Diversity in Life - Chapter 25 - PDF

Quiz 3 Diversity in Life Chapter 25  Origins of the earth & how it has changed How did life begin? How did life change on earth and why? Lecture Outline 25.1 Deep Time 25.2 Origins of Life 25.3 Evidence for...

Quiz 3 Diversity in Life Chapter 25  Origins of the earth & how it has changed How did life begin? How did life change on earth and why? Lecture Outline 25.1 Deep Time 25.2 Origins of Life 25.3 Evidence for Early Life 25.4 Earth’s Changing System 25.5 Ever-Changing Life on Earth Jeff Hunter/The Image Bank/Getty Images 4 The Hadean Earth Meteor hit the earth 4.6 billion years ago (BYA) forming the earth we know today > Hadean Earth Hadean Earth heavy asteroid activity Very unstable, moon formation, temperature variable and extreme ; no life 6 Archean Eon 4-2.5 bya Asteroid activity declined Continents appear Emergence of life Atmosphere These wavelike mounds of 3.7-billion-year-old sediment are called stromatolites (marked by dashed lines). This rock may house the oldest known fossilized evidence of life on Earth. A. NUTMAN, A.C. ALLWOOD/NATURE 2016 Proterozoic Eon Super continents appear Atmosphere change Eukaryotes and multicellular life appear Fossils of early eukaryotes. Porter, 2020. Figure 25.1 9  Eukaryotes began to evolve; organelles started to differentiate 1500 MYA Life Begins 3500 MYA Biointeractive Time – 5-10 minutes https://www.biointeractive.org/classroom-resources/deep-history -life-earth click on “Start Interactive” Explore the geological history of the earth by clicking on different boxes Use the arrows in the upper right corner to move down the timeline Major Changes of early earth 1. Temperature 2. Atmosphere 3. Continents 4. Life 1. Temperature Changes on Early Earth The atmosphere of the early earth was thought to be very different from the atmosphere currently Adapted from CenCO2PIP, Science 2023 Co2 ppm MYA 15 Weather Changed Earth’s Temperature Weathering = conversion of silicate rock to soil Conditions are hot and wet > weathering occurs more rapidly CO2 + H2O > H2CO3 ( carbonic acid i.e., acid rain) Carbonic acid interacts with rock > bicarbonate ions and Ca+2 ions are released Bicarbonate and Ca+2 moved into water ways to form calcium carbonate (CaCO3), Carbon was sequestered in the ocean, lowering CO2 levels in the atmosphere Cooling affect on the earth 16 17 Plants Changed Earth’s Temperature First photosynthetic organisms ~ 3.5-4 bya Plants emerged ~ 700 mya Removal of CO2 from the atmosphere Resulted in a cooling which led to an abrupt glaciation Vascular plants diversification concurrent with second glaciation 400 to 360 mya. Plants contributed to glacial events (snowball earth) 18 Atmospheric O2 levels over time What’s going on here? Snowball Earth Hypothesis First occurred about 2.2 BYA Second and third < 1BYA Each period lasted thousands of years Thawing likely due to volcanic activity > CO2 in atmosphere 21 2. Atmospheric Changes on Early Earth Geological changes explain many changes in atmosphere Extreme heat and rain accelerated weathering and led to carbon sequestration into the ocean (overall decline in atmospheric CO2 This reduced temperature and stabilized CO2 in the atmosphere Rise of plants and weather suggested causes of global glacial event 22 Early Earth Atmosphere Greenhouse gases in the Cretaceous period increased global temperatures led to increase in sea level resulting in large continental areas being submerged (glacial melt) reproductive isolation Ice ages then caused large sheets of ice to form allowed populations to migrate facilitating evolution > Gene flow 23 3. Continents Changed in early earth Earth’s crust formed rigid slabs of rock called plates These exist under oceans and continents Move frequently Over the eons, movement of the plates has changed the very face of the earth 24 https://www.youtube.com/watch?v=KfYn9KVya-Q&embeds_euri=https%3A%2F%2Fhubblecontent.osi.office.net %2F&feature=emb_logo&ab_channel=PBSEons Supercontinents 1. Columbia ~ 1800 Ma 2. Rodinia ~ 1100 Ma 3. Gondwana ~ 500 Ma 4. Pangea ~ 250 Ma BioInteractive: Earth Viewer ~ 5 min Navigate to the website https://www.biointeractive.org/classroom-resources/earthviewer Click “Start Interactive” On the left side of the screen are located different earth time periods Toggle between them to see what the earth looked like in each period Click the tabs along the bottom of the screen to see more interesting facts about earth’s past Charts View In Depth Lecture Outline 25.1 Deep Time 25.2 Origins of Life 25.3 Evidence for Early Life 25.4 Earth’s Changing System 25.5 Ever-Changing Life on Earth Jeff Hunter/The Image Bank/Getty Images 30 4. Life in early earth Life appeared in the Archean Eon Two billion years after earth formed, life emerged