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第 2 章 Adaptation and Evolution
鄭先祐
生態主張者 Ayo
Chap. 2 Adaptation and Evolution
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The interaction of Ecology and Evolution
Evolution in Populations
Mechanisms of Evolution
Fitness and the Evolutionary stable strategy
Optimality of adaptation and constraints on
selection
Sexual selection and Kin selection
The Evolution of interactions among species
生態學 2001
The interaction of Ecology and
Evolution
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Evolution is genetic change in a population of
organisms over time.
生態學與演化學，兩者關係密切。
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生物族群的生態情況導引其演化。
生物對其生態情況的反應，可能也會造成演化。
沙漠的環境，有利於如同仙人掌的植物。
幾千年前，野狼的原始行為是單獨的獵捕小型動物，只
有在繁殖季節才聚集。後來，大型草食動物出現，野狼
發現獵捕小型動物愈來愈難，獵捕大型的動物，單獨行
動又沒有辦法。因此逐漸地產生集體獵捕的行為。
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Adaptation (適應)
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每個生態情況都是一個影響演化化解(solution)
生態問題的力量。
每個演化化解都是一種適應(adaptation)。
適應，族群基因庫分布改變，促進族群於特定的
生態環境中可有較好的生存能力或繁殖力。
Huchinson(1965) The ecological theater and
the evolutionary play.
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生物學的時間與空間的範圍
基本資料取自Kohn (1989), p.1096。
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地球：生物界
生物學
台灣生態
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空
1km
2
間
的
生物体
1m
0
小型生物
量
度
大型生物
-2
無脊椎動物
1mm
原生物
-4
胞器
1um -6
細胞
病毒
蛋白質
-8
小分子
1A -10
5
-16 -14 -12 -10
1 微秒
-8
-6
1分
-4 -2 0 2
1天
1年
時 間 的 量 度
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6
8
10
1 百萬年
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Evolution in
Populations
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圖2.1 Frequency
distributions for four
different characters in
different organisms.
The curves superimposed
on the raw data in each
graph show that each of
these characters has a
normal distribution.
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一般生命的延續過程
Phenotype space
P‘2
P2
t‘2
P‘1
t2
P1
t1
t3
t‘1
t’3
t“1
Genotype space
G‘2
t‘4
G2
t4
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G1
G‘1
G“1
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Fundamentals of population
genetics
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Gene pool (基因庫)– the sum total of all the
genes in a population
Hardy-Weinberg equilibrium
假定： AA 30個體， Aa 20個體， aa 50個體
P(A) = p = (2(30) + (20)) / 200 = 0.4
P(a) = q = (20 + 2x50) / 200 = 0.6
AA：Aa：aa = 0.16 ： 0.48 ： 0.36
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Conditions leading to evolutionary
change
Hardy-Weinberg equilibrium 的條件：
1. The population must be large(族群必要夠大)
2. No emigration and no immigration
3. No differential mortality or reproduction of the
different genotypes. (沒有天擇的作用)
4. No new mutations
 以上任何一項的不吻合，就會產生演化的現象。
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Table 2.1 condition and violations
of the Hardy-Weinberg Equation
Condition for equation
Violations
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Infinitely large population
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Genetic drift
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No net immigration or
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Gene flow
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Natural selection
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Mutation pressure
emigration of alleles
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No differential mortality
or survival by genotype
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No new mutations
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演化的機制
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1. Genetic drift (基因飄
移)– a stochastic
(random) shifts in allele
frequencies of a
population.
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1. Genetic drift
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圖2.3 因為基因飄移所
造成的對偶基因數量分
布的改變
有效族群數量 – the
number of individuals
participating in random
mating.
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2. Gene flow (基因循流)
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Gene flow – the loss or gain of alleles via
emigration or immigration in a population.
圖2.4 mean distances
over which bees
dispense pollen in the
yellow fawn lily.
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3. Natural selection
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Natural selection -- the differential representation of
genotypes in future generations, resulting from
heritable differences among them in survival and
reproduction.
Darwin 的觀點：
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1. 每個個體都有不同的遺傳特質(基因型)。
2. 資源是有限的。
3. 表現型的好壞，影響其是否可以成功的遺傳至下一代。
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Fig. 2.5 Selection on
bill size in Geospiza
fortis and relationship
to changes in food
supply.
