Phylogenetic Tree Practice Problems

What year on this phylogenetic tree did the Heleni clade form?

~60-65 million years ago

True or False: According to the phylogeny below, turtles were the most recent common ancestor of lizards, crocodiles, and

birds.

False.

True or False: In the phylogeny below, turtles are more closely related to mammals than to birds.

False

According to the phylogeny by Schultz et al (2024), which term best describes fungal-farming ants? (Red indicates fungal-

farming.)

Polyphyletic

Are the evolutionary relationships depicted in these two trees the same or different? Justify your answer.

Yes, evolutionary relationships are defined by common ancestry (nodes), not by the order of taxa across the tips. Internal nodes on a phylogenetic tree can be rotated 180 degrees without changing the branching pattern or phylogenetic meaning.

Which of the four trees depicts a different pattern of relationships than the others?

A, because the position of the E, D, and B is in different nodes

Did the dentist infect his patients?

Yes, the dentist infected many of his HIV+ patients, but a few were infected by someone else.

The phylogeny below, from Knie et al (2015) shows the relationship amongst true plants.  Ferns (monilophytes) are represented by the red branches in the phylogeny below.  Horsetails (Equisetales) and ferns make up a group of plants known as the seedless vascular plants. True or false: Ferns (all red branches) form a monophyletic group.

True

Which of the following statements are TRUE given the larger phylogeny of plants shown on the left:

A. Seed plants are the most advanced plants.

B. Horsetails (Equisetales) are equally related to ferns (in red) and lycophytes.

C. The red triangle at the base of the fern lineages represents a tip on the phylogenetic tree.

D. Ferns are most closely related to horsetails (Equisetales).

D. Ferns are most closely related to horsetails (Equisetales).

Ungulates are hooved animals (Pan-Perissodactyla).  This includes extant animals like horses, rhinos, tapirs, and even whales as well as many extinct groups.  Panels A & B show unique teeth features that evolved in ungulates.  Panel C shows unique foot features that evolved in ungulates. According to the phylogeny on the left, which of the following features would Kollpaniidae have inherited?  Select ALL that apply.

A. Shared tusk and trunk features with Afrotheria

B. Unique tooth features indicated by Panel A

C. Unique tooth and jaw features indicated by Panel B

D. Unique hoof features indicated by Panel C

B. Unique tooth features indicated by Panel A

Above is a phylogeny of vertebrates.  Many primates and adult frogs do not have a post-anal tail.  If the MRCA of all vertebrates (e.g. the entire tree) had a post-anal tail, what term best describes taillessness in frogs and primates?

Homoplasy

What is used to determine phylogeny?

DNA

What do scientists in the field of systematics accomplish?

Organize and classify organisms

Which statement about the taxonomic classification system is correct?

Subspecies are the most specific category of classification.

On a phylogenetic tree, which term refers to lineages that diverged from the same place?

Sister Taxa

Which statement about analogies is correct?

They are derived by similar environmental constraints.

What do scientists use to apply cladistics?

Homologous traits

What is true about organisms that are a part of the same clade?

They evolved from a shared ancestor

Why do scientists apply the concept of maximum parsimony?

To decipher accurate phylogenies