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Lesson 1: Early Study of Evolution, Lesson 2: Natural Selection, Lesson 4:…
Lesson 1: Early Study of Evolution
Curiosity about how life changes
A variation is any difference between individuals of the same species. Charles Darwin worked to develop a theory of
evolution
, the procces by wich organism have descended from ancient oraganism
Linnaeus´ System of Classification
(1707-1778) He developed the first scientific system of classifying and naming living things.he collected samples of organism from around the world.
Lamarck´s Idea
A french Sceintist, Jean-Baptiste Lamarck (1744-1829), was put in charge of a museum department of insects and worms. Lamarck devoted himself to learning everything he could about invertebrates. After much study, Lamarck developed the first attempt at a scientist theory of evolution.
Lamarck´s Theory of transformation
He believed that organism could change during their lifetime by selectivley using or not using various parts of their bodies.
For exmaple
: Moles could develop long, strong claws by digging through dirt.
Lamarck hypothesized that if two adult moles with long claws mated, their offspring would inherit those claws.
Charles Lyell´s Rocks
Not long after lamarck proposed his ideas, a young lawyer named Charles lyell (1797-1875) began studyng naturally formed layers of rocks and fossils.
He also stated that the processes that created land features in te past were still active.
Mary Anning´s Fossils
Mary Anning (1799–1847) lived a much different life than Linnaeus, Lamarck, or Lyell.
Mary Anning would roam up and down the beach while searching for fossils in the steep cliffs along the English Channel.
Anning taught herself how to reconstruct the bodies of fossilized animals. Many of these animals had never before been seen.
Darwin´s Journey
In 1831, 22-year-old Charles Darwin set out on a five-year trip around the world aboard a British navy ship, the HMS Beagle. Darwin was a naturalist—a person who observes and studies the natural world.
Galapagos Organism
The Beagle sailed to many different locations, as shown in Figure 6, and made several stops along the coast of South America. From what is now Ecuador on the Pacific coast, the ship traveled west to the Galápagos Islands.
Lesson 2: Natural Selection
Evolution by Natural Selection
Living in a small body of water can be dangerous for fish.
If water conditions become unhealthy, there is nowhere for the fish to go.
Too little rain, too many fish, and an overgrowth of algae can work together to reduce oxygen levels in water.
Darwin´s Search for a Mechanism
After his return to England, Darwin was not satisfied with his theory of evolution. He struggled to determine evolution’s mechanism.
A mechanism is the natural process by which something takes place.
Artificial selection
Darwin studied farm and pet animals produced by artificial selection. In artificial selection, only individuals with a desired trait, such as color, are bred by humans in the hope that the next generation will inherit the desired trait.
Darwin thought that a process similar to artificial selection might happen in nature. But he wondered what natural process performed the selection.
Natural Selection
Darwin understood how evolution could work when he read an essay by Thomas Malthus. Malthus noted that both animals and humans can produce many offspring.
The Origin of species
Darwin waited a long time to publish his ideas. He thought they might be too revolutionary for the public to accept. Then, in 1858, Alfred Russel Wallace sent Darwin a letter.
Then, in 1858, Alfred Russel Wallace sent Darwin a letter.
The next year, Darwin published his theory in The Origin of Species. In his book, Darwin proposed that evolution occurs by means of natural selection, a process by which individuals that are better adapted to their environment are more likely to survive and reproduce than other members of the same species.
How natural selection Works
Darwin identified three factors that affect the process of natural selection:
Overproduction
Variation
Competition
First, there must be overproduction, shown in Figure 3 below. Darwin knew that most species produce more offspring than can possibly survive
Secondly, there must be variation. Members of a population differ from one another in many of their traits.
Selection
Darwin observed that some variations make individuals better adapted to their environment. Those individuals were more likely to survive and reproduce, and their offspring would inherit the helpful characteristic.
Genes and natural selection
Darwin did a brilliant job of explaining natural selection, but he was never able to figure out where variations come from. He also did not understand how traits were passed from parents to offspring.
Mutuation
Sexual reproduction causes existing gene variations to be recombined in each member of a population. To get a new variation, there must be a gene mutation. A mutation is any change to the genetic material. Figure 7 shows a flower with an obvious mutation.
Epigenetic Changes
Epigenetics
is the study of small changes to DNA that turn genes on or off but do not change the genetic code itself. All the cells in your body have identical DNA, but functions vary greatly.
Lesson 4: Evidence in the fossil Record
How Fossils Form
Most fossils form when living things die and sediment buries them.
Sediment is the small, solid pieces of material that come from rocks or the remains of organisms and settle to the bottom of a body of water.