BL = bill length
BD = bill depth
BW = bill width
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fitness
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Fitness – the relative genetic contribution by an
individual’s descendants to future generations.
Absolute fitness – the expected number of
offspring produced by a particular genotype.
Relative fitness – relative ability of a genotype
to obtain representation in the next generation.
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Three important properties of
fitness
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1. Fitness is property of a genotype, not of an
individual or a population. Individuals with the
same genotype share the same fitness.
2. Fitness is specific to a particular environment.
3. Fitness is measure over one generation or
more.
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Modeling Natural Selection
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運用Hardy-Weinberg equilibrium為基礎。
加入 selection coefficient, s
s= relative decrease in survival of aa individuals
Hardy-Weinberg p2 +2pq +q2
P(A) = (2(p2 ) + 2pq)/ 2(p2 +2pq +q2) = p
P’(A) = (2(p2 ) +2pq)/ 2(1-sq2) (因為aa的減少s量)
= p / (1-sq2)
P(A) = P’(A) – P(A) = p / (1-sq2) – p = spq2 / (1-sq2)
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圖2.6 Changes in allele frequency (p) as a
function of the number of generations, for
three different selection coefficients (s).
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Selection force
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天擇要完全的清除任何一個隱性基因，是很難的。
甚至是s=1，aa就會致死的天擇壓力。經過9000
代的天擇，仍然未能完全的清除。
這是因為 the recessive allele is protected from
selection within the heterozygote.
It is very difficult for selection alone to
completely eliminate such an allele.
3/5/2001
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Modes of Natural Selection
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Directional selection
Stabilizing selection
Disruptive selection
Soft selection – K-selection (density-dependent)
Hard selection – r-selection (density-independent)
Frequency-dependent selection – 譬如：性別
就是，selection favor rare phenotype.
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圖2.7 Changes in phenotypes under three
modes of selection. The shaded regions
represent phenotypes selected against.
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Natural selection and adaptation
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Adaptations are heritable features of
organisms that increase their fitness.
Adaptations can affect virtually any aspect of
an organism: its morphology, physiology,
biochemistry or behavior.
Convergent evolution (趨同演化)
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圖2.8 新大陸的cacti 與舊大陸的euphorbs
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圖2.9 similarities between pairs of Australian
marsupial mammals and placental mammals
represent examples of convergent evolution.
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Marsuplals
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Placental Mammals
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Evolutionarily Stable Strategy
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If the current genotype cannot be replaced by
an invading one, it is said to represent the
evolutionarily stable strategy (ESS)
Natural selection acts to increase the average
fitness of a population. 倘若這個平均 fitness 已
經達到高峰，任何的改變都會被排斥。
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圖2.10 Fitness of three hypothetical
genotypes, A. B, and C.
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ESS的範例：caller 和satellite達到平衡。
Alternative reproductive strategies
圖 A mail bullfrog (left) calls from his territory and attracts
a female who is entering the pond on the right. In the
middle of the picture is a small male who sits silently in the
larger male’s territory as a satellite and attempts to
intercept the female on her way to the caller.
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Optimality of Adaptation
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Are the organisms optimally(最佳化) designed
for the interactions in which they participate?
目前所有研究過的，都未能達到最佳化。
Why
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1. Our expectation is incorrect. Optimal 未必是best
solution.
2. Constraints on the evolution
3. There has not been sufficient time.
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Constraints on Selection
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1. 天擇只能作用於現有的基因型。
2. 生物體本身的特質，限制其adaptation的能力。
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譬如同一地區，有單子葉的樹木(棕櫚樹)和雙子葉的
樹木，雙子葉的樹木可以形成分枝，擴大其樹葉的覆
蓋面積，但單子葉的樹木就沒有辦法。雖然分枝可有
較高的adaptation。
The giant panda 的 thumb，雖然是不完美，但卻是
較容易演化轉變的途徑。
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圖2.11 The giant panda，
竹子是它唯一的食物。
圖2.12 Panda’s thumb,
which is not a true thumb
but an extra digit derived
from the radial sesamoid
bone.
