Descent with Modification: A Darwinian View of Life Chapter 22 Descent with Modification: A Darwinian View of Life

Assignments: - Study Chapter 22 - Do the MasteringBiology exercises for Chapt 22 http://www.wellcometreeoflife.org/video/

Overview: Endless Forms Most Beautiful A new era of biology began in 1859 when Charles Darwin published The Origin of Species Darwin noted that current species are descendants of ancestral species Evolution can be defined by Darwin’s phrase descent with modification Evolution can be viewed as both a pattern and a process © 2011 Pearson Education, Inc.

1809 Lamarck publishes his hypothesis of evolution. 1798 Malthus publishes “Essay on the Principle of Population.” 1812 Cuvier publishes his extensive studies of vertebrate fossils and Proposed catastrophism. 1858 1795 While studying species in the Malay Archipelago, Wallace (shown in 1848) sends Darwin his hypothesis of natural selection. Hutton proposes his principle of gradualism. 1830 Lyell publishes Principles of Geology. 1790 1870 1809 183136 1859 Charles Darwin is born. Darwin travels around the world on HMS Beagle. On the Origin of Species is published. Figure 22.2 The intellectual context of Darwin’s ideas. 1844 Darwin writes his essay on descent with modification. 1707 - 1778 Linnaeus developed binomial naming for species . The Galápagos Islands

Paleontology Sedimentary rock layers (strata) Younger stratum Figure 22.3 Formation of sedimentary strata with fossils. Younger stratum with more recent fossils Older stratum with older fossils

1809 Lamarck publishes his hypothesis of evolution. 1798 Malthus publishes “Essay on the Principle of Population.” 1812 Cuvier publishes his extensive studies of vertebrate fossils and Proposed catastrophism. 1858 1795 While studying species in the Malay Archipelago, Wallace (shown in 1848) sends Darwin his hypothesis of natural selection. Hutton proposes his principle of gradualism. 1830 Lyell publishes Principles of Geology. 1790 1870 1809 183136 1859 Charles Darwin is born. Darwin travels around the world on HMS Beagle. On the Origin of Species is published. Figure 22.2 The intellectual context of Darwin’s ideas. 1844 Darwin writes his essay on descent with modification. 1707 - 1778 Linnaeus developed binomial naming for species . The Galápagos Islands

© 2011 Pearson Education, Inc.

1809 Lamarck publishes his hypothesis of evolution. 1798 Malthus publishes “Essay on the Principle of Population.” 1812 Cuvier publishes his extensive studies of vertebrate fossils and Proposed catastrophism. 1858 1795 While studying species in the Malay Archipelago, Wallace (shown in 1848) sends Darwin his hypothesis of natural selection. Hutton proposes his principle of gradualism. 1830 Lyell publishes Principles of Geology. 1790 1870 1809 183136 1859 Charles Darwin is born. Darwin travels around the world on HMS Beagle. On the Origin of Species is published. Figure 22.2 The intellectual context of Darwin’s ideas. 1844 Darwin writes his essay on descent with modification. 1707 - 1778 Linnaeus developed binomial naming for species . The Galápagos Islands

Figure 22.5 The voyage of HMS Beagle. Darwin in 1840, after his return from the voyage HMS Beagle in port Great Britain EUROPE NORTH AMERICA ATLANTIC OCEAN The Galápagos Islands AFRICA PACIFIC OCEAN Pinta Genovesa Equator Marchena Malay Archipelago Equator SOUTH AMERICA PACIFIC OCEAN Santiago Daphne Islands Chile Brazil AUSTRALIA Fernandina Pinzón PACIFIC OCEAN Andes Mtns. Isabela Figure 22.5 The voyage of HMS Beagle. Santa Cruz Cape of Good Hope Santa Fe San Cristobal Argentina Tasmania 20 40 Florenza Española Cape Horn Kilometers New Zealand

(a) Cactus-eater (b) Insect-eater (c) Seed-eater Figure 22.6 Figure 22.6 Three examples of beak variation in Galápagos finches. (c) Seed-eater

The Origin of Species Darwin explained three broad observations: The unity of life The diversity of life The match between organisms and their environment © 2011 Pearson Education, Inc.

Figure 22.8 Descent with modification. Elephas maximus (Asia) Hyracoidea (Hyraxes) Sirenia (Manatees and relatives) †Moeritherium †Barytherium †Deinotherium †Mammut †Platybelodon †Stegodon †Mammuthus Figure 22.8 Descent with modification. Elephas maximus (Asia) Loxodonta africana (Africa) Loxodonta cyclotis (Africa) 60 34 24 5.5 2 104 Millions of years ago Years ago

Artificial Selection Cabbage Selection for apical (tip) bud Brussels sprouts Selection for axillary (side) buds Broccoli Selection for flowers and stems Figure 22.9 Artificial selection. Selection for stems Selection for leaves Kale Wild mustard Kohlrabi

Observation #1: Members of a population often vary in their inherited traits © 2011 Pearson Education, Inc.

