In-Text Art, Ch. 16, p. 316 (1)

In-Text Art, Ch. 16, p. 316 (2)

In-Text Art, Ch. 16, p. 316 (4)

In-Text Art, Ch. 16, p. 317

Figure 16.1 Clades Represent All the Descendants of a Common Ancestor

Figure 16.2 The Bones Are Homologous, the Wings Are Not Analogous trait = homoplasies Shared derived trait = synapomorphies

Table 16.1 Eight Vertebrates and the Presence or Absence of Some Shared Derived Traits

Figure 16.3 Inferring a Phylogenetic Tree

A monophyletic group consists of the ancestor species and all its descendants A polyphyletic grouping consists of various species with different ancestors A paraphyletic grouping consists of an ancestral species and some, but not all, of the descendants (a) Monophyletic group (clade) (b) Paraphyletic group (c) Polyphyletic group A A A B Group  B B Group  C C C D D D E E Group  E F F F G G G 9

Individual genes vary in how clocklike they are Molecular Clocks A molecular clock uses constant rates of evolution in some genes to estimate the absolute time of evolutionary change Assumption: nucleotide substitutions are proportional to the time since they last shared a common ancestor Molecular clocks are calibrated against branches whose dates are known from the fossil record Individual genes vary in how clocklike they are © 2011 Pearson Education, Inc. 12

Divergence time (millions of years) 90 60 Number of mutations 30 Figure 26.19 A molecular clock for mammals. 30 60 90 120 Divergence time (millions of years) 13

Figure 16.9 A Molecular Clock of the Protein Hemoglobin

Problems with Molecular Clocks The molecular clock does not run as smoothly as neutral theory predicts Irregularities result from natural selection in which some DNA changes are favored over others Estimates of evolutionary divergences older than the fossil record have a high degree of uncertainty The use of multiple genes may improve estimates © 2011 Pearson Education, Inc. 15

It is also important to distinguish homology from analogy in molecular similarities Mathematical tools help to identify molecular homoplasies, or coincidences Molecular systematics uses DNA and other molecular data to determine evolutionary relationships © 2011 Pearson Education, Inc. 16

1 1 2 Figure 26.8 Aligning segments of DNA. 17

1 1 2 Deletion 2 1 2 Insertion Figure 26.8 Aligning segments of DNA. 18

1 1 2 Deletion 2 1 2 Insertion 3 1 Figure 26.8 Aligning segments of DNA. 2 19

1 1 2 Deletion 2 1 2 Insertion 3 1 Figure 26.8 Aligning segments of DNA. 2 4 1 2 20

Figure 24.3 Amino Acid Sequences of Cytochrome c (Part 2)

Figure 24.1 Amino Acid Sequence Alignment (Part 1)

Figure 24.1 Amino Acid Sequence Alignment (Part 2)

Figure 24.2 Multiple Substitutions Are Not Reflected in Pairwise Sequence Comparisons