Further Thought

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Further Thought

Use the questions at the end of the chapter to explore concepts and connections in greater depth through application and synthesis.

1. What do homeotic genes do? [Hint]
To create paragraphs in your essay response, type at the beginning of the paragraph, and at the end.

2. Why is it significant that Hox and MADS-box genes contain a DNA-binding domain? [Hint]
To create paragraphs in your essay response, type at the beginning of the paragraph, and at the end.

3. Does the number of Hox genes vary among animal phyla? If so, how did multiple copies of Hox genes come to be? If not, how can different body types be organized by the same number of genes? [Hint]
To create paragraphs in your essay response, type at the beginning of the paragraph, and at the end.

4. Why is it logical for researchers to infer that the ancestor of all bilaterally symmetric animals had about 10 Hox genes? [Hint]
To create paragraphs in your essay response, type at the beginning of the paragraph, and at the end.

5. What does the animal gene called Distal-less do? [Hint]
To create paragraphs in your essay response, type at the beginning of the paragraph, and at the end.

6. Are the same MADS-box genes involved in the formation of sepals, petals, stamens, and carpels, or is each floral organ coded for by unique genes? [Hint]
To create paragraphs in your essay response, type at the beginning of the paragraph, and at the end.

7. What is the difference between microevolution and macroevolution? [Hint]
To create paragraphs in your essay response, type at the beginning of the paragraph, and at the end.

8. What data from this chapter support the claim that mutation, selection, drift, and gene flow are sufficient to explain both microevolution and macroevolution? [Hint]
To create paragraphs in your essay response, type at the beginning of the paragraph, and at the end.

9. What is "deep homology?" [Hint]
To create paragraphs in your essay response, type at the beginning of the paragraph, and at the end.

10. During the evolution of animals, when did an increase in the number of Hox genes present appear to correlate with significant changes in morphological complexity? [Hint]
To create paragraphs in your essay response, type at the beginning of the paragraph, and at the end.

11. During the evolution of animals, when did changes in the timing and spatial location of Hox gene expression appear to correlate with important morphological innovations, even though the total number of Hox genes stayed the same? [Hint]
To create paragraphs in your essay response, type at the beginning of the paragraph, and at the end.

12. During the evolution of animals, when did changes in the sequence of a Hox gene appear to correlate with an important morphological innovation, even though the total number of Hox genes and their location and timing of expression stayed the same? [Hint]
To create paragraphs in your essay response, type at the beginning of the paragraph, and at the end.

13. How might different alleles of the MADS-box genes AP1, AP3, and AG lead to differences in the size or shape of flowers? [Hint]
To create paragraphs in your essay response, type at the beginning of the paragraph, and at the end.

14. What did the ancestor of the bilateral animals look like? Was it segmented? Did it have limbs, eyes, and a heart? [Hint]
To create paragraphs in your essay response, type at the beginning of the paragraph, and at the end.

15. Recall that vertebrates have four Hox gene clusters. Develop a hypothesis for what would happen in a mouse embryo if a gene from one Hox cluster were swapped with its sibling gene from another cluster. Assume that regulatory sequences are left in place and that only the coding sequence of each gene is moved. Then look up the following paper and see if you were right.

Greer, J. M., J. Puetz, K. R. Thomas, and M. R. Capecchi. 2000. Maintenance of functional equivalence during paralogous Hox gene evolution. Nature 403: 661–665. [Hint]
To create paragraphs in your essay response, type at the beginning of the paragraph, and at the end.

16. In fruit flies, the protein product of the Ubx gene turns off the gene called Distal-less Go back to Section 18.2 and review the evolutionary changes that have occurred in Ubx sequences and the function of Dll in limb development. Why is the observation that Ubx represses Dll important? [Hint]
To create paragraphs in your essay response, type at the beginning of the paragraph, and at the end.

17. How does the finding that different MADS-box proteins physically bind to one another relate to the ABC model of flower development? [Hint]
To create paragraphs in your essay response, type at the beginning of the paragraph, and at the end.

18. Hox and MADS-box genes are often called "selector genes." Why? [Hint]
To create paragraphs in your essay response, type at the beginning of the paragraph, and at the end.




1.	What do homeotic genes do? [Hint] To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.



2.	Why is it significant that Hox and MADS-box genes contain a DNA-binding domain? [Hint] To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.



3.	Does the number of Hox genes vary among animal phyla? If so, how did multiple copies of Hox genes come to be? If not, how can different body types be organized by the same number of genes? [Hint] To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.



4.	Why is it logical for researchers to infer that the ancestor of all bilaterally symmetric animals had about 10 Hox genes? [Hint] To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.



5.	What does the animal gene called Distal-less do? [Hint] To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.



6.	Are the same MADS-box genes involved in the formation of sepals, petals, stamens, and carpels, or is each floral organ coded for by unique genes? [Hint] To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.



7.	What is the difference between microevolution and macroevolution? [Hint] To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.



8.	What data from this chapter support the claim that mutation, selection, drift, and gene flow are sufficient to explain both microevolution and macroevolution? [Hint] To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.



9.	What is "deep homology?" [Hint] To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.



10.	During the evolution of animals, when did an increase in the number of Hox genes present appear to correlate with significant changes in morphological complexity? [Hint] To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.



11.	During the evolution of animals, when did changes in the timing and spatial location of Hox gene expression appear to correlate with important morphological innovations, even though the total number of Hox genes stayed the same? [Hint] To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.



12.	During the evolution of animals, when did changes in the sequence of a Hox gene appear to correlate with an important morphological innovation, even though the total number of Hox genes and their location and timing of expression stayed the same? [Hint] To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.



13.	How might different alleles of the MADS-box genes AP1, AP3, and AG lead to differences in the size or shape of flowers? [Hint] To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.



14.	What did the ancestor of the bilateral animals look like? Was it segmented? Did it have limbs, eyes, and a heart? [Hint] To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.



15.	Recall that vertebrates have four Hox gene clusters. Develop a hypothesis for what would happen in a mouse embryo if a gene from one Hox cluster were swapped with its sibling gene from another cluster. Assume that regulatory sequences are left in place and that only the coding sequence of each gene is moved. Then look up the following paper and see if you were right. Greer, J. M., J. Puetz, K. R. Thomas, and M. R. Capecchi. 2000. Maintenance of functional equivalence during paralogous Hox gene evolution. Nature 403: 661–665. [Hint] To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.



16.	In fruit flies, the protein product of the Ubx gene turns off the gene called Distal-less Go back to Section 18.2 and review the evolutionary changes that have occurred in Ubx sequences and the function of Dll in limb development. Why is the observation that Ubx represses Dll important? [Hint] To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.



17.	How does the finding that different MADS-box proteins physically bind to one another relate to the ABC model of flower development? [Hint] To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.



18.	Hox and MADS-box genes are often called "selector genes." Why? [Hint] To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.

Chapter 18: Development and Evolution

Further Thought