Plants & Human Affairs (BIOL106) - Stephen G. Saupe, Ph.D.; Biology Department, College of St. Benedict/St. John's University, Collegeville, MN 56321; ssaupe@csbsju.edu; http://www.employees.csbsju.edu/ssaupe |
Evolution vs. Creationism: Some Case Studies
General Directions:
The following case studies describe situations that have been observed by
biologists. Biologists seek to understand and explain how these situations
arose. Read each case study and then describe how how each of the following
individuals would explain it: (1) Darwin - evolution via natural
selection; (2) Lamarck - evolution via acquired characteristics; (3) a
�scientific� creationist
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Case Study #1: Mines,
Grass & Wales
The soils and workings (mining tailings) around mines in Wales are enriched in
heavy metals such as lead, copper and nickel. Populations of a small grass,
Agrostis tenuis, are tolerant of toxic levels of these heavy metals.
However, other individuals of this same species of grass, growing on
uncontaminated sites only a few meters away, cannot survive and grow on the
tailings. In fact, these sensitive individuals will die if transplanted to the
site with tailings. Likewise, individuals growing in the tailings will not grow
well if transplanted to uncontaminated sites. Heavy metal tolerance/sensitivity
is inherited. Explain why the grasses on the tailings can grow in the presence
of heavy metals but grasses meters away cannot.
Case Study #2: Finches on
the Galapagos Islands
As you know, the Galapagos Islands are an archipelago (cluster of islands) off
the coast of Ecuador. These islands are volcanic. Darwin and others have long
noted that the species of finches that occur on the Galapagos are unique and
occur no where else in the world. However, these species are most similar to
finches on the Ecuador mainland. Explain why the Galapagos finches are unique
yet similar in appearance to mainland ones.
Case Study #3: Maize
Maize (=corn) does not occur in the wild. The only reason that it persists is
because humans collect and plant its seeds from season to season.
Archaeological records show that the first cobs appeared about 10,000 ybp in
Central America. These early cobs were smaller than modern ones, but otherwise
relatively similar. Prior to 10,000 ybp no evidence has ever been found.
Explain how a new species such as maize could arise.
Case Study #4: Crabs and Periwinkles
This case study was provided on the handout in class.
Explain why the thickness of the periwinkle shells increased from 1850's to the
present.
Last updated: 10/14/2008 � Copyright by SG Saupe