Transcript Chap. 9 Competition

Chap. 9 Competition
鄭先祐 生態主張者 Ayo工作室
Part III Community Ecology
 Chap.
9
 Chap.10
 Chap.11
 Chap.12
 Chap.13
Competition
Predation
Community structure
Species diversity
Succession
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Chap. 9 Competition
 The
concept of the niche
 Types of competition defined
 Methods for obtaining evidence of
competition
 The relationship between intra-specific
and inter-specific competition
 The Effects of competition
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資源(食物)隨
時間會增長，
但族群成長更
加快速。
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The concept of the niche(職位)
 Habitat
(棲息地)
 Niche (ecological niche, functional niche)
 The first to use the term niche was
Charles Elton(1927).
 The concept of Hutchinsonian niche
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Three dimensions of the
niche
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Types of competition defined
 Resource
competition
 preemptive competition (for space)
 Exploitation competition (使用權)
 Interference competition (干擾權)
 Diffuse competition (多種影響)
 Interspecific and intraspecific
competition
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Methods for obtaining
evidence of competition
 Experimentation
A
classic example was performed by J. H.
Connell (1961) in his study of two species of
barnacles that inhabit the rocky intertidal zone
off Scotland.(Fig. 9-5, 9-6, 9-7)
 Observation
and inference
 Diamond
(1975) noted that some closely
related species of birds have a “checkerboard”
distribution pattern. (Fig. 9-8)
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Observation and inference
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現象與推論

The mainland has snowshoe hares in taiga
habitats and arctic hares in the tundra (Fig.
9.9).
 Both habitats in Newfoundland island were
occupied by arctic hares, the only species on
the island.
 When the snowshoe hare was introduced to
the island, arctic hares were soon found only
in tundra habitats.
 推論：因為競爭，迫使arctic hares 讓出 taiga
habitats給snowshoe hare。
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結果發現這是錯誤的推論！

A predator, the lynx, plays a critical role.
 When the snowshoe hare was introduced to
Newfoundland, lynx numbers increased
because of the greater abundance of prey.
 The arctic hare is far more vulnerable to
predation in taiga than is the snowshoe hare.
 結果：這是因為掠食者的壓力，而不是因為來
自種間的競爭。
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Intra-specific and inter-specific
competition

In plants, a phenomenon known as selfthinning attests to the importance of intraspecific competition.
 The rye grass Lolium perenne, exemplifies
this phenomenon.(Fig. 9.10)
 The straight line associated with the decline
in density over time has a slope of –3/2.
 This slope is found in many plant self-thinning
lines (Fig. 9.11)
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Fig. 9.10 Selfthinning in the
rye grass.
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Fig. 9.11 Regression lines
from self-thinning curves for
31 stands of different
species of plants.
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Replacement series 實驗

128 seeds of the two species were planted in
each pot.
 But the relative numbers of seeds of the two
species varied in the series of pots.
 At one extreme, all 128 seeds were A. fatua;
at the other extreme, all 128 seeds were A.
barbata.
 Other pots were shown with 16 fatua and 112
barbata, 32 fatua and 96 barbata, and so
forth.
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Intra- vs. inter-specific
 Approximately
75% of all seedlings
survive under pure stands of each
species. (pure intra-specific competition)
 If intra- and inter-specific competition
were equivalent, we would expect 75%
of the seedlings to survive.
 What they found? (Fig. 9.12)
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Fig. 9.12 Results of replacement series competition
experiments in Avena barbata and A. fatua
(a) survival of seedlings.
The dotted lines represent the expected result based on pure
intra-specific competition.
The solid lines and data points represent the actual performance
in competition.
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Fig. 9.12 Results of replacement series competition
experiments in Avena barbata and A. fatua
(b) seed production.
The dotted lines represent the expected result based on
pure intra-specific competition.
The solid lines and data points represent the actual
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performance in competition.
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The effects of competition
 The
long-term effect, known as
character displacement, operates on an
evolutionary time scale – that is, over
many generations.
 The short-term effect, called competitive
exclusion, occurs in ecological time –
that is, within a single or a few
generations.
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Character Displacement
 相近的物種，於重疊分布的區域，其
間的差異會因為競爭而擴大。
 這是否普遍存在？
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Fig. 22-25 The
phenomenon
of character
displacement.