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Constraints on Selection
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3. Physical laws
constrain evolution. 任何
的生命現象，無法違反物
理定律。譬如：大小人國。
4. Nature of the selection
process itself may
constrain the adaptations
it produces. The
concept of the adaptive
landscape. (Fig. 2.13)
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Sexual Selection
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If females choose the males with which they
will mate, then they constitute a selective force
on males. -----sexual selection
Sexual selection – 相當強烈的selection
譬如：highly exaggerated morphological
features that attract mates may be deleterious
in other ways.
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圖2.14 a The male sage grouse
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圖2.14 b The male peacock (孔雀)
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圖2.14 c
Males of the
Irish elk
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Sexual Selection
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Runaway selection – 因為sexual selection 的結
果通常都會異常的誇張，甚至會達到有害生活的
程度。
Truth in advertising – the females choose
mates according to their phenotype as
indicators of the general fitness of the male. 譬
如：雄性麋鹿擁有巨大的角，代表其較有能力防
衛家人。
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Kin selection
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Kin selection – 按 inclusive fitness 來運作的 selection.
Inclusive fitness – the relative ability of an organism to
get its genes, or copies of them, into the next
generation.
Coefficient of relationship, r – The average proportion
of genes shared by two individuals
如此就有可能產生 Altruistic behaviors (利它行為)
Altruistic behaviors – behaviors that enhance the
fitness of other individuals in the population at the
expense of the individual performing them.
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Table 2.2 Values of r, the coefficient of
relationship, for different relatives in a
diploid species.
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Mother/ child
Father /child
Full siblings
Half siblings
Grandparent/grandchild
Aunt or uncle/nephew or niece
First cousins
0.5
0.5
0.5
0.25
0.25
0.25
0.125
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Calculation of r, the coefficient of
relatedness.
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Calculation of r,
the coefficient
of relatedness.
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Hamilton’s argument
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An altruistic allele will increase if
k > 1/ r
k is the ratio of the increase in fitness of the
recipient to the decrease in fitness of the
altruist.
譬如：altruistic behavior 朝向自己的兄弟，
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r =0.5
如此 k > 1/ r = 2
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Belding’s ground squirrels, live in colonies. In this
picture a female has seen an approaching coyote and
is giving an alarm call. By calling she is increasing her
risk of being attacked by the predator but the warning
benefits neighboring females who retreat down their
burrows. Neighboring females are closely related.
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The evolution of interactions
among species
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Batesian mimicry – a benign species resembles a
noxious or dangerous one.
Müllerian mimicry – several noxious species come to
resemble each other.
Aggressive mimicry – a noxious or dangerous species
comes to resemble a benigh one.
Aposematic coloration – bright or distinctive coloration
that indicates that the species is dangerous or noxious.
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圖2.15
An example of
Batesian mimicry,
similarities in color
patterns of colubrid
snakes and coral
snakes in different
central American
locations. The
presumed models
(coral snakes) are on
the left, the mimics are
on the right. In (e),
two colubrids living in
the same locality
mimic one coral
snake(center).
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Fig. 2.16 The toxic pitohuis of New Guinea, a
group of Mullerian mimics.
(a) Pitohui dichrous
(b) P. kirhocephalus
© P. ferrugineus.
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Coevolution
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Table 2.3 The effects (positive, negative, or none) of
various kinds of interactions among species.
species
A
B
Parasitism
+
–
Commensalism
+
0
Mutualism
+
+
Predation/herbivory
+
–
Competition
–
–
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Parasitism (寄生現象)
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寄生蟲有兩個特質：
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1. 有a dispersal phase
2. 有a reproductive phase ，並產出大量的offspring.
The host species is under intense selection
imposed by the presence of the parasite.
Parasites are under selection to decrease their
virulence.
Parasitism 最後可能會轉變為commensalism
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中
間
寄
主
進入人體
圖2.17a. Life cycles of two parasites
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中
間
寄
主
進入羊的身體
圖2.17b. Life cycles of two parasites
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Myxomatosis virus and hares 範例
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於澳洲：歐洲的野兔引進，大量繁殖，大量耗用
草原。控制野兔族群擴張的方法，就是有意的引
入Myxomatosis virus，可以殺死野兔。
幾年之後，the mortality rate of infected hares
declined. Why?
