Chapter 34: HW

Which of the following statements best describes the overall process of descent with modification?

A trait present in an ancestral organism is modified by natural selection over time in descendants of that ancestor. - Characteristics present in an ancestral organism are altered in its descendants over time as they face different environmental conditions. One result of descent with modification is that related species can have characteristics that have an underlying similarity yet different functions. Descent with modification occurring in different evolutionary lineages may result in species in each of those lineages having characteristics that function similarly yet are not due to common descent as those species have independently adapted to similar environmental conditions.

Based on this phylogeny, which vertebrate groups would you expect to have lungs or lung derivatives? Select all that apply.

Actinopterygii, Actinistia, Dipnoi, Amphibia, Reptilia, Mammalia - All of these groups originate to the right of (evolved after) the hatch mark indicating the appearance of lungs or lung derivatives in their lineage.

The graph shows mortality and brain size data for 14 species of birds. Deviation from expected brain size is shown on the x-axis, and the mortality rate is shown on the y-axis. Deviation values < 0 indicate brain sizes smaller than expected; values > 0 indicate sizes larger than expected. What can you conclude about the relationship between deviation from expected brain size and mortality rate?

Adult mortality tends to be lower in birds with unusually large brains for their body size, suggesting that these unusually large brains confer an advantage in survival. - The slope of the best-fit line indicates that adult mortality is lower in birds with brains that are larger than expected for their body size. This suggests that these unusually large brains confer an advantage in survival.

Which of the following chordate groups include(s) humans

Amniotes, Gnathostomes, Hominins

Select the vertebrate taxon or taxa whose origin(s) involved duplication of Hox genes.

Craniates, Gnathostomes

What is the significance of the evolution of Hox gene clusters during vertebrate evolution?

Duplication of Hox genes made increased morphological complexity possible. - As a result of gene duplication, craniates possess two or more sets of Hox genes (lancelets and tunicates have only one). Other important families of genes that produce signaling molecules and transcription factors are also duplicated in craniates. The additional genetic complexity due to duplication of Hox genes may have made it possible for craniates to develop more complex morphologies than those of lancelets and tunicates. Read about Hox gene clusters as derived characters of craniates.

Which of the following statements describing hominin evolution is/are correct

Homo sapiens is the only surviving member of a highly branched evolutionary tree of hominin species.

Why might natural selection have favored the evolution of large brains despite their high maintenance costs?

Large brains may make individuals more likely to survive and reproduce. - As long as the benefits of brains that are large relative to body size are greater than the costs, large brains can evolve. Natural selection might favor the evolution of brains that are large relative to body size because such brains confer an advantage in obtaining mates and/or an advantage in survival.

As a consequence of size alone, larger organisms tend to have larger brains than smaller organisms. However, some organisms have brains that are considerably larger than expected for their size. There are high energetic costs associated with the development and maintenance of brains that are large relative to body size. The fossil record documents trends in which brains that are large relative to body size evolved in certain lineages, including hominins. In such lineages, what can you infer about the costs and benefits of large brains?

Natural selection favored the evolution of larger brains, suggesting that the benefits of large brains outweighed the costs. - Because brain size tends to increase consistently in these lineages, we can conclude that natural selection favored the evolution of larger brains and hence that the benefits outweighed the costs.

Vertebrates and tunicates share

a notochord and a dorsal, hollow nerve cord.

What did the Haikouella, a primitive early chordate fossil, lack that vertebrates have? See Concept 34.2 (Page 722)

a skull - Haikouella lacked a skull, a trait found in vertebrates.

Which of the following could be considered the most recent common ancestor of living tetrapods?

a sturdy-finned, shallow-water lobe-fin whose appendages had skeletal supports similar to those of terrestrial vertebrates

Which of the following chordates is most likely to look the LEAST like other chordates? See Concept 34.1 (Page 719)

adult tunicate - An adult tunicate does not have a notochord (or vertebrae), a nerve cord, or a post-anal tail. The only chordate feature it retains is pharyngeal slits.

Listed below are four adaptations of terrestrial vertebrates. Which is a characteristic only of truly terrestrial animals with no need to return to water at any stage of the life cycle? See Concept 34.5 (Page 732)

amniotic eggs - In contrast to the shell-less eggs of amphibians, amniotic eggs (of most reptiles, and a few mammals) have a shell that retains water and can be laid in a dry place.

Most members of which of the following groups are most closely associated with a wet or moist environment? See Concept 34.4 (Page 729)

amphibians - Amphibians typically have a water-permeable skin that does not easily resist drying. Thus, amphibians tend to be found in moist environments.

The diagnostic feature of Chondrichthyes is _____. See Concept 34.3 (Page 724)

an endoskeleton of calcified cartilage - The cartilaginous skeleton of sharks and their relatives is reinforced with calcium.

As hominins diverged from other primates, which of the following appeared first?

bipedal locomotion

Jaws evolved _____. See Concept 34.3 (Page 724)

by modification of the skeletal rods that previously supported the anterior pharyngeal gill slits - According to a leading hypothesis, this marked a reduction in the number of pharyngeal gill slits and a change in the function of gills from feeding to respiration.

Which clade does not include humans?

diapsids

Based on the highlighted (white) branches in the phylogenetic tree shown, which of the following labels refers to a paraphyletic group?

green algae - A monophyletic group consists of an ancestral species and all of its descendants. Examples of monophyletic groups in this phylogenetic tree include red algae, plants, chlorophytes, charophytes, and the supergroup Archaeplastida. In contrast, a paraphyletic group consists of an ancestral species and some, but not all, of its descendants. In this tree, green algae are a paraphyletic group, because they consist of chlorophytes, charophytes, and their common ancestor, but not plants, which are also descended from the same common ancestor.

Unlike eutherians, both monotremes and marsupials

have some embryonic development outside the uterus.

There are three major groups of mammals, categorized on the basis of their _____. See Concept 34.6 (Page 739)

method of reproduction - Monotremes are egg-laying mammals, marsupials are pouched mammals, and eutherians are placental mammals.

Neural crest cells appear on the edges of the neural tube and spread throughout the embryo, giving rise to all of the following structures except __________. See Concept 34.2 (Page 723)

pharyngeal slits (or clefts) of invertebrate chordates - The neural crest is unique to vertebrates and does not exist in earlier chordate lineages, such as invertebrates.

Which of the following statements about hominin evolution is correct? As hominins have evolved, _____. See Concept 34.7 (Page 747)

sexual dimorphism was significantly reduced - Reduced sexual dimorphism is associated with pair-bonding.

Living vertebrates can be divided into two major clades. Select the appropriate pair.

the cyclostomes and the gnathostomes

Which of the following is NOT a diagnostic feature of the Chordata? See Concept 34.1 (Page 717)

vertebrae - Lancelets and tunicates are two subgroups of chordates that lack vertebrae. Hagfishes do, too.

In the phylogenetic tree shown, which of the following are shared ancestral characters for members of the turtle-leopard group?

vertebral column; four limbs - A shared ancestral character is a character that is not unique to a particular group, having originated in an ancestor of that group. For members of the turtle-leopard group, the phylogeny shows that a vertebral column, hinged jaws, and four limbs are all shared ancestral characters, having originated before the turtle-leopard group diverged from other lineages shown in the tree. In contrast, a shared derived character is an evolutionary novelty that is unique to a particular group; in the phylogeny shown here, an amnion is a shared derived character for the turtle-leopard group.