allows the population numbers to be maintained or increased over time

46
Q

reasons for sustainable harvesting

A
  • Subsistence
  • Direct consumption
  • Use as feedstock for other food species
  • For derived by-products like oils, etc.
47
Q

what happens if we don’t sustainably harvest?

A
  • Population collapse
  • Can lead to ecological collapse and economic collapse
  • Examples: Orange Roughy; Newfoundland Cod
48
Q

newfound cod (unsustainable harvest)

A
  • stock collpase in early 1990s
  • no reasonable quota set
  • technology improved and so did harvest rate
  • example of the tragedy of the commons
49
Q

how to harvest sustainably

A
  • harvest at the rate at which population is growing most quickly
  • Most wild population have an r of 0 > so before harvest can occur, a population must be stimulated to increase
50
Q

problems with maximum sustainable yield

A
  • for MSY to be sustainable, very accurate population data is required
  • if MSY is exceeded, the population will shrink
  • assumes individuals are identical
  • growth rate is limited by environment - may change every year
51
Q

calculating a sustainable harvest

A

Modify normal logistic growth model to calculate population growth under harvesting (should also include environmental stochasticity)

52
Q

information needed to calculate a sustainable harvest

A
  • Population size
  • Age structure
  • Fecundity
  • Recruitment rates
53
Q

types of harvests

A
  • constant (harvesting quota set to an absolute number)
  • proportional (H varies with N)
54
Q

economics vs biology in harvesting

A
  • Economics emphasizes maximizing profit, whereas biologists work to maximize resource persistence
  • “Future discounting” is the higher value of resources used now than being saved for the future
  • The best biological strategy for the best economic strategy only coincide when the populations r max exceeds the discounting rate
  • When r max is lower than the discounting rate, it remains most profitable to over-harvest
  • This is a particular problem for shared resources = tragedy of the commons
55
Q

PVA

A
  • Essentially a quantitative risk assessment for the future that is species-specific
  • Estimates the likelihood of population extinction
  • Estimates the MVP size for a population to be self-sustainable
56
Q

what does PVA attempt to answer

A
  • how large must a population be to have a reasonable chance of survival for a reasonably long period of time?
  • Reasonable chance = 95%
  • Reasonably long period of time = 100 years
57
Q

quasi-extinction

A

populations cease being ecologically functional well before they became extinct

58
Q

stochastic events that affect population parameters

A
  • extrinsic (environmental)
  • intrinsic (demographic)
59
Q

what is a meta-population

A
  • population of populations
  • immigration and emigration rates between populations are important
  • These differences make their dynamics different from closed, single populations
60
Q

meta-population ecology

A
  • Migration rates influence populations dynamics
  • Connectivity between populations is key and extinction of local populations may be commonplace
  • Single populations are less stables than meta-populations
  • Connectivity between populations allows movement between areas, making meta-populations less vulnerable to stochastic events
61
Q

why is meta-population ecology a useful concept?

A

Many population models assume that natural populations are widespread and continuous – this is not correct

62
Q

why is meta-population ecology important?

A
  • populations are much more fragmented in today’s world
  • critical population sizes, intensive intervention and management
63
Q

meta-population types

A
  • classical/levins
  • mainland-island
  • non-equilibrium rate
  • patchy
64
Q

classical/levins meta-population type

A
  • Assumes equal size and quality of patches
  • An early and simple method for occupancy of habitat
  • “Patches” are considered either occupied or unoccupied
  • Interaction among individuals within patches is assumed to be considerably higher than between patches
65
Q

mainland-island meta-population type

A

assumes a constant source of species (mainland)

66
Q

non-equilibrium rate meta-population type

A

rate of extinction exceeds colonization (without intervention > extinction)

67
Q

patchy meta-population type

A

mobility between populations so high that act as a single population

68
Q

The MacArther and Wilson equilibrium theory

A
  • There is a relationship between area and species number
  • Species number is based on the ratio of colonization and extinction
  • Size and distance of habitat from other sources of species will affect immigration rate
69
Q

source-sink dynamics

A
  • Habitat patches are likely to be of different quality
  • Some patches would go extinct without immigration from source areas
  • Different from mainland and levin models in that differences in habitat quality are recognised as key in regulating population numbers
70
Q

incidence function model

A
  • Combines mainland-island, classical and source-sink meta-population assumptions
  • Developed to create a more realistic set of measures that could be applied to real populations
  • Predicts patch occupancy as a function of the spatial structure of the entire meta-population (the location and size of other patches)
  • Identifies long-distance dispersal events are important, and animals move with different ease through the landscape
71
Q

what does incidence function model assume

A
  • Assumes: finite number of patches, patches of different size, interactions amoung patches are localized in space
  • Assumes: extinction probability depends on population size, which is a function of patch areas
72
Q

