Chapter 22 (2)

__ was born in western England and loved nature. He left medical school and traveled via __ in Dec 1831.

Darwin observed that the plants and animals in temperate regions of __ more closely resembled species living in the __ tropics than species living in temperate regions of __. Furthermore, the fossils he found were distrinctly __ in their resemblance to the lliving organisms of that continent.

Darwin studied __, reading Lyell's Principle of Geology while aboard the __. He examined rocks after a violent earthquake in Chile. He found fossils of ocean organisms in the Andes. Darwin inferred that rocks containing the fossils must have been raised there by a series of many similar earthquakes. these observations reinforced what he'd learned from Lyell: the physical evidence did not suport the tranditional view of a __ earth only a few thousand years old.

True or False:
Darwin was interested in the unusual organisms he found om the Galapagos. The birds he collected there included several kinds of mockingbirds that seemed to be different species although similar. Some were unique to individual islands, while others lived on two or more adjacent islands. Furthermore, althugh the animals on the Galapagos resembled species living on the South american mainland, most of the Galapagos species were not known from anywhere else. He hypothesized that the Galapagos had been colonized by organisms that had strayed from S. America and then diversified, giving rise to new species ont eh various islands.
True False

During the voyage of the Beagle, Darwin observed many examples of __, characteristics of organisms that enhance their survival and reproduction in specific environments. Later, as he reassessed his observations, he began to perceive __ to the environment and the origin of new species as closely related processes.

Example: Finches' various beaks and behaviors are adapted to the specific foods available on their home islands. Darwin realized that explaining such __ was essential to understanding evolution. His explanation of how __ arise centered on __, a process in which individuals with certain inherited traits leave more offspring than individuals with other traits.

By the early 1840s, Darwin worked out the major features of his hypothesis. He was hesitant, but Lyell told him to publish them before someone else does. Someone else did: __.
Darwin still wrote a book, __, and published it and although not first with the ideas, he was known as the architect.

In his book, Darwin stated two main ideas. What were they?

In the first edition of The Origin of Species, Darwin never used the word __, but used __, a phrase that summarized his view of life. Darwin perceived __ in life, which he attributed to the descent of al organisms from an ancestor that lived in the remote past. He also thought that as the desendants of that ancestral organism lived in various habitats over millions of years, they had accumulated diverse modifications, or __, that fit them to specific ways of life. Darwin reasoned that over long periods of time, descet with modification eventually led to the rich diversity of life we see today.

Darwin viewed the history of life as a __, with multiple branchings from a common trunk out to the tips of the youngest twigs. The tips of the twigs represen t the __ of organisms living in the present. Each fork of the tree represents an ancestor of all the lines of evolution that subsequently branch from that point.

Closely related species are very similar because they shared the same line of descent until a relatively recent split from their common ancestor. Many branches of ___, even some major ones, are dead ends. Scientists estimate that over __ of all species that have ever lived are now extinct.

In his efforts at __, Linnaeus had realized that some organisms resemble each other more closely than others, but he had not linked these resemblances to __. Nonetheless, because he had recognized that the great diversity of organisms could be organized into "groups subordinate to groups" (Darwin's phrase), __ system meshed well with Darwin's hypothesis. To Darwin, the __ hierarchy reflected the branching history of the tree of life, with organisms at the various levels related through descent from commo ancestors.

Darwin proposed a mechanism, __, to explain the observable patterns of evolution. He crafted his argument carefully, to persuade even the most skeptical readers. First, he discussed familiar examples of selective breeding of domesticated plants ad animals.

Humans have modified other species over many generations by selecting and breeding individuals that possess desired traits- a process called __.

As a result of __, crop plants and animals bred as livestock or pets often bear little resemblance to their wild ancestors.

What are Darwin's four observations?

What are Darwin's two inferences?

Darwin perceived an important connection between ___ and the capacity of organisms to "__". He began to make this connection after reading an essay by economist Thomas Mathus, who contended that much of of human suffering- disease, famine, and war- was the inescapable consequence of the human population's potential to increase faster than food supplies and other resources.

Darwin realized that the capacity to __ was characteristic of all species. Of the many eggs laid, young born, and seeds spread, only a tiny fraction complete their development and leave offspring of their own. The rest are eaten, starved, diseased, unmated, or unable to tolerate physical conditions of the environment such as salinity or temperature.

An organsim's traits can influence not only its own performance, but also how well its offspring cope with environmental challenges.
For example: An organism might have a __ trait that gives its offspring an advantage in escaping predators, obtaining food, or tolerating physical condition. When such advantages increase the number of offspring that survive and reproduce, the traits that are favored will likely appear at a greater frequency in the next generation.

Thus, over time, __ imposed by factors such as predators, lack of food, or adverse physical conditions can increase the proportion of favorable traits in a population.

Darwin reasoned that if __ can bring about dramatic change in a relatively short period of time, then __ should be capable of substantial modification of species over many hudnreds of generations. Even if the advantages of some heritable traits over others are slight, the advantageous variations will gradually accumulate in the population, and less favorable variations will diminish. Over time, this process will increase the frequency of individuals with favorable __ and hence refine the match between organims and their environment.

What is the first main idea of natural selection?

What is the second main idea of natural selection?

What is the third main idea of natural selection>

One subtle but important point is that although __ occurs through interatctions between individual organisms and their environment, _(phrase). Rather, it is the __ that evolves over time.

A second key point is that __ can amplify or diminish __- traits that are passed from organisms to their offspring. Though an organism may become modified during its lifetime, and these acquired characteristics may even help the organism in its environment, there is little evidence that such acquired characteristics can be inherited by offspring.

Third, remember that __ vary from place to place to place and over time. A trait that is favorable in one place or time may be useless- or even detrimental- in other places or times. __ is always operating, but which traits are favored depends on the environmental context.