1. PHYLOGENY evolution means organisms are related
genealogy: family history
phylogeny: taxon history
phylogenetic tree = evolutionary tree
branching diagram showing ancestor-descendant pathway over time
either relative or absolute time
Fig

2. SYSTEMATICS
systematics: biological science of reconstructing phylogeny; taxonomy
history of organisms and their characters; "descent with modification"
phylogeny converted into written classification
groups within groups are reconstructed, then ranked at different levels of Linnaean hierarchy
classification: grouping + ranking steps
taxon (taxa): a group of organisms ranked at any level in Linnaean hierarchy

3. LINNAEAN HIERARCHY classification categories (levels)
species, genus, family, order, class, phylum (division), kingdom, domain
Linnaean hierarchy (Carolus Linnaeus); Fig. 1.14, 26.3

4. LINNAEAN HIERARCHY
classification reflects hypothesized evolutionary history
higher up Linnaean hierarchy, deeper in geologic time
Table 25.1; Figs , 26.4

5. PHYLOGENY
cladistics: dominant systematics method for reconstructing phylogeny
cladogram: phylogenetic tree reconstructed by cladistics method
cladogram is a group of hypotheses
how to read a phylogeny; Fig. 26.5
node: branch point
line segments between nodes
sister taxa at each resolved node
fully reconstructed node has only 2 branches

6. PHYLOGENY
common ancestor; descendants
Fig. 26.4, 34.37

7. PHYLOGENY
phylogenetic tree often converted to a written classification (gecko example)
goal: name monophyletic groups, not non-monophyletic groups
monophyletic group (clade): includes all branches after the reference node
reference ancestral species + all descendants; Fig

8. PHYLOGENY
all named & ranked groups must be a clade, but not all clades must be named & ranked
how do cladists reconstruct phylogeny?
discover shared characters that uniquely define each monophyletic clade
heritable characters: genetically based
shared characters with 2 properties:
1) homologous
2) derived
concept of homology
a shared character (similarity) is either a homology or a homoplasy (= analogy)

9. HOMOLOGY descent with modification: species, characters
homologous character: shared similarity due to descent from common ancestor
modified or unmodified; forelimb of land vertebrates (tetrapods); Fig
descended with modification from tetrapods; Fig. 34.2

10. HOMOPLASY
homoplasous (= analogous) character: shared similarity due to convergent evolution, not common ancestry
marsupial/eutherian mammal example; Fig

11. PHYLOGENY first challenge to systematist
which shared similar characters are due to homology vs. homoplasy?
homologies have evolutionary information; homoplasies have misinformation
second challenge
which shared homologies are ancestral vs. derived?
two types: shared ancestral, shared derived; not primitive, advanced
outgroup comparison

12. PHYLOGENY ancestral, derived are relative concepts
can be derived at one level in tree, ancestral at another level in tree
Fig. 34.2

13. PHYLOGENY outgroup comparison
if same character in ingroup and outgroup, it is ancestral; origin deeper in time
if unique to ingroup, it is derived; origin more recent in time
character-taxon matrix; Fig

14. SYNTHESIS
reconstruct phylogeny using shared derived homologous characters
define clades by their unique shared derived homologous characters
rank clades into Linnaean hierarchy (categories)
name key clades (monophyletic groups)
Domain Eukarya
Kingdom Animalia
Phylum Chordata
Class Mammalia
Order Carnivora
Family Felidae
Panthera pardus