1. 18.2 Modern Systematics I. Traditional ______________
A. Scientists use similarities in ___________ & ____________ to group organisms.
1. this approach is ____________.
2. Some groups look ____________ but turn out to be _____________ related.
3. Other groups look __________ but turn out to be _______________ related.

2. II. Phylogenetics
A. Def – The study of the ___________ relationships between __________.
B. It’s like trying to draw a huge family ____ over millions of _______________.
C. Not all similar ____________ are inherited from a common _____________.
1. Ex.-_______ of an insect & the _______ of a bird.
D. _____________ evolution = similarities in groups that are _____ closely related.

3. 2. ___________ characters = Similarities that
2. ___________ characters = Similarities that arise through ______________evolution.
E. This family tree, or __________ tree, represents a hypothesis of the relationships between ___________ groups.
III. _______________
A. Objective method that unites ______________ with _______________.
1. Focuses on finding _____________ that are shared between ___________ groups because of shared ________________.

4. 2. Ancestral character is defined as
2. Ancestral character is defined as having evolved in a common ________ of __________ groups.
3. ______ character = one that evolved in ____ group but ______ the other.
C. Constructing a Cladogram
1. A __________ is a phylogenetic tree that is drawn in a ____________ way.
2. A ______ is a set of groups that are related by descent from a single ancestral ____________.
3. Outgroup = group that lacks some of the shared ___________________.

6. IV. Inferring Evolutionary Relatedness
1. refers to the ____________ structure or ____________ of organisms.
2. Organisms that share ancestral genes often show similarities during _______________.
B. Molecular Evidence
1. Scientists now use __________ info. to infer phylogenies.
2. DNA _______ in a _______ is determined for several species
3. Then, each letter at each position is ____________.

8. C. Evidence of Order and Time
1. Cladistics can determine only the relative _______ of divergence, or ____________, in a phylogenetic tree.
2. The ________ record can often be used to infer the actual _______ when a group may have begun to “branch off.”
D. Inference Using _____________
1. This principle holds that the __________ explanation for something is the most ___________, unless strong evidence exists __________ that explanation.
2. Given two possible cladograms, the one that implies the _________ character changes between _________ is preferred