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The Imperiled Planet: An introduction. How evolutionary change, natural selection, & deep time hold the world steady and sustain the world that created us.
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J. V. Siry Ph.D. |
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"How one species, Homo sapiens, has become so powerful that it can significantly undermine the ability of the Earth's environment to support much lifeÐincluding our ownÐis a central theme of this book." The Dominant Animal. p. 3.
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Darwin & Mendel: the two sides of a biological ÒcoinÓ – behavior & inheritance.
1, Darwin and Mendel's legacy–Òlessons about limits in another person's eyesÓ
2, The Tangled Bank– more lessons of natural laws from all around us
3, Our Distant Past– Òrocks of agesÓ unseen remnants of a forgone world
introduction
Unknown to one another Darwin and Mendel discovered that variability and selection work
in tandem to produce viable offspring—members of a potentially breeding population.
Eight significant points are the heart of the chapter, foreshadowing the book: within limits,
Òdescent with modificationÓ from a common ancestor leads to diversity over time, random
mixture generates genetic variability, immunity or resistance, and biotic potential. Thus this
hereditary composition of a population assures our effective survival, if not breeding.
moths, birds, anoles, fruit flies, human blood cells, eye color, and enzymes.
argument
Conditional (surroundings) change + genetic inheritance = descent with deviations
Òit is usually very hard to select for just one characteristic.Ó
Òa gene consists of a series of nucleotides with different bases that determine the
sequence... proteinsÓ [with alterations = modifications = deviations]
meaning
proteins (enzymes & hormones) are lifeÕs essential constituents, arbiters, & threads.
The new tree of life -- the five kingdoms of three Eukaryots organisms and their cousins the bacteria and the Archaea, or bacterial-like creatures thriving in extreme conditions.
We like all of natureÕs species are the products of variation & selection. To know truly what limits we have & how this biological treasure we are endowed with functions, we must unravel a complex puzzle among: the earth, ethology (behavior), ecology (surroundings), & molecular biology (competing means of regulatory feedback). Our task is to better know the world in us!
vocabulary
limitations of natural selection & inheritance,
Manchester UK,
genotype vs. phenotype,
diversity, diversification,
inorganic & organic limitations,
biotic species,
predator – prey relations,
populations.
warblersÕ song,
Monarch butterflies,
mimicry, selection,
DDT resistance.
origins & loss in descent,
missing links,
Archaeopteryx,
Tiktaalik,
traits,
deep time,
ratio,
Paleolithic,
tool-making,
Olduwan culture,
exodus,
rock-solid
divergence and convergence
Why do your eye colors differ only within a limited range?
Descent from a common ancestor creates a contingent inheritance of colors, shape, mass, or size, as Mendel realized with his peas. He grasped in his garden, what Darwin's saw in the world: a variety of traits inherited by descendents from a common, ancestral source.
Three laws of thermodynamics
| 1 | energy (and matter) can neither be created nor destroyed; energy (E) is constant (k) |
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| 2 | no transfer of energy is ever completely efficient; so that heat, as a loss, accumulates |
| 3 | eventually the universe will have insufficient energy for life |
Said another way, by Garret Hardin
1, You canÕt win
2, You are bound to lose
3, You cannot get out of the game
Evolution,
descendants vary with respect to the traits they inherit and thus what survives depends on what was produced earlier[1] by variable parents and grandparents.
Nothing really evolves, but descendants vary greatly from their ancestors
Some of that variable inheritance is passed on
Not all traits are passed on, but natural selection favors functional assets, or at least non-lethal traits.
So in a population many traits survive that can endow future offspring with variety
Variety is insurance against the storm
There are no guarantees of success
Life has the capacity to adapt to conditions that are not too extreme
Over time due to isolation and variation, populations give rise to new species:
Finches on the Galapagos Islands
Turtles
Rails
Eight significant points:
1. Populations change within limits [milieuÕs limits + genomeÕs limits]
2. Natural selection favors some traits among very variable offspringÕs genomes
3. Isolation (loss) and the pace of change among organisms can be rapid or slow
4. Linking evolution to genetics is the Modern synthesis and a foundation of biology
5. Artificial selection by humans and other organisms can change other creatures (fruit flies, cows, cats & dogs, sheep, GMOs]
6. Change in the hereditary composition of populations over time is due to DNA and RNAÕs variability and functionally replicable chemistry.
7. Genotype & phenotype act in such a way as phenotype is selected for as an expression of genotype [eye color in humans].
8. Changes in a populationÕs genome is the raw material of evolution or shifts–alterations–in populations of organisms over time.
We are the products of the world we see around us, limited by its conditions plus our inherited and acquired traits to wither or prosper; as we can become proper caretakers, or unreasonable exploiters of an unimaginably expensive endowment, which I will call lifeÕs diversity, beauty, and integrity on an imperiled planet.
a. Laws enabling limits and optimization
b. descent from a common ancestor
c. inherited resistance
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