Life forms became more complex during the Proterozoic Eon Rodinia supercontinent Life consisted of simple forms, largely prokaryotes The Cambrian explosion occurred about 500 MYA (~3,000 MY after the first signs of life) Marked by extreme diversification of multicellular organisms 31 Early organic molecules For life to exist, organic (carbon-based) molecules must be present Scientists do not know how the first organic molecules formed Theory 1: As meteorites and comets slammed into early earth, some may have carried organic materials Tagish Lake Meteorite found in British Columbia in 2000 was found to have organic matter, like glycine Panspermia theory Does not ultimately address the issue of “how did organic molecules form” 33 Early organic molecules For life to exist, organic (carbon-based) molecules must be present Scientists do not know how the first organic molecules formed Theory 2: Organic molecules must have originated on earth 34 Early Earth’s atmosphere Was the early atmosphere conducive to organic molecule creation? Popular view of early atmosphere Carbon dioxide (CO2) Nitrogen gas (N2) Water vapor (H2O) Hydrogen gas (H2) Other sulfur, nitrogen, and carbon compounds Notice what is not present in the suggested early atmosphere 35  Harold Urey Miller-Urey Experiment 1953 - Stanley Miller and Harold Urey did an experiment that replicated the early atmosphere in hopes of obtaining spontaneously appearing organic molecules 1. Assembled reducing atmosphere rich in Stanley Miller hydrogen with no oxygen gas 2. Atmosphere placed over liquid water 3. Temperature below 100° C 4. Simulate lightning with sparks 36 37 Miller-Urey Experiment Results Within one week, methane gas (CH4) had been converted into other simple carbon compounds Compounds combined to form simple molecules and then more complex molecules The result of later experiments resulted in the production of more than 30 carbon compounds including amino acids Conclusion: that organic molecules could have spontaneously formed from inorganic sources on the early Earth This experiment DID NOT prove that life originated this way 38 New Experiments “detected all of the RNA canonical nucleobases—uracil, cytosine, adenine and guanine—together with urea and the simplest amino acid, glycine… “ Findings support the idea that the early earth atmosphere could have been used as a starting environment “not only for the formation of amino acids, but also of RNA nucleobases.” Martin Ferus et al. 2017 Conclusion: that organic molecules could have spontaneously formed from inorganic sources on the early Earth Lecture Outline 25.1 Deep Time 25.2 Origins of Life 25.3 Evidence for Early Life 25.4 Earth’s Changing System 25.5 Ever-Changing Life on Earth Jeff Hunter/The Image Bank/Getty Images 40 Changes in Early Metabolism Primitive organisms may have been autotrophic or heterotrophic The first life likely to be a single-celled organism (prokaryote) Eukaryotes evolved later as simple organelles and nucleus began to form Landmarks in the evolution of metabolism Oxygenic photosynthesis Carbon fixation Nitrogen fixation 41 Early Metabolism Major metabolic landmarks 1. Nitrogen fixation – genetic analysis reveals that biological nitrogen fixation appeared first in archaea ~ 2 BYA Significant because now organisms can convert inorganic nitrogen to useable forms 42 43 Early Metabolism Major metabolic landmarks 1. Nitrogen fixation – genetic analysis reveals that biological nitrogen fixation appeared first in archaea ~ 2 BYA Significant because now organisms can convert inorganic nitrogen to useable forms 2. Oxygenic photosynthesis – large pulses of oxygen into the atmosphere during late Archaean and late Proterozoic suggest photosynthesis appeared in the late Archaean It is also thought that the increase in available oxygen led to the Cambrian Explosion 44 Early Genetic Material Living organisms must pass on hereditary information to future generations RNA is thought to have been the first genetic material However, because DNA is more stable, it eventually became the primary genetic information Why might the use of RNA have been beneficial to the diversity of life? Fossil evidence for early life Oldest rock formations 3.5-3.8 billion years old Early life emerged during the Archean Earliest microfossils (3.5 bya) microfossils represent the oldest living life forms (bacteria, archaea) Supported by isotopic data (although controversial) 46  Fossil evidence for early life Stromatolites appeared about 2.7 BYA Stromatolites ancient biofilm (mats of cyanobacterial cells) became trapped within mineral deposits and fossilized This is indirect evidence for life Analyzed carbon isotopes in organic biomarkers to age stromatolite fossils However, the use of C-12 dating is