Chapter 19 Q/A

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19.1 Q/A

1) Explain Charles Darwin's contribution to our understanding of evolution in the context of those that come before him as well as his contemporaries.

People such as Aristotle, Leonardo Da Vinci, and Jean Baptiste de Lamarck had theorized concerning the origin of species, like Aristotle saying organisms were moving towards a more perfect state and Da Vinci thinking that fossils were something from great antiquity. Darwin spent 20 years accumulating evidence through observation, experimentation, and collaboration before proposing that evolution happens by natural selection.

2) Explain how Charles Lyell’s theory of uniformitarianism influenced Darwin’s ideas about evolution. Explain how an essay by the Rev. Thomas Malthus influenced Charles Darwin.

Uniformitarianism says that the same scientific principles which govern our current world have always been in effect. This would explain why Natural selection works, as it would be a constant balancing of favorable genes through the eons.

The essay on a nation's food production is growing arithmetically and the population growing exponentially would explain why Darwin said that only the favorable genes will remain in a gene pool when push comes to shove.

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19.2 Q/A

1) Define adaptation and give an example.

A heritable trait that helps an organism's survival and reproduction is an example of an adaptation. Like platypus's karate skills and webbed feet.

2) Describe evidence Darwin observed on his journey aboard the H.M.S. Beagle that led to his proposal of Evolution by Natural Selection

The evidence that Darwin found corroborating Evolution by Natural Selection was that Galapagos islands, there were several species of ground finches each with a unique beak size and shape with very small differences between the most similar. These ground finches also resembled another species on the mainland of South America. Studying further, he found that each type of beak allowed each type of finch to get a certain type of food easier. He postulated that the birds had changed over time to be able to acquire food sources without competition from the other birds.

3) What are 3 principles that lead to natural selection?

1) Most characteristics of organisms are inherited, or passed from parent to offspring and the variation in the parents is passed down to the offspring.

2) More offspring are produced than are able to survive, so resources for survival and reproduction are limited.

3) Offspring vary among each other in regard to their characteristics and those inherited characteristic variations lead to differential survival and reproduction.​​​​​​​

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19.3 Q/A

1) Describe the evidence supporting the theory of evolution by Natural selection derived from studies of the fossil record, direct observations of evolution, homology (anatomical and molecular homologies), and biogeography.

Fossils show examples from the past and can be lined up to show a linear progression. Structures can show that either they are: A) no longer needed and are being removed, B) they were needed and two different species took two different paths to get to it, or C) We can see species have similar structures and deduce a common ancestor. Biogeography is the study of the distribution of living things and this distribution of plants and animals supports evolution, as distance and new situations would force evolution. Like anatomical structures, the molecular structures of life reflect descent with modification. Molecular comparisons among organisms provide evidence for evolution. The analysis of nucleotide and amino acid sequences provides clues about evolution.

2) Explain how the fossil record may be used to test our current understanding of evolutionary patterns.

Fossils provide solid evidence that organisms from the past are not the same as those today, and fossils show a progression of evolution.

3) Explain how the existence of vestigial structures can be explained by and is evidence for Darwin’s theory of natural selection.

Some structures exist in organisms that have no apparent function at all and appear to be residual parts from a past common ancestor. We call these unused structures without function vestigial structures. Things like leaves on a cactus, and are evidence since it is showing how the once-needed structure is slowly being removed as it is no longer necessary for the species' survival.

4) Explain how DNA or protein comparisons may allow us to assess evolutionary relationships between species. How has this changed our understanding of some species evolution?

5) Distinguish between homologous and analogous features. Give an example of each. What is Convergent evolution?

Homologous structures are similar structures based on common ancestry seen in evolutionarily related organisms. (Ex. Bone structures, as all warm-blooded animals have a similar arm (A fore arm, a hand, etc.)

Homoplastic structures (also known as analogous structures) are similar structures seen in organisms that are very distantly evolutionarily related but show convergent evolution, as they have evolved to meet similar environmental or anatomical demands. (Ex. Bird and grasshopper wings: not derived from a common ancestor, but both have wings.)

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19 extra

1) Describe some of the main misconceptions about evolution and explain why they are not correct.

Evolution is not random. The mutations are, but the stressors which test the mutations aren't.

We can see Natural Selection in action.

Natural selection can create complex systems.

We have seen new species evolve, like during WW2 with underground mosquitos.

Nature is survival of the good enough.

Some traits are pointless but harmless.

Earth is not a closed system, so things can go more complex.

Evolution does create new information by duplicating DNA first and then changing one of the new copies.

Apes still exist because a common ancestor branched off, not them themselves and the same goes for every other split in the genetic tree.

Humans are still evolving.

Evolution loves all her children. Evolution has no point.