Fossils can form from any kind of living thing, from bacteria to dinosaurs.
Body fossils preserve the shape and structure of an organism. We can learn about what a plant or animal looked like from a body fossil. Body fossils of trees are called petrified wood.
Trace Fossils
We can learn what an animal did from trace fossils. Footprints, nests, and animal droppings preserved in stone are all trace fossils
Early Earth
When Earth first formed, more than 4.5 billion years ago, it was extremely hot. Earth was likely mostly melted. As Earth cooled, solid rocks became stable at Earth’s surface
The oldest known fossils are from rocks that formed about a billion years after Earth formed.
Scientists think that all other forms of life on Earth arose from these simple organisms.
Fossils and evolution through time
The fossil record provides evidence that life on Earth has evolved. Rock forms in layers, with newer layers on top of older layers. When we dig deeper, we see older rocks with fossils from earlier time periods.
The oldest rocks contain fossils of only very simple organisms. Younger rocks include fossils of both simple organisms and also more complex organisms.
Embryological Development
An embryo is a young organism that develops from a fertilized egg (called a zygote). The growing embryo may develop inside or outside the parent’s body. The early development of different organisms in an embryo shows some striking similarities.
Beginning of end of species
Gradual Change
The time scale of the fossil record involves thousands or millions of years. There is plenty of time for gradual changes to produce new species. The fossil record contains many examples of species that are halfway between two others.
Rapid Change
Rapid evolution can follow a major change in environmental conditions. A cooling climate, for example, can put a lot of stress on a population.
Extinction
A species is extinct if it no longer exists and will never again live on Earth. A rapid environmental change is more likely to cause a species to become extinct than to bring about a new species.
lesson 5: Other evidence of Evolution
Genetic Material and evolution
The diverse shapes, body structures, and lifestyles are all due to differences in genetic material, the set of chemical instructions that guide the function and growth of an organism.
Genetic Evidence for a Common Ancestor
Every living thing uses DNA for genetic material. Mosquitoes, humans, plants, and bacteria all have cells with the same system of genetic material. The shared use of DNA is one piece of evidence that every organism on Earth has a common ancestor
Dawn of Evolution
DNA is a complex molecule, difficult to copy without making any mistakes. LUCA started to change as it accumulated mutations, or changes to its DNA. Natural selection and other processes shaped LUCA’s evolution.
Proteins
Recall that genes code for different proteins, which are complicated molecules that carry out important cellular functions.
Proteins And Evolution
The new version of the protein may increase the individual’s fitness. More likely, the mutation will lower the individual’s fitness or leave it unchanged. Changes in proteins lead to variations within a population. Natural selection acts on those variations, causing evolution.
Proteins, analyse, and evolution
Scientists compare proteins to see how closely any two species are related. In most cases, evidence from DNA and protein structure confirms conclusions based on fossils, embryos, and body structure.
Gene Transfer between species
The transfer of genes can happen when one cell engulfs another or when bacteria share their DNA with other cells.
Being immune to antibiotics could provide a big boost for the bacterium in fitness for the bacterium. DNA analysis shows scientists which genes have passed from one species to another.
Symbiosis
Two organisms of different species that have a close relationship that involves living with each other is called symbiosis.
Just as a bacterium cell contains its own DNA and ribosomes, so do mitochondria and chloroplasts.
Lesson 3: The Process of Evolution
The Process of evolution
Charles Darwin’s theory of natural selection is straightforward. Any population of living things has inherited variations. In addition, the population produces more young than can survive.
According to natural selection, only the individuals that are well-adapted to their environments will survive and reproduce. An organism’s fitness describes how well it can survive and reproduce in its environment.
Betond Natural Selection
How could natural selection result in traits that hurt the male duck’s chance of survival? Answer: There is more to evolution than “survival of the fittest.”
Mutuation
Mutations can create multiple alleles, or forms of a gene. Different alleles cause variations in traits such as eye color, ear shape, and blood type.
How mutuation Happen?
Mutations are created in two ways. First, a dividing cell can make an error while copying its DNA (see Figure 2). There are approximately six billion units in one copy of human DNA
Secondly, mutations also occur when an organism is exposed to environmental factors such as radiation or certain chemicals that damage the cell’s DNA.
Effects of mutuation
Secondly, mutations also occur when an organism is exposed to environmental factors such as radiation or certain chemicals that damage the cell’s DNA.
Need for Mutuation
Mutations create all the variations among members of a species and account for the diversity of organisms on Earth.
Gene Flow
Mutations are not the only source of new alleles in a population. Alleles also enter a population through gene flow. As you know, a gene is a unit of genetic material that acts as instructions for a specific protein or function.