Observation #2: All species can produce more offspring than the environment can support, and many of these offspring fail to survive and reproduce © 2011 Pearson Education, Inc.

Individuals in a population vary in their heritable characteristics. Figure 22.UN02 Observations Individuals in a population vary in their heritable characteristics. Organisms produce more offspring than the environment can support. Inferences Individuals that are well suited to their environment tend to leave more offspring than other individuals. Figure 22.UN02 Summary figure, Concept 22.2 and Over time, favorable traits accumulate in the population.

Natural Selection: A Summary Individuals with certain heritable characteristics survive and reproduce at a higher rate than other individuals Natural selection increases the adaptation of organisms to their environment over time If an environment changes over time, natural selection may result in adaptation to these new conditions and may give rise to new species

Evolution is supported by an overwhelming amount of scientific evidence Direct Observations of Evolutionary Change Homology Fossil records biogeography © 2011 Pearson Education, Inc.

Direct Observations of Evolutionary Change FIELD STUDY Figure 22.13 Inquiry: Can a change in a population’s food source result in evolution by natural selection? Soapberry bug with beak inserted in balloon vine fruit

On native species, southern Florida Figure 22.13b RESULTS Beak 10 On native species, southern Florida 8 6 4 2 Ballon vine fruit Number of individuals Museum-specimen average 10 8 On introduced species, central Florida Figure 22.13 Inquiry: Can a change in a population’s food source result in evolution by natural selection? 6 4 2 6 7 8 9 10 11 Goldenrain tree fruit Beak length (mm)

Chromosome map of S. aureus clone USA300 Figure 22.14 1 2,750,000 250,000 base pairs 2,500,000 Chromosome map of S. aureus clone USA300 500,000 2,250,000 Key to adaptations Methicillin resistance Ability to colonize hosts 750,000 Increased disease severity 2,000,000 Increased gene exchange (within species) and toxin production Figure 22.14 Impact: The Rise of MRSA 1,000,000 1,750,000 1,250,000 1,500,000

CONCLUSION: Natural selection does not create new traits, but edits or selects for traits already present in the population The local environment determines which traits will be selected for or selected against in any specific population © 2011 Pearson Education, Inc.

Homology Homology is similarity resulting from common ancestry Homologous structures are anatomical resemblances that represent variations on a structural theme present in a common ancestor Examples of homologies at the molecular level are genes shared among organisms inherited from a common ancestor © 2011 Pearson Education, Inc.

Mammalian forelimbs: homologous structures Humerus Radius Ulna Carpals Metacarpals Figure 22.15 Mammalian forelimbs: homologous structures. Phalanges Human Cat Whale Bat

Comparative embryology reveals anatomical homologies not visible in adult organisms Pharyngeal pouches Post-anal tail Figure 22.16 Anatomical similarities in vertebrate embryos. Chick embryo (LM) Human embryo

Vestigial structures are remnants of features that served important functions in the organism’s ancestors

Homologies and “Tree Thinking” Evolutionary trees are hypotheses about the relationships among different groups Homologies form nested patterns in evolutionary trees Evolutionary trees can be made using different types of data, for example, anatomical and DNA sequence data © 2011 Pearson Education, Inc.

Homologous characteristic Figure 22.17 Branch point Lungfishes Amphibians 1 Tetrapods 2 Mammals Digit- bearing limbs Amniotes 3 Lizards and snakes Amnion 4 Crocodiles Homologous characteristic Figure 22.17 Tree thinking: information provided in an evolutionary tree. 5 Ostriches 6 Birds Feathers Hawks and other birds

A Different Cause of Resemblance: Convergent Evolution Convergent evolution is the evolution of similar, or analogous, features in distantly related groups Analogous traits arise when groups independently adapt to similar environments in similar ways Convergent evolution does not provide information about ancestry

The Fossil Record The fossil record provides evidence of the extinction of species, the origin of new groups, and changes within groups over time Fossils can document important transitions © 2011 Pearson Education, Inc.

Transition from land to sea in the ancestors of cetaceans Other even-toed ungulates Hippopotamuses †Pakicetus †Rodhocetus Common ancestor of cetaceans Figure 22.20 The transition to life in the sea. †Dorudon Living cetaceans 70 60 50 40 30 20 10 Key Pelvis Tibia Millions of years ago Femur Foot

Biogeography Present Cenozoic North America Eurasia 65.5 Africa Biogeography, the geographic distribution of species, provides evidence of evolution Earth’s continents were formerly united in a single large continent called Pangaea, but have since separated by continental drift South America India Madagascar Australia Antarctica Laurasia 135 Millions of years ago Gondwana Mesozoic Figure 25.14 The history of continental drift during the Phanerozoic eon. 251 Pangaea Paleozoic

What Is Theoretical About Darwin’s View of Life? In science, a theory accounts for many observations and data and attempts to explain and integrate a great variety of phenomena Darwin’s theory of evolution by natural selection integrates diverse areas of biological study and stimulates many new research questions Ongoing research adds to our understanding of evolution © 2011 Pearson Education, Inc.