Chapter 26: Phylogeny and the Tree of Life (MasteringBiology- Pearson)

Monophyletic

(of a group of organisms) descended from a common evolutionary ancestor or ancestral group, especially one not shared with any other group.

Systematists have used a wide variety of traits to reconstruct the phylogenies of particular groups of organisms. Which one of the following traits produces a good estimate of phylogeny?

- behavioral traits - molecular traits - biochemical traits - gross morphological traits

If you were using cladistics to build a phylogenetic tree of cats, which of the following would be the best outgroup? -tiger -lion -wolf -domestic cat -leopard

-wolf

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. If cetaceans are determined to have diverged from the lineage leading to the artiodactyls before the divergence of lineages leading to the modern artiodactyls (including hippos), then the cetaceans can be considered 1. a sister order to the order Artiodactyla. 2. an ingroup of the order Artiodactyla. 3. the common ancestor of the order Artiodactyla.

1 only

If the figure is an accurate depiction of relatedness, then which of the following should be correct? 1. The entire tree is based on maximum parsimony. 2. If all species depicted here make up a taxon, this taxon is monophyletic. 3. The last common ancestor of species B and C occurred more recently than the last common ancestor of species D and E. 4. Species A is the direct ancestor of both species B and species C. 5. The species present at position 3 is ancestral to C, D, and E.

1, 2, and 3

Rank the species from most closely related to horseflies to most distantly related to horseflies. If two species are equally close in their relatedness to horseflies, overlap them.

1. flea 2. katydid and human body louse 3. dragonfly and mayfly 4. silverfish

A possible phylogenetic tree for the three domains of life. If the early history of life on Earth is accurately depicted by the figure, then which statement is least in agreement with the hypothesis proposed by this tree?

Eukaryotes are more closely related to archaeans than to bacteria.

If you were the evolutionary biologist in charge of a project to create a phylogenetic tree that better clarified the evolutionary relationships between the species listed in the accompanying figure, what would be a logical first step?

Evaluate evidence to determine the relationships of species D, E, and F.

Members of which kingdom have cell walls and are all heterotrophic?

Fungi

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. If it turns out that the whale lineage diverged from the lineage leading to hippos after the divergence of the lineage leading to the pigs and other artiodactyls, and if the whales continue to be classified in the order Cetacea, then what becomes true of the taxon Cetartiodactyla?

It should be considered as one monophyletic superorder.

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?

Molecular

A large proportion of archaeans are extremophiles, so called because they inhabit extreme environments with high acidity, salinity, and/or temperature. Such environments are thought to have been much more common on the primitive Earth. Thus, modern extremophiles survive only in places that their ancestors became adapted to long ago. Which of the following is, consequently, a valid statement about modern extremophiles, assuming that their habitats have remained relatively unchanged?

On a phylogenetic tree whose branch lengths are proportional to the amount of genetic change, the branches of the extremophiles should be shorter than the non-extremophilic archaeans.

Select the correct statement about phylogenetic trees.

Phylogenetic trees may expand quickly to maximum width and then narrow over time.

Systematics

The branch of biology that deals with classification of organisms; taxonomy. Meant to reflect evolutionary history.

Homoplasy Example

The eye, which has originated independently in many different species.

Orthologous Genes

The genes in different species that evolved from a common ancestral gene by speciation. Normally, they retain the same function in the course of evolution. Identification of these genes is critical for reliable prediction of gene function in newly sequenced genomes.

This phylogenetic tree was constructed by comparing sequences for a homologous gene involved in development. Select the correct statement.

The nucleotide sequence of this gene in a mouse is more similar to the sequence in a chicken, and both are less similar to the nucleotide sequence of this gene in a frog.

What does the x-axis of a Phylogenetic Tree represent?

Time

Systematics Example

When you learn that a chimpanzee is a primate, and all primates are mammals. The fact that Humans and Chimpanzees are both primates, but a Cat is not, reflects the fact that Humans and Chimpanzees share a more recent evolutionary history than Humans and Cats or Chimpanzees and Cats.

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

chimpanzees and humans

To apply parsimony to constructing a phylogenetic tree, _____.

choose the tree that represents the fewest evolutionary changes, either in DNA sequences or morphology

Animals that possess homologous structures probably _____.

evolved from the same ancestor

Species that are not closely related and that do not share many anatomical similarities can still be placed together on the same phylogenetic tree by comparing their _____.

homologous genes that are highly conserved

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 ______.

homoplasies

If, someday, an archaean cell is discovered whose rRNA sequence is more similar to that of humans than the sequence of mouse rRNA is to that of humans, the best explanation for this apparent discrepancy would be _____.

homoplasy

Which process occurred frequently in the early history of the three domains on Earth, and makes determining phylogenetic relationships of that time difficult?

horizontal gene transfer

Regarding these sequence homology data, the principle of maximum parsimony would be applicable in _____.

inferring evolutionary relatedness from the number of sequence differences

A clade is _____.

monophyletic

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

mutations to homologous genes

A researcher wants to determine the genetic relatedness of several breeds of dog (Canis lupus familiaris). The researcher should compare homologous sequences of this type of biochemical________-which can be described as ________.

nucleic acids, poorly conserved

Molecular clocks are based on the idea that _____.

on average neutral mutations arise at a constant rate

Humans, chimpanzees, gorillas, and orangutans are members of a clade called the great apes, which shared a common ancestor about 18 million years ago. Gibbons and siamangs comprise a clade called the lesser apes. Tree-branch lengths indicate elapsed time. Together, the lesser apes and great apes shared a common ancestor most recently with other members of their _____.

order

Concerning growth in genome size over evolutionary time, which of these is least associated with the others?

orthologous genes

Humans, chimpanzees, gorillas, and orangutans are members of a clade called the great apes, which shared a common ancestor about 18 million years ago. Gibbons and siamangs comprise a clade called the lesser apes. Tree-branch lengths indicate elapsed time. Assuming chimps and gorillas are humans' closest relatives, removing humans from the great ape clade and placing them in a different clade has the effect of making the phylogenetic tree of the great apes _____.

paraphyletic

The various taxonomic levels (namely, genera, classes, etc.) of the hierarchical classification system differ from each other on the basis of _____.

their inclusiveness

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

shared derived characters

Homoplasy

A character shared by a set of species but not present in their common ancestor.

Phylogenetic Tree

A way of depicting the evolutionary history of a group of organisms. They are all works in progress. Represents a hypothesis of the history of the species.

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

Bones in the bat wing and bones in the human forelimb

As the evolutionary biologist in charge of a student project to create a phylogenetic tree that better clarified the evolutionary relationships between the species listed in the accompanying figure, you asked the students to pose a question that would be a logical first step to better understand the evolutionary history of the group. Which student question would be the best starting point?

Can we evaluate evidence to determine the relationships of species D, E, and F?

Which of the following taxonomic categories contains all the others listed here? 1. Species 2. Family 3. Order 4. Genus 5. Class

Class

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?

D and F

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 _____.

possession of analogous structures

Fossil evidence indicates that some dinosaurs had feathers. If birds are indeed descended from dinosaurs, feathers are what kind of character?

shared ancestral character