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BIOL10010 Introductory Biology: Life's Complexity > 04. DYNAMIC POPULATIONS > Flashcards

04. DYNAMIC POPULATIONS Flashcards

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1
Q

Define population

A
  • grp of indiv
  • same spp
  • same location
  • rely on same resources
  • influ by similar environ cond
  • interact w e/o
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2
Q

What four factors influence population size?

A

births, deaths, emigration, immigration

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3
Q

What are the three types of population distribution

A

clumped, uniform, random

*occurs @ subpop lvl too

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4
Q

What causes a uniform distribution of individuals within a population?

A

comp for resources - either defensive/protective measure or simply X enough indiv in pop to live in close prox to e/o

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5
Q

Define population ecology

A

study of r/ship bw pops + environ + its resources. considers biotic + abiotic influences on pop abundance/distrib/comp

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6
Q

How can population ecology be applied?

A

measure:

  • abundance
  • birth/death rates
  • mvmt
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7
Q

How might we reduce the size of a population?
Use rabbits as an example.

A

e.g. rabbits

  • inc deaths - intro disease
  • dec births - contraceptive in bait
  • dec immig - fences
  • inc emig - intro predator
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8
Q

Which members of a deer population would be most effective to target to control population size?

A

females

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9
Q

What two factors influence precision when estimating abundance via plot sampling?

A
  • no. of plots
  • variation in counts bw plots
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10
Q

Outline how sampling works

A
  • select plots across portion of pop range
  • count indiv in plot
  • est avg density and detectability
  • extrapolate to est whole pop
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11
Q

Equation for estimating abundance

A

N=n/p

N → abundance

n → # seen

p → prob of detection

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12
Q

Outline how mark-recapture works

A
  • capture indiv + mark all of them - incl double colours to ID indiv
  • return to pop + allow time to remix
  • recapture + record how many were from 1st trap
  • est prob of detection
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13
Q

Outline the key assumptions of mark-recapture

A
  • marks remain
  • marking is benign
    • ethical - X harm indiv
    • sci integrity - prob of recapture X impacted by org learning avoidant behaviour from 1st trap

failure → bias = systemic over/underest

  • closed pop - X birth/death/mig
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14
Q

List some marking methods

A
  • leg bands
  • ear tags
  • collars
  • paints/dyes
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15
Q

List methods for counting/sampling

A
  • mark-recapture
  • natural marks (e.g. fur or fin patterns)
  • genetic methods (collect genetic info to ID indivs)
  • signs as indices (e.g. footprint, droppings)
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16
Q

Pros/cons of the use natural marks to estimate abundance

A

pros - non-interference w animals (ethical + X impact quality of data bc X learn avoidant behaviour)

cons - poss that patterns change during study period

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17
Q

Name the three broad phases of the life cycle

A

juvenile, reproduvtive, post-reproductive

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18
Q

How is the life cycle defined?

A

according to length of gen (several, annual, perennial) AND # reprod events/yr (interoparous vs semelparous)

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19
Q

Examples of semelparous vs iteroparous annuals

A

semelparous annuals - wheat, gypsy moth

iteroparous annuals - common groundsel, field grasshopper

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20
Q

What do perennial life cycle patterns indicate about food availability?

A

seasonal breeding → reprod in times of high food availability

consistent breeding → spp in areas w high food availability e.g. primates in tropics

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21
Q

Example of semelparous animal

A

pacific salmon - breeds once then dies

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22
Q

Define demography

A

study of birth/death rates of pops + how they change over time

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23
Q

What does a life table do?

A

tracks the fate of a set cohort from birth to death + records how many indiv survive each yr + how many offspring they prod

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24
Q

Outline the three types of survivorship curves

A

time vs log10(#surviving indiv)

Type I = log curve → most indiv die late e.g. elephants

Type II = linear slope → indiv die at uniform rate e.g. squirrels

Type III = neg exponential curve → most indiv die @ young age e.g. butterflies

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25
Q

What characterises population growth, decline and stability?

