Brooklyn College BIOL 1010 // Biology: The Study of Life : Lab Notes
Classification
Phylogeny
- The evolutionary history of a species or a group of related species
Phylogenetic Tree
- A branching diagram that represents a hypothesis about the evolutionary relationship among organisms.
Two systems are used to classify organisms:
Traditional (Aristotelian) analysis
- This system of classification is based on similarities and differences, whichs shows increasing complexity.
- This diagram tells us that lizards, snakes, and crocodiles (all reptiles) are more closely related to each other than to birds.
- It also tells us both reptiles and birds originated from a common ancestor over time.
Cladistic analysis
- Classification system which is based on evolutionary relationships.
Using this method, we see a different organization of our animals.
- This analysis shows us that a common ancestor gave rise to two branches. One branch consists of lizards and snakes, while the other branch consists of crocodiles and birds.
- This means that crocodiles are more closely related to birds than to lizards, in terms of evolution.
- The theory that birds evolved from dinosaurs is a highly debated theory among scientists is based on the Cladistical way of analysis.