TOPIC 16 DAY 1 CHANGES IN CLASSIFICATION

Linnaeus’s system was based on his judgment of the importance of various similarities among living things. Scientists have traditionally used similarities in appearance and structure to group organisms. However, this approach has proven problematic. What is one way that this approach could be problematic?

• Some groups look different but turn out to be related.

• Some groups look similar but turn out to be closely related.

• There is always a clear pattern between appearance and relatedness.

• There is no consistent relationship between structures and relatedness.

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A researcher recently discovered a species of bacteria. DNA sequences were obtained from it and from several other species of bacteria. The DNA sequences came from the same part of the bacterial chromosome of each species. According to the data above, the unknown bacteria are most closely related to which species?

• Species I

• Species II

• Species III

• Species IV

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This diagram shows a cladogram of six species based on amino acid similarities. Which two species are the most closely related?

• I and II

• II and IV

• I and V

• V and VI

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Based on the cladogram below, what derived characters are shared by a hamster and a lizard?

• claws or nails and lungs

• fur, claws or nails, and lungs

• only lungs

• only claws or nails

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Biologists are not certain how to classify the North American red wolf in relation to other, similar species. Some biologists claim that the red wolf existed as a species before both the gray wolf and the coyote. Other biologists claim that the red wolf is actually a hybrid of the gray wolf and the coyote.

What type of evidence would BEST support the hypothesis that the red wolf existed before the gray wolf and the coyote?

• Fossils of gray wolves and coyotes but not of red wolves

• Different mating behaviors among all three species

• Similar body plans between red wolves and gray wolves but not red wolves and coyotes

• A DNA sequence shared by the gray wolf and the coyote but not the red wolf

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