Transcript Photosynthetic

Ecology
Chapter 07
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Outline
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Energy Sources
Solar-Powered Biosphere
Photosynthetic Pathways
Using Organic Molecules
Chemical Composition and Nutrient
Requirements
Using Inorganic Molecules
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Energy Sources
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Organisms can be classified by trophic levels.
 Autotrophs use inorganic sources of
carbon and energy. (自營)
 Photosynthetic: Use CO2 as carbon
source, and sunlight as energy. (光合成)
 Chemosynthetic: Use inorganic
molecules as source of carbon and
energy. (化學合成)
 Heterotrophs use organic molecules as
sources of carbon and energy. (異營)
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Prokaryotes which have cells with no
membrane-bound nucleus or organilles,
include the bacteria and the archaea.(原核生
物;古菌)
The archaea are prokaryotes distinguished
from bacteria on the basis of structural,
physiological, and otherbiological features.
Rhodopsin are light-absorbing pigments
found in animal eyes and in the bacteria and
archaea.(視紫質)
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Solar - Powered Biosphere
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Light propagates through space as a wave.
 Photon: Particle of light bears energy.
 Infrared (IR) Long-wavelength, low
energy.
 Interacts with matter, increasing
motion.
 Ultraviolet (UV) Short wavelength, high
energy.
 Can destroy biological machinery.
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Solar - Powered Biosphere
Photosynthetically Active Radiation (PAR,
光合有效輻射)
 Between two extremes. (可見光)
 PAR makes up about 42% of the total
energy content of the solar spectrum at
sea level.

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Photosynthetically Active Radiation
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Fig. 6.3
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Fig. 6.3a
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Solar - Powered Biosphere
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PAR
 Quantified as photon flux density (光通
量密度).
 Number of photons striking square
meter surface each second.
Chlorophyll absorbs light as photons.
 Landscapes, water, and organisms can
all change the amount and quality of
light reaching an area.
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Fig. 6.1
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Fig. 6.2-2
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NADPH
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在生物體中之合成作用，皆屬於還原反應，
其中NADPH（reduced form，nicotinamide
adenine dinucleotide phoshphate，菸鹼醯胺嘌
呤雙核苷磷酸鹽）是主要的電子提供者，其
氧化態為NADP+，且需ATP的參與。
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Photosynthetic Pathways
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C3 Photosynthesis (Phosphoglyceric acid)
 Used by most plants and algae.
 CO2 + ribulose bisphosphate 雙磷酸核酮
糖(RuBP, 5 carbon sugar) =
phosphoglyceric acid 磷酸甘油酸(PGA, 3
carbon acid)
 To fix carbon, plants must open stomata
to let in CO2 .
 Water gradient may allow water to
escape.
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C3 Photosynthesis
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PGA
Phosphoglyceric acid; PGA
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Photosynthetic Pathways
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C4 Photosynthesis (C4: Oxaloacetate)
 Reduce internal CO2 concentrations.
 Increases rate of CO2 diffusion inward.
 Need fewer stomata open.
 Conserving water
 Acids produced during carbon fixation
diffuse to specialized cells surrounding
bundle sheath. (維管束鞘)
 PEP: phosphoenol pyruvate 磷酸烯醇丙酮酸
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C4 Photosynthesis
phosphoenol pyruvate
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Photosynthetic Pathways
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CAM Photosynthesis (景天酸代謝光合作用)
 (Crassulacean Acid Metabolism)
 Limited to succulent plants (多汁植物) in
arid and semi-arid environments.
 Carbon fixation takes place at night.
 Reduced water loss.
 Low rates of photosynthesis.
 Extremely high rates of water use
efficiency.
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CAM Photosynthesis
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Using Inorganic Molecules
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1977 - Organisms found living on sea floor.
 Near nutrients discharged from volcanic
activity through oceanic rift (裂口).
 Autotrophs depend on chemosynthetic
bacteria.
 Free-living forms.
 Living within tissue of invertebrates.
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Chemosynthesis
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Chemosynthetic bacteria oxidize
ammonium(NH4+), nitrite(NO2-), iron(Fe2+),
hydrogen(H2), or carbon monoxide(CO).
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Chemical Composition
and Nutrient Requirements
Five elements make up 93-97% of biomass
of plants, animals, fungi and bacteria:
 Carbon
 Oxygen
 Hydrogen
 Nitrogen
 Phosphorus
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Essential Plant Nutrients
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Potassium
Calcium
Magnesium
Sulfur
Chlorine
Iron
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Manganese
Boron
Zinc
Copper
Molybdenum
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Using Organic Molecules
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Three Feeding Methods of Heterotrophs:
 Herbivores: Feed on plants. (草食者)
 Carnivores: Feed on animal flesh. (肉食者)
 Detritivores: Feed on non-living organic
matter. (屑食者;腐食者)
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Herbivores (草食者)
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Face substantial nutritional chemistry
problems.
