ive Read some posts re evolution in the theology section. Ngunit ano nga ba ang evolution at natural selection???..here is my attempt to simplify (cant simplify it further e...
) some thoughts on Evolution and natural selection using Cut pasted texts from the ff links:
http://www.globalchange.umich.edu/globalchange1/current/lectures/selection/selection.html; http://evolution.berkeley.edu/evosite/evo101/IIIENaturalSelection.shtml. Just slightly rearranged them....
Nawa'y magamit nyo ito para sa mga walang hanggang diskusyon nyo sa kabitbahay na "THeology section".PS: hindi sinabi ni Darwin na galing ang mga Espiya sa Unggoy.... 
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Evolution and Natural Selection (
http://www.globalchange.umich.edu/globalchange1/current/lectures/selection/selection.html)
Darwin's theory of evolution fundamentally changed the direction of future scientific thought, though it was built on a growing body of thought that began to question prior ideas about the natural world.
The core of Darwin's theory is natural selection, a process that occurs over successive generations and is defined as the differential reproduction of genotypes(the genetic constitution of a cell, an organism, or an individual usually with reference to a specific character under consideration."Wikipedia def" ).. Natural selection requires heritable variation in a given trait, and differential survival and reproduction associated with possession of that trait. Examples of natural selection are well-documented, both by observation and through the fossil record.
The (R)Evolution of TheoryThe theory of evolution is one of the great intellectual revolutions of human history, drastically changing our perception of the world and of our place in it. Charles Darwin put forth a coherent theory of evolution and amassed a great body of evidence in support of this theory. In Darwin's time, most scientists fully believed that each organism and each adaptation was the work of the creator. Linneaus established the system of biological classification that we use today, and did so in the spirit of cataloguing God's creations.
In other words, all of the similarities and dissimilarities among groups of organisms that are the result of the branching process creating the great tree of, were viewed by early 19th century philosophers and scientists as a consequence of omnipotent design.
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However, by the 19th Century, a number of natural historians were beginning to think of evolutionary change as an explanation for patterns observed in nature.
• Discoveries of fossils were accumulating during the 18th and 19th centuries. At first naturalists thought they were finding remains of unknown but still living species. As fossil finds continued, however, it became apparent that nothing like giant dinosaurs was known from anywhere on the planet. Furthermore, as early as 1800, Cuvier pointed out that the deeper the strata, the less similar fossils were to existing species.
• Similarities among groups of organisms were considered evidence of relatedness, which in turn suggested evolutionary change. Darwin's intellectual predecessors accepted the idea of evolutionary relationships among organisms, but they could not provide a satisfactory explanation for how evolution occurred.
• Darwin was influenced by observations made during his youthful voyage as naturalist on the survey ship Beagle. On the Galapagos Islands he noticed the slight variations that made tortoises from different islands recognizably distinct. He also observed a whole array of unique finches, the famous "Darwin's finches," that exhibited slight differences from island to island. In addition, they all appeared to resemble, but differ from, the common finch on the mainland of Ecuador, 600 miles to the east. Patterns in the distribution and similarity of organisms had an important influence of Darwin's thinking.
• In 1858, Darwin published his famous On the Origin of Species by Means of Natural Selection, a tome of over 500 pages that marshalled extensive evidence for his theory. Darwin's theory of evolution has four main parts: 1.
Organisms have changed over time, and the ones living today are different from those that lived in the past. Furthermore, many organisms that once lived are now extinct. The world is not constant, but changing. The fossil record provided ample evidence for this view.
2.
All organisms are derived from common ancestors by a process of branching. Over time, populations split into different species, which are related because they are descended from a common ancestor. Thus, if one goes far enough back in time, any pair of organisms has a common ancestor. This explained the similarities of organisms that were classified together -- they were similar because of shared traits inherited from their common ancestor. It also explained why similar species tended to occur in the same geographic region.
3.
Change is gradual and slow, taking place over a long time. This was supported by the fossil record, and was consistent with the fact that no naturalist had observed the sudden appearance of a new species. [This is now contested by a view of episodes of rapid change and long periods of stasis, known as punctuated equilibrium].
4.
The mechanism of evolutionary change was natural selection. This was the most important and revolutionary part of Darwin's theory, and it deserves to be considered in greater detail.
Let's look at an example to help make natural selection clear.:Natural Selection (
http://evolution.berkeley.edu/evosite/evo101/IIIENaturalSelection.shtml)
To find out how Natural selection works,imagine a population of beetles:1.
There is variation in traits.For example, some beetles are green and some are brown.
2.
There is differential reproduction. Since the environment can’t support unlimited population growth, not all individuals get to reproduce to their full potential. In this example, green beetles tend to get eaten by birds and survive to reproduce less often than brown beetles do.
3.
There is heredity.The surviving brown beetles have brown baby beetles because this trait has a genetic basis.
4.
End result:
The more advantageous trait, brown coloration, which allows the beetle to have more offspring, becomes more common in the population. If this process continues, eventually, all individuals in the population will be brown. If you have variation, differential reproduction, and heredity, you will have evolution by natural selection as an outcome. It is as simple as that. [/i]
Local Adaptation -Some Evidence of Natural Selection (
http://www.globalchange.umich.edu/globalchange1/current/lectures/selection/selection.html)
o Galapagos finches are the famous example from Darwin's voyage. Each island of the Galapagos that Darwin visited had its own kind of finch (14 in all), found nowhere else in the world. Some had beaks adapted for eating large seeds, others for small seeds, some had parrot-like beaks for feeding on buds and fruits, and some had slender beaks for feeding on small insects . One used a thorn to probe for insect larvae in wood, like some woodpeckers do. Six were ground-dwellers, and eight were tree finches
To Darwin, it appeared that each was slightly modified from an original colonist, probably the finch on the mainland of South America, some 600 miles to the east. It is probable that adaptive radiation led to the formation of so many species because other birds were few or absent, leaving empty niches to fill; and because the numerous islands of the Galapagos provided ample opportunity for geographic isolation.
o Industrial melanism is a phenomenon that affected over 70 species of moths in England. It has been best studied in the peppered moth, Biston betularia. Prior to 1800, the typical moth of the species had a light pattern . Dark colored or melanic moths were rare and were therefore collectors' items. During the Industrial Revolution, soot and other industrial wastes darkened tree trunks and killed off lichens. The light-colored morph of the moth became rare and the dark morph became abundant. In 1819, the first melanic morph was seen; by 1886, it was far more common -- illustrating rapid evolutionary change.
Eventually light morphs were common in only a few locales, far from industrial areas. The cause of this change was thought to be selective predation by birds, which favored camouflage coloration in the moth.
In the 1950's, the biologist Kettlewell did release-recapture experiments using both morphs. By observing bird predation from blinds, he could confirm that conspicuousness of moth greatly influenced the chance it would be eaten.
o The rat snake, Elaphe obsoleta, has recognizably different populations in different locales of eastern North America (see Figure 4). Whether these should be called geographic "races" or subspecies is debatable. These populations all comprise one species, because mating can occur between adjacent populations, causing the species to share a common gene pool (see the previous lecture on speciation).
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