Phylogeny and Systematics

1
Phylogeny and Systematics
2
Phylogeny

• Evolutionary history of a species or a group of
  related species
• Information used to construct a phylogeny
• Fossil record
• Molecular evidence (DNA, RNA, protein comparison)

3
Systematics

• Study of biological diversity in an evolutionary
  context
• Goal is to trace phylogeny

4
Cladogram

• Cladistics form of taxonomy based on shared
  characteristics not found in ancestral group
• Clade evolutionary branch of in cladogram
• consists of ancestral species and all descendents

5
Crocodile closer related to birds than snakes and
lizards
6
Constructing a Cladogram

• Start sorting homologous from analogous

• Homologous
• Similar structure and shared ancestry
• Greater of homologous parts the more closer
  related

• Analogous
• Different structure similar function
• Ex wings of butterfly and bird

7

• 2) Identify shared derived characters

• Shared Primitive Characters
• Not limited to group being studied
• Ex backbone and mammals (backbone not limited to
  mammals)

• Shared Derived Characters
• Evolutionary novelty unique to clade
• Ex hair unique to mammals

8

• 3) Outgroup comparison
• - Outgroup species closely related to the
  species being studied
• - Ingroup species being studied
• Identify characteristics to be studied
• Create data matrix comparing characteristics
• Create cladogram

9
Salamander
Leopard
Turtle
Tuna
10

• Phylogeny from molecular data

donkey
whale
penguin
snake
chicken
horse
common ancestor Most closely related donkey
and horse Least closely related snake and horse