The document discusses phylogeny and its role in modern taxonomy. It explains that phylogeny is the study of evolutionary relatedness between species through phylogenetic trees, which function similar to family trees. Phylogenetic trees show how species have evolved over time from common ancestors. Modern taxonomy uses phylogenetics and DNA barcoding to more accurately determine evolutionary relationships compared to traditional taxonomy which was based on physical characteristics.

2. Recall:
Phylogeny: the study of the evolutionary relatedness
between and among species.

3. Phylogeny and Modern Taxonomy
Humans have family trees that go back for many generations
to show our lineage and our ancestors.
These family trees show how 2 people may be related to each
other and by how many generations.

4. Phylogenetic trees share the same idea as family
trees. They show how species have grown apart
(evolved) over time.
Phylogeny and Modern Taxonomy

5. Phylogeny
Many
Years
Ago
Present
Branches
are
Common
Ancestors

6. DNA Barcoding

7. Phylogeny: Clades
Clade: a branch of a phylogenetic tree that
represents all of the organisms that share a single
common ancestor.

8. Phylogeny: Clades
Clades can be any size, and occur at branches in
phylogenetic trees.
Clades are different from taxa, but taxonomists do try
make them match-up.

9. Think. Pair. Share
Identify a
clade in this
tree.

10. Phylogeny: Clades
Yes

11. Phylogeny: Clades
Yes

12. Phylogeny: Clades
Yes

13. Phylogeny: Clades
Yes

14. Phylogeny: Clades
No

15. Phylogeny: Clades
Yes

16. Phylogeny: Clades
Yes

17. Phylogeny: Clades
Yes

18. Phylogeny: Clades
Yes

19. Phylogeny: Clades
Yes

20. To which other organism is Cervus elaphus most closely related?
At what rank and taxon are they related?
Think. Pair. Share.

21. Think. Pair. Share.
Group these species.

22. * In modern taxonomy, crocodiles
are grouped with birds because
they share a more recent common
ancestor.
Traditional Classification Phylogenetic Classification
Class
Mammalia
Rodents Mammaliaformes
Clade
Rodents
Class
Reptilia
Snakes
Lizards
Crocodiles
"Reptile"
Clade
Turtles
Lizards
Class
Aves
Birds Archosaur
Clade
Crocodiles
Birds
* In traditional taxonomy,
crocodiles are grouped with lizards
and turtles based on physical and
behavioural characteristics.
Phylogeny and Modern Taxonomy

23. "Reptile"
Clade
Archosaur
Clade
Phylogeny and Modern Taxonomy

24. Phylogeny and Modern Taxonomy:
Think. Pair. Share
What are the drawbacks of traditional taxonomy?
- dichotomous keys may be ambiguous or subjective.
- following a dichotomous key takes time.
- mutations may lead to incorrect classification.
This cat has a feline
dwarfism mutation.

25. Phylogeny and Modern Taxonomy:
Think. Pair. Share
What are the drawbacks of traditional taxonomy?
- different genetic structures may lead to similar physical structures.
- evolutionary relatedness is only a guess using physical features.

26. Phylogeny and Modern Taxonomy:
Think. Pair. Share
How are all of these obstacles be overcome?
Hint:
Phylogenetics.

27. How can all of these obstacles be overcome?
By collecting and comparing DNA samples of specimens,
their identity and evolutionary relatedness can be
determined efficiently and accurately.
This is how phylogenetic trees are made.
Phylogeny and Modern Taxonomy

28. Phylogeny and Modern Taxonomy:
Think. Pair. Share
Why is modern taxonomy important?
- Organism research can be applied to other similar organisms.
- Transmission and vulnerability to disease can be traced more easily.
- Crop yield and disease resistance can be improved in plants by
crossing certain species.