A

stable → R=1

growth → R>1

decl → R<1

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26
Q

Outline the difference between density-dependent and independent limits to population growth

A

ind - affects pop growth regardless of pop density (often abiotic) e.g. wildfires

dep - affects pop growth diff acc to pop density + often BC of pop density (often biotic) e.g. resource depletion

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27
Q

What is the ‘carrying capacity’ of a population?

A

max pop size that an environ can sustain i.e. births=death → stable pop

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28
Q

Outline negative density-dependent population regulation

A
  • inc pop → dec growth rate
  • occurs when carrying capacity = surpassed
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29
Q

Why does negative density-dependent population regulation occur?

A
  • comp for resources
  • inc opp for disease spread
  • predation (preds pick more abundant prey spp)
  • inc prod of toxic waste
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30
Q

What is a potential shortfall of the exponential growth projection?

A

ignores movement - only considers survivors/recuits

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31
Q

Under exponential growth…

A

the rate of inc (r) = constant

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32
Q

What does logistic growth project?

A

for density-dep growth, growth rate decl w inc abundance

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33
Q

Logistic growth equation

A

Image 4

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34
Q

Key assumptions of logistic growth model

A
  • X variability of environ cond
  • X effect of chance - esp influ in sml pops
  • linear change in per cap growth rate w density
  • X consider pop structure e.g. reprod stage → impact fecundity
  • pop growth rate adjusts instantaneously → approach K smoothly i.e. X delays - esp problematic bc if delays do occur, pop will overshoot + overexploit resources → dec K
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35
Q

Compare stochastic and deterministic processes

A

diff = certainty of outcome - stoch process → outcome = uncertain vs determ process → outcome = certain

stoch = randomness

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36
Q

How does environmental stochasticity influence population dynamics?

A

variable resources/predators/shelter → variable birth/death rates

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37
Q

How does environmental stochasticity relates to density?

A

Environ stoch encompasses both density-dep and ind factors - either/both influ pop dynamics of diff spp at diff times

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38
Q

What does the term ‘demographic stochasticity’ mean?

A

random fluctuations in demographics of a pop
arises from chance birth/death of indiv

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39
Q

Which populations are most impacted by demographic stochasticity?

A

sml pop - chance of extinction = higher

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40
Q

How does demographic stochasticity affect the risk of extinction of a population?

A

always a chance of extinction, though v unlikely. Likelyhood dec as pop size inc

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41
Q

What does dispersal mean?

A

when indiv moves from one breeding location to another

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42
Q

What are the two types of dispersal?

A

natal disp - mvmt from birthplace to breeding place

breeding disp - change of breeding site

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43
Q

What two factors influence dispersal?

A
  • age - mvmt prior to breeding
  • sex - fem bias in birds vs male bias in mammals
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44
Q

Outline the modes of dispersal

A

animals

  • active - fly, walk swim
  • passive - currents, floods, attach to other animals/vehicles

plants

  • gravity, wind, water, animals (attach/in gut), vehicles, machinery
45
Q

How have humans introduced new modes of dispersal?

A
  • attach to clothes
  • purposefully intro invasive/non-native spp
  • trades routes/vehicles = new vectors for mvmt e.g. starfish attach to bottom of cargo ship
46
Q

How does dispersal commonly regulate population size

A
  • migration out of pop → decl pop size
  • intro of invasive pred spp → inc pred pop size/decl prey pop size
47
Q

What are the three ways we can measure dispersal?

A
  1. marking & observation
  2. tracking tech
  3. instrinsic markers
48
Q

What are the limitaions of measuring dispersal via marking and observation?

A
  • observation effort
  • gaps in data
  • X track long dist mvmt
49
Q

What are the three types of tracking technology used for measuring dispersal?

A
  • radio tracking
  • satellite tracking
  • geotrackers
50
Q

What are the pros/cons of measuring dispersal via radio tracking?

A

cons - researcher needs to be near animals to recieve signal

51
Q

What are the pros/cons of measuring dispersal via satellite tracking?

A

pros - researcher X need to be nearby
cons - heavy

52
Q

What are the pros/cons of measuring dispersal via geotrackers?

