Answer the following questions as you proceed through the activity slides. 1. Briefly explain how scientists draw relationships between organisms based on shared anatomical features.
The more anatomical features organisms share the more likely they are to be closely related.

2. How are DNA sequences used to deduce evolutionary relationships?
Scientists look for similarities and differences in the dna sequences to determine relationships.

3. What is one advantage of building phylogenetic trees using DNA comparisons rather than anatomical features?
It is more objective to use DNA comparisons.

4. Watch the video clip on slide 3 and then draw a simple tree illustrating the evolutionary relationships between gorillas, chimpanzees, humans, and orangutans.

5. Watch the short video on slide 4. How has biotechnology affected the process of building phylogenetic trees from DNA sequences?
It has made it possible to see everything as sequence and therefore draw the parallels between related organisms.

6. What do evolutionarily related organisms share?
They share a common ancestor with an ancestral DNA sequence.

7. What are two common types of mutations?
SNPs and indels

8. Explain the difference between distantly related and closely related organisms in terms of their DNA sequences.
Closely related organisms have less differences in their DNA sequences than distantly related ones because of the amount of time it takes for mutations to build up in the DNA sequences.

9. Define the term homologous as used in comparing DNA sequences.
Homologous in this connotation refers to DNA sequences being evolutionarily related.

10. How is a SNP identified in an alignment?
SNPs are identified when letters in a column don’t match.

11. How is an indel identified in an alignment?
Indels are identified with dashes or gaps.

12. Look at the information on slide 15. From left to right, identify the base in each box as an indel or a SNP. Write your answers in the spaces below. a. Box 1 (left) __________indel________ b. Box 2 (center) _______snp___________ c. Box 3 (right) ________indel__________

13. Watch the video clip on slide 18 and describe the link between the length of the line and time.
The longer the line the more time has passed.

14. What is surprising about the placement of hippos on the phylogenetic tree?
That the hippos are more closely related to whales than camels.

15. Define a branch point (also called a node) on a phylogenetic tree and describe what it represents.
It’s a place where two branches split and denotes the most recent common ancestor of all the species on those branches.

16. What is the root?
The root is a single branch point from which all the branches originate.

17. What does the node closest to the root represent?
The node closest to the root is the most recent common ancestor for the entire tree.

18. Describe what an unrooted phylogenetic tree represents.
An unrooted tree only shows you relative relationships between compared organisms but not the common ancestor.

19. Address the following concepts in short answer format in the space provided below.
Phylogeny is the evolutionary history of a species: d. The evolution of a species is dependent on changes in the genome of the species. Identify two mechanisms of genetic change, and explain how each affects genetic variation.

*DNA sequence changes (SNPs, indels) can build up over time and affect phenotype.

*Migration can affect allele frequencies due to intermixing of different gene pools.

e. Describe two types of evidence–other than the comparison of DNA sequences–that can be used to determine the phylogeny of organisms. Discuss one strength of each type of evidence you described.
*similarities in anatomy—gives a good predictor of common ancestry

*fossil records—show direct evidence of the evolution of organisms from a common ancestor over time