Cladogram

By reference to the tree above, which of the following is an accurate statement of relationships?

• A green alga is more closely related to a red alga than to a moss

• A green alga is more closely related to a moss than to a red alg

• A green alga is equally related to a red alga and a moss

• A green alga is related to a red alga, but is not related to a moss

Answer explanation

The most recent common ancestor of a green alga and a moss is at node x whereas the most recent common ancestor of a red alga and a moss is at the “deeper” node, y. If you picked ‘c’ you might be reading along the tips.

By reference to the tree above, which of the following is an accurate statement of relationships?

• A crocodile is more closely related to a lizard than to a bird

• A crocodile is more closely related to a bird than to a lizard

• A crocodile is equally related to a lizard and a bird

• A crocodile is related to a lizard, but is not related to a bird

Answer explanation

The most recent common ancestor of a crocodile and a bird is at node x whereas the most recent common ancestor of a crocodile and a lizard is at the “deeper” node, y. If you picked ‘a’ you might be reading along the tips.

By reference to the tree above, which of the following is an accurate statement of relationships?

• A seal is more closely related to a horse than to a whale

• A seal is more closely related to a whale than to a horse

• A seal is equally related to a horse and a whale

• A seal is related to a whale, but is not related to a horse

Answer explanation

The most recent common ancestor of a seal and a whale is at node y, as is the most recent common ancestor of a seal and a horse. All descendants of node x are equally related to the seal. If you picked ‘a’ you might be reading along the tips.

Which of the five dots in the tree above corresponds to the most recent common ancestor of a mushroom and a sponge?

• A

• B

• C

• D

Answer explanation

‘a’ is a living species and is not an ancestor. ‘e’ is an ancestor of a sponge but not of a mushroom. ‘b’ and ‘c’ are common ancestors of a sponge and a mushroom, but they are more ancient common ancestors than ‘d’.

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

• A

• B

• C

• D

Answer explanation

In all the other trees B is more closely related to D and E than is C. In ‘a,’ C is more closely related to D and E than is B

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

• A

• B

• C

• D

Answer explanation

In all the other trees C is more closely related to E and D than to B. In ‘c,’ C is more closely related to B than to E or D.

In the above tree, assume that the ancestor had a long tail, ear flaps, external testes, and fixed claws. Based on the tree and assuming that all evolutionary changes in these traits are shown, what traits does a sea lion have?

• long tail, ear flaps, external testes, and fixed claws

• short tail, no ear flaps, external testes, and fixed claws

• short tail, no ear flaps, abdominal testes, and fixed claws

• short tail, ear flaps, abdominal testes, and fixed claws

• long tail, ear flaps, abdominal testes, and retractable claws

Answer explanation

Tracing up from the ancestor to sea lions, one sees that the only changes are in tail length and testes position. For the other traits, they have retained the ancestral condition.

In the above tree, assume that the ancestor was an herb (not a tree) without leaves or seeds. Based on the tree and assuming that all evolutionary changes in these traits are shown, which of the tips has a tree habit and lacks true leaves?

• Lepidodendron

• Clubmoss

• Oak

• Psilotum

• Fern

Answer explanation

Clubmosses are not trees. Oak (and yew) are trees but they have leaves. Psilotum lacks leaves, but it is not a tree. A fern has leaves and is not a tree.

The trees show the phylogeny estimated for the same mammalian H1 influenzas based on portions of the haemaglutin genes. Tree A was estimated from bases 310-870 whereas tree B was estimated from bases 1070-1650. Under the assumption that these trees are correctly rooted, how does this result support the inference that the South Carolina 1918 strain (the only exemplar from the 1918 flu pandemic) arose from recombination between a human and a swine virus?

• The fact that the South Carolina 1918 strain is near the root of both trees suggests that it is of mixed identity

• The fact that the South Carolina 1918 strain is more closely related to the swine strains in tree A but to the human strains in tree B

• The fact that the South Carolina 1918 strain is a direct ancestor of all the swine strains in tree A but was isolated from a human

• The fact that the South Carolina 1918 strain is more closely related to the Iowa 30 swine strain than to the Scotland 94 human strain in both trees

Identify the characteristic feature of the phylogenetic tree

• more complex and are mostly used to determine the evolutionary relationship between different groups of organisms

• give an actual representation of the evolutionary history of the organisms

• The external taxa are  might or might not line up in a row or a column

• all answers are correct