EARTH 7 Lecture Notes - Lecture 6: Maternal Sensitivity, Osteichthyes, Monophyly
How do we figure out relationships?
Need to determine shared derived characters
- Aka evolutionary novelties
Ex of characters
- Physical features
- Wings, hair color, etc
- Behavioral features
- Maternal care
- Biochemical features
- DNA or protein sequence
Homologous vs. Convergent characters
- Homologous: similar due to inheritance from common ancestor
- Convergent : similar but NOT inherited from a common ancestor
- Independently acquired
Convergent
- Usually only superficially similar
- Similarity is often due to similar function
Homology
- Arms, legs, fins, and wings in these groups are all pretty different, but their underlying
similarity is indicative of their shared ancestry
- Feathers and wings are homologous in eagles and ducks
Groups are defined by the evolutionary novelties that set them apart from other species
Important caveat:
- Defining characters are sometimes lost
- Snakes don’t have limbs but they are still tetrapods bc ancestor of snakes had limbs
V. Types of Groups
Paraphyletic group
- Ancestor + some descendants - bad
Monophyletic group
- All osteichthyes have air sacs
Fleshy-limbed vertebrates
- 1 bone, 2 bones, many bones
find more resources at oneclass.com
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Document Summary
Homologous: similar due to inheritance from common ancestor. Convergent : similar but not inherited from a common ancestor. Similarity is often due to similar function. Arms, legs, fins, and wings in these groups are all pretty different, but their underlying similarity is indicative of their shared ancestry. Feathers and wings are homologous in eagles and ducks. Groups are defined by the evolutionary novelties that set them apart from other species. Snakes don t have limbs but they are still tetrapods bc ancestor of snakes had limbs: types of groups.
