Chapter 22 Descent With Modification Title page from

Chapter 22 - Descent With Modification Title page from The Origin of Species published 1859 Charles Darwin - wrote – Origin of Species by Means of Natural Selection - naturalist - sailed on the Beagle, survey ship, 22 years old - collected specimens: plants and animals - he found fossils different from modern species - Darwin was influenced by Lyell’s Principles of Geology and thought that the earth was more than 6000 years old * - He observed adaptations of plants and animals that inhabited many diverse environments

Linnaeus (classification) Hutton (gradual geologic change) Lamarck (species can change) Malthus (population limits) Cuvier (fossils, extinction) Lyell (modern geology) Darwin (evolution, natural selection) Wallace (evolution, natural selection) American Revolution French Revolution U. S. Civil War 1800 1900 1750 1850 1795 Hutton proposes his theory of gradualism. 1798 Malthus publishes “Essay on the Principle of Population. ” 1809 Lamarck publishes his hypothesis of evolution. 1830 Lyell publishes Principles of Geology. 1831– 1836 Darwin travels around the world on HMS Beagle. 1837 Darwin begins his notebooks. 1844 Darwin writes essay on descent with modification. 1858 Wallace sends his hypothesis to Darwin. 1859 The Origin of Species is published.

Historical Ideas Taxonomy - Linnaeus: naming and classifying the diverse forms of life “for the greater glory of God”: kingdom, phylum, class, order, family, genus, species paleontologist, fossils, recognized that extinctions occurred he argued it must have been due to catastrophism Paleontology – Cuvier: Gradualism - Hutton: geologist: profound change in the Earth’s features, slow and continuous Uniformitarianism - Lyell : geologist, geologic processes have not changed throughout Earth’s history rates of building and eroding same now as in past Evolution - Lamark : Lamarck hypothesized that species evolve through use and disuse of body parts and the inheritance of acquired characteristics The mechanisms he proposed are unsupported by evidence Populations - Malthus : studied populations human suffering was due to populations Natural Selection - Darwin : Inheritance - Mendel : 2 ideas: 1. descent with modification 2. natural selection through adaptation parents pass traits to offspring

Acquired traits are not inherited

The Voyage of HMS Beagle - discovered that most of the animal species on the Galapagos lived nowhere else in the world but they resemble species on the South American mainland - Darwin studied Finches (birds) adaptation -In reassessing his observations, Darwin perceived to the environment and the origin of new species as closely related processes

(a) Cactus-eater (c) Seed-eater (b) Insect-eater

In the Darwinian view, the history of life is like a tree with branches representing life’s diversity

Artificial Selection, Natural Selection, and Adaptation • Darwin noted that humans have modified other species by selecting and breeding individuals with desired traits, a process called_____________ artificial selection • Darwin then described four observations of nature and from these drew two inferences Observation #1: Members of a population often vary greatly in their traits Observation #2: Traits are inherited from parents to offspring Observation #3: All species are capable of producing more offspring than the environment can support Observation #4: Owing to lack of food or other resources, many of these offspring do not survive • Inference #1: Individuals whose inherited traits give them a higher probability of surviving and reproducing in a given environment tend to leave more offspring than other individuals • Inference #2: This unequal ability of individuals to survive and reproduce will lead to the accumulation of favorable traits in the population over generations

Observation #1: Members of a population often vary greatly in their traits

• individuals populations evolve over time Note that _______do not evolve; _______ • Natural selection can only increase or decrease heritable traits in a population • Adaptations ________ vary with different environments • edits or _____ selects for Natural selection does not create new traits, but ____ traits already present in the population • selected for The local environment determines which traits will be _________ or selected against _________ in any specific population

Fig. 22 -12 b (b) A stick mantid in Africa

Fig. 22 -12 a Observation #2: Traits are inherited from parents to offspring (a) A flower mantid in Malaysia

The Evolution of Drug-Resistant HIV • selects for viruses resistant to these The use of drugs to combat HIV ________ drugs • reverse transcriptase to make a DNA version of HIV uses the enzyme ____________ its own RNA genome • The drug 3 TC is designed to interfere and cause errors in the manufacture of DNA from the virus • variation Some individual HIV viruses have a _______ that allows them to produce DNA without errors • greater reproductive success These viruses have a ________________ and increase in number relative to the susceptible viruses • developed resistance to 3 TC The population of HIV viruses has therefore ___________ • The ability of bacteria and viruses to evolve rapidly poses a challenge to our society

The Evolution of Drug-Resistant HIV Percent of HIV resistant to 3 TC Fig. 22 -14 100 Patient No. 1 Patient No. 2 75 50 Patient No. 3 25 0 0 2 4 6 Weeks 8 10 12

The Fossil Record • provides evidence of the extinction of species, the origin of The fossil record _________ new groups, and changes within groups over time • transitions The Darwinian view of life predicts that evolutionary _________ should leave signs in the fossil record • Paleontologists have discovered fossils of many such transitional forms

A transitional fossil linking past and present Vestigal structures historical remnants of structures that had important functions in ancestors ex. snakes – pelvis, leg bones

Fig. 22 -16 ab The transition to life in the sea (a) Pakicetus (terrestrial) (b) Rhodocetus (predominantly aquatic)

Fig. 22 -16 cd Pelvis and hind limb (c) Dorudon (fully aquatic) Pelvis and hind limb (d) Balaena (recent whale ancestor)

Homologous structures: anatomical signs of descent with modification new species descend from ancestral species ce n ide on v e uti e r vol o m re fo anatomical homologies Homologous structures - similarity in characteristics resulting from common ancestors Homologies – ex. forelimb: human, cat, whale, bat - anatomical - embryological – ex. pharyngeal pouches in throat – all vertebrates have - molecular – all use same genetic material (DNA) Analogous structures – body parts resemble one another - evolved independently ex. fins/body shape: sharks, penguins, porpoise all are adaptations for swimming

Fig. 22 -18 Pharyngeal pouches Post-anal tail Chick embryo (LM) Human embryo

Homologies and “Tree Thinking” • evolutionary tree of life can explain The Darwinian concept of an __________ homologies • relationships among Evolutionary trees are hypotheses about the _________ different groups • Evolutionary trees can be made using different types of data, for example, anatomical and DNA sequence data ________________________

Fig. 22 -19 Branch point (common ancestor) Lungfishes Amnion Lizards and snakes 3 4 Homologous characteristic Amniotes Tetrapod limbs Mammals 2 Crocodiles Ostriches 6 Feathers Hawks and other birds Birds 5 Tetrapods Amphibians 1

Convergent Evolution • Convergent evolution is the evolution of similar, or ________, analogous _________ features in distantly related groups • independently adapt Analogous traits arise when groups ______________ similar environments to ____________ in similar ways • ancestry Convergent evolution does not provide information about _______

Fig. 22 -20 Sugar glider NORTH AMERICA AUSTRALIA Flying squirrel