Chapter 14 History and Evidence of Evolution Flashcards
Briefly summarize the history of evolutionary thought.
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Explain how Darwin’s voyage on the Beagle influenced his thinking.
Most important observation was on the galopogos
Individual Galápagos islands differ from one another in important ways. Some are rocky and dry. Others have better soil and more rainfall. Darwin noticed that the plants and animals on the different islands also differed. For example, the giant tortoises on one island had saddle-shaped shells, while those on another island had dome-shaped shells (see Figure below ). People who lived on the islands could even tell the island a turtle came from by its shell. This started Darwin thinking about the origin of species. He wondered how each island came to have its own type of tortoise.
Explain how the work of Lamark, Lyell, and Malthus influenced Darwin’s development of the idea of natural selection.
Jean Baptiste Lamarck (1744–1829) was an important French naturalist. He was one of the first scientists to propose that species change over time. However, Lamarck was wrong about how species change. His idea of theinheritance of acquired characteristics is incorrect. Traits an organism develops during its own life time cannot be passed on to offspring, as Lamarck believed.
Charles Lyell (1797–1875) was a well-known English geologist. Darwin took Lyell’s book, Principles of Geology, with him on the Beagle . In the book, Lyell argued that gradual geological processes have gradually shaped Earth’s surface. From this, Lyell inferred that Earth must be far older than most people believed.
Thomas Malthus (1766–1834) was an English economist. He wrote an essay titled On Population . In the essay, Malthus argued that human populations grow faster than the resources they depend on. When populations become too large, famine and disease break out. In the end, this keeps populations in check by killing off the weakest members.
Explain how Darwin was influenced by the process of artificial selection.
Artificial selection-humans speeding up the process of evolution (dog breeding, plant crossing)
When Darwin saw that humans could influence the process of artificial selection it led him to surmise about the fact that this process could occur natural
Describe Darwin’s observations and inferences in developing the concept of natural selection.
It took Darwin years to form his theory of evolution by natural selection. His reasoning went like this:
Like Lamarck, Darwin assumed that species can change over time. The fossilshe found helped convince him of that.
From Lyell, Darwin saw that Earth and its life were very old. Thus, there had been enough time for evolution to produce the great diversity of life Darwin had observed.
From Malthus, Darwin knew that populations could grow faster than their resources. This “overproduction of offspring” led to a “struggle for existence,” in Darwin’s words.
From artificial selection, Darwin knew that some offspring have variations that occur by chance, and that can be inherited. In nature, offspring with certain variations might be more likely to survive the “struggle for existence” and reproduce. If so, they would pass their favorable variations to their offspring.
Darwin coined the term fitness to refer to an organism’s relative ability to survive and produce fertile offspring. Nature selects the variations that are most useful. Therefore, he called this type of selection natural selection.
Darwin knew artificial selection could change domestic species over time. He inferred that natural selection could also change species over time. In fact, he thought that if a species changed enough, it might evolve into a new species.
Explain why individuals cannot evolve and why evolution does not lead to perfectly adapted organisms.
Natural selection is limited by a population’s existing genetic variation.
Describe two examples of natural selection known to occur in nature. Note three key points about how natural selection works.
In the past, giraffes had short necks. But there was chance variation in neck length. Some giraffes had necks a little longer than the average. Then, as now, giraffes fed on tree leaves. Perhaps the environment changed, and leaves became scarcer. There would be more giraffes than the trees could support. Thus, there would be a “struggle for existence.” Giraffes with longer necks had an advantage. They could reach leaves other giraffes could not. Therefore, the long-necked giraffes were more likely to survive and reproduce. They had greater fitness. These giraffes passed the long-neck trait to their offspring. Each generation, the population contained more long-necked giraffes. Eventually, all giraffes had long necks.
At the start of the Industrial revolution, peppered moths were white, matching the light trees they inhabited, and making it hard for predators to spot them. a small portion of the population was black, but overwhelmingly, the moths were white. But as sut came over from factories, the trees turned black, and the moths were visavle tot ehir predators. And so the white moths were eaten more frequently, and the black moths became the more abundant variation
Explain how fossils form, noting examples of each process.
fossils serve as evidence to piece together the puzzle so we can get a better example of our evolutionary history
skull of organisms, casts of organisms,
sediment deposits filed in the negative space of a shell
ice man-man frozen so everything was kept in place so we could understand a lot about humans of the time
Explain how the fossil record provides some of the strongest evidence of evolution.
If you find different fossils from different time periods and you’re able to see specific changes in an animal or plant it is evidence of evolution
Sometimes there is a series of fossils that show us the change of evolution
dating-absolute or relative–as sediment piles older fossils are located below newer fossils. So based on their position in the strata, we can see which came first (this is relative, because we know which is older) absolute we can determine by radiometric dating which is using types of isotopes, by looking at the amount of decay in the isotope you can measure how old it is (certain isotopes decay at a certain rate, so you can determine how old it is) carbon dating is an example
Explain how biogeography, comparative anatomy, comparative embryology, and molecular biology support evolution.
Comparative anatomy-
homologous structures-all have the same structure but different function (cat arm vs human arm vs whale arm vs bat arm) Similarities come from a common ancestor.
analogous structures-similar due to similar function-similarity is not because of a common ancestor
vestigial structure-a structure that has almost evolved out but there is a small piece of structure left over (e.g. tailbone)
biogeography-
Biogeography is the study of how and why plants and animals live where they do. It provides more evidence for evolution. Let’s consider the camel family as an example.
Biogeography of Camels: An Example
Today, the camel family includes different types of camels. They are shown inFigure below . All of today’s camels are descended from the same camel ancestors. These ancestors lived in North America about a million years ago.
Early North American camels migrated to other places. Some went to East Asia. They crossed a land bridge during the last ice age. A few of them made it all the way to Africa. Others went to South America. They crossed the Isthmus of Panama. Once camels reached these different places, they evolved independently. They evolved adaptations that suited them for the particular environment where they lived. Through natural selection, descendants of the original camel ancestors evolved the diversity they have today.
On island chains, such as the Galápagos, one species may evolve into many new species to fill available niches. This is called adaptive radiation.
current distribution of animals and see that there are closely related organisms on different continents and they look different and they are adapted to those different places
comparative embryology
Comparative embryology is the study of the similarities and differences in the embryos of different species. Similarities in embryos are evidence of common ancestry. All vertebrate embryos, for example, have gill slits and tails. Most vertebrates, except for fish, lose their gill slits by adulthood. Some of them also lose their tail. In humans, the tail is reduced to the tail bone. Thus, similarities organisms share as embryos may be gone by adulthood. This is why it is valuable to compare organisms in the embryonic stage. See
molecular biology
we are very similar in amino acids to apes and other animals
Explain how evolutionary trees are constructed and used to represent ancestral relationships.
shows which structures share a common ancestor
