Chapter 11 - BIOLOGY

Evidence of EvolutionChapter 11

11.1 Impacts/IssuesReflections of a Distant Past

Events of the ancient past can be explained by the same physical, chemical, and biological processes that operate in todays world

From Evidence to Inference

Scientists infer from evidence such as the K-T boundary layer that an asteroid impact near the Yucatn 65 million years ago caused the mass extinction of dinosaurs

Mass extinction Simultaneous loss of many lineages from Earth

From Evidence to InferenceBarringer crater, Arizona

Video: Measuring time

Video: ABC News: Asteroid menace

Video: ABC News: Creation vs. evolution

11.2 Early Beliefs, Confusing Discoveries

By the 19th century, naturalists were returning from globe-spanning survey expeditions with increasingly detailed observations of nature

Naturalist Person who observes life from a scientific perspective

Pioneers of Biogeography

Late 1800s: Alfred Wallace and other naturalists observed patterns in where species live, how they might be related, and how natural forces might shape life

Biogeography Study of patterns in the geographic distribution of species and communities

BiogeographyWallace thought similarities in birds on different continents might indicate a common ancestor

Biogeography Some plants that lived in similar climates on different continents had similar features, but were not closely related

Comparative Morphology

Naturalists studying body plans were confused by vestigial body parts with no apparent function

Comparative morphology Scientific study of body plans and structures among groups of organisms

Vestigial Body Parts

Fig. 11-3, p. 198coccyxleg bones

Figure 11.3Vestigial body parts. (A) Pythons and boa constrictors have tiny leg bones, but snakes do not walk. (B) We humans use our legs, but not our coccyx (tail) bones.

GeologyIdentical rock layers in different parts of the world, sequences of similar fossils, and fossils of giant animals with no living representatives also puzzled early naturalists

Confusing Discoveries

Taken as a whole, findings from biogeography, comparative morphology, and geology did not fit with prevailing beliefs of the 19th century

Increasingly extensive observations of nature led to new ways of thinking about the natural world

Animation: Comparative pelvic anatomy

11.3 A Flurry of New Theories

Nineteenth-century naturalists tried to explain the accumulating evidence of evolution

Georges Cuvier proposed that catastrophic geologic forces unlike those of the present day shaped Earths surface (catastrophism)

Jean-Baptiste Lamarck proposed that changes in an animal over its lifetime were inherited

Evolution

Naturalists suspected that environmental factors affected affect a species traits over time, causing changes in a line of descent

Evolution Change in a line of descent (in a line from an ancestor)

Voyage of the Beagle

1831: Charles Darwin set out as a naturalist on a five-year voyage aboard the Beagle

He found many unusual fossils and observed animals living in many different environments

Darwin and the Voyage of the Beagle

Lyells Theory of Uniformity

Darwin was influenced by Charles Lyells Principles of Geology, which set forth the theory of uniformity in contrast to catastrophism

Theory of uniformity Idea that gradual repetitive processes occurring over long time spans shaped Earths surface

Shared TraitsDarwin collected fossils of extinct glyptodons, which shared traits with modern armadillos

Limited Resources

Thomas Malthus observed that:A population tends to grow until it begins to exhaust environmental resourcesfood, shelter from predators, etc When resources become scarce, individuals must compete for them

Darwin applied these ideas to the species he had observed on his voyage

Fitness

Darwin realized that in any population, some individuals have traits that make them better suited to the environment than others, and therefore more likely to survive and reproduce

Fitness The degree of adaptation to an environment, as measured by an individuals relative genetic contribution to future generations

Adaptation

Adaptive traits that impart greater fitness to an individual become more common in a population over generations, compared with less competitive forms

Adaptation (adaptive trait) A heritable trait that enhances an individuals fitness

Natural Selection

Darwin concluded that the process of natural selection, through variations in fitness and adaptation, is a driving force of evolution

Natural selection Differential survival and reproduction of individuals of a population that vary in the details of shared, heritable traits

Great Minds Think Alike

Alfred Wallace, the father of biogeography, proposed the theory of natural selection in 1858, at the same time as Darwin

Darwin published On the Origin of Species the following year, in which he described descent with modification, or evolution

