Diversity and Evolution SC.912.L.151SC.912.L.15.10 SC.912.N.1.3 SC.912.N.2.1SC.912.L.15.8
Origins of Life on Earth
Original Conditions on Primitive Earth to make life….• Presence of liquid water• Moderate temperature range• Free oxygen in the atmosphere• Adequate sunlight• Absence of toxic substances in atmosphere• Absence of lethal radiation
Volcanoes Play a BIG Role• Water vapor (eventually condensed and fell as RAIN)• Methane• Hydrogen• Nitrogen• Ammonia• Carbon Dioxide (we now have oxygen b/c of photosynthetic bacteria)• Carbon Monoxide
Earth History• Evolution is studied using concepts about earth history. The earth is between 4.3 and 4.5 billion years old.• Approximately 3.9 billion years ago, the surface was likely cool enough for water vapor to condense and form oceans• Geological evidence suggests that cells similar to modern bacteria were common 3.8 billion years ago.
How did life on Earth begin? Until the 1700’s people believed that living things could come from nonliving substances, spontaneous generation.
Spontaneous generation: Pasteur’sexperiment• Experiment: Pasteur filled a flask with broth with a long S shaped neck. He boiled it to kill all life. It was open and exposed to air, but anything in the air got stuck on the curves of the neck.• Conclusion: Spontaneous generation was disproved and biogenesis theory was substantiated. Contamination came from other microorganisms, not ―air‖.QUESTIONS• What was the hypothesis? What was the experimental group? The control group? The constants? The variable?
Theory of Chemical Evolution “Primordial Soup Theory”• Conditions on the early Earth were very different.• The atmosphere had no oxygen• Energy sources, such as lightning, volcanic activity, and ultraviolet sunlight (no ozone layer)
Chemical Evolution• Earth’s early atmosphere: HCN, CO2, CO, N, H, S, H2O• “Life arose from the oceans”• He believed that energy from lightning and the sun can spark chemical reactions to create AMINO ACIDS that made proteins.
Chemical Evolution Urey and Miller• created in the laboratory, th e conditions of early Earth.• They discharged sparks in an “atmosphere” of the Miller- Urey model consisted of H2O, H2, CH4, and NH3 gases.• produced a variety of
Chemical Evolution • Alternate sites proposed for the synthesis of organic molecules include • submerged volcanoes and deep-sea vents where hot water and minerals gush into the deep ocean.
Prokaryotes• Prokaryotes were the earliest organisms on Earth and evolved alone for 1.5 billion years.• two prokaryotic domains:Bacteria and Archaea
Prokaryotes„ have a cell wall external to the cell membrane• Lack membrane bound nuclues and organelles• Double-stranded DNA molecule is in a single ring shaped
OXYGEN The evidence of oxygen gas• ATMOSPHERE Remember the atmosphere of formation can be seen in rocks when layers of iron oxide on the early Earth was made up of bottoms of oceans stopped nitrogen, carbon forming when oxygen appeared. dioxide, water vapor, but no free oxygen• Oxygen comes from photosynthesis when leaving oxygen gas.• About 2 billion years ago, the Cyanobacteria created the oxygen level in the oxygen in the atmosphere. atmosphere started to rise.• Aerobic metabolism, much more efficient than anaerobic, became possible. Question
Evolution• Process by which species of organisms change over time• Thing evolve around us all the time• Based on scientific evidence such as… – Fossils – Comparative morphology/anatomy of organisms – Embryology – Analysis of genetic material (DNA analysis…DNA fingerprinting!)
Terms to Know• Species – a group of organisms that share similar characteristics and can interbreed to produce fertile offspring – As species EVOLVE, they produce new traits and lose other traits….• Adaptation – Any physical or behavioral trait that improves an organisms chance for
Fossil Evidence• Fossils: Evolution for – Remains or evidence of organisms that have lived in the past – Provided clues of when different species lived• Law of Superposition – States that in undisturbed sedimentary rock, older rock layers lie beneath younger rock layers – By Identifying the fossils indifferent layers of rock and applying the law of
Biogeography• Study of the distribution of Earth’s organisms• Continental Drift Hypothesis – States that the continents were once joined in a single, large landmass called PANGAEA – Pangaea broke up over millions of years and continents ended up where they are today
ComparativeAnatomy/Morpholog y• Do other organisms have arms like us?• Many species share similar structures..• Do flamingos and blue jays have feathers? – Yes…the presence of feathers suggest that both groups of birds descended from an animal with feathers – Flamingos and blue jays
Homologous Structures• Body parts of different organisms that have similar structure but NOT similar FUNCTION• Homologous structures DO indicate shared ancestor
Analogous Structures• Body parts that have a SIMIALR FUNCTION but NOT similar structure• Body parts with Different structure, same function• Do NOT indicate shared ancestry• An analogous structure found in two different species
Homologous vs. Analogous Structures• Homologous= Same structure, DIFFERENT Function• Analogous= Different Structure, SAME Function
Comparative Anatomy Anatomical features that are similar in structure are called homologous structures, and they indicate common ancestry.
Vestigial Structures• Structures that do not seem to play a role in the body functions of the organism – Appendix • Rats digestion • Humans no use…appendix is a vestigial structure • It can be concluded that the common ancestor of the human and rat had an appendix
Embryology• Study of embryos• Embryo early stage in the development of an organism• Scientists compare the development of the embryos of different species• Similarities in development =shared ancestor• More traits in common=more closely relatedModern Organisms EVOLVED from COMMON
Chemical Evidence of Evolution• Chemicals found in living things also provide clues to ancestry..what chemical? – DNA!!!• Comparisons of the sequences of the nucleotides in DNA and the amino acids in certain proteins can also be used to show more common ancestry• More similarities in two
ALL organisms have DNA made up of thesame Amino Acids…The only thing that’s different is theARRANGEMENT/sequence of aminoacids…The More similar AA sequences= themore closely related the organisms are!
