Origin and Evolution of Life PDF

The Origin & Evolution Of Life Lecture 2 I-Evolution A-History of Evolutionary Thought -Darwin, 22 year-old -Naturalist  I-Evolution - A-History of Evolutionary Thought Charles Darwin Theory of Evolution Darwin’s principle of Evolution:...

The Origin & Evolution Of Life Lecture 2 I-Evolution A-History of Evolutionary Thought -Darwin, 22 year-old -Naturalist  I-Evolution - A-History of Evolutionary Thought Charles Darwin Theory of Evolution Darwin’s principle of Evolution: Species rise, change and become extinct due to natural, not supernatural forces >> due to Natural Selection Published in 1859 Observations & Experimentations  I-Evolution - A-History of Evolutionary Thought Prior to Darwin, heated debate on life: Fixity vs. Evolution Faith vs. Science Linnaeus (18th century) -Leclerc (18th century,) Erasmus Darwin, Cuvier (19th century,) developed Taxonomy, confused between fixity the grandfather believed in fixity, which was used to and evolution. Hinted of Darwin, created Paleontology. organize life, based on however at evolution due hinted strongly When faced with the fixity of species and to environmental causes. at evolution fossils having different Judeo-Christian beliefs Lack of support from his structures in colleagues made him lose sediments, he interest in evolution, and proposed that the reverted back to fixity of difference was due to species. catastrophes, Catastrophism, versus environmental pressures.  I-Evolution - A-History of Evolutionary Thought Prior to Darwin, heated debate on life: Fixity vs. Evolution Faith vs. Science - Fossils Examples of Fossils of Eukaryotes -Fossils: remains and traces of past life. -Fossils are the alphabet with which the history of life on earth is written. Dinosaur (land) Trilobite (sea) -How are fossils generated? When animals die, most of the time, soft parts decompose (they sometimes can be preserved, mummification, amber); but the hard parts may persist (made of calcium) Early Bird (air, land) Fish (sea) -Fossils include: trails, footprints, burrows, holes in the underground, bones, teeth, worm casts, preserved droppings, shells, etc.. Plant (land) Ammonite (sea) I-Evolution - A-History of Evolutionary Thought Prior to Darwin, heated debate on life: Fixity vs. Evolution, Faith vs. Science Lamarck (18th century,) was the first to make observations that supported evolution. -He suggested that: * more complex organisms arise from less complex, *but he believed that this evolution was driven by Perfectionism, not by survival, and that the newly acquired characteristics become inheritable  I-Evolution - B-Darwin’s Theory of Evolution -Enters Darwin: -As a young naturalist, Darwin took a trip around the world and made numerous biological and geological observations. -He discovered fossils of extinct animals during his exploration of South America -He observed species, gathered information, and collected Darwin fossils. -He found seashells on highest mountains; evidence that part of earth was once covered with water. -He also was convinced that the earth is very old, unlike what religion stated at that time. -Darwin came to the conclusion that living forms could be descended from extinct forms known only from fossil records. Examples:  I-Evolution - B-Darwin’s Theory of Evolution Present day Armadillo Descendant of Glyptodon? Darwin discovered fossils of extinct animals Glyptodon and Mylodon, during his exploration of South America. Noticed resemblance with Present day Sloth Living Armadillo and Sloth respectively Descendant of Mylodon?  I-Evolution - B-Darwin’s Theory of Evolution - Evidence. -It would seem that species are not fixed, they change over time: Why? *In the island of Galapagos: Perfectionism? (Lamarck) -Long-necked tortoise turtle lived in the Catastrophism? (Cuvier) dry areas Survival? (Darwin) -Short-necked turtles lived in areas with -Darwin presented evidence that support abundant vegetation Survival and adaptation:  I-Evolution B-Darwin’s Theory of Evolution - Natural Selection -Upon these observations, Darwin proposed Natural Selection as the driving force behind evolution. -Natural Selection is based on the following: *Organisms compete for available resources: >>Individuals with better traits have easy access to food resources. Unfavorable traits (handicap) result in elimination. >>Competing also restricts the population to naturally manageable levels (e.g. without natural selection, a paired elephant would result in 19 million descendants 750 years later, a very unmanageable population size.)  I-Evolution B-Darwin’s Theory of Evolution - Natural Selection -Upon these observations, Darwin proposed Natural Selection as the driving force behind evolution. -Natural Selection is based on the following: *Reproduction: Individuals within a population differ in terms of their reproduction success, also called Fitness. >>Individuals with favorable traits have access to more resources and can devote more energy and time to reproduction. >>Animals with unfavorable would spend time looking for food, have no time to reproduce.  