population cycles
DESCRIPTION
POPULATION CYCLES. I. WHAT IS A CYCLE?. A. The Concept of Cycles. CYCLE CHARACTERISTICS. MORE CHARACTERISTICS OF CYCLES. Regional synchrony in fluctuations of coexisting species, Summer crashes in abundance A gradual disappearance of cycles southward. I. WHAT IS A CYCLE?. - PowerPoint PPT PresentationTRANSCRIPT
POPULATION POPULATION CYCLESCYCLES
I. WHAT IS A CYCLE?I. WHAT IS A CYCLE?
A. The Concept of Cycles
CYCLE CHARACTERISTICSCYCLE CHARACTERISTICS
Time
Ab
un
dan
ce
IncreasePhase
Peak Phase
Decline Phase
LowPhase
MORE CHARACTERISTICS MORE CHARACTERISTICS OF CYCLESOF CYCLES
Regional synchrony in fluctuations of coexisting species,
Summer crashes in abundance A gradual disappearance of cycles
southward
I. WHAT IS A CYCLE?I. WHAT IS A CYCLE?
B. Cycles and Body Size Biological times scale as :
nerve conduction time cardiac cycle time respiratory cycle time generation time lifespan
1 4W
I. WHAT IS A CYCLE?I. WHAT IS A CYCLE? B. Cycles and Body Size
Mass (kg)
10-2 10-1 100 101 102 103 104
Cyc
le L
eng
th (
yrs)
100
101
102
Cycle = 8.15M0.26
Source: Peterson et al. (1984, Science 224:1350-1352)
n = 40 species
I. WHAT IS A CYCLE?I. WHAT IS A CYCLE?
D. Longer-Period Cycles: Hares
I. WHAT IS A CYCLE?I. WHAT IS A CYCLE?D. Longer-Period Cycles: Hares
Year
1865 1875 1885 1895 1905
Nu
mb
er
of
Ha
res
0
25000
50000
75000
100000
125000
150000 period
am
pli
tud
e
I. WHAT IS A CYCLE?I. WHAT IS A CYCLE?
D. Longer-Period Cycles: Hares Coincident
cyclic speciesanimaldiversity.ummz.umich.edu
www.aquatic.uoguelph.ca
www.arttoday.com
II. A GENERAL THEORY OF II. A GENERAL THEORY OF POPULATION CYCLESPOPULATION CYCLES
Archbishop Olaus Magnus and Lemmings
II. A GENERAL THEORY OF II. A GENERAL THEORY OF POPULATION CYCLESPOPULATION CYCLES
Archbishop Olaus Magnus and Lemmings
Intrinsic Versus Extrinsic factors
Some Theories
1) Chitty’s Hypothesis- NS
2) Social Fence Hypothesis -
Time
Ab
un
da
nc
e
IncreasePhase
Peak Phase
Decline Phase
LowPhase
Pop Size increases
Competition increases: tolerants stay but low fertility
Pop size decreasing = emmigration & fertility
Animals spaced out & competition reduced
Some Theories
3) Climate- indirect/direct
Some Theories
4) Nodal Lunar Cycles & Sun Spots- 9.3 yr phase of moon = full moon during spring breeding
-
Some Theories
Some Theories
5) Trophic-Level Interactions* plant-herbivore* predator-prey* parasite-host* seasonality* predator switching
II. A GENERAL THEORY OF II. A GENERAL THEORY OF POPULATION CYCLESPOPULATION CYCLES
A. Increase Phase high fertility rate low mortality rate young age structure large litters early age at first reproduction few predators
Time
Ab
un
da
nc
e
IncreasePhase
Peak Phase
Decline Phase
LowPhase
II. A GENERAL THEORY OF II. A GENERAL THEORY OF POPULATION CYCLESPOPULATION CYCLES
B. Peak Phase fertility rate declines hares: decline in quality and
quantity of food
Time
Ab
un
dan
ceIncreasePhase
Peak Phase
Decline Phase
LowPhase
II. A GENERAL THEORY OF II. A GENERAL THEORY OF POPULATION CYCLESPOPULATION CYCLES
B. Peak Phase fertility rate declines voles and lemmings: social
factors
II. A GENERAL THEORY OF II. A GENERAL THEORY OF POPULATION CYCLESPOPULATION CYCLES
C. Decline Phase low fertility rates high mortality rates old age structure
Time
Ab
un
da
nc
e
IncreasePhase
Peak Phase
Decline Phase
LowPhase
II. A GENERAL THEORY OF II. A GENERAL THEORY OF POPULATION CYCLESPOPULATION CYCLES
C. Decline Phase Role of food quality
Proteinase inhibitors common plant toxin pancreatic enlargement build up during peak and year
1 decline phase
II. A GENERAL THEORY OF II. A GENERAL THEORY OF POPULATION CYCLESPOPULATION CYCLES
Proteinase inhibitors could cause: drastic declines in herbivore density changes in body size and organ
mass the high degree of synchrony in
fluctuations
II. A GENERAL THEORY OF II. A GENERAL THEORY OF POPULATION CYCLESPOPULATION CYCLES
C. Decline Phase Role of food quality
Reversion to juvenility woody plants and winter
browsing by hares juvenile defenses time lags of 2-3 years
Winter Dormant Twigs of Alaska Paper Birch Winter Dormant Twigs of Alaska Paper Birch
(B. neoalaskana)(B. neoalaskana)Mature Stage
Juvenile Stage
Note Resin Glands
Note Catkin And The Lack Of Resin Glands
Resin Gland on Current Year Twig Resin Gland on Current Year Twig InternodeInternode
Results ofResults of B. neoalaskana B. neoalaskana Mature Vs. Juvenile Feeding Mature Vs. Juvenile Feeding TrialTrial
Mature Stage Twigs
Juvenile Stage Twigs
Note That These Twigs Do Not Have Catkins At Their Tip.
II. A GENERAL THEORY OF II. A GENERAL THEORY OF POPULATION CYCLESPOPULATION CYCLES
C. Decline Phase Role of predators
Pro
po
rtio
n S
urv
ivin
g
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
Source: Krebs (1996, J. Mammal. 77:8-24)
June July August
Predator exclosure
Lemmingcontrols
II. A GENERAL THEORY OF II. A GENERAL THEORY OF POPULATION CYCLESPOPULATION CYCLES
C. Decline Phase: Role of Predators
www.abdn.ac.uk
II. A GENERAL THEORY OF II. A GENERAL THEORY OF POPULATION CYCLESPOPULATION CYCLES
Indirect effects of predators
% Bank Voles in Diet
0 10 20 30 40 50 60
An
tip
red
ato
r R
es
po
ns
es
0
1
2
3
4
Source: Ylonen (1994, TREE 9:426-430)
Raccoondog
PolecatRed fox
Marten
Stoat
Weasel
www.abdn.ac.uk
II. A GENERAL THEORY OF II. A GENERAL THEORY OF POPULATION CYCLESPOPULATION CYCLES
Indirect effects of predators diurnal raptors and indoor plumbing by
lemmings
www.goals.com
European kestrel
Collared lemming
II. A GENERAL THEORY OF II. A GENERAL THEORY OF POPULATION CYCLESPOPULATION CYCLES
C. Decline and Low Phase Interaction of Food and Predators
>2-3x when food added or predators removed
>11x when food added and predators removed