Figure 39. 4 Phototropism experiment, step by step (fig394. jpg)




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BIOL121, Ecology, Genetics, & Evolution

Detailed course note by Luan Dang

Instructor: Wayne Goodey

Textbook: Campbell & Reece, Biology, 6th Edition




Note: all images mentioned here will have their position in the book and their filename. Their title might have been changed by me to sound catchier or easier to understand.


Hiuck! Hi y'all! I are GeekStone, now second year undergrad at B.C. University. I are write this course note. I are quite evolved for my time y' know.


Course synopsis: go for it. (In progress)


Jump to topic (bookmark list)

(In progress)


DETAILED COURSE NOTE

Sept 4, 2002 First day of class


Admin stuff

  • Group project announcement



Sept 6, 2002 How science is done


About the scientific method

  • Observations: are made to gain more understanding on a subject and whose merit depends on previous understandings.

You may be surprised, but the English court actually received reports of 15-legged, 5-eyed, fire breathing lizards keenly "observed" in Africa by an exploration party. (misc2.jpg)

  • Explanations: there is never one X answer for an X question; there are X, M, Z, V potential explanations, called hypotheses.

  • Evaluation: testing by experiment  science works not by proving, but disproving, as Sherlock Holmes said, “When you have eliminated the impossible, whatever remains, however improbable, must be the truth.”

  • More evaluation: in science, the test must be repeatable and must yield results consistent with the predictions made by the hypothesis.

  • Theory: after surviving extensive testing, a hypothesis may be considered “ripe” and be accepted as right. Yet no theory is ever exhaustive; history has proven that corrections will always be made, and widely accepted theories may be mowed down later with the light of more accurate observations and data inputs by newer instruments. If you believed in high school that the world has 3-D, prepare to be proven wrong by Einstein.


Experimental design

Figure 39.4 Phototropism experiment, step by step (fig394.jpg)





There will be figure studies all around BIOL121. They are simply just figures from the textbook. Why? When you spend around a hundred on a book, it is a waste to use example images elsewhere. Most figs used were up to date with your 6th edition text, but some were from the 5th. Figure 39.4 means figure 4 of chapter 39. Still can’t find that number? Just be patient and look around a bit.


  • Phototropism is the bending of plants toward light.

Experiment to determine the mechanism of phototropism

  • Control: The factor being tested is left at the treatment level normally encounter in the specimen's natural habitat. All other conditions are kept the same as the testing specimens to ensure that any changes observed are caused by only the factor being tested.

  • Hypothesis: only the tip of the coleoptile can sense light direction. (H.1)

  • Testing:

    Supporting hypothesis

    • Tip removed: the coleoptile doesn’t bend, suggested that hypothesis 1 is right.

    • Tip covered with opaque cap: no light passes thru → no bending, confirm H.1

    • Tip covered by transparent cap: light passes thru → bending, confirm H.1

    Disproving null hypothesis

    • Base covered by opaque shield: tip exposed → normal bending; the base does not sense light, confirm H.1.

  • Hypothesis 2: bending response occurs below the tip.

    • Tip separated by mica → tip exposed, yet no bending; light is sensed, but a signal must travel downward from the tip, and it cannot pass thru impermeable mica.

  • Hypothesis 3: the signal is a biochemical one, so it cannot pass through a membrane.

    • The signal turns out to be auxin, a plasma membrane hormone that weakens the cellulose wall of cells on the far side of the light, allowing them to elongate. This figure is also an illustration of scale in the scientific method. When designing an experiment, it is important to choose the appropriate scale. You can start from a large, visible scale like the change in the whole plant, then move done to parts of the plant, the tip/body/stem/root/leaf..., and then to the plants biochemistry. Our hypothesis gets more and more specific as our scale gets smaller




  • The day ends.



Sept 9th, 2002


Ecology: The study of how organisms interact in the environment.


Concepts in Ecology:

  • Scale:

  • Spatial: The dimensions of an experimental organism; the boundary of a population or community... All scale is only meaningful if there is a point of reference.

    E.g. All right, Ontario is 60 km away, but away from what? Without a frame of reference, a measurement is meaningless. Same for a map without a scale bar. Luckily, the scale we are concerned with in ecology is no smaller than some nanometers (10-9 m, for some viruses) and no bigger than Earth’s diameter (~107 m, for the biosphere)

  • Temporal: time/frequency/repeating patterns

E.g. unlike most animal of its size, human lives really long and grows really slow too.