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1. 野兔產生抵抗力
2. The virus became less virulent.
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Nests parasites 範例
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Cuckoo 鳥，寄生在 warbler鳥的巢。
雌cuckoo鳥安靜的觀察warbler鳥巢的動靜。
當發現 warbler鳥巢的雄雌鳥都離開時，cuckoo鳥即溜
進warbler鳥巢，並產下一個卵，且將鳥巢中warbler產
下的一個卵推出巢外。整個過程只要10秒鐘。
Cuckoo鳥卵與warbler鳥卵外型相似。
Cuckoo鳥卵的孵化速度較快，發育也較快。最後將
warbler鳥巢中的所有的warbler小鳥全部排出到鳥巢外。
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Mutualism
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Mistletoe(榭寄生) is a parasitic species that
lives on trees. Its seeds are adapted to
enhance its dispersal by tanagers (風琴鳥).
The seed’s outer pulp layer is highly nutritious.
Inside the pulp is a layer of vicin, a substance
that protects the seed from digestion and
enhances its passage through the bird’s gut.
而且vicin也會黏住鳥的 cloaca，迫使鳥必要去
磨擦樹枝，而讓種子可以在樹上成長。
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典型的食虫鳥類之消化道
一般的風琴鳥
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圖2.18
專食mistletoe的風琴鳥
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The yucca and the moth 範例
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Yucca 於夜間開花，夜行性的 yucca moth協助
yucca 授粉。
Yucca moth 停在花上，爬入花朵中，用特殊的
嘴收集花粉，形成花粉球，含在嘴裡。隨後飛到
另一朵花，moth 將自己的一個卵注入花的子房
內，然後再爬到花柱上，再將嘴中的花粉吐出在
柱頭上，完成授粉。
當moth的孵化出來，幼蟲吃食整串Yucca種子的
中間部分，然後冒出來，爬下到地面，結繭。
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 Moth-Yucca mutualism
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Star orchid 和 hawk moth 範例
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Orchid is characterized by an extremely long
floral tube
The hawk moth has an incredibly long
proboscis(針狀吻).
假若要有授粉成功，蘭花的花管要比蛾類的針狀
吻還要長。如此，才能迫使蛾類的身體擠入，如
此才可有效的授粉。
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Conditions leading to mutualism
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Mutualism 於低緯度地區較常見。
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Ant-plant mutualism 只分布到14oN以南。
Nectarivorous 和frugivorous bats 則到22oN。
Many mutualistic systems end not far north or south of
the equator.
Stable and benign climate 和少干擾，有助於長期的演
化。
另外，不同種類，也會有不同程度的傾向。(fig. 2.20)
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圖2.20 The
proportions of
various insect
taxa in the
British Isles that
have mutualistic
microorganisms.
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 Mutualism
範例
Bull’s horn acacia
(Acacia cornigera) that
attract its ant mutualist
(a) protein-rich Beltian
bodies at the tips of
the leaflets(小葉).
(b) Hollow thorns used
by the ants as nesting
sites.
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Competition
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Character displacement
圖2.21 Diagram of the process of character
displacement.
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Fig. 22-25 The
phenomenon of
character
displacement.
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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
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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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Predator-prey and herbivore-plant
evolution
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Coevolutionary arms race (共同演化的武器競賽)
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Frog-eating bat (Trachops cirrhosus)
Frog 被掠食的壓力，演化出對哺乳類有毒的腺體。
The adaptive response by the bats has been to
discrimicate between the calls of poisonous and non
poisonous frogs.
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Herbovores and plants
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植物的防衛：
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可能是形態上的，諸如：針狀，毛狀，粗糙面的葉子。
也可能是用化學的方法來防衛，含有secondary
compounds。
草食動物的掠食：突破植物的防衛
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植物運用結構和化學防衛，對抗草食動物。
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結構防衛(structure defenses) (Fig. 7-17)
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煙草含有尼古丁(nicotine)，是很強的殺虫劑。因為尼古
丁可以阻斷虫類的神經傳導。但是煙草虫(Fig.7-19)的神經
細胞可以排出nicotine。
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Coevolutionary arms race
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Red queen problem – had to run faster and
faster just to stay in the same place.
