The Imperiled Planet: An introduction.
How evolutionary change, natural selection, & deep time hold the world steady and sustain the world that created us.
J. V. Siry Ph.D.
“There is a grandeur in this view of life.”
"How one species, Homo sapiens, has become so powerful that it can significantly undermine the ability of the Earth's environment to support much life–including our own–is a central theme of this book."
The Dominant Animal. p. 3.
Darwin & Mendel: the two sides of a biological “coin”
– behavior & inheritance.
1, Darwin and Mendel's legacy–“lessons about limits in another person's
2, The Tangled Bank– more
lessons of natural laws from all around us
3, Our Distant Past– “rocks of ages”
unseen remnants of a forgone world
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,
“descent with modification” 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.
Conditional (surroundings) change + genetic
inheritance = descent with deviations
“it is usually very hard to select for just one
“a gene consists of a series of
nucleotides with different bases
that determine the
sequence... proteins” [with alterations = modifications = deviations]
proteins (enzymes & hormones) are life’s 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
nature’s 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!
limitations of natural selection & inheritance,
genotype vs. phenotype,
inorganic & organic limitations,
predator – prey relations,
origins & loss in descent,
divergence and convergence
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
(and matter) can neither be created nor destroyed; energy (E) is constant (k)
transfer of energy is ever completely efficient; so that heat, as a loss, accumulates
the universe will have insufficient energy for life
Said another way, by Garret Hardin
are bound to lose
cannot get out of the game
descendants vary with respect to
the traits they inherit and thus what survives depends
on what was produced earlier by variable parents and grandparents.
really evolves, but descendants vary greatly from their ancestors
of that variable inheritance is passed on
all traits are passed on, but natural selection favors functional assets, or at least non-lethal traits.
in a population many traits survive
that can endow future offspring with variety
is insurance against the storm
are no guarantees of success
has the capacity to adapt to conditions that are not too extreme
time due to isolation and variation, populations give rise to new species:
on the Galapagos Islands
Eight significant points:
1. Populations change within
limits [milieu’s limits + genome’s limits]
2. Natural selection favors
some traits among very variable offspring’s 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 RNA’s 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 population’s 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 life’s diversity, beauty, and integrity on an imperiled planet.
a. Laws enabling limits and
b. descent from a common ancestor
c. inherited resistance
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