LO1 - Describe the differences between homology, analogy and homoplasy

What is meant by Homology?

Homology is similarity between traits due to shared inheritance from a common ancestor.

What is meant by Analogy?

Analogy is similarity in function between traits that evolved independently, not from a common ancestor.

What is meant by Homoplasy

Homoplasy is similarity between traits that is not due to shared ancestry, often caused by convergent evolution or evolutionary reversal.

How does homology differ from analogy?

Homology is similarity due to shared ancestry, whereas analogy is similarity due to independent evolution for a similar function.

How does homology differ from homoplasy?

Homology reflects common ancestry, while homoplasy reflects similarity that evolved independently and does not indicate shared ancestry.

How are analogy and homoplasy related?

Analogy is a type of homoplasy, because analogous traits are similar due to convergent evolution rather than shared ancestry.

Are the wings of birds and bats homologous or analogous?

Explain your reasoning.

Analogous as wings because flight evolved independently, but homologous as forelimbs because they share the same underlying bone structure from a common ancestor.

Are vertebrate forelimbs (human arm, whale flipper, bat wing) homologous or analogous? Why?

Vertebrate forelimbs are homologous because they share the same basic bone structure inherited from a common ancestor, despite having different functions.

Why is homoplasy particularly common in molecular data?

Because the same mutation can arise independently in different lineages by chance, producing similar DNA sequences without shared ancestry.

Simplest breakdown of LO1

• homology = shared ancestry

• homoplasy = looks similar but not shared ancestry

• analogy = a type of homoplasy (functional similarity)