Homology Flashcards
Homology
a similar character inherited from the same ancestor
genealogical inheritance
Homoplasy
A similar character that evolved independently
Criteria of homology after Remane
- Position (extremities)
- continuity
- Specific quality
Criteria of position & example
Structures are homologous if they obtain an
identical position in the organism
- Ex. vertebrate extremities
Criteria of continuity & example
If their position doesn’t
match, but intermediate forms are recognizable
intermediates only visible during ontogenesis or in
extinct forms.
Ex. lungs tetrapods
Criteria of specific quality & example
Complex structures are also
homologous if they match in many
details even if they cannot match by
position or continuity
Ex. Tetrapodd teeth or scales of a shark
Analogy
Functional similarity, not based on genealogy, but
on adaptation to different habitats.
Convergence
Parallel development of traits in two not directly
related animals due to adaptation to similar
habitats (Kind of homoplasy)
Ex. Wings of Birds and Insects
•Torpedo shape of dolphins and penguins
•Eyes in octopus and vertebrates