A

pros - lightweight

cons - limited accuracy bc relies on assumption that animal is in same spot @ sunrise/set - X acct for mvmt w/in day

53
Q

How can we measure dispersal using intrinstic markers?

A
  • measure stable isotopes - chemical composition reflects environ/diet
  • genetic markers reveal where animal was born
  • parasites = clues abt locations visited
54
Q

Outline the factors influencing what dispersal measurement system is used

A

-size of animal
- habitat
- cost
- accuracy
- impact on animal + sci integrity

55
Q

What are the five categories of metapopulation spatial dynamics?

A
  • classic
  • mainland-island (source-sink)
  • patchy pop
  • non-equilibrium (extinction w/out recol - often caused by habitat fragmentation by humans)
  • mixtures
56
Q

What characterises a ‘classic’ metapopulation?

A

frequent extinction and recolonisation in habitat patches

57
Q

Populations that inhabit patchy habitats are not always metapopulations. Why?

A

metapop req some lvl of interaction bw pops

58
Q

At the regional scale, what two factors drive metapopulation dynamics?

A

extinction + recol

59
Q

Do metapopulations arise in natural or in transformed habitats?

A

transformed - habitat patches often arise from habitat fragmentation

60
Q

What factors influence how prone a population is to extinction and recolonisation?

A
  • larger terr → lower prob extinct
  • larger aquatic veg cover → lower prob extinct
  • inc connectictivity → lower prob extinct + inc prob recol
61
Q

What is a life history strategy?

A

a spp’s pattern of growth, survival + reprod events

62
Q

How have different life history strategies arisen?

A

LH strats = shaped by NS bc traits that max offspring survival = favoured over time - whether this is high fec/low PI or low fec/high PI depends on environ cond

63
Q

What are the three categories of reproductive behaviour that reflect different life history strategies?

A
  • fecundity vs parental care
  • age at maturity (early vs late reprod)
  • semelparity vs iteroparity (# of reprod events w/in lifetime)
64
Q

Fecundity and parental investment have an _ relationship

A

inverse

65
Q

What does a high fecundity/low parental investment life history strategy entail?

A

prod as many offspring as poss BUT each have low chance of survival bc too energetically expensive to protect(see Dihkstra 1990 - Eurasian kestrels caring for more offspring neg impact survival of parents)

h/e only 1 offspring has to survive for pop = stable

66
Q

Pros/cons and characteristics of early reprod strategy

A

characteristics: short-lived + sml body size bc early E invested into reprod, X growth

pros: reduces risk of X reprod at all

cons: lim ability to prov parental care bc short life cycle → dec prob of survival

67
Q

Examples of late reprod strategy

A
  • elephant
  • sharks - fishing esp problematic bc target larger animals = adults → X able to prov parental care to max capacity → impacts survival prob of young too (double whammy)
68
Q

Define semelparous and give two examples

A

single reprod events before death e.g. pacific salmon, desert agave

69
Q

Define iteroparous and give two examples

A

multi reprod events across lifetime e.g. humpback whales, mountain ash, humans

70
Q

Most perennial plants are…

A

iteroparous

71
Q

Example of an semelparous Australian mammal

A

monotremes

72
Q

Characteristics of r-selected species

A
  • density ind
  • high fec rate
  • short gestation
  • low PI
  • high mortality before indiv reach AoM
73
Q

Characteristics of K-selected species

A
  • density dep
  • low fec
  • higher PI
  • low mort rate of indiv before reach AoM i.e. high survival prob
74
Q

Example of how r-selected species rapidly adapt to changing environmental conditions

A
  • desert locust pop boom when food = abundant + heavy RF
  • this is bc fem mature early (1-6mo) + can lay 100s eggs + die after 3-6mo → makes 2-5 gens per yr
  • altogether contrib to x10-16 inc in pop size each gen → swarm of 10K locusts can inc to 100bn in 7 gens = 2yrs
75
Q

How do boom/bust cycles of r-selected species impact ecosystems?