I-Evolution B-Darwin’s Theory of Evolution - Natural Selection -Upon these observations, Darwin proposed Natural Selection as the driving force behind evolution. -Natural Selection is based on the following: Penguins *Organisms become adapted to harsh conditions as the environment changes. Examples: >>Penguins >>Venus-Flytrap: this plant lives in Nitrogen poor soils, it needs to trap insects and use them as a source of Nitrogen Venus Flytrap (adaptation to Nitrogen-poor soil)  I-Evolution B-Darwin’s Theory of Evolution Natural vs. Unnatural Selection/Artificial Selection -Unnatural Selection: *Selection at work also called Artificial Selection. E.g.: Dogs are the result of man- made artificial selection. *Interference with nature. *Today, existence of many breeds of domesticated dogs, all descended from the animal wolf.  I-Evolution - B-Darwin’s Theory of Evolution Unnatural Selection/Artificial Selection Kale -Artificial selection *Done by man to produce better animals, plants and fruits.  I-Evolution - C-Evidence of Evolution - Fossil Evidence Examples of Fossils of Eukaryotes -Fossils: remains and traces of past life. -This includes: trails, footprints, burrows, holes Dinosaur (land) Trilobite (sea) in the underground, bones, teeth, worm casts, preserved droppings, shells, etc.. -When animals die, most of the time, soft parts decompose (they sometimes can be preserved, mummification, amber); but the Early Bird (air, land) Fish (sea) hard parts may persist (made of calcium) Plant (land) Ammonite (sea)  I-Evolution - C-Evidence of Evolution - Fossil Evidence Trails Footprints Burrows Amber Teeth Bones: Lucy Worm cast Preserved Shells dropping  I-Evolution - C-Evidence of Evolution Fossil Evidence -Transitional Fossils: *Transitional fossils represent the intermediate evolutionary forms of life in transition from one type to another. *Transition is gradual and may last years. *Transitional fossils allow tracing the evolution of organisms over long periods of times. *Example: Archaeopteryx Dinosaurs to > Archaeopteryx > to Birds *Archaeopteryx has reptile and bird features, may therefore be the Transitional Fossil or Link between Dinos and Birds.  I-Evolution C-Evidence of Evolution - Fossil Evidence Transitional Fossils: From Fish to Tetrapod  I-Evolution C-Evidence of Evolution Fossil Evidence Lucy AMNH (Fossil of Human ancestor) Our Ancestors  I-Evolution C-Evidence of Evolution Bio Geographical evidence Pangea: in early Earth, Hundreds of Millions years ago, Continents were joined.  I-Evolution - C-Evidence of Evolution - Anatomical evidence -Anatomical evidence is supported by homologous structures and suggests a common ancestor. Examples: Bones in animals are homologous. -Analogous structures serve the same function, but originated independently in different groups of organisms that do not share an immediate common ancestor. E.g.: the wings of insects and birds are analogous structures. Bird Wings common to birds and insects, but they are simply Analogous structures Insect Homologous Structures  I-Evolution - C-Evidence of Evolution - Anatomical evidence -Also developmental similarities suggest a common ancestor. Book  I-Evolution - C-Evidence of Evolution - Biochemical evidence All living organisms use the same basic atoms, molecules, amino acids, DNA, RNA, proteins, ATP, polysaccharides (sugars). It can be concluded that these molecules were present in the first living cell from which life, as we know it, originated. Kit gene  II-The Origin of Life -Darwin’s evolution theory by natural selection suggests that: all life on earth can be traced to a common ancestor from which life on earth originated. The ancestor is called LUCA: Last Universal Common Ancestor. -Several theories on the origin of life have been proposed:  II-The Origin of Life – Spontaneous Generation Theory -Origin of microorganisms? Recall that Microorganisms = life. Flies arise from Manure -Until mid 1800, several scientists and philosophers believed that life could arise spontaneously from non-living matter. -This belief is referred to as the hypothesis of Spontaneous Generation. (SG) According to this belief: Mice arise from cloth + food *flies from manure; *maggot larvae from decaying corpses. Maggots arise from decaying corpses  II-The Origin of life Lightning/Electrical Energy Materialistic Theory Radiation UV Light Methane Nitrogen Ammonia A. Oparin John Haldane Carbon Dioxide B. 1894-1980 1892-1964 Early Earth’s Atmosphere In the 1920ies, Oparin and Haldane Simple Organic molecules: proposed that life originated from the -Simple Sugars evolution of inorganic