Alfred WallaceThe codiscoverer of natural selection

Principles of Natural Selection

Animation: The Galapagos Islands

11.4 About Fossils

FossilsPhysical evidence of organisms from the pastHard fossils include mineralized bones, teeth, shells, spores and other hard body partsTrace fossils include footprints, nests, trails, feces and other evidence of activities

Process of Fossilization

Layers of sediment cover an organism or its traces pressure and mineralization change remains to rock

Younger fossils usually occur in more recently deposited layers of sedimentary rock, on top of older fossils in older layers

The Fossil Record

Fossils are relatively scarce, so the fossil record will always be incomplete

The fossil record helps us reconstruct the lineage of some species, such as whales

Lineage Line of descent from a common ancestor

Fossil Links Ancient Artiodactyl to Modern Whale Lineage

Fig. 11-7a, p. 202A A 30-million-year-old fossil of Elomeryx. This small terrestrial mammal was a member of the same artiodactyl group that gave rise to hippopotamuses, pigs, deer, sheep, cows, and whales.

Figure 11.7New links in the ancient lineage of whales. With their artiodactyl-like ankle bones, Rodhocetus and Dorudon were probably offshoots of the ancient artiodactyl-to-modern-whale lineage as it transitioned back to life in water. Modern cetaceans do not have even a remnant of an ankle bone.

Fig. 11-7b, p. 202

Figure 11.7New links in the ancient lineage of whales. With their artiodactyl-like ankle bones, Rodhocetus and Dorudon were probably offshoots of the ancient artiodactyl-to-modern-whale lineage as it transitioned back to life in water. Modern cetaceans do not have even a remnant of an ankle bone.

Fig. 11-7b, p. 202B Rodhocetus, an ancient whale, lived about 47 million years ago. Its distinctive ankle bones point to a close evolutionary connection to artiodactyls. Inset: compare a Rodhocetus ankle bone (left) with that of a modern artiodactyl, a pronghorn antelope (right).

Figure 11.7New links in the ancient lineage of whales. With their artiodactyl-like ankle bones, Rodhocetus and Dorudon were probably offshoots of the ancient artiodactyl-to-modern-whale lineage as it transitioned back to life in water. Modern cetaceans do not have even a remnant of an ankle bone.

Fig. 11-7b (1), p. 202

Figure 11.7New links in the ancient lineage of whales. With their artiodactyl-like ankle bones, Rodhocetus and Dorudon were probably offshoots of the ancient artiodactyl-to-modern-whale lineage as it transitioned back to life in water. Modern cetaceans do not have even a remnant of an ankle bone.

Fig. 11-7b (2), p. 202

Figure 11.7New links in the ancient lineage of whales. With their artiodactyl-like ankle bones, Rodhocetus and Dorudon were probably offshoots of the ancient artiodactyl-to-modern-whale lineage as it transitioned back to life in water. Modern cetaceans do not have even a remnant of an ankle bone.

Fig. 11-7b (3), p. 202

Figure 11.7New links in the ancient lineage of whales. With their artiodactyl-like ankle bones, Rodhocetus and Dorudon were probably offshoots of the ancient artiodactyl-to-modern-whale lineage as it transitioned back to life in water. Modern cetaceans do not have even a remnant of an ankle bone.

Fig. 11-7c, p. 202

Figure 11.7New links in the ancient lineage of whales. With their artiodactyl-like ankle bones, Rodhocetus and Dorudon were probably offshoots of the ancient artiodactyl-to-modern-whale lineage as it transitioned back to life in water. Modern cetaceans do not have even a remnant of an ankle bone.

Fig. 11-7c, p. 202C Dorudonatrox, an ancient whale that lived about 37 million years ago. Its artiodactyl-like ankle bones (left) were much too small to have supported the weight of its huge body on land, so this mammal had to be fully aquatic.

Figure 11.7New links in the ancient lineage of whales. With their artiodactyl-like ankle bones, Rodhocetus and Dorudon were probably offshoots of the ancient artiodactyl-to-modern-whale lineage as it transitioned back to life in water. Modern cetaceans do not have even a remnant of an ankle bone.

