Sunday, January 24, 2010
DARWIN, ON THE ORIGIN OF SPECIES BY NATURAL SELECTION, OUTLINE, 1984
Sumatran Tiger family in Auckland, New Zealand Zoo: http://www.aucklandzoo.co.nz/
See photo credit in margin.
Unpublished outline for Charles Darwin’s book On The Origin of Species by Means of Natural Selection, 1984-1985, instructor Barbara Pope, Interdisciplinary Studies in Letters and Science (ISLS) program, Chabot College, Hayward, CA, by Lurene Helzer. This book by Mr. Darwin, originally published on November 24, 1859, is today almost as important as it was when it first appeared.
Lurene's email in 2014: email@example.com
It remains widely misunderstood because of Darwin’s popular phrase “survival of the fittest.”
The phrase means that species, for example, that can swim will survive in the ocean and species that can not swim will not be as suited for oceanic life. The poor swimmers will die out naturally. It does not mean that some vengeful club of hateful, bloodthirsty sharks murder smaller sharks for amusement.
Chapter IV Natural Selection N.S. = Natural Selection
On The Origin of Species by Charles Darwin
Can the principal of selection apply in nature? Natural Selection: The preservation of favorable variations and the rejection of injurious variations.
Natural Selection caused by climatic changes: Extinction, chain reaction, immigration of inhabitants to other places.
Unless there are natural or other barriers.
Unless profitable variations do occur, N.S. can do nothing.
No country is so stable, species-wise, that it is so well adjusted as to no need of further variation.
The superiority of nature in its methods of gradual adoption and variation: Compare and contrast of man vs. nature, Survival of the Fittest.
The perpetuity of N.S. – Civilizations inability to observe it in its intricate capacity (daily, hourly).
Variations of color and flesh & N.S.
The role of N.S. in keeping a species’ characteristics true and constant.
Unknown correlations of growth: Variation and N.S. or variation leads to Natural Selection eventually.
Natural Selection guarantees that the modifications will not be injurious to the species. Insect example.
The vastness of N.S.:
Does not work singularly, but always to the eventual benefit of the community, or to the species. But not for an individual organism.
Caused or put into effect by the struggle of Males for the Females. Ensures or helps preserve strong, healthy offspring. Applies mostly to carnivorous or polygamous animals.
Sexual Selection in Birds:
The coloring and characteristics of birds is selected by the mating habits of successive generations: The most “beautiful” bird (male) is always chosen by the female: Characteristics are passed through Generations.
Conclusion on Sexual Selection in Birds: Slight variations in birds are due to sexual selection. These various characteristics have survived because they are advantageous to the males when the females select or mate. Or, the females find these attractive. But there are some contradictions to this theory.
Example of N.S. in Wolves: Swiftest wolves will survive when Deer population decreases.
Examples of N.S. due to innate individual tendencies in certain species. Specifically, eating habits. Different climates also cause variation in eating habits. Explanation on why these habits may differ in species.
Example of N.S. in cross breeding and the benefits. Those oftenest crossed will be selected.
Division of Labor to Separate the sexes – may be temporary for N.S.
Example of how bees and their flowers might adapt to each other through N.S. or – gradual deviations in structure.
Argument for previous examples: Use previously disputed geological theory to back up this theory. Uses analogy. Tries to dispel “instant modification” idea.
Theory: Hermaphrodites, at some time, concur for reproduction of their kind. Introduction to brief digression.
Why Hermaphrodites must, at least occasionally, interbreed: Cross breeding gives strength and vigor to species while close interbreeding weakens.
Example: Bees who carry pollen from one Hermaphrodite to another.
Further example of how bees assist in Hermaphrodite reproduction process: Proves by using example of contradictions in self-reproductive process.
Asserts that interbreeding between “varieties” is advantageous, but when between “species” is the reverse.
Differences between Flowering tree reproduction in different countries. Digression.
Introduces idea of Hermaphrodite animals occasionally crossing: Says there is no proof to the contrary. All animals, at some time, cross.
States that, if Hermaphrodites do intercross, they have very small functional differences.
Concludes digression on Hermaphrodite reproduction: An occasional intercross is the law of nature. Self-fertilization can not be truly perpetual.
Circumstances favorable to N.S.: Although inheritable and diversified variability is favorable, mere individual differences suffice.
Theorizes that not only is N.S. favorable to the preservation of the species, it is necessary in a competitive environment to avoid extinction of the species.
N.S. and Intercrossing and Size of Environment: Man’s breeding will be unsuccessful if intercrossing takes place. But when this breeding is less deliberate, it can be successful. In a large area, different districts will present different conditions of life. Intercrossing will most affect animals who unite for a birth. Slow breeding animals.
The effects of intercrosses, even in slow breeding animals, will not completely retard N.S.
The role of Intercrossing in keeping a species uniform: Intercrossing can only sustain the species if the conditions of life remain the same, through inheritance, and through N.S. weeding out the variations. Otherwise, the principals of N.S. must sustain them.
Isolation’s Role in N.S.: In these areas, life will be uniform, intercrosses will be prevented, will allow new species to evolve if a change in environment occurs.
If the area is small, the number of individuals will be small and retard new species through N.S.
Although a small enclosed area, like an island, is instrumental in the evolution of new species, it is impossible to conclude whether or not these conditions are superior to a large area, such as a continent, because of the differing time scales.
Small Area –vs- Large Area to produce New Species; Large Area is Superior: Because,
1.) Large Area species endure and expand widely over the area
2.) Because of large number of individuals, there is a better chance of favorable variations
3.) Conditions of life are complex, which is advantageous to the growth of Species
4.) The strongest species have strength because they have had to compete with a wide variety of individuals to survive
5.) They will, therefore, give rise to new species and change the organic world
The effect of diminished competition on the Species: On a small island, where there is little competition, there is less competition and less modification of the Species. Darwin referred to these island Species as “living fossils” since they have been subject to few variations over time.
Conclusion: Reiteration of principals concerning large and small areas. But when small area joins a large area, extinction may take place. N.S. will resume over the area.
Asserts that the slow rate at which N.S. operates is consistent with geological studies.
Darwin talks about the perpetuity of N.S. as compared to Man’s methods of artificial selection.
Extinction: Less favored species will become rare, then extinct. Darwin uses geology to back up his argument. The number of specific forms does not increase indefinitely. Yet, no region of the world is fully stocked.
Species with the largest number of variations will have the best chance of surviving.
Form closest to those undergoing favorable variations will suffer the most. The forms of any species will, likewise, press hardest against their closest kindred. The same applies to domestic selection.
Varieties are species in the Process of formation: incipient species. Mere chance might cause variations in individual animals of the same species, but it is more than simple chance when the variation shows up habitually.
Horse example of divergence of character using domestic Selection as an illustration.
Looks good – accurate. Can you look over the whole outline and see any major parts? And in relation to previous chapters? To later ones?
Sorry you missed the lecture on structural analysis of whole book and especially Ch. 1 – 4 today, Friday.
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