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Fig. 9.13 The process of character displacement
(a) individuals of one species that use resources in
regions that do not overlap with the other species
have a selective advantage.
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Fig. 9.13 The process of character displacement
(b) over time, selection will separate the niches of
the two species.
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Fig. 9.14 Head-body lengths of male weasels as a
function of latitude.
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Fig. 9.15 The coefficient of variation (CV) in mandible length
in Veromessor pergandei as a function of the number of
granivorous ants in the community.
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Fig. 9.16a Frequency distributions of mandible sizes at
different sites. The mean mandible lengths of the most
similar competitors of Veromessor pergandei are indicated
by the arrows.
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Fig. 9.16b Frequency distributions of mandible sizes at
different sites. The mean mandible lengths of the most
similar competitors of Veromessor pergandei are indicated
by the arrows.
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Fig. 9.16d Frequency distributions of mandible sizes at
different sites. The mean mandible lengths of the most
similar competitors of Veromessor pergandei are indicated
by the arrows.
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Fig. 9.16e Frequency distributions of mandible sizes at
different sites. The mean mandible lengths of the most
similar competitors of Veromessor pergandei are indicated
by the arrows.
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Fig. 9.16f Frequency distributions of mandible sizes at
different sites. The mean mandible lengths of the most
similar competitors of Veromessor pergandei are indicated
by the arrows.
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
 Fig. 22-26
Proportions
of
individuals
with breaks
of different
sizes in
populations
of ground
finches on
several of
the
Galapagos
islands.
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Fig. 1 The considerable difference in beak
morphology between these three species of
Darwin's finches, Geospiza, which coexist on many
Galapagos islands, has been the subject of much
debate concerning its cause.
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Fig. 2 The beak morphology of Geospiza
conirostris shows significant variation on
different species on different islands.
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Fig. 3. The average beak depths of four species of
Darwin's finches on three islands where they coexist
show considerable variation from island to islands, even
though the same set of possible competition occurs on
each island.
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範例：filaree
Two species of annual plants
 Erodium
cicutarium和 E. obtusiplicatum
 運用replacement series 方法。
分成三類：
 1. Sympatric populations.
 2. Allopatric populations.
 3. Transposed populations.
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Fig. 9.17 The experimental design to examine the
evolution of competitive interactions.
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Fig. 9.18 Total seed production at
different levels of intra- and
interspecific competition for
populations of two species of
Erodium.
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Competitive exclusion
 Gause’s
law：the competitive exclusion
principle
Fig. 9.19 Growth curves for
Paramecium aurelia and P.
caudatum in separate and
mixed cultures.
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Fig. 9.20 The skulls of the
saber-toothed cat Smilodon
californicus, a placental
mammal, and the marsupial cat
Thylacosmilus.
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Environmental application
Introduced species: Potentially
devastating competitors
Zebra mussels were released into
North America from the ballast of
ships from Asia and Europe.
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Major invasions to Australia
 The
European rabbit was imported from
Great Britain and soon reached such
numbers that it destroyed immense
tracts of rangeland.
 Estimates made in the 1950s put the
population at over 1 billion rabbits.
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Why do these introduced
species cause such problem?
 Two
factors probably account for the
more intractable exotics:
 (1) the species’s ability to colonize new
habitats
 (2) its ability to out-compete native biota.
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範例：freshwater fishes in
California