Fig. 11-7c (1), p. 202

Figure 11.7New links in the ancient lineage of whales. With their artiodactyl-like ankle bones, Rodhocetus and Dorudon were probably offshoots of the ancient artiodactyl-to-modern-whale lineage as it transitioned back to life in water. Modern cetaceans do not have even a remnant of an ankle bone.

Fig. 11-7c (2), p. 202

Figure 11.7New links in the ancient lineage of whales. With their artiodactyl-like ankle bones, Rodhocetus and Dorudon were probably offshoots of the ancient artiodactyl-to-modern-whale lineage as it transitioned back to life in water. Modern cetaceans do not have even a remnant of an ankle bone.

Fig. 11-7c (3), p. 202

Figure 11.7New links in the ancient lineage of whales. With their artiodactyl-like ankle bones, Rodhocetus and Dorudon were probably offshoots of the ancient artiodactyl-to-modern-whale lineage as it transitioned back to life in water. Modern cetaceans do not have even a remnant of an ankle bone.

Radiometric DatingThe age of rocks and fossils can be determined using radiometric dating

Half-life Characteristic time it takes for half of a quantity of a radioisotope to decay into daughter elements

Radiometric dating Estimates age of a rock or fossil by measuring the ratio of a radioisotope and daughter elements

Half-Life and Radiometric Dating

Animation: Radioisotope decay

Animation: Radiometric dating

11.5 Putting Time Into Perspective

Transitions in the fossil record, found in characteristic layers of sedimentary rock, became boundaries for great intervals of the geologic time scale

Geologic time scale Chronology of Earth historyCorrelates with evolutionary events

The Geologic Time Scale

The Geologic Time Scale

Animation: Geologic time scale

Drifting Continents, Changing Seas

Theory of continental driftEarths continents were once part of a single supercontinent that split up and drifted apartExplains how the same types of fossils can occur on both sides of an ocean

Pangea Supercontinent that formed about 237 million years ago and broke up about 152 million year ago

Plate Tectonics: A Mechanism of Continental Drift

Theory of plate tectonics Earths outer layer of rock is cracked into platesSlow movement rafts continents to new positions over geologic timeWhere plates spread apart, molten rock wells up from deep inside the Earth and solidifiesWhere plates collide, one slides under the other and is destroyed

Plate Tectonics

Fig. 11-10a, p. 206trenchhot spotridgetrenchrift1234

Figure 11.10Plate tectonics. Huge pieces of Earths outer layer of rock slowly drift apart and collide. As the plates move, they raft continents around the globe. (1) At oceanic ridges, huge plumes of molten rock welling up from Earths interior drive the movement of tectonic plates. New crust spreads outward as it forms on the surface, forcing adjacent tectonic plates away from the ridge and into trenches elsewhere. (2) At trenches, the advancing edge of one plate plows under an adjacent plate and buckles it. (3) Faults are ruptures in Earths crust where plates meet. Plates move apart at rifts. The aerial photo in (B) shows about 4.2 kilometers (2.6 miles) of the San Andreas Fault, which extends 1,300 km (800 miles) through California. This fault is a boundary between two tectonic plates slipping by one another. (4) Plumes of molten rock rupture a tectonic plate at what are called hot spots. The Hawaiian Islands have been forming this way.

Gondwana

Certain fossils of ferns and reptiles that predate Pangea are found in similar rock layers in Africa, India, South America, and Australia evidence of an even earlier supercontinent

Gondwana Supercontinent that formed more than 500 million years ago

Gondwana and Pangea

Fig. 11-11, p. 207A 420 myaB 237 myaC 152 myaD 65.5 myaE 14 mya

Figure 11.11: Animated!A series of reconstructions of the drifting continents. (A) The supercontinent Gondwana (yellow) had begun to break up by the Silurian. (B) The supercontinent Pangea formed during the Triassic, then (C) began to break up in the Jurassic. (D) KT boundary. (E) The continents reached their modern configuration in the Miocene.

