A) Pre-Darwin History:

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1 Darwin Notes A) Pre-Darwin History: Ancient Greek philosophers such as and believed species were permanent and did not evolve. These ideas prevailed for 2,000 years. In 1859 Charles Darwin published. This book challenged the scientific views of the time including the belief that the earth was just years old and populated by life forms individually made during the that the Creator formed the entire universe. This Judeo-Christian belief was further supported by - a philosophy dedicated to discovering God s plan by studying. sought to discover order in the diversity of life and is the founder of. Taxonomy is concerned with and all life forms. Linnaeus developed a 2 part naming system called which uses a and. He grouped looking species into general categories, implying no evolutionary kinship. was a paleontologist who studied fossils in layers of rock called. He documented the succession of fossil species in the and noted the (older) the stratum, the more dissimilar the plant ( ) and animal ( ) life from today s modern organisms. He also noticed had occurred and developed the idea of - each strata corresponded in time to a catastrophe (flood or drought) that destroyed many species of that time. Then the ravaged region was repopulated by species from other areas. Geologist explained the various land forms on earth today (canyons, fossils, etc.) as having arisen slowly by. For example, he proposed that canyons formed by rivers cutting through rocks slowly. Geologist developed the idea of. This is the idea that geological processes changed over time. For example, the forces that mountains in the past, are the same ones working today.

2 was the first to suggest a model to explain how life. By comparing current living species to fossil forms he could see a series of older to younger fossils leading to modern day species. On the lowest rungs of the ladder were organisms which Lamarck thought arose via from nonliving material. At the top of the evolutionary ladder were plants and animals. Lamarck is most remembered for 2 ideas: #1) His idea of -the idea that if you use a body part a lot that body part will become and stronger, if you don t use a body part it will. For example, a had a short neck and it got longer by it to reach leaves on high branches. #2) His belief of of - modifications an organism acquires can be passed onto offspring. So the long neck of the giraffe evolved gradually over many generations of stretching higher and higher to reach branches and then was onto offspring. Today we know acquired characteristics change genes and are not passed onto children, but Lamarck was a visionary in his time nevertheless. B) Darwin: After being bored with medical school, Charles Darwin became a clergyman/ naturalist. In 1831 at the age of 22 he was asked to voyage around the world in a ship called the. The mission of the voyage was to chart the South American coastline, but Darwin was to, and thousands of exotic faunas and floras. He was especially interested in the fauna of the - islands of relatively recent origin west of S.A. Most of the animals on the Galapagos live in the world, bearing to species living on the mainland of S.A. It was as though the islands were colonized by plants and animals that strayed from the mainland and then on the different islands. Darwin also collected types of that were similar, but different species. The most striking difference among these birds was their and what they ate. One species has a large beak adapted to, another had a beak to grasp, another used a small twig as a tool to probe for wood-boring insects, etc. Darwin began to view the origin of and to new environments as related processes. For example, if a geographical barrier like a separated 2 islands-isolating 2 populations of a species, the populations would diverge more and more to adapt to local environmental conditions. Then over time, the 2 populations would be 2 separate. A species is defined as sharing similar characteristics, members can and produce offspring. Darwin s essay on The Origin of Species was not yet published when a naturalist named also developed a similar theory of natural selection. This encouraged Darwin to quickly publish his book which was much more and is why Darwin receives credit today for his ideas on evolution via natural selection.

3 Darwin believed all organisms descended from a single ancestor and over millions of years accumulated diverse or adaptations to fit their environment. In the first publishing of his book he did not use the term, but instead said: with. He saw closely related species like and as both descending from a similar ancestor along the tree of life -where each branch shows. This enabled organisms to be grouped into categories: C) Natural Selection: Darwin s main points on Natural Selection: #1) Production of individuals than the can support leads to a struggle for. #2) Survival in the struggle for existence is not, but depends in part on. Those best fit to the survive and - survival of the. #3) The unequal ability of some individuals to survive and reproduce will lead to change in a. Darwin already recognized the struggle for existence when he read an essay by on human. This essay spoke of human suffering that would occur as the human population faster than food supplies and other resources. The capacity to is characteristic of all species. Darwin also saw not only natural selection occurring, but selection. The breeding of plants and animals for desired traits. Humans have modified many species over generations that now bear resemblance to their wild ancestors. So if humans can cause so much change via artificial selection, Darwin reasoned selection should also bring about change less favorable variations over 100 s to 1000 s of generations. A is the smallest unit that can evolve. A population is a species that can and shares a common area. Evolution is measured by, it is variations in populations over many.

4 Natural selection is. A favorable adaptation in one situation may be useless or in different circumstances. The environment create variations in a population. Both arise by chance and are responsible for variation. If they are favorable they enhance an organism s reproductive success and are passed onto offspring. D) Evidence of Evolution: #1) Darwin documented evolution mainly by evidence from the distribution of species called. For example, islands have many species (found only there), yet they resemble mainland species. #2) Also Darwin based his observations on the record. Paleontologists have discovered many forms that link older fossils to modern species. While Darwin used these 2 sources as proof of evolution today we use other sources as well. #3) structures are also evidence for evolution. Many of the same structures are similar between different organisms. For example, the of humans, cats, whales, bats and all other mammals have many of the same elements but very different. It makes no sense to have similar unless they all descended from a common ancestor.

5 Some other homologous structures are also organs historical remnants of structures that had importance in ancestors. Vestigial organs are reduced versions of organs and it would be wasteful to continue providing, nutrients and space to organs that no longer have major functions. Q: Name examples of vestigial organs: #4) Closely related species go through similar stages of development. For example, all embryos, including humans go through a stage where they have / pouches. #5) biology supports relationships between species reflected in similar and. All life forms are related to some extent through branching descent from the earliest organisms. Even humans and have some proteins in common. In addition, a common genetic code shared by life forms is evidence of the branching of the tree of life ever since the code s beginning in an early life form.

6 E. A Theory??? Some people dismiss Darwin s ideas as. This is flawed because it fails to separate the idea that modern species did indeed evolve from ancestral forms and that natural selection is the main mechanism for this evolution. To biologists, evolution is a. The part of it is the of natural selection. Even now scientists are questioning whether natural selection accounts for evolution. Q: Images such as this one are often used as evidence that organisms have evolved. What is shown in this image?