A

pop fluctuation in r-selected spp has conseq across food chain → pop flux can be biotic, abiotic or both

76
Q

Define parasite

A

org that obtains nutrients from another org, commonly harming host + poss causing death

77
Q

Define infection

A

when parasite colonises host org

78
Q

Define disease

A

when infection causese symptoms in host

79
Q

Define pathogen

A

??

80
Q

Define vector

A

org that carries + transmits infectious pathogen to another org

81
Q

Define virulence

A

severity/harmfulness of disease

82
Q

Outline the characteristics of micro- and macro-parasites

A

micro:

  • sml + intra-cell
  • multiply rapidly w/in host
  • transmitted dir
  • v numerous - viruses, bacteria, protozoa
  • e.g. covid (virus) or Plasmodium falciparum (protozoa) → colonises human RBCs - mosquitos = vectors

macro:

  • grow on/in body cavities
  • reprod by releasing infectious stages into environ - poss col same host as parent
  • rarely complete life cycle w/in one host
  • e.g. helminths, nematode worms, lice, fleas, tapeworms
83
Q

Outline the differen ways parasites are transmitted

A
  • direct - X req vector e.g. smallpox
  • trophic - eaten by host e.g. Leucochloridum = parasitic flatworm
  • vector-transmitted - carried by other org e.g. dengue virus by mosq
84
Q

Outline the different strategies employed by parasites

A
  • parasitic castration - sterilise host + redir E/space typically used for reprod → grow/fuel parasite
  • parasitoids - insects that kill host thru 1) stinging host + laying egg on dead body = food for young or 2) laying eggs dir inside host → emerge + kill host after hatching e.g. alien wasp
  • micropredation - attack several hosts + usually feed on blood e.g. ticks, leeches, fleas
  • brood parasites - use other spp to raise young e.g. Channel-billed cuckoos uses magpies/currawongs/crows
85
Q

How common are parasites?

A

> 50% spp + >50% indiv = parasites (Windsor DA 1998)

86
Q

Definition and characteristics of epidemics

A
  • rapid changes in disease prevalence - often cause waves of infection
  • can cause mass mortality
  • disappear from host pop for period of time
  • rapid inc pop growth rate after event bc more resource available per indiv
  • e.g. 1995/98 pilchard herpesvirus in pilchard fish → 75% mortality
87
Q

Definition and characteristics of endemic infections

A
  • persist in specific pop for LT period w minimal prevalence flux
  • can suppress pop #
  • only dir caused spp extinct x1 - protozoan parasite caused Partula turgida snail extinct in 1996
  • BUT can make pop more vulnerable to extinction bc suppress pop size (sml pops are more prone to extinct) e.g. TAS devil pop # decl 90% bc disease = v vulnerable
88
Q

When is culling used to control disease spread?

A

when transmission = density dep i.e. when disease spreads best when too many animals

→ cull infected/vectors

89
Q

What are three strategies for disease prevention and control of microparasites?

A
  • culling (infected orgs/vectors)
  • behav modif incl quarantine/soc dist
  • vax e.g. measles
90
Q

Why do parasites harm their host?
Provide a case study to support your claim.

A

virulence-transmission trade-off hypothesis argues optimal ongoing transmission occurs at an intermediate virulence lvl

i.e. beyond intermed virulence lvl cost of inc host mortality trumps benefit of inc transmission = X desirable for parasite survival/reprod

e.g. monarch butterflies + protazoan parasite (de Roode et al. 2008) shows optimal fitness (replication) = intermed vir

91
Q

Outline two host responses to parasites

A
  • host tolerance - ability to cope w infection of pathogen by minimising damage (but X reduce transmission)
  • host resistance - ability to reduce prob of pathogenic infection/replication/transmission OR inc speed of pathogen clearance (recovery)
92
Q

What is a threatened species?

A

pop/spp on path towards extinction

93
Q

How many species are threatened with extinction?

A

> 32K = 27% all assessed spp (IUCN)

amphibians = most @ risk (41% spp) IUCN

94
Q

What characteristics of a population make is more at risk of extinction?