Animation: Continental drift

Impacts on Evolution

Evidence suggests that supercontinents have formed and broken up at least five times

The resulting changes in the Earths surface, atmosphere, waters and climates have had profound impacts on evolution

Animation: Plate margins

Animation: Five major extinctions

Animation: Geologic forces

Video: ABC News: Indonesian earthquake

11.6 Similarities in Body Form and Function

Similarities in structure of body parts are often evidence of a common ancestor

Homologous structures Similar body parts that reflect shared ancestryMay be used for different purposes in different groups, but the same genes direct their development

Morphological Divergence

A body part that appears very different in appearance may be quite similar in underlying aspects of form evidence of shared ancestry

Morphological divergence Evolutionary pattern in which a body part of an ancestor changes in its descendants (homologous structures)

Morphological Divergence Among Vertebrate Forelimbs

Fig. 11-12, p. 208pterosaurchickenpenguinstem reptileporpoisebathumanelephant

Figure 11.12Morphological divergence among vertebrate forelimbs, starting with the bones of a stem reptile. The number and position of many skeletal elements were preserved when these diverse forms evolved; notice the bones of the forearms. Certain bones were lost over time in some of the lineages (compare the digits numbered 1 through 5). The drawings are not to the same scale.

Morphological Convergence

Some body parts look alike in different lineages, but did not evolve in a common ancestor

Analogous structuresSimilar structures that evolved separately in different lineages

Morphological convergence Evolutionary pattern in which similar body parts evolve separately in different lineage

Morphological Convergence

Fig. 11-13a, p. 209

Figure 11.13Morphological convergence. The flight surfaces of a bat wing (A), a bird wing (B), and an insect wing (C) are analogous structures. (D) The independent evolution of wings in the three separate lineages that led to bats, birds, and insects. You will read more about diagrams that show evolutionary relationships in Section 12.7.

Fig. 11-13b, p. 209

Figure 11.13Morphological convergence. The flight surfaces of a bat wing (A), a bird wing (B), and an insect wing (C) are analogous structures. (D) The independent evolution of wings in the three separate lineages that led to bats, birds, and insects. You will read more about diagrams that show evolutionary relationships in Section 12.7.

Fig. 11-13c, p. 209

Figure 11.13Morphological convergence. The flight surfaces of a bat wing (A), a bird wing (B), and an insect wing (C) are analogous structures. (D) The independent evolution of wings in the three separate lineages that led to bats, birds, and insects. You will read more about diagrams that show evolutionary relationships in Section 12.7.

Fig. 11-13d, p. 209

Figure 11.13Morphological convergence. The flight surfaces of a bat wing (A), a bird wing (B), and an insect wing (C) are analogous structures. (D) The independent evolution of wings in the three separate lineages that led to bats, birds, and insects. You will read more about diagrams that show evolutionary relationships in Section 12.7.

Fig. 11-13d, p. 209InsectsBatsHumansCrocodilesBirdswingswingswingslimbs with 5 digits

Figure 11.13Morphological convergence. The flight surfaces of a bat wing (A), a bird wing (B), and an insect wing (C) are analogous structures. (D) The independent evolution of wings in the three separate lineages that led to bats, birds, and insects. You will read more about diagrams that show evolutionary relationships in Section 12.7.

Comparative Embryology

Embryos of related species tend to develop in similar ways

Similarities in patterns of embryonic development are the result of master genes (homeotic genes) that have been conserved over evolutionary time

Comparative Embryology

Fig. 11-14a, p. 210

Figure 11.14Comparative embryology. All vertebrates go through an embryonic stage in which they have four limb buds and a tail. From top to bottom: human, mouse, bat, chicken, and alligator embryos.

Fig. 11-14b, p. 210

Figure 11.14Comparative embryology. All vertebrates go through an embryonic stage in which they have four limb buds and a tail. From top to bottom: human, mouse, bat, chicken, and alligator embryos.

Fig. 11-14c, p. 210

Figure 11.14Comparative embryology. All vertebrates go through an embryonic stage in which they have four limb buds and a tail. From top to bottom: human, mouse, bat, chicken, and alligator embryos.

Fig. 11-14d, p. 210

Figure 11.14Comparative embryology. All vertebrates go through an embryonic stage in which they have four limb buds and a tail. From top to bottom: human, mouse, bat, chicken, and alligator embryos.