 Low nitrogen concentrations.
Must overcome plant physical and chemical
defenses.
 Physical
 Cellulose; lignin; silica
 Chemical
 Toxins (alkaloids, 生物鹼)
 Digestion Reducing Compounds
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Herbivores (草食者)
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Digestion Reducing Compounds are generally
phenolic compounds such as tannins that bind to
plant proteins, inhibiting their breakdown by
enzymes and further reducing the already low
availability of nitrogen in plant tissue.
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The cellulose and lignin in plant may be a
first line of chemical against herbivores, a
defense that most herbivores overcome with
the help of other organism (bacteria, fungi,
or protists)
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Proportion of temperate and tropical plants bearing toxic
alkaloids, potent defenses against potential herbivores.
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Urchin 海膽
Tropical seaweeds are better
defended against attack by
herbivores
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Average N contents of
living and dead leaves of
many plant species of
environments from tropical
rain forests through deserts
and temperate forests
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Detritivores (屑食者)
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Consume food rich in carbon and energy,
but poor in nitrogen.
 Dead leaves may have half nitrogen
content of living leaves.
Fresh detritus (碎屑) may still have
considerable chemical defenses present.
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Carnivores
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Consume nutritionally-rich prey
Both predators and prey have low C:N and C:P
ratios.
Carnivores cannot choose their nutritionally rich prey
at will, because most prey species are masters of
defense. One of the most basic prey defense is
camouflage. Predator cannot eat prey they cannot
find.
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Carnivores
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Other prey defense include anatomical defenses
such as spines, shells, repellents, and poison, and
behavioral defenses such as flight, taking refuge in
burrow, banding together in groups, playing dead,
fighting, flashing bright colors, spitting, hissing, and
screaming at predators.
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Carnivores
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Prey Defenses:
 Aposomatic (起警戒作用的) Coloring - Warning
colors.
 Műllerian mimicry: Comimicry among several
species of noxious organisms. (共同擬態) 穆勒氏
擬態，有毒害者相互模仿。
Batesian mimicry: Harmless species mimic noxious
species. 貝慈氏擬態，無毒者模仿有毒者。
next
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穆勒氏擬態理論 (Műllerian mimicry) 是天擇理
論中的典型範例之一，其內容主要是說，在
同一棲地裡，不同種的有毒生物，為了警告
掠食者遠離他們，會傾向演化出相同或是類
似的體色。如此一來，掠 食者便會在很短的
時間內學到教訓，遠離帶有類似體色斑紋的
生物。
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在厄瓜多熱帶雨林中的Heliconius屬蝴蝶，正是穆勒氏擬
態理論的活教材。三種散居在不同地區的Heliconius屬蝴
蝶，H. sapho 帶有白色色斑﹔H. eleuchia 帶有黃色色
斑﹔而H. cydno則有黃白兩種不同體色。這三種蝴蝶在
幼蟲期都會蠶食有毒植物的葉子，並將有毒物質保存在
體內直到成蟲。Kapan將117隻 H. cydno 蝴蝶的翅膀加以
編號，分別帶至 H. sapho 與 H. eleuchia 的原棲地野放，
觀察當地的掠食者對這些外來的蝴蝶有什麼反應，並在
兩週後計算野放的 H. cydno 的存活率。
在偽裝網的掩蔽下，Kapan 發現在白斑的 H. sapho 棲地，
掠食者對帶有白色色斑的 H. cydno 一樣敬而遠之﹔而帶
有黃斑的 H. cydno 在相似體色的 H. eleuchia 棲地裡也不
會被當地的掠食者攻擊。
若將白斑的 H. sapho 移至黃斑的H. eleuchia 棲地的，便
特別引起掠食者注目，其存活率約下降了64%。
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Mullerian Mimicry between the Cuckoo bee and
Yellow Jacket
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食蚜蠅模仿蜜蜂
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Batesian mimicry：皇蛾
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King snakes (無毒)
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Coral snake
(有毒)
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Carnivores (肉食者)
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Predators are usually selection agents for
refined prey defense.
 Usually eliminate more conspicuous (易看
見的) members of a population (less
adaptive).
 Must catch and subdue (制伏) prey - size
selection.
Predator and prey species are engaged in a
co-evolutionary race.
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甲殼類
The diets of river otters show
great geographic variation
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美洲獅
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Review
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Energy Sources
Solar-Powered Biosphere
Photosynthetic Pathways
Using Organic Molecules
Chemical Composition and Nutrient
Requirements
Using Inorganic Molecules
Energy Limitation
Food Density and Animal Functional
Response
Optimal Foraging Theory
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