Phylogeny Chapter 20

The legless condition that is observed in several groups of extant reptiles is the result of

If organisms A, B, and C belong to the same class but to different orders and if organisms D, E, and F belong to the same order but to different families, which of the following pairs of organisms would be expected to show the greatest degree of structural homology?

The best classification system is that which most closely

Which of the following are the best examples of homologous structures?

Some molecular data place the giant panda in the bear family (Ursidae) but place the lesser panda in the raccoon family (Procyonidae). Consequently, the morphological similarities of these two species are probably due to

The importance of computers and of computer software to modern cladistics is most closely linked to advances in

The common ancestors of birds and mammals were very early (stem) reptiles, which almost certainly possessed three-chambered hearts (two atria, one ventricle). Birds and mammals, however, are alike in having four-chambered hearts (two atria, two ventricles). The four-chambered hearts of birds and mammals are best described as

When using a cladistic approach to systematics, which of the following is considered most important for classification?

Cladograms (a type of phylogenetic tree) constructed from evidence from molecular systematics are based on similarities in

A phylogenetic tree constructed using sequence differences in mitochondrial DNA would be most valid for discerning the evolutionary relatedness of

The most important feature that permits a gene to act as a molecular clock is

Which of these would, if it had acted upon a gene, prevent this gene from acting as a reliable molecular clock?

When it acts upon a gene, which of the following processes consequently makes that gene an accurate molecular clock?

What kind of evidence has recently made it necessary to assign the prokaryotes to either of two different domains, rather than assigning all prokaryotes to the same kingdom?

Which kingdom has been replaced with two domains?

Which extinct species should be the best candidate to serve as the outgroup for the clade whose common ancestor occurs at position 2 in Figure 26.1?

If you were using cladistics to build a phylogenetic tree of cats, which of the following would be the best outgroup?

Traditionally, whales and hippopotamuses have been classified in different orders, the Cetacea and the Artiodactyla, respectively. Recent molecular evidence, however, indicates that the whales' closest living relatives are the hippos. This has caused some zoologists to lump the two orders together into a single clade, the Cetartiodactyla. There is no consensus on whether the Cetartiodactyla should be accorded order status or superorder status. This is because it remains unclear whether the whale lineage diverged from the lineage leading to the hippos before or after the other members of the order Artiodactyla (pigs, camels, etc.) diverged (see Figure 26.2). Figure 26.2 contrasts the "Within the artiodactyls" origin of the whale lineage with the "Without the artiodactyls" origin of the whale lineage Placing whales and hippos in the same clade means

Humans, chimpanzees, gorillas, and orangutans are members of a clade called the great apes, which shared a common ancestor about 18 million years ago (Figure 26.4). Gibbons and siamangs comprise a clade called the lesser apes. Tree-branch lengths indicate elapsed time. The great apes comprise the family Hominidae, whereas the lesser apes comprise the family Hylobatidae. If the extant organisms on the far right side of Figure 26.5 comprise the next-most exclusive (i.e., specific) taxon, then they comprise different

The relative lengths of the frog and the mouse branches in the phylogenetic tree in the figure given indicate that...

The next question refer to the following table, which compares the % sequence homology of four different parts (two introns and two exons) of a gene that is found in five different eukaryotic species. Each part is numbered to indicate its distance from the promoter (e.g., Intron I is the one closest to the promoter). The data reported for species A were obtained by comparing DNA from one member of species A to another member of species A. Based on the tabular data, and assuming that time advances vertically, which cladogram (a type of phylogenetic tree) is the most likely depiction of the evolutionary relationships among these five species?

To apply parsimony to constructing a phylogenetic tree,

In the figure shown below, which similarly inclusive taxon descended from the same common ancestor ans Canidae?

Based on the tree below, which statement is not correct?