Fig. 11-14e, p. 210

Figure 11.14Comparative embryology. All vertebrates go through an embryonic stage in which they have four limb buds and a tail. From top to bottom: human, mouse, bat, chicken, and alligator embryos.

Animation: Morphological divergence

Animation: Mutation and proportional changes

11.7 Biochemical Similarities

Each lineage has unique characters that are a mixture of ancestral and novel traits, including biochemical features such as the nucleotide sequence of DNA

We can discover and clarify evolutionary relationships through comparisons of nucleic acid and protein sequences

Mutations and SpeciationGenes for essential proteins (such as cytochrome b) are highly conserved across diverse species

Neutral mutations tend to accumulate in DNA at a predictable rate

Lineages that diverged recently have more nucleotide or amino acid sequences in common than ones that diverged long ago

Comparing Amino Acids in Cytochrome b

Animation: Cytochrome C comparison

11.8 Impacts/Issues Revisited

The K-T boundary layer (formed 65 million years ago at a time of mass extinction) is made up of clay rich in iridium rare on Earth but common in asteroids

Digging Into Data: Abundance of Iridium in the K-T Boundary Layer

Figure 11.3Vestigial body parts. (A) Pythons and boa constrictors have tiny leg bones, but snakes do not walk. (B) We humans use our legs, but not our coccyx (tail) bones.

Figure 11.7New links in the ancient lineage of whales. With their artiodactyl-like ankle bones, Rodhocetus and Dorudon were probably offshoots of the ancient artiodactyl-to-modern-whale lineage as it transitioned back to life in water. Modern cetaceans do not have even a remnant of an ankle bone.Figure 11.7New links in the ancient lineage of whales. With their artiodactyl-like ankle bones, Rodhocetus and Dorudon were probably offshoots of the ancient artiodactyl-to-modern-whale lineage as it transitioned back to life in water. Modern cetaceans do not have even a remnant of an ankle bone.Figure 11.7New links in the ancient lineage of whales. With their artiodactyl-like ankle bones, Rodhocetus and Dorudon were probably offshoots of the ancient artiodactyl-to-modern-whale lineage as it transitioned back to life in water. Modern cetaceans do not have even a remnant of an ankle bone.Figure 11.7New links in the ancient lineage of whales. With their artiodactyl-like ankle bones, Rodhocetus and Dorudon were probably offshoots of the ancient artiodactyl-to-modern-whale lineage as it transitioned back to life in water. Modern cetaceans do not have even a remnant of an ankle bone.Figure 11.7New links in the ancient lineage of whales. With their artiodactyl-like ankle bones, Rodhocetus and Dorudon were probably offshoots of the ancient artiodactyl-to-modern-whale lineage as it transitioned back to life in water. Modern cetaceans do not have even a remnant of an ankle bone.Figure 11.7New links in the ancient lineage of whales. With their artiodactyl-like ankle bones, Rodhocetus and Dorudon were probably offshoots of the ancient artiodactyl-to-modern-whale lineage as it transitioned back to life in water. Modern cetaceans do not have even a remnant of an ankle bone.Figure 11.7New links in the ancient lineage of whales. With their artiodactyl-like ankle bones, Rodhocetus and Dorudon were probably offshoots of the ancient artiodactyl-to-modern-whale lineage as it transitioned back to life in water. Modern cetaceans do not have even a remnant of an ankle bone.Figure 11.7New links in the ancient lineage of whales. With their artiodactyl-like ankle bones, Rodhocetus and Dorudon were probably offshoots of the ancient artiodactyl-to-modern-whale lineage as it transitioned back to life in water. Modern cetaceans do not have even a remnant of an ankle bone.Figure 11.7New links in the ancient lineage of whales. With their artiodactyl-like ankle bones, Rodhocetus and Dorudon were probably offshoots of the ancient artiodactyl-to-modern-whale lineage as it transitioned back to life in water. Modern cetaceans do not have even a remnant of an ankle bone.Figure 11.7New links in the ancient lineage of whales. With their artiodactyl-like ankle bones, Rodhocetus and Dorudon were probably offshoots of the ancient artiodactyl-to-modern-whale lineage as it transitioned back to life in water. Modern cetaceans do not have even a remnant of an ankle bone.Figure 11.7New links in the ancient lineage of whales. With their artiodactyl-like ankle bones, Rodhocetus and Dorudon were probably offshoots of the ancient artiodactyl-to-modern-whale lineage as it transitioned back to life in water. Modern cetaceans do not have even a remnant of an ankle bone.

