The Living World

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SCI 2020

Study Guide for Exam 1 on September 14, 2012

Ch. 14

How did reading books by Lyell and Malthus influence Darwin’s development of the theory of evolution?

- From Lyell, Darwin saw that species gradually changed over time

o Example: the Finches

- From Malthus, Darwin perceived the idea of natural selection

o Survival of the fittest

o Those species that possessed physical, behavioral or other attributes survived over those who didn’t (Natural Selection)

What evidence is there to support the theory of evolution through natural selection?

- Fossil- are preserved remains, tracks, or traces of once-living organisms

o Most direct evidence of macroevolution

o By dating the rock we can get an accurate idea of how old the fossil is (history of evolutionary change)

- Anatomical- reveals similarities between structures of species

o Homologous, analogous, vestigial organs

- Experimental-

- Artificial Selection – breeder selects the desired characteristics through breeding individuals with the correct/desired indviduals

What was special about the appearances of the finches and other animals on the Galapagos Islands, given the origin and location of the islands?

- According to Darwin the finches all looked like they descended from a related ancestor

- The only difference was the birds’ beaks. The sizes and shapes differed around the island depending on environment, as well as differing from the main land finches too.

- These species had adapted to the particular foods and other conditions where they inhabited.

What is the significance of homologous, analogous, and vestigial structures in evolution? What is an example of each?

- Homologous- although the structure and function of the bones have diverged, they are derived from the same body part present in a common ancestor.

- Analogous – sometimes features found in different lineages come to resemble each other as a result of parallel evolutionary adaptations to similar environments (birds, bats, etc.)

- Vestigial Organs- structures are put to no use at all (human appendix, whale pelvis bones)

What are the “5 agents of evolution?”

- Mutation – is the change in a nucleotide sequence in DNA

o Some are harmful, while others are neutral, rare or beneficial

- Nonrandom Mating- individuals with certain genotypes sometimes mate with one another more or less commonly than would be expected on random basis

o Sexual Selection- choosing a mate often based on on certain physical characteristics

o Inbreeding- mating with relatives

- Genetic Drift- random changes in alleles frequencies

o Founder Effect- when one or few individuals migrate and become founders of a new/isolated population at a distance from original place of origin. This causes the rare alleles or combinations to become more apparent/common

o Bottleneck Effect- genetic variability. From drastic change in environment, the surviving individuals constitute a random genetic sample of its original population. (Very low levels of genetic variability)

- Migration- movement of individuals between populations

o Immigration- movement into a population

o Emigration- movement out of a population

o Individuals differ from those already there, causing the individuals to adapt and if they survive in the new area and mate successfully then genetic composition of the receiving population may be altered.

- Selection- individuals leave behind more progeny than others, and the likelihood they will do so is affected by their inherited characteristics

o Artificial selection- breeder selects for the desired characteristics

o Natural Selection- environment plays this role, with conditions in nature determining...
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