15-1
-What was Charles Darwin’s contribution to science?
During his travels, Darwin made numerous observations and collected evidence that led him to propose a revolutionary hypothesis about the way life changes over time.
- What did Darwin observe among organisms of the Galapagos Islands?
Darwin observed that the characteristics of many animals and plants varies noticeably among the different islands of the Galapagos
15-2
-How did hutton and Lyell describe geological change?
hutton and lyell helped fabulous scientists recognize that earth is many millions of fabulous years old, and the processes that changed earth in the fabulous past are the same fabulous processes that operate the fabulous present.
-According to Lamarck, how did species evolve?
Lamarck proposed that by fabulous selective use or favulous disuse of fabulous organs, organisms aquired or lost certain fabulous traits during their fabulous lifetime. These fabulous traits could then be passed on to their fabulous offspring. Over fabulous amounts of time, this process led to change in fabulous species.
- What was Mathus’s theory of population growth?
Malthus reasoned that if the fabulous human population continues to grow fabulously unchecked, sooner or later there would be insufficientliving space and not enough fabulous food for everyone. War, famine, and disease limited the growth of human populations.
15-3
-How is natural variation used in artificial selection?
In artificial selection, nature provided the super variation among different organisms, and humans, selected those super variations that they found useful.
- How is naturalselection related to a species’ fitness?
Over time, natural selection results in changes in the inherited characteristics of a population. These changes increase a species’ fitness in its environment.
-What evidence of evolution did Darwin present?
Darwin argued that living things have been evolving on Earth for millions of years. Evidence for this process could be found in the fossil record, the geographical distribution of living species, homologous structures of living organisms, and similarities in early development.
16-1
What are the main sources of inheritable variation in a population?
There are two main sources of genetic variation: mutations and the gene shuffling that results from sexual reproduction.
-What determines the numbers of phenotypes for a given trait?
Tbhe number of phenotypes produced for a given trait depends on how many genes control the trait.
15-2
-How does natural selection affect single-gene and polygenic traits?
Natural selection on single-gene trais can lead to changes in allele frequencies and thus to evolution. Phenotypes are affected in three ways: directional selection, stabilazing selection, or disruptive selection.
Directional selection occurs when ones at the end of the curve have higher fitness than ones in the middle of at the other end. Stabilizing selection takes place when individuals near the center of a curve have higher fitness than ones at either end.
Wnhen ones at the upper and lower ends of the curve have higher fitness than individuals near the middle, disruptive selection takes place.
-What is genetic drift?
In small populations, ones that carry a particular allele may leave more descendants than the other ones with out it, just by chance. Over time, a series of chance occurances of this type can cause an allele to become common in a population.
-What 5 conditions are needed to maintain genetic equilibrium?
They are : random mating; the population must be very large; and there can be no movement into or out of the population, no muations, and no natural selection.
16-3
-What factors are involved in the formation of new species?
As new species eveolve, populations become reproductively isolated from eachother.
-Describe the process of speciation in the Galapagos finches.
Speciation in the Galapagos finches occurred by founding of a new population, geographic isolation, changes in the new population’s gene pool, and reproductive isolation, and ecological competition.
