Summary of Chapter 22

Chapter 22 covers the basics of evolution and the scientists that researched it. It covers Lamarck’s theory of organisms passing on their acquired traits and why that is incorrect. The chapter also goes over Charles Darwin and his theory of Descent with modification and natural selection. this chapter also goes into detail about Adaptation, artificial selection, fossil record and convergent evolution.

Info on the scientist that studied Evolution
The first scientist to propose a mechanism for how life evolves was Jean-Baptiste de Lamarck. who proposed that an organism could change its features and pass them onto their offspring. For example the giraffe, Lamarck suggested that the giraffe stretched his neck out over time to reach the leaves at the top of trees and then passed their stretched necks onto their offspring. Lamarck also believed that organisms have the innate desire to become more complex. Lamarck was wrong on both accounts.

Then there was Charles Darwin. Darwin studied the Galapagos finches while on a voyage around 1831. He realized that the birds on these series of islands were very similar but had distinct differences depending on the environment that they inhabited. (for more info read the Beak of the Finch). It wasn’t until after Darwin returned from his voyage and brought the birds to an Ornithologist where he was told that they were in fact all Finches. From this point on Darwin was able to put together his theory of evolution.

Darwin’s four observations of nature
1) Members of a population often vary greatly in their traits
2) Traits are inherited from parents to offspring
3) All species are capable of producing more offspring than their environment can hold
4) Owing to lack of food or other resources, many of these offspring do not survive

From these observations Darwin came up with two inferences
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) This unequal ability of individuals to survive and reproduce will lead to the accumulation of favorable traits in the population over generations

It was through these inferences that he proposed the mechanism Natural Selection which he states drives the evolutionary process

Evolution- descent with modification
Fossils- remains or traces of organisms from the past found in sedimentary rock
Paleontology- the study of fossils
Catastrophism- the principle that events in the past occurred suddenly and were caused by mechanisms different from those operating in the present
Uniformitarianism- mechanisms of change are constant over time
Adaptations-characteristics of organisms that enhance their survival and reproduction
Natural Selection- a process in which individuals with certain inherited traits leave more offspring than individuals with other traits
Artificial selection- breeding for selective traits, example; humans have breed the wild mustard plant for specific traits like a large terminal bud of a cabbage and the lateral buds of Brussels sprouts
Homology- organisms that have characteristics that share a similarity but that similarity may have very different uses.
Homologous Structures - similarities in the way skeletons are put together.
Example: the forelimbs of all mammals including humans, cats, whales, and bats show the same arrangement of bones from the shoulder to the tips of the digits
Vestigial structures- the remains of structures that were important to the organisms’ ancestors but are not to the existing organisms
Example: the whale has a pelvis limb that doesn’t do anything for the organism.
Evolutionary Tree- a diagram that reflects evolutionary relationships among groups of organisms
Convergent Evolution- the independent evolution of similar features in different lineages
Example: a marsupial in Australia developed traits similar to the flying squirrel in North America
Biogeography- the geographic distribution of species
Continental drift- the slow movement of earth’s continents over time
Pangaea- the large piece of land mass that broke up into the continents that we live on today
Endemic- organisms that are unique to the island they inhabit

Figures to assist with chapter and vocabulary
Vestigial structures: this whale doesn’t use its pelvis bone but its ancestor did
Evolutionary Tree: this shows the common ancestor of these organisms and how closely related they are
Pangaea: this shows how the land on earth separated from the Pangaea super continent to the seven we have today

Adaptations: each of these finches has a adaptation that helps with the environment in which it lives

Here are some videos that can help you with the understanding of this chapter

The movement of Pangaea
Convergent evolution
Adaptations (finches)

Online lessons

Online tests (to test your knowledge AFTER you read the chapter, don’t get discouraged if you don’t get this by just reading the webpage)

News Articles about Evolution

Other Interesting Websites

Works Cited
All the information I used for the definitions and the chapter summary came from the textbook you’re using. The pictures I acquired from Google images and some videos are from YouTube.