Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Unit 05 13.4 The study of fossils provides strong evidence for evolution • The fossil record shows that organisms have evolved in a historical sequence – The oldest known fossils are prokaryote cells Copyright © 2009 Pearson Education, Inc. The oldest eukaryotic fossils are a billion years younger Tappania, a unicellular eukaryote Multicellular fossils are even more recent Dickinsonia costata 2.5 cm 1 B Ammonite casts E Insect in amber D Fossilized organic matter of a leaf C Dinosaur tracks A Skull of Homo erectus F “Ice Man” 2 13.4 The study of fossils provides strong evidence for evolution – Many fossils link early extinct species with species living today – A series of fossils documents the evolution of whales from a group of land mammals Copyright © 2009 Pearson Education, Inc. Pakicetus (terrestrial) Rhodocetus (predominantly aquatic) Pelvis and hind limb Dorudon (fully aquatic) Pelvis and hind limb Balaena (recent whale ancestor) 3 Pakicetus (terrestrial) Rhodocetus (predominantly aquatic) Pelvis and Dorudon (fully aquatic) hind limb Pelvis and hind limb Balaena (recent whale ancestor) 13.5 A mass of other evidence reinforces the evolutionary view of life – Biogeography, the geographic distribution of species, suggested to Darwin that organisms evolve from common ancestors – Darwin noted that animals on islands resemble species on nearby mainland more closely than they resemble animals on similar islands close to other continents Copyright © 2009 Pearson Education, Inc. – Comparative anatomy is the comparison of body structures in different species – Homology is the similarity in characteristics that result from common ancestry – Vertebrate forelimbs Copyright © 2009 Pearson Education, Inc. 4 Humerus Radius Ulna Carpals Metacarpals Phalanges Human Cat Whale Bat – Which of the following pairs are homologous structures? Human limb and whale flipper X Insect wing and bat wing Human thumb and chimpanzee thumb Oak leaf and oak root Oak leaf and lichen X X Oak leaf and maple leaf Copyright © 2009 Pearson Education, Inc. – Comparative embryology is the comparison of early stages of development among different organisms – Many vertebrates have common embryonic structures, revealing homologies – When you were an embryo, you had a tail and pharyngeal pouches (just like an embryonic fish) Pharyngeal pouches Post-anal tail Chick embryo Human embryo Copyright © 2009 Pearson Education, Inc. 5 – Some homologous structures are vestigial organs – For example, the pelvic and hind-leg bones of some modern whales Pelvis and Dorudon (fully aquatic) hind limb Pelvis and hind limb Balaena (recent whale ancestor) Copyright © 2009 Pearson Education, Inc. Molecular biology: Comparisons of DNA and amino acid sequences between different organisms reveal evolutionary relationships – All living things share a common DNA code for the proteins found in living cells – We share genes with bacteria, yeast, and fruit flies Head Thorax Abdomen (a) Adult 0.5 mm Dorsal BODY AXES Anterior Right Posterior Left Ventral Copyright © 2009 Pearson Education, Inc. 6 13.6 Homologies indicate patterns of descent that can be shown on an evolutionary tree Darwin was the first to represent the history of life as a tree Copyright © 2009 Pearson Education, Inc. Copyright © 2009 Pearson Education, Inc. 7 Homologous structures and genes can be used to determine the branching sequence of an evolutionary tree Lungfishes Mammals 2 Tetrapod limbs Amnion Tetrapods Amniotes Amphibians 1 Lizards and snakes 3 4 Crocodiles Ostriches 6 Feathers Birds 5 Hawks and other birds THE EVOLUTION OF POPULATIONS Copyright © 2009 Pearson Education, Inc. 13.7 Populations are the units of evolution • A population is a group of individuals of the same species living in the same place at the same time • Evolution is the change in heritable traits in a population over generations • Populations may be isolated from one another (with little interbreeding), or individuals within populations may interbreed Copyright © 2009 Pearson Education, Inc. 8 • A gene pool is the total collection of genes in a population at any one time • Microevolution is a change in the relative frequencies of alleles in a gene pool over time • Population genetics studies how populations change genetically over time • The modern synthesis connects Darwin’s theory with population genetics Copyright © 2009 Pearson Education, Inc. MAJOR EVENTS IN THE HISTORY OF LIFE Copyright © 2009 Pearson Education, Inc. on ic e Cenozoic ozo ner Pha oe M s zoic ic Humans zo o le Pa Colonization of land Origin of solar system and Earth Animals 1 4 Proterozoic Archaean eon eon Bil lio ns 2 of o ag ars 3 ye Multicellular eukaryotes Single-celled eukaryotes Prokaryotes Atmospheric oxygen 9 – Prokaryotes lived alone on Earth for 1.5 billion years – They created our atmosphere and transformed Earth’s biosphere – Virtually all metabolic pathways evolved within prokaryotes – Atmospheric oxygen appeared 2.7 billion years ago due to prokaryotic photosynthesis – Cellular respiration arose in prokaryotes, using oxygen to harvest energy from organic molecules Copyright © 2009 Pearson Education, Inc. 15.4 The origins of single-celled and multicelled organisms and the colonization of land are key events in life’s history – The eukaryotic cell probably originated as a community of prokaryotes, when small prokaryotes capable of aerobic respiration or photosynthesis began living in larger cells – Oldest fossils of eukaryotes are 2.1 billion years old Copyright © 2009 Pearson Education, Inc. – Multicellular forms arose about 1.5 billion years ago – The descendents of these forms include a variety of algae, plants, fungi, animals – The oldest known fossils of multicellular organisms were small algae, living 1.2 billion years ago Copyright © 2009 Pearson Education, Inc. 10 – The diversity of animal forms increased suddenly and dramatically about 535–525 million years ago in the Cambrian explosion – Fungi and plants colonized land together 500 million years ago – Roots of most plants have fungal associates that exchange water and minerals for nutrients Copyright © 2009 Pearson Education, Inc. – Arthropods and tetrapods are the most widespread and diverse land animals – Human lineage diverged from apes 7–6 million years ago – Our species originated 160,000 years ago Copyright © 2009 Pearson Education, Inc. 15.5 The actual ages of rocks and fossils mark geologic time – Radiometric dating measures the decay of radioactive isotopes – “Young” fossils may contain isotopes of elements that accumulated when the organisms were alive – Carbon-14 can date fossils up to 75,000 years old – Potassium-40, with a half-life of 1.3 billion years, can be used to date volcanic rocks that are hundreds of millions of years old – A fossil’s age can be inferred from the ages of the rock layers above and below the strata in which the fossil is found Copyright © 2009 Pearson Education, Inc. 11 Fraction of Carbon-14 remaining 1 – 2 1 – 4 0 5.7 1 – 8 1 –– 16 11.4 22.8 17.1 Time (thousands of years) 1 –– 32 28.5 15.6 The fossil record documents the history of life – The fossil record documents the main events in the history of life – The geologic record is defined by major transitions in life on Earth Copyright © 2009 Pearson Education, Inc. 12