1. Phylogeny & the Tree of Life
Chapter 26

2. Phylogeny & Systematics
Evolutionary history of a species or group of species
Determined by evidences from fossil record, homologous structures, molecular homologies
Systematics:
Helps us understand phylogeny (data analysis of phylogeny)

3. Phylogenies show evolutionary relationships
26.1

4. Taxonomy Grouping according to evolutionary similarities
Binomial nomenclature (Linnaeus)
Domains  Species
Taxon (plural: taxa): named taxonomic hierarchy
Ex: Panthera is the taxon at the genus level

5. Phylogenetic Tree Links taxonomy and phylogeny Branch points
Divergence of two lineages from a common ancestor
Most recent common ancestor

6. How to read a phylogenetic tree

7. Phylogenies are inferred from morphological and molecular data
26.2

8. Recall: Homology Analogy Similarities due to common ancestry
Similarities due to convergent evolution

9. Morphology & DNA
Physical traits and genetics are homologous in organisms with recent shared common ancestors

10. Molecular Systematics
Uses DNA and other molecules to hypothesize evolutionary history

11. Shared characters are used to construct phylogenetic trees
26.3

12. Cladistics
Science of constructing a cladogram

13. Cladistics
Clades
Groups of organisms sharing a common ancestor

14. Monophyletic
A valid clade is monophyletic, it consists of the ancestor species and all its descendants

15. Paraphyletic
A paraphyletic clade consists of an ancestral species and some, but not all, of the descendants

16. Polyphyletic
A polyphyletic clade includes many species that lack a common ancestor

17. Species Change Over Time (Nodes)

18. Characteristics Shared primitive character
Homologous structure that is older than the branching of a particular clade from other members of that clade
It is shared by more than just the taxon we are trying to define.
Example – mammals all have a backbone, but so do other vertebrates.

19. Characteristics Shared derived character
New evolutionary feature, unique to a particular group
Example - all mammals have hair, and no other animals have hair.

20. Ingroup & Outgroup In: Group of study (make comparisons)
Out: Group that diverged prior to ingroup

21. New information continues to revise our understanding of the tree of life
26.6

22. A Changing Approach to Classification of Life
New evidence means continued revision of classification
Genome (DNA) sequencing

23. Tree of Life
Current classification:
Three domains
6 kingdoms

24. 3 Domains
First life on Earth

25. Tree of Life Video