  • Characterization: Classifying life

  • By genetic similarity and common origin (functional definition of species).

  • By morphology/behavior features (descriptive definition).


Figure 1.10 Canis lupus, a taxonomic scheme of the wolf (fig110.jpg)


“Biodiversity is a hallmark of life... Evolution is the key to understanding this biological diversity.” (Campbell, p.9)


The taxonomic scheme consists of groups contain within more comprehensive groups. Species that are closely related are placed in the same genus; genera are grouped into families, and so on...


  • Interaction: never look at just one organism alone; look at its community type and the interactions within it.

  1. Interaction determines behavior.

  2. Interaction can be...




Btw species Btw individuals of the same species


  • Wolf distribution:

1. Wolf used to appear throughout N. America and N. Asia, but now scattered for various reasons. Not only is “wolf” placed on the classification scheme, it is

also placed on the ecological one. This means that wolf does not exist in isolation but in a very complex network of interaction with many types of prey and

competitors, other wolfs and other species of predator. They are also affected by the weather, quality of habitat, and random catastrophic natural events.


That is, wolf must be seen in its environment; if you have seen a wolf once in the zoo, you cannot say you know “wolf.”


Definitions: Community is an assemblage of populations of different species in an area of habitat.

Population is the collective appearance of one species in an area of habitat.

Biome refers to a set of environmental conditions and is defined as one of the major types of ecosystems; e.g. coniferous forests, deserts, and grasslands.

Biomes determine climate/ soil/ rainfall/ temperature... Thus biomes define the specific characteristic of the organism in a community.

Interspecific interaction is between members of different species.


Figure 53.1 Interaction diagram (fig531.jpg not scanned)

  • Competition (-/-) can be inter- or intraspecific.

    • You go to the Pit Pub, there’s only ONE hamburger left. Another hungry guy is on the way; both of you run; you fight the guy for the burger. The loser gets nothing but a fight; whoever wins has won the meal for a cost.

  • Predation (+/-) between different species.

    • You eat the hamburger: fatal cost for the beef, protein benefit for you.

  • Mutualism (+/+) between different species.

    • Rhizobium bacteria in leguminous root nodules fixed nitrogen, part of which used by the tree; the tree protects the rhizobia from oxygen, which oxidize the very fragile Nitrogenase enzyme; both are happy.

  • Commensalism (+/0) interactions in which one species benefit from the other, while causing almost no harm nor good to the other. (Darwinian fitness-wise)

    • There are disputes about the existence of this kind of interaction, since it is much easier to measure a positive or negative effect, whereas there is no way to prove “zero effect.”








  • Interaction can change

  1. Over time, this topic will get more coverage later in Evolution.

  2. With the introduction of new species


Figure 50.7 Introduced exotic species, the African honeybee (fig507.jpg)

  • Spread of the African honeybee in the Americas since 1956

  • Read page 1097. This fig is explained extensively in the book and will be mentioned again with more detail.



  • The day ends.



Sept 11, 2002 Abiotic forces


Environmental factors affecting organismshabitat

Moisture (precipitation)

Temperature

Are the two most important climatic factors in species distribution.

Each species has different needs and tolerance for temperature and moisture due to there morphology and biochemistry.

Other more complex conditions are combinations of the above in different ways.

Rock and Soil (substrate), etc.

Soil moisture, texture, and nutrient content – It affects the plant distribution of an area.

And because plants are the primary producer, plant distribution affects the distribution of other organisms as well.

Amount of light

Why is light so important?

Definition: Primary Production is that of Photosynthesis Activity.

When primary production is affected, every other activity is affected as well.

→ Air circulation

The wind, air circulation, and air temperature is also important to the distribution of organisms.

E.g. it helps the dispersion of spores and seeds.

It is also an important influence of climate.


Figure 50.10 climograph of major kinds of ecosystems (fig5010.jpg)

  • Different ranges of annual mean temperature and precipitation reflects different biomes in different geographical regions.

  • The ranges overlapped! Nothing strange, this fig actually oversimplified things by showing the means. In reality, two regions with the same mean rainfall may have completely different rainfall distribution. E.g. 4 seasons vs. 2 (near the equator). Also, there are other factors operating in addition to temperature and rainfall.

