1. Phylogeny & Systematics
Chapter 25

2. Phylogeny: the evolutionary history of a species

3. The study of biological diversity in an evolutionary context
Analytical approach
Focuses on morphological, biochemical and molecular resemblances
Systematics

4. Constructing a Phylogeny:
The fossil record: the ordered array of fossil, within layers (strata) of sedimentary rock
Constructing a Phylogeny:

5. The fossil record Sedimentary rock(?): Richest source of fossils
Lake Turkana Boy(1984)
The fossil record

6. Limitations?
The fossil record

7. Inferring a Phylogeny:
Morphological and Molecular Homologies:
Homologies= similarities do to shared ancestry
Inferring a Phylogeny:

8. Inferring a Phylogeny::
Homology vs. analogy
Homoplasies- independent evolution of analogous structures
Bat and butterfly wings
Inferring a Phylogeny::

9. Inferring a Phylogeny:
Homology vs. analogy
Convergent(independent) evolution vs shared ancestry
Similar environmental pressures can produce analogous adaptations in organisms from different lineages
Example of Convergent Evolution:
Steatopygia
Inferring a Phylogeny:

10. The tracing of evolutionary relationships (phylogenetic tree)
Linnaeus(taxonomy)
Binomial Nomenclature
Phylogenetics

11. Phylogenetics Binomial Nomenclature-two part naming system
First part: genus(genera)
Second part: species(specific epithet)
Phylogenetics

12. Hierarchical Classification:

13. Hierarchical Classification
1. Domain
2. Kingdom
3. Phylum
4. Class
5. Order
6. Family
7. Genus
8. Species
Hierarchical Classification

14. Example: 2. Animalia 3. Chordata 4. Mammalia 5. Primate 6. Hominidae
1. Eukarya
2. Animalia
3. Chordata
4. Mammalia
5. Primate
6. Hominidae
7. Homo
8. sapiens
Example:

15. What is the connection between classification and phylogeny?:
Classification is reflected in the branching of the phylogenetic trees
Evolutionary relationships are traced between some of the taxa
What is the connection between classification and phylogeny?:

16. Phylogenetic systematics:
Cladograms: diagrams that show patterns of shared characteristics
Clade: a group of species that includes an anestral species and all its descendants.
Phylogenetic systematics:

19. Cladistics: the analysis of how species may be grouped into clades
Phylogenetic Trees

20. Valid vs. non valid clades
Monophyletic- single ancestor that gives rise to all species in that taxon and to no species in any other taxon
The only valid clade(cladogram)
Valid vs. non valid clades

21. Valid vs. non valid clades
Paraphyletic- lacks information about some species
Consists of an ancestral species but not all descendants
Not valid
Valid vs. non valid clades

22. Valid vs. non valid clades
Polyphyletic-grouping of several species that lack a common ancestor
Not valid
Valid vs. non valid clades

24. A Cladogram