The environment constantly changes and
organisms must continue to evolve to survive.
Fitness is relative to the environment.
The evolutionary play develops differently in
different “theaters”.
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 Adaptive radiation in the Hawaiian
honeycreepers (Drepanididae).
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附加的資料
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Environmental Application
Summary
Self-assessment
Problems and study questions
Projects and additional study
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Environmental application
Loss of genetic variation
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小族群的基因庫容易單調化。Why？
1. Genetic drift
2. Inbreeding depression (homozygosity 上升)
3. Bottleneck effect：族群縮小後，再成長，其
基因庫仍然是單調。
譬如：cheetah ( Acinonyx jubata)，其族群內個
體間的DNA差異小於1%。於人類族群中，個體
間的差異可高達32%。
生態學 2001
Summary
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1. Ecology and evolution are intimately related
biological fields.
2. 個體間有基於不同基因型所呈現的表現型之差異。
3. Gene pool.
4. Hardy-Weinberg equilibrium
5. Natural selection and genetic drift
6. Adaptation constrains
7. Sexual selection
8. Kin selection
9. Coevolution
生態學 2001
Self-assessment
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1. 族群的演化，其有何重要機制？
2. 為何有時候，我們看不到生物適應的表現？
3. 所有天擇的類型與內涵？
4. Hardy-Weinberg equation的意義。
5. Ecology and evolution 的關係？舉例說明。
6. Coevolutionary interactions，有哪些類別？
生態學 2001
Problems and study questions
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1. 名詞定義：
2. 有一個鳥類族群密集的生活。因為大部分的
幼鳥都會遷移出去，這個族群內的個體間，親
緣關係很低。倘若有突變產生會發出警告聲音，
當發現有掠食者接近時。
a.
b.
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這是否為一種ESS？這個突變基因是否會改變原本
的基因庫的基因分布？
假若另外一種突變發生，可以讓發出警告聲音者，
可以不被掠食者發現。那麼情況會有何改變？
生態學 2001
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3. 設計一個研究計劃，可以來確定mimic 現象中，何種
是model ，何種是 mimic。
4. Fitness的定義。倘若我們要對某種adaptations 研析
其 fitness advantages，且要再野外進行。我們需要測
定個體的fitness。我們要如何的進行測定。
5. Aposematically colored species 假若是致死，這可能
會產生演化上的問題。假想第一個接觸到的是coral
snake ，因而造成致死。如此，其他的個體如何學習到
這種aposematic coloring是代表致死的象徵？
6. 某種雙套的動物，每個雌性只產生兩個子代。掠食的
壓力很大，許多幼體都會被吃掉。父母企圖要保護其幼
體，結果自己也會被吃掉。倘若現在有突變產生，父母
會放棄保護自己的子代，轉而去保護其親戚的子代。這
會是一種ESS嗎？請說明理由。
生態學 2001
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7. 一個族群有100個個體。
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b.
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AA：Aa：aa = 50：15：35
What are the values of p and q?
這是否於Hardy-Weinberg equilibrium?
8. 按上題的數據，假若隱性的同型基因是有害的，只
有80%可以存活而繁衍後代。其他基因型的個體都是
100%。經過一代後，其p和q的數值是多少？
9. 於果蠅中，sepia眼睛是隱性基因所表現的。假若你
發現一個族群中有16%是具有sepia 眼睛的個體。那其
相對的顯性基因，存在的比率是多少？要解決這個問
題，需要有哪些假設？
10. 大貓熊的thumb是由radial sesamoid演變而來，為
何不是由first digit演變而來。
生態學 2001
Projects and additional study
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1. Incomplete dominance
2. 查詢 相關 coevolution 的文獻
3. Genetic variation 與其effects文獻查詢：
desert pupfish, Royal catchfly, northern
elephant seal, North American wolves, bison
4. Wells, J. 1999. Second thoughts about
peppered moths. The Scientist 13:13. 質疑
Kettlewell 的研究結果。
生態學 2001
 問題與討論！
[email protected]
Ayo 文化站 http://faculty.pccu.edu.tw/~ayo
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生態學 2001