Meta-populations and genetic diversity

A
  • Smaller patch size and decreasing connectivity results in lower genetic diversity
  • Lower connectivity leads to increase in inbreeding
  • Leads to increase in susceptibility to disease, infertility
73
Q

competition

A

An interaction between two (or more) individuals, due to both requiring a shared resource in limited supply, that leads to a reduction in the survival, growth, condition and/or reproduction of all competing individuals

74
Q

intraspecific competition

A
  • Limits population growth by energy being diverted to competing
  • Causes adaptation for sexual differentiation through competition for mates
75
Q

types of intraspecific competition

A
  • Interference – a limited resource can be completely monopolized
  • Scramble – a limited resource that all individuals can access
76
Q

costs of competition

A
  • Why does the winner of competition still incur a cost?
  • Because competing costs energy
  • Even without injury, time and energy is used when that could have been used to forage, mate, reproduce, nest, etc.
  • Time allocation
77
Q

inter-specific competition

A
  • Limits population growth
  • Leads to adaptations that enable niche differentiation
78
Q

niche differentiation

A

Complete competition cannot coexist indefinitely, but niche differentiation does allow species to coexist when using similar (but not identical) resources

79
Q

fundamental vs realised niche

A
  • A fundamental niche depends on physical, abiotic conditions
  • The realised niche depends on biotic as well as abiotic conditions
80
Q

how to determine if a species is being outcompeted? IMPORTANT

A
  • Competitive release – niche of the competitively-inferior species expands in the absence of the competitively-superior species
81
Q

lotka-volterra competition model

A
  • Very useful to determine if one species will drive the other to extinction and the effect that one species will have on another
  • Uses the single species framework and converts the density of the other (competing) species into an equivalent number of the focal species
82
Q

predation

A

True predation is the direct killing and consumption of one thing (generally an animal) by another

83
Q

numerical response

A

the extent to which predator abundance changes according to variation to food supply

84
Q

functional response

A

the extent to which per capita kill rate fluctuates according to prey density

85
Q

functional + numerical response

A

total response, or overall predation rate

86
Q

Lotka-Volterra model

A

assumes:
- In the absence of predators, prey population grows logistically or exponentially
- Population growth of predators is entirely regulated by prey
- Environment does not change to favour one species over the other
- Predation rate is related to encounter rate (i.e. it’s density dependent)
- All individuals are identical (both population)

87
Q

prey population growth

A

The growth of a prey population will be its intrinsic growth rate minus the rate at which individuals are removed by predators

88
Q

predator population growth

A

The growth of a predator population will be its intrinsic growth rate minus its mortality rate limited by the encounter probability with prey and efficiency at converting them to predators

89
Q

graphing predator-prey relationships

A
  • When the predator population’s rate of increase is positive, prey density declines
  • Equally, when the rate of increase in prey is negative, predator populations decline
  • the combination of the two processes overlapping leads to a cycling of the rates
90
Q

Why is defining functional response important?

A
  • Because it reflects the stability of predator-prey interactions
  • If prey are at greater risk when prey density is high, predation will have a stabilizing effect
  • If prey are at greater risk when prey density is low, predation will have a destabilizing effect
91
Q

four factors that affect predation rate

A

search, capture, handling, digestion

92
Q

type 1 response

A

A linear relationship between prey density and their consumption by predators

93
Q

causes of type 1 response

A
  • Search time limits predation
  • If prey are scattered in the environment, and they cannot hide, type 1 response is the most common functional response
94
Q

example of animals that use type 1 response

A

Filter feeders, grazers, specialists

95
Q

type 2 response

A

An initial non-linear increase in consumption with prey density, followed by deceleration to a plateau as handling time begins to affect consumption rate more than searching time

96
Q

causes of type 2 response

A
  • Predator handling time of captured prey is the limiting factor, rather than search time
  • If prey are easy to catch, but take time to consume, this leads to a type 2 response
97
Q

example of animals that use type 2 response

A

invertebrate predators, some mammals (leopard)

98
Q

type 3 response

A
  • Prey consumption rates are low until a critical density is reached where rate increases
  • Consumption rate then increases rapidly before reaching a plateau
  • Characteristic of prey-switching interactions
99
Q

expected situations where type 3 response is used

A
  • Where predators need time to learn to capture a new prey type efficiently
  • Where prey has a refuge, so at low densities the ability to capture them is reduced
  • Where the predator has multiple prey species, leading to the economics of profitability
100
Q

Why do we care about functional response curves?

A

It could affect our management decision, e.g. biological control of agricultural pests ( would not choose type 3 response as it may have limited effect on pest)

101
Q

Applications for functional response type

A
  • Cane toads are from Venezuela, were introduced to control beetle pests of sugarcane plantations
  • They are very effective prey switchers and their population and range is expanding rapidly
  • Native water rats in the Kimberley eat them but die from eating them
102
Q

Stable age distribution

A

mortality and fecundity have been stable for some time

103
Q

reproductive value

A

current and future contribution of offspring to the population of females at any given age

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