BIO Chapter 26: Phylogeny and the Tree of Life (up to 26.4)
1.Explain two terms: phylogeny and systematics.
Phylogeny – evolutionary history of a group or species of related species
Systematics – discipline focused on classifying organisms and determining their evolutionary relationships
2.Every organism on Earth may be referred to by a unique binomial, or a two-part name. These are in Latin, or latinized. What is your binomial? What does it mean?
Binomial – two-part scientific name made of genus and species in order for species hierarchical classification
3.What are the two components of every binomial? Genus and Species
4.Taxonomy uses hierarchical categories that nest within each other, like Russian dolls. The following figure shows the categories, each called a taxon. Label each taxonomic category and then give the one that applies exclusively to this panther to the side of each level.
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5. What does a branch point of a phylogenic tree represent? divergence of two evolutionary lineages from a common ancestor
6. What are sister taxa? groups that share a common ancestor that is not shared by any other group
7. Why are fishes considered the basal taxon? They diverged from all other members of the group in the phylogenetic tree early in history
8. Which of the trees shown here depicts an evolutionary history different from the other two? Explain.
Answer -Figure C. Trees a and b show that taxon C and D share the most recent common ancestor, and that clade is most closely related to the B lineage. However, the C tree suggests that C and B share the most recent common ancestor, and that clade is closely related to the lineage leading to D.
9. Why is it important to sort homologous from analogous structures? Which are appropriately used in
creating phylogenetic trees? It is important to know the difference because they inform us about different aspects of an organism’s history and linage. Homologous structures are better for creating phylogenetic trees.
Homology – similarity dur to ancestry
Analogy - Similarity due t convergent evolution
10. Mutations accumulate in similar gene sequences in different species over time. How can DNA
Homologies be determined after these genetic changes? Through sequence alignment similarities and differences. (deletion, or Insertion in DNA mutation)
11. The following figure shows three cladograms. A)What is a clade? A group of species that contains their ancestors and all of its descendants B)Why is Group I monophyletic? It contains its ancestor and all desendants C) Explain why Group II is paraphyletic. It contains ancestors and some descendants D) Why is Group III polyphyletic? Contains commonly related species but not their most recent ancestor
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12. Clades are developed by using shared derived characters. What are these? Ancestry and descendants
13. Explain why, for mammals, hair is a shared derived character, but a backbone is a shared ancestral character. Hair is a derived character specific to mammals (specific Group) and backbone is a shared ancestral character shared with other vertebrate groups reflecting common ancestry
· Shared ancestral character is a character that originated in an ancestor of the taxon
· Shared derived character is an evolutionary novelty unique to a particular clade
14. Phylogenetic trees represent a hypothesis about how the organisms in the tree are related to one another.
16. Gene duplication leads us to distinguish two types of homologous genes. Explain the difference
between orthologous and paralogous genes.
Orthologous genes can only diverge after speciation has taken place, that is, after the genes are found in separate gene pools. Paralogous genes result from gene duplication; hence, multiple copies of these genes have diverged from one another within a species because they are present in more than one copy in the genome.
17. Explain why mice are often excellent model organisms that can be used in the study of human diseases. Because of genetic similarities