controversial due to its short half life Isotopic data Living organisms incorporated C-12 into their cells By analyzing carbon compounds in the oldest rocks, scientists may be able to find evidence for the oldest life as far as 3.8 BYA https://www.youtube.com/watch?v=osA8TX0cwYI&ab_channel= BeverlyBiology 48 Biomarkers Biomarkers, like organic molecules, can be used to look for ancient life Hydrocarbons derived from fatty acid tails of lipids were found in ancient rocks Analyzed for carbon isotope ratios to indicate biological origin. Indicates that cyanobacteria are at least 2.7 billion years old. 49 Lecture Outline 25.1 Deep Time 25.2 Origins of Life 25.3 Evidence for Early Life 25.4 Earth’s Changing System 25.5 Ever-Changing Life on Earth Jeff Hunter/The Image Bank/Getty Images 50 Diversification Life on Earth Eukaryotes Three monophyletic domains 1. Eubacteria (early bacteria) 2. Archaea 3. Eukaryotes 5 supergroups Oldest eukaryotic fossil 1500 MYA 51 Eukaryotes Specialized Bacteria and archaea ruled the Earth for 1 billion years Eukaryotes began to diverge and specialize ~ 1.5 BYA Evolved membrane-bound organelles facilitated compartmentalization within the cell enabled them to preform different metabolic functions in different places within the cell Endomembrane system evolved Considered a major evolutionary advancement 52 Parts of the Endomembrane System Nucleus Nucleus bound by nuclear membrane Not found in bacteria/archaea Important > separation of transcription and translation adds the ability to regulate gene expression much more tightly Golgi Apparatus and ER Facilitate the synthesis and intracellular transport of proteins 53 54 Cellular Generators There are two major organelles in the eukaryotic endomembrane system that generate cellular energy 1. Mitochondria – produce energy (ATP) through oxidative metabolism 2. Chloroplasts – convert light energy into usable forms of chemical energy (byproduct is oxygen and energy) Endosymbiosis theory Mitochondria and chloroplasts were the result of organisms that were engulfed by other organisms Rather than digestion, they were incorporated into the metabolic processes of the cell Mitochondria descendant of Rickettsia (parasites) Chloroplasts are derived from cyanobacteria 56  Photosynthetic prokaryote Chloroplast Mitochondrion Aerobic prokaryote 57 Multicellularity leads to cell specialization Unicellular body plan highly successful Unicellular prokaryotes and eukaryotes constitute about half of the biomass on Earth But a single cell has limits with cell specialization Multicellularity allowed organisms to deal with environment in novel ways through differentiation Multicellularity arose independently in different eukaryotic supergroups Cooperation between several individuals of Dictyostelium discoideum (unicellular amoebae) to forms a colonial organism 59 Multicellularity leads to cell specialization Multicellular characteristic facilitated the development of cell communication and connection 60 Rapid diversification occurred during the Cambrian Period Extremely rapid expansion of life called the Cambrian explosion (542 to 488 MYA). Evolutionary innovations occurred while life was primarily aquatic Established the foundations for tremendous diversity 61 Earth’s Changing System Continental shifts likely affected gene flow and impacted evolution Shifting plates affect evolution by … 1. reproductively isolating populations 2. allowing previously separate populations to interbreed Carboniferous and Permian periods continental collisions created large mountain ranges >> isolated previously interbreeding populations 66 MYA, Australia and Antarctica; Greenland and North America, separated > reproductive isolation 62 Major innovations allowed for the move onto land Plants colonized terrestrial environments after Cambrian radiation Evolution of photosynthesis protected organisms on land increase in oxygen led to increase in ozone, which serves as a UV blanket After plants, animals evolved First animals were likely invertebrates Successful movement from water to land required innovations to prevent desiccation and to obtain water. What would some of these innovations be? 63 Helpful Links https://biologos.org/ https://www.youtube.com/watch?v=12XO8vYqBsA&ab_channel =ThePenguinProf https://www.youtube.com/watch?v=CPcNfQfjjiw&t=142s&ab_ch annel=ProfessorDaveExplains https://biologos.org/articles/human-evolution-genes-genealogies -and-phylogenies https://biologos.org/personal-stories/a-scientists-search-for-an-i ntellectually-strong-faith?mc_cid=6657f5e963&mc_eid=a46fc0ff 79 Extra Resources Six literal Days https://biologos.org/resources/interpreting-genesis-1-11-with-tre mper-longman Age of the Earth https://www.youtube.com/watch?v=615MPR4eUeE&ab_channel =BioLogos