* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Ch 22 lecture - D and F: AP Biology
Survey
Document related concepts
Sexual selection wikipedia , lookup
Natural selection wikipedia , lookup
On the Origin of Species wikipedia , lookup
Organisms at high altitude wikipedia , lookup
Evidence of common descent wikipedia , lookup
Punctuated equilibrium wikipedia , lookup
Evolutionary history of life wikipedia , lookup
Hologenome theory of evolution wikipedia , lookup
Theistic evolution wikipedia , lookup
Paleontology wikipedia , lookup
Saltation (biology) wikipedia , lookup
Transcript
Chapter 22 Descent with Modification: A Darwinian View of Life Overview: Darwin Introduces a Revolutionary Theory • A new era of biology began on November 24, 1859, the day Charles Darwin published On the Origin of Species by Means of Natural Selection • Book made two major points: 1.Many current species are descendants of ancestral species 2.Natural selection is a method for this evolutionary process Resistance to the Idea of Evolution • The Origin of Species – Shook the deepest roots of Western culture – Challenged a worldview that had been prevalent for centuries The Scale of Nature and Classification of Species • Aristotle: species as fixed and unchanging • Old Testament: species were individually designed by God and therefore perfect • Carolus Linnaeus: organismal changes are evidence that the Creator has designed each species for a specific purpose – Linnaeus was a founder of taxonomy, the branch of biology concerned with classifying organisms Fossils, Cuvier, and Catastrophism • Fossils: remains/traces of organisms, usually found in sedimentary rock, which appears in layers or strata – Paleontology: the study of fossils • Cuvier: developed paleontology; advocated catastrophism – Catastrophism: speculating that each boundary between strata represents a catastrophe (disaster) Lamarck’s Theory of Evolution • Lamarck hypothesized that species evolve through use and disuse and the inheritance of acquired traits – The mechanisms he proposed are unsupported by evidence – Except pertaining to epigenetics The Voyage of the Beagle • Charles Darwin had a consuming interest in nature • After receiving his B.A. degree, he was accepted on board the HMS Beagle – Darwin collected plants and animals from South American – He observed changes in plants and animals that lived in many diverse environments – His interest in geographic distribution of species was fuelled by a stop at the Galápagos Islands England EUROPE NORTH AMERICA PACIFIC OCEAN ATLANTIC OCEAN AFRICA Galápagos Islands HMS Beagle in port Equator SOUTH AMERICA Darwin in 1840, after his return AUSTRALIA Cape of Good Hope Tasmania Cape Horn Tierra del Fuego New Zealand Darwin’s Focus on Adaptation • Darwin thought that adaptations to the environment and the origin of new species as closely related processes • From studies made years after Darwin’s voyage, biologists have concluded that this is indeed what happened to the Galápagos finches Cactus eater. The long, sharp beak of the cactus ground finch (Geospiza scandens) helps it tear and eat cactus flowers and pulp. Seed eater. The large ground finch (Geospiza magnirostris) has a large beak adapted for cracking seeds that fall from plants to the ground. Insect eater. The green warbler finch (Certhidea olivacea) used its narrow, pointed beak to grasp insects. Descent with Modification • “Descent with modification” summarized Darwin’s view of how life is united – All organisms are related through an ancestor that lived in the remote past • In the Darwinian view, the history of life is like a tree with branches representing life’s diversity Sirenia Hyracoidea (Manatees (Hyraxes) and relatives) 0 10,000 2 5.5 24 34 Elephas Loxodonta Loxodonta cyclotis maximus africana (Africa) (Africa) (Asia) Natural Selection and Adaptation • The work of Darwin has been summarized into two observations and two inferences • Observation 1: Members of a population often vary in their inherited traits • Observation 2: all species can produce more offspring than their environment can support and many of these offspring fail to survive and reproduce • Inference 1: Individuals whose inherited traits give them a higher probability of surviving and reproducing in a given environment tend to leave more offspring • Inference 2: This unequal ability of individuals to survive and reproduce will lead to the accumulation of favorable traits in the population over generations Artificial Selection • In artificial selection, humans have modified other species over many generations by selecting and breeding individuals with desired traits Summary of Natural Selection • Natural selection: differential success in reproduction from interactions between individuals that vary in heritable traits and their environment – Produces an increase over time in adaptation of organisms to their environment – If an environment changes over time, natural selection may result in adaptation to these new conditions A flower mantid in Malaysia A stick mantid in Africa The Evolution of Drug-Resistant Bacteria • An example of ongoing natural selection that has had an effect on humans is the evolution of drug-resistant pathogens – The evolution of Staphyloccocus aureus into methicillin-resistant S. aureus or MRSA – Some bacteria had enzymes that could break down penicillin and other antibiotics Homology, Biogeography, and the Fossil Record • Evolutionary theories provide a cohesive explanation for many kinds of observations Anatomical Homologies • Homology: similarity resulting from common ancestry – Homologous structures: anatomical resemblances that represent variations on a structure present in a common ancestor – Vestigial organs are remnants of structures that served important functions in the organism’s ancestors Human Cat Whale Bat • Comparative embryology reveals anatomical homologies not visible in adult organisms Pharyngeal pouches Post-anal tail Chick embryo (LM) Human embryo Molecular Homologies • Examples of homologies at the molecular level are genes shared among organisms inherited from a common ancestor – Anatomical resemblances among species are generally reflected in their molecules, genes, and gene products Species Percent of Amino Acids That Are Identical to the Amino Acids in a Human Hemoglobin Polypeptide Human 100% Rhesus monkey 95% 87% Mouse 69% Chicken 54% Frog Lamprey 14% Biogeography • Darwin’s observations of biogeography, the geographic distribution of species, formed an important part of his theory of evolution: convergent evolution – Some similar mammals that have adapted to similar environments have evolved independently from different ancestors NORTH AMERICA Sugar glider AUSTRALIA Flying squirrel The Fossil Record • The succession of forms observed in the fossil record is consistent with other inferences about the major branches of descent in the tree of life • The Darwinian view of life predicts that evolutionary transitions should leave signs in the fossil record – Paleontologists have discovered fossils of many such transitional forms