ap bio chapter 20: Concept 20.2: Phylogenies are inferred form morphological and molecular data

What do systematists use to infer phylogeny?

Morphologies, genes (DNA), and biochemistry of living organisms.

Why is comparing a human bone to a whale fin useful in phylogeny?

Their similarity suggests a shared common ancestor.

What must similarities used in phylogenies result from?

Shared ancestry.

What is the key idea when two organisms share traits?

They likely came from the same place—a common ancestor.

What are homologies?

Phenotypic or genetic similarities due to shared ancestry.

What do homologies provide evidence for?

Evolution and common ancestry.

What does it suggest if two organisms have similar morphologies or DNA?

They are likely more closely related.

If two organisms have the same basic bone structure but different sizes, what does that suggest?

They are probably related (homologous structure).

What is homology?

Similarity due to shared ancestry.

What is analogy?

Similarity due to convergent evolution.

Do analogous structures come from the same ancestor?

No, they have different structures but similar functions.

Give examples of analogous structures.

Wings of birds, bats, and butterflies (all used for flight, but not built the same).

What causes convergent evolution?

Similar environmental pressures and natural selection in different evolutionary lineages.

Why don’t butterflies, bats, and birds share a recent common ancestor?

They belong to different lineages; wings developed separately due to similar environments.

Are bat and bird wings homologous or analogous?

Analogous as wings (function), but homologous as forelimbs (structure).

What are homoplasies?

Analogous structures or molecular sequences that evolved independently.

How can we distinguish homology from analogy?

By using fossil evidence and comparing complexity of structures.

Why is complexity important in identifying homologies?

Complex structures are unlikely to evolve independently in separate lineages.

How are molecular homologies determined?

By comparing nucleotide (DNA) sequences between taxa.

What does more DNA sequence similarity suggest?

A closer evolutionary relationship and molecular homology.

What tools help analyze molecular homologies?

Computer programs and databases like BLAST.

What are molecular homoplasies?

Shared bases in nucleotide sequences that evolved independently and are otherwise dissimilar.