Cladograms 17 2 State Standard SB 3 C
Cladograms (17. 2) State Standard SB 3 C. Examine the evolutionary basis of modern classification systems.
Chapter 17 Organizing Life’s Diversity 17. 2 Modern Classification § Cladistics classifies organisms according to the order that they descended from a common ancestor & reconstructs phylogenies based on shared characters. § Scientists consider two main types of characters when doing cladistic analysis. § An ancestral character is found within the entire line of descent of a group of organisms. § Derived characters are present in members of one group of the line but not in the common ancestor.
Chapter 17 Organizing Life’s Diversity 17. 2 Modern Classification Cladograms § Cladograms are created using derived characters. It is a branching diagram that represents proposed evolutionary history of species. § The greater the number of derived characters shared by groups, the more recently the groups share a common ancestor.
Reading Cladograms • If the trait (character) falls below the organism, then the organism has that trait. • If the trait is above the organisms, then the organisms lacks that trait. • The organism with the least traits shared with the others is called the outgroup. • The organisms that share the most derived characters are considered the most closely related.
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