compounds (gases -Amino-acids in the atmosphere) into organic -Nucleotides monomers, under bombardment with cosmic radiation, UV light from the sun More Energy: Polymerization and electrical energy from thunderstorms and lightning. Biomolecules: -Carbohydrates -Proteins -Their theory is called Materialistic or -Nucleic acids Primordial Soup hypothesis. -Lipids  Materialistic Theory Origin of life by Chemical Evolution followed by Biological Evolution Stage 4. Once the protocell contained DNA genes, a true cell had evolved. The first genes may have been RNA molecules, but later DNA became the information storage molecule of heredity. Biological evolution—and the history of life—had begun and LUCA is born. Biological Evolution Stage 3. The aggregation of polymers inside a plasma membrane produced a protocell, which had enzymatic properties such that it could grow. Protocells developed in ocean or at hydrothermal vents. Biological Evolution Stage 2. These monomers joined together to form polymers along the shoreline (warm seaside rocks or clay) or at the vents. The first polymers could have been proteins or RNA, or they could have evolved together. Chemical Evolution Stage 1. An abiotic synthesis process created small organic molecules such as amino acids and nucleotides, perhaps in the atmosphere or at hydrothermal vents. Chemical Evolution  II-The Origin of life - Materialistic Theory Chemical Evolution followed by Biological Evolution  II-The Origin of life - Panspermia Theory -Panspermia Theory suggests that life exists throughout the universe, and is distributed by meteoroids, asteroids and planetoids.  III-History of life and the Geological Timescale -Geologists devised a Geologic Timescale, which divides the history of the earth into eras, periods and epochs. -Biologists traditionally begin the Geological Timescale at the Precambrian time since it was the era when life began on earth. During this long period of time (87% of Geological Timescale), life arose and the first cells came into existence. -Man as we know him today started to live in the Holocene epoch. 87% of Geological Timescale  III-History of life and the Geological Timescale Cellular History -Life started with Prokaryotic cells (ancestors of bacteria, archaea.) -Prokaryotic Fossils exist that support this finding: Stromatolite, Primaevifilum3.46 BYA  III-History of life and the Geological Timescale Cellular History -The Eukaryotic cells arose after the prokaryotic cell, first unicellular, then pluricellular. -Prokaryotic Cell: *No envelope around the DNA -The cells obtain energy from metabolism in the *Unicellular (made of 1 cell) presence of oxygen. Example: Bacteria, Archea -It is believed that early eukaryotic cells engulfed (ingested) bacteria, which then became the -Eukaryotic Cell organelles known as mitochondria in animal cells *Envelope around the DNA and chloroplasts in plants. -Mitochondria and Chloroplasts carry out important energy functions. *Unicellular *Pluricellular Examples: (Multicellular) -Bacteria (made of many cells -Archea Examples: -Protists -Animals -Fungi-Yeast -Plants -Fungi-Mold In Eukaryotes, Unicellular cells assemble and generate Pluricellular organisms.  III-History of life and the Geological Timescale Cellular History - Endosymbiotic Theory -Evidence exists that supports this theory called Endosymbiotic Theory: (notice also that in addition to chloroplasts, plant cells have mitochondria.) *Bacteria, mitochondria and chloroplasts have same size. *Mitochondria and chloroplasts have their own DNA and make some of their own proteins. (Humans inherit mitochondria and mitochondrial DNA only from the mother.) *Mitochondria and chloroplasts divide by binary fission, similar to bacteria. *Mitochondrial have 2 membranes: outer (exterior) and inner (interior) membranes. Mitochondria’s outer memb is similar to eukaryotic membrane. Inner membrane is similar to bacterial membrane. -Later in evolution, unicellular cells assemble and generate multicellular organisms. Review for Lecture 2: Evolution – Tree of Life -Understand the meaning of the following words: fixity, evolution, perfectionism, natural selection, catastrophism, survival, adaptation, fossils, homologous and analogous structures, tree of life, LUCA, geological timescale and Holocene (epoch associated with man) -Theory of evolution, natural selection, unnatural selection, variation -Fossils are the language by which history of life is written on earth. -Fossil evidence: anatomical, developmental, biochemical, bio-geographical, -Homologous vs. analogous structures -Origin of life: understand the basis of Spontaneous generation, Materialistic Theory, Panspermia theory -Evolution = Chemical evolution + biological evolution -Eukaryote vs. prokaryote (difference). Unicellular vs. pluricellular. Which forms of life are unicellular, pluricellular