A
  • sml pop size (low genetic div + poss allee effects)
  • sml geog range
  • slow devt/reprod
  • narrow eco niches
95
Q

What is an allee effect?

A

when growth rate of sml pop = dec bc of undercrowding i.e. low pop density

96
Q

Why do allee effects occur?

A

bc mate lim (most common), coop defense, pred saturation, coop breeding, coop feeding/dispersal

97
Q

Why are allee effects relevant to conservation efforts?

A

sometimes even if remove threat that originally caused pop to decl, pop might still X be able to recover from Allee effects w/out help e.g. mt pygmy possum ‘love tunnel’ @ mt hotham

98
Q

Outline how an allee affect via mate limitation can cause extinction

A

e.g. habitat fragmentation/destruction → trees too far apart from neighbours to pollinate

99
Q

Outline how low genetic diversity can cause extinction

A

inbreeding depression

  • inbreeding → inc homozyg → inc prob of indiv born w delet recessive alleles → threatens indiv survival/reprod → cascading conseq for pop survival in sml pops
  • can cause extinct bc lower reprod fitness/opps (bc indiv death) → dec evol potential → less able to adapt to changing/new environ → poss extinct
100
Q

Outline how small geographic range can cause extinction

A

sml range = inc risk that habitat destruction/fragmentation impacts spp entire range → disruptive events (a/biotic) impact survival of whole spp

101
Q

Outline how a slow reproductive rate can cause extinction

A

inc risk that deaths>births bc X able to replace indiv as rapidly e.g. kakapo parrot only breeds every couple yrs + only lays 1-4 eggs/breeding cycle

102
Q

Outline how narrow ecological niches can cause extinction

A

bc spp heavily relies on specific habitat + its resource → X able to adapt to new/changing environ → lack of fitness = fatal → decl pop numbers

e.g. mt pygmy possum rely on bogong moths = food

103
Q

What are the key threats to threatened species globally? How do they differ from threats to Australian species and why?

A

global threats = habitat loss + overexploitation

Aus threats = invasive spp + changes in habitat bc historic genetic iso of Aus spp → high lvls endemism + specialisation → Aus spp X well adapted to cope w novel spp/environs

104
Q

Outline habitat loss and degradation as a threat to threatened species globally

A

clearing for agri + urbanisation → habitat loss/degred/frag

→ creates habitat patches → pops can shrink bc:

  • stochastic processes
  • allee effects
  • low genetic div
105
Q

Outline overexploitation as a threat to threatened species globally

A
  • animals/plants collected for food/medicines/pets
  • lg/slow reprod spp = most vulnerable
  • e.g. sharks = absent from 15% coral reefs bc overexpl
106
Q

Outline invasive species as a threat to threatened species globally

A
  • pest animals, plants + diseases
  • impact pop size thru pred, comp for terr/resources or inc deaths bc toxic
  • 10% Aus mammals = invasive spp → 22 spp native Aus mammals = extinct
107
Q

Example of how threats are often overlapping

A

extinction of passenger pigeon from Nth Am

  • pop = bns in early C19 → extinct in wild by 1901
  • habiatat loss AND overexploitation
108
Q

Name and outline three types of conservation interventions

A
  • threat reduction
    • habitat restoration, dec exploitation, dec invasive spp
    • facilitated by est reserves
    • e.g. croc hunting ban 1970s → saltwater croc pop recover from ~3000 to >100K now
    • e.g. humpback whales - dec hunting → pop recover from 100s in 1960s
  • population boosting
    • captive breeding
    • combo w threat reduction to ensure LT success
    • e.g. Lord Howe stick insect - captive breeding program @ melb zoo + removal of rats from LHI → pop successfully recovered
  • genetic rescue
    • recieve genes from diff pop to inc genetic div → resolves inbreeding depression
    • e.g. mt pygmy possum - intro males from nearby pop into struggling Buller pop → successful pop growth + inc genetic div (Weeks et al. 2017)

BIOL10010 Introductory Biology: Life's Complexity (8 decks)

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