UNIT 2 – Evolution, Change and Diversity
Introduction
Evolution is a concept in biology that links yesterday with today. This unit focuses on the history,
importance and mechanisms of the process of evolution and how a change in the DNA blueprint creates
new traits that propel evolution. It builds upon what the students have learned about mutations and genetic
variability and shows how these can lead to changes in species based upon natural selection. This unit also
outlines scientific evidence and arguments pertaining to the origin, development, and diversity of living
organisms on Earth.
Evolutionary Theory
Outcomes
It is expected that students will:
• Explain various scientific hypotheses for the origin, development, and diversity of living organisms
on Earth.
• Describe historical and cultural contexts that have influenced evolutionary concepts.
• Explain the theory of evolution and its importance to biological sciences.
• Define the terms evolution, variation, natural selection and adaptation and be able to give examples of
where scientists have shown these processes to occur in the natural world.
• Explain the modern theory of evolution and demonstrate an understanding of the scientific evidence to
support it.
PH Biology
pp. 368-386
“Quick Lab” p.379 (use the picture on page 379 – you don’t need to have the actual plants)
“Exploration” p.387
Page 370-1
 Why do you think the islands are drier at lower elevations and wetter at higher elevations?
 What traits do you think an animal might need to survive on a hot, dry, rocky island?
 What traits might an animal need to survive on an island with a lot of rainfall and vegetation?
Page 374-5
 How did Hutton’s and Lyell’s proposals about Earth support Darwin’s ideas about the changes he
had observed in living things?
 The Grand Canyon formed through the erosion of rock layers by the Colorado River. The
Colorado River is currently eroding the Earth’s surface at a rate of about 0.3m per millennium.
The Grand Canyon is as deep as 1800m in some places. Using the current rate of erosion, how
long did it take the Colorado River to erode the Grand Canyon to its current depth?
Page 376-7
 “The bird evolved a larger beak.” This sounds as if the individual bird has intentionally changed
its biological traits. What would be a more accurate way of stating this?
 Design an experiment to test Lamarck’s hypothesis of the inheritance of acquired traits. Include a
specific hypothesis, procedure, and possible outcomes. Explain how the different possible
outcomes of your experiment would or would not support Lamarck’s hypothesis.
 Assume there are 275 seeds in a green pepper. If all the seeds grow into plants that produce the
same number of seeds, how many generations will it take to produce a billion plants?
 Create a concept map summarizing the contributions of other scientists to Darwin’s ideas about
evolution
Page 378-9
 What current areas of scientific research are controversial, much as evolution was controversial in
Darwin’s time?
Page 382 -3
 What might eventually happen to organic remains that are covered over with sediments?
Page 384 – 5
 Are bat and butterfly wings homologous or analogous structures?
 Figure 15-15: What similarities in the limbs suggest that they developed from the same basic
structure? How is the form of each limb adapted for a specific type of movement?
 Would you expect the vestigial limb bones of a snake to be more like the bones of a bird’s wing or
a rabbit leg?
 Why do DNA comparisons provide the most direct evidence of evolutionary relationships?
Mechanisms and Patterns of Evolution
Outcomes
It is expected that students will:
• Describe some of the ways in which genes can change and become the basis of variation within a
population of organisms and within viruses.
• Analyze the role of sexually produced genetic variations and mutations in the process of natural
selection.
• Explain the Hardy-Weinberg principle, and its role in population genetics.
• Explore patterns of evolution.
PH Biology
pp. 392-402, 404-410, 435-439
“Quick Lab” p.401
“Issues in Biology” p.403
“analyzing Data” p.408
“Analyzing Data” p.438
Page 392-3
 How many ABO genotypes are possible?
 How many genotypes would be possible with four alleles?
Page 394-5
 Figure 16-2: If the relative frequency of the B allele decreased in the gene pool, what would
happen to the relative frequency of the other allele?
Page 396-7
 Figure 16-5: How does color affect the fitness of the lizards? What do you predict the lizard
population will look like by generation 50?
Page 398-9
 Besides height and birth weight, what are some other polygenic traits that show continuous
variation?
 Figure 16-7: If the fitness of phenotypes at both ends of the curve were to decrease even more,
how would it affect the shape of the curve?
Page 408-9
 Besides the formation of islands by volcanoes, how might an area come to support so many niches
established by invading species through adaptive radiation?
 How does competition increase the differences between species?
Page 435
 Do you think extinctions are occurring at a faster rate today than they were in 1900? Explain.
Page 436-7
 If mass extinction was not responsible for the adaptive radiation of Darwin’s finches, what was?