Similarities in Molecular Biology Common amino acid sequences suggest an evolutionary relationships between various species of organisms.
Observed Evolutionary• Speciation Change – Evolution of a new species from an existing species• Occurs when a population is separated into groups that cannot reach each other to interbreed• Once groups are separated, environmental conditions in each area influence which traits are helpful or harmful to members of each population – Less helpful traits disappear – Helpful traits become more popular• Overtime, these changes can produce 2 distinct species that can no longer interbreed
Two Ways Evolution is believed to have• Gradualism Occurred – Evolution occurring over a long period of time – Slow and constant change – Small difference between generations – This is how Darwin believed NATURAL SELECTION worked• Punctuated Equilibrium – Evolution occurs in spurts – Changes occur rapidly followed by long period without change – Causes:
Microevolution• When evolution occurs quickly enough for scientists to observe• Bacteria – Reproduce rapidly – Trait for Resistance to antibiotics is passed down to offspring – This is how bacteria become resistant to certain medicines…NOT GOOD
Convergent evolution • organisms that descended from different ancestors • Evolve similar anatomies and/ or behaviors if they live in similar environments
• Organisms Divergent from the same Evolution ancestor have developed different anatomies/be haviors (and eventually form new species)• Environment influences their new
Darwin’s Theory of Evolution by Natural Selection
Ideas that shaped Darwin– Before Darwin people believed Earth was less than 10,000 years old and also relatively unchanged • Buffon- Studied the fossil record which showed that the Earth might be much older.(4.3 and 4.5 billion years old) • Hutton - Layers of rock are moved by forces beneath Earth’s surface. Most geological processes operate extremely slowly. • Lyell - geologic process that shaped the Earth in the past still continue today.
Ideas that shaped Darwin Before Darwin people believed that species were fixed, plants and animals had always been the way they are today Cuvier – based fossils from different rock layers gave evidence that organisms from the past differed greatly from living species,
Ideas that shaped Darwin• Lamarch’s Use or disuse 1st to suggest that species change evolve or evolve over time. But his explanation was flawed. He thought characteristics acquired through your life could be passed down from parent to offspring.
• Malthus – suggested that if the human population continued to grow unchecked, eventually there wouldn’t be enough food and living space for everyone.
• As Malthus predicted, worl d population growth is exponential:• 1 billion in 1830• 2 billion in 1930• 3 billion in 1960• 4 billion in 1974• 5 billion in 1987• 6 billion in 1999• 7 billion in 2013
Voyage of the Beagle• Darwin made a voyage around the word collecting thousands of plant and animal specimens.• His observations and collected evidence led him to propose hypothesis that living things change over time• Theory of Evolution through natural selection.
Voyage of the Beagle• Darwin noticed that plants and animals on the Galapagos islands of the coast of Ecuador were different from those on the mainland and also from island to island• .
Neck-size vs. Vegetation height
Darwin’s Theory• In 1859, Darwin published a book titled,• “On the Origin of Species”• In this book he presented all the evidence he had gathered over the past several years supporting his theory that evolution has been taking place for millions of years—and continues in all living things.• In his book he also proposed a mechanism for evolution called• Natural Selection
Summary of Evolution• DNA is the blue-print for building ALL living things on planet Earth.• DNA sequences are changed by: • random mutations • Radiation • Viruses • Chemicals • sexual reproduction • Migration • geological events• As a result there is variation within populations of a species.• Those individuals of a particular species with a phenotype (as a result of their genotype) that is more fit to survive in a given environment has a better chance to reproduce.
NATURAL SELECTION The ability of an organism to survive and reproduce in its specific environment is called fitness.• Individuals with characteristics that are not well suited to their environment either die or leave few offspring• Individuals that are better suited to their environment survive and reproduce most successfully.• Darwin called this process Survival of the Fittest, or Natural Selection.
4 Principles of Natural Selection• Variation• Competition• Excess offspring• Survival of the Fittest
4 Main Principles of Natural 1. Selection Variation exists within a population 2. Organisms compete for limited resources 3. Organisms produce more offspring than can actually survive
• Three species of lizard.• B- The ones at the bottom live in the shrubland, and are colored to blend in. •The top pictures show the same species of lizard, but the variety that lives in the White Sands •They all evolved to become white (camouflage) •The DNA on the bottom shows the location of the mutation that gives the white color
1. Inherited VariationIndividual organisms within the population differ. Most of thisvariation is determined by genetic inheritance (recombination), butsometimes it is the result of genetic mutations.
2. Struggle for ExistenceBecause so many offspring are produced, many will die due to alack of resources, predation, disease, or other unfavorableconditions.
3. Overproduction of OffspringOrganisms produce more offspring than can survive.Many of the offspring do not survive to reproductive age.
4. Differential ReproductionIndividuals best suited to their environment survive and reproducemost successfully. Therefore these organisms pass theiradvantageous traits to their offspring while offspring withdisadvantageous traits die or produce fewer offspring.
Descent with Modification• Natural selection causes species to change over time.• Species alive today descended with modification from ancestral species.
Evolution of populations• Genetic Drift• Sometime changes in the allele frequency within a population occur by chance. This is called genetic drift. Before After• The genes of the next generation will be the genes of the “lucky” individuals, not necessarily the
Gene Flow• the process of genes moving from one population to another. and emigration of organisms. For example: The immigration The dispersal of seeds or spores.