Figure 11.10Plate tectonics. Huge pieces of Earths outer layer of rock slowly drift apart and collide. As the plates move, they raft continents around the globe. (1) At oceanic ridges, huge plumes of molten rock welling up from Earths interior drive the movement of tectonic plates. New crust spreads outward as it forms on the surface, forcing adjacent tectonic plates away from the ridge and into trenches elsewhere. (2) At trenches, the advancing edge of one plate plows under an adjacent plate and buckles it. (3) Faults are ruptures in Earths crust where plates meet. Plates move apart at rifts. The aerial photo in (B) shows about 4.2 kilometers (2.6 miles) of the San Andreas Fault, which extends 1,300 km (800 miles) through California. This fault is a boundary between two tectonic plates slipping by one another. (4) Plumes of molten rock rupture a tectonic plate at what are called hot spots. The Hawaiian Islands have been forming this way.

Figure 11.11: Animated!A series of reconstructions of the drifting continents. (A) The supercontinent Gondwana (yellow) had begun to break up by the Silurian. (B) The supercontinent Pangea formed during the Triassic, then (C) began to break up in the Jurassic. (D) KT boundary. (E) The continents reached their modern configuration in the Miocene.

Figure 11.12Morphological divergence among vertebrate forelimbs, starting with the bones of a stem reptile. The number and position of many skeletal elements were preserved when these diverse forms evolved; notice the bones of the forearms. Certain bones were lost over time in some of the lineages (compare the digits numbered 1 through 5). The drawings are not to the same scale.

Figure 11.13Morphological convergence. The flight surfaces of a bat wing (A), a bird wing (B), and an insect wing (C) are analogous structures. (D) The independent evolution of wings in the three separate lineages that led to bats, birds, and insects. You will read more about diagrams that show evolutionary relationships in Section 12.7.Figure 11.13Morphological convergence. The flight surfaces of a bat wing (A), a bird wing (B), and an insect wing (C) are analogous structures. (D) The independent evolution of wings in the three separate lineages that led to bats, birds, and insects. You will read more about diagrams that show evolutionary relationships in Section 12.7.Figure 11.13Morphological convergence. The flight surfaces of a bat wing (A), a bird wing (B), and an insect wing (C) are analogous structures. (D) The independent evolution of wings in the three separate lineages that led to bats, birds, and insects. You will read more about diagrams that show evolutionary relationships in Section 12.7.Figure 11.13Morphological convergence. The flight surfaces of a bat wing (A), a bird wing (B), and an insect wing (C) are analogous structures. (D) The independent evolution of wings in the three separate lineages that led to bats, birds, and insects. You will read more about diagrams that show evolutionary relationships in Section 12.7.Figure 11.13Morphological convergence. The flight surfaces of a bat wing (A), a bird wing (B), and an insect wing (C) are analogous structures. (D) The independent evolution of wings in the three separate lineages that led to bats, birds, and insects. You will read more about diagrams that show evolutionary relationships in Section 12.7.

Figure 11.14Comparative embryology. All vertebrates go through an embryonic stage in which they have four limb buds and a tail. From top to bottom: human, mouse, bat, chicken, and alligator embryos.Figure 11.14Comparative embryology. All vertebrates go through an embryonic stage in which they have four limb buds and a tail. From top to bottom: human, mouse, bat, chicken, and alligator embryos.Figure 11.14Comparative embryology. All vertebrates go through an embryonic stage in which they have four limb buds and a tail. From top to bottom: human, mouse, bat, chicken, and alligator embryos.Figure 11.14Comparative embryology. All vertebrates go through an embryonic stage in which they have four limb buds and a tail. From top to bottom: human, mouse, bat, chicken, and alligator embryos.Figure 11.14Comparative embryology. All vertebrates go through an embryonic stage in which they have four limb buds and a tail. From top to bottom: human, mouse, bat, chicken, and alligator embryos.