Essay on RG chap 22

2102 Words Oct 27th, 2013 9 Pages
Name _______________________ Period _________

Chapter 22: Descent with Modification: A Darwinian View of Life
As you study this chapter, read several paragraphs at a time to catch the flow of ideas and understand the reasoning that is being described. In some places, the text describes a narrative or story of events that led to
Darwin’s theory of evolution. Therefore, first read the narrative to absorb the big picture and then return to answer the few questions that accompany this material.

Define evolution broadly and then give a narrower definition, as discussed in the overview.
Evolution: Descent with modification; the idea that living species are descendants of ancestral species that were different from the
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These variations (traits) are heritable. Variation in closely related species of elephants; offspring resemble close relatives more than other members of a population. 3. Species overproduce.

Dandelions produce thousands of seeds.

4. There is competition for resources; not all offspring survive.

Not all dandelion seeds germinate or survive to maturity


From these four observations, what two inferences did Darwin make?
1. Individuals whose inherited traits give them a higher probability of surviving and reproducing in a given environment tend to leave more offspring than other individuals.
2. The unequal ability of individuals to survive and reproduce will lead to the accumulation of favorable traits in the population over generations.


It is important to remember that differences in heritable traits can lead to differential reproductive success. This means that the individuals who have the necessary traits to promote survival in the current environment will leave the most offspring. How can this differential reproductive success affect the match between organisms and their environment?
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.


To demonstrate your understanding of this section, complete the following sentences:
Individuals do

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