48 of 137 species of freshwater fish are
nonnative.
 Of these 48 introduced species, only 6 are
found in undisturbed or pristine waters, and 4
of those are species of trout or salmon
introduced into fishless lakes in the high
Sierra.
 Of the 26 species of exotics for which data
exist, 24 are known to have a negative impact
on native fish.
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Fugitive species
 Species
that inhabit transient
environments are often very susceptible
to competitive exclusion.
 Fugitive species typically colonize
habitats immediately after a disturbance.
 They are called fugitives because they
or their offspring must always be in
search of the next disturbance site for
colonization.
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Fig. 9.21 Blossoms of fireweed, a fugitive
species that depends on fire disturbance.
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The prairie forb colonizes small disturbed area caused
by badger excavations of ground squirrel burrows.
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The Lotka-Volterra Models
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The logistic equation
 dN/dt
= rN (K-N)/K
 dNi/dt = riNi (1-Ni/Ki - aijNj/Ki)
 dNj/dt = rjNj (1-Nj/Kj - ajiNi/Kj)
 at equilibrium
 (Ki - Ni - aijNj) / Ki = 0
 (Kj - Nj - ajiNi) / Kj = 0
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Fig. 9.22
(b) Ki - Ni - aijNj = 0
(c) Kj - Nj - ajiNi = 0
二元一次方程式 Ni 和 Nj .
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Fig. 9.23 Graphic representation f the equilibrium
conditions for two species of which species i is the
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better competitor.
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Fig. A-1. The course of competition between two
populations.
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Fig. 9.24-25 (a) conditions for the stable coexistence of
two competing species.
(b) outcome of competition between two species that are
both more strongly limited by interspecific competition
than by intraspecific competition. The populations tend
to diverge from the equilibrium point.
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 請應用Lotka-Volterra
model 預測兩種相互競
爭的族群, 其間競爭的最後結果。假設甲族
群對乙族群的競爭系數是β; 乙族群對甲族
群的競爭系數是α; 甲族群的族群數量是Ｎ1;
而其承載量是Ｋ1; 乙族群的族群數量是Ｎ2;
而其承載量是Ｋ2。起初時, 甲族群數量是50,
乙族群有90。請按下列(4與5題)的數值, 寫
出甲乙族群最後的數量(Ｎ1, Ｎ2)。
※ 同時必要寫出其相關的計算過程，才可得分。
公式如下(參考用)：
※
※
dN1/dt = r1N1 (k1 - N1 - αN2)/K1 ，
dN2/dt = r2N2 (k2 - N2 - βN1)/K2 。
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計算出其結果
若 α=1.2 β=0.8 Ｋ1 =200 Ｋ2 =200,
 (2) 若 α=0.8 β=1.2 Ｋ1 =160 Ｋ2 =250,
 (3) 若 α=1.4 β=1.4 Ｋ1 =260 Ｋ2 =260,
 (1)
期末考題範例
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Empirical examples of the
Models’ predictions
 In
the laboratory one can determine the
critical light intensity for a species, the
minimum amount of light required to
sustain population growth.
 The predicted competitive abilities of the
four species were as follows:
 Chlorella > Aphanizomenon > Microcystis
> Scenedesmus
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Fig. 9.26a Results of competition between pairs
of Phytoplankton species.
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Fig. 9.26b Results of competition between pairs
of Phytoplankton species.
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Aphanizomenon
Fig. 9.26c Results of competition between pairs
of Phytoplankton species.
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Fig. 9.26d Results of competition between pairs
of Phytoplankton species.
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Chlorella
Fig. 9.26e Results of competition between pairs
of Phytoplankton species.
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Fig. 9.26f Results of competition between pairs
of Phytoplankton species.
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Empirical examples of the
Models’ predictions
 K1
= K2 =1.0
a12 = a21
 Populations of Drosophila melanogaster
and D. simulans in the laboratory.
 These populations do not exhibit
competitive exclusion, as the LotkaVolterra models predict for these values.
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Fig. 9.27 Lotka-Volterra competition graphs for Drosophila
serrata and D. pseudoobscura. The solid lines are observed
isoclines; the dashed lines are isoclines predicted by the
model.
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•於不同的環境狀態，競爭的能力與結果就可能會有所不同。
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兩種蚊子的競爭
 Native
North American treehole
mosquito, Aedes triseriatus
 Introduced Asian species, A. albopictus.
 In Figure 9.28 we see that stable
coexistence is expected in tree holes,
whereas extinction of A. triseriatus is
predicted in abandoned tires containing
small pools of water.
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 問題與討論！
[email protected]
Ayo 文化站 http://faculty.pccu.edu.tw/~ayo
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