  • Different climates happen in different areas in different times! Another excuse for the overlapping. E.g. monsoon rain in India when it’s hot in Madagascar, and vice versa. (I'm not completely sure of this example)


Geography review

  • The figures here are only to help you understand the basic mechanisms operating these abiotic factors. They will not be tested.

  • What you need to know in this section is be able to explain a case of distribution based on those abiotic factors.



Figure 50.12 Seasons and temperature (fig5012.jpg not scanned)

The 23.5o tilt of the Earth on its axis causes some regions to receive more or less sunlight as the Earth revolves around the sun.

  • This is just to brush up on your geography and will not be tested.

  • Skim through page 1102.


Figure 50.13 Global air circulation and precipitation (fig5013.jpg not scanned)

  • The movement of air by heating and the movement of the earth are factors that constitute to the overall global air circulation and wind patterns. This in turn affects precipitation and temperature.

  • Read page 1103

  • Again, this will not be tested.


Local and seasonal effects on climate

  • Read Textbook p.1102: Ocean currents influence the climate along the coasts of continents by heating or cooling overlying air masses, which may then pass across the land.

  • The oceans and large inland bodies of water tend to moderate the climate of nearby terrestrial environment.

  • Mountains: south-facing slopes in the N. Hemisphere receive more sunlight than north-facing slopes  different organisms.

  • Mountains affect rainfall.


Figure 50.14 Mountains Affect Rainfall (fig5014.jpg)

  • Vancouver and the Okanagan – air moves in from the Pacific Ocean.

  • At the windward side of the elevation, much precipitation occurs. Vancouver gets the name “boring city” from this rain.

  • Moist air from the ocean has already lost most moisture, and now descends to central BC and sucks up all moisture there, creating a much dryer/ hotter rain shadow.

  • If you don’t like BC, you can enjoy desert summer and icebox winter in Alberta, the leeward side.



Lake ecology is easily affected by local and seasonal climate changes.


Figure 50.15 Lake Ecology (fig5015.jpg)

  • Keep in mind: cold water oxygenates better.

organisms constantly consume oxygen in water

  • Spring and autumn: there is a turnover in the body of water, bringing oxygenated water from the surface to the bottom and nutrient-rich water from the bottom up.

  • Winter: There is a thin layer of ice on the surface of the lake. Only the middle layer of the lake contains the highest oxygen concentration. Because most organisms don’t thrive at freezing temperatures, most photosynthesis happens in the middle layer.

  • Summer: there is a sharp thermocline separating the upper layer of high temperature and the lower layer of very cold bottom water, as solar radiation can’t penetrate deep under the top layer.


Thus, it's not surprising that lake communities changes dramatically over seasons.

Ocean ecology, on the contrary, is affected very little by surrounding changes.


Figure 50.22 Zones in ocean ecology (fig5022.jpg)

  • Keep in mind:

  • The ocean bed is mostly flat plain, not volcanoes.

  • The ocean’s average depth is 3000 m.

  • Ocean temperature changes very little regardless of outside condition due to its sheer size and depth, so little convection occurs. The zonation of ocean ecology is quite stable over the seasons.

  • The photic zone, where light shines to, could reach 1000 m in theory, but in reality is usually less than 200 m and very often less than 20 m.

  • Go scuba diving and see for yourself. Very little photosynthesis actually happens beyond this depth.

  • Deep-water organisms are mostly scavengers feeding from the detritus, dead/ waste matter, falling from the upper layer.


The moral: the oceans are NOT nearly as productive as were claimed to be (more on this in later lectures). Do not expect endless food from the seas.


An overview of ecosystem (community) dynamics

  • The first law of thermodynamic, law of conservation of energy.

  • Energy can only changes from one system to another or one form to another; some energy is always lost as heat, the most randomized form of energy.

  • High-energy forms, such as light, eventually become heat, which dissipates into space.

  • Nutrient is recycled, but energy is not, the only way ecosystem kept running is because of a constant supply of energy, the sun.

  • Organisms use energy for maintaining body temperature, vaporizing water, movement, and structure. (light energy, for example, is turned into more organized chemical bonding energy)




Figure 54.1 Basic ecosystem dynamics (fig541b.jpg)

  • Detritivores: microorganisms that decompose dead/ waste matter (e.g. dead remains, feces, fallen leaves, and wood) for energy.

  • Decomposer plays a central role in material cycling. They return unused (dead) organic nutrients to primary producers as inorganic nutrients.

  • Read page 1199.




  • End of the day



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