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Evidence for Change We have talked about different evidences for changes in populations over time ➔ Fossil Record ➔ Biogeography ➔ Anatomy ➔ Biochemistry ➔ Artificial Selection https://www.youtube.com/watch?v=P3GagfbA2vo Fossil Record Palaeontology is the study of fossils Fossils are found all over the world giving insight to what the Earth once looked like Fossils are formed when an organism dies and is covered very quickly by sedimentation to protect it from the full decomposition process Fossil Record Palaeontologists spend their time studying these fossils and searching for connections between them With the use of carbon dating and radiometric dating, scientists are able to see how old these fossils are Biogeography This evidence can be linked to the fossil record as well Scientists believe that the continents on Earth were once one big super-continent called Pangea There are many fossils being found today that are found in multiple continents that are no where near each other Biogeography When looking at organisms in different areas of the world, scientists can see that they may share similarities but also show many unique differences Islands or places that are isolated have species that aren’t found anywhere else which supports the theory that they evolved separately from their ancestors Anatomy This evidence is looking more at what organisms actually look like and what similarities arise Analogous Structures: features that are similar in structure and function but do not have the same origin ex. wings in birds and butterflies Homologous Structures: features with similar structures but different functions ex. limbs in different organisms Biochemistry This evidence goes as deep as you can by looking at the genetics of different organisms Science has come a long way in the field of genetics and especially in mapping out genomes and the genetic code We can take these genetic sequences and begin to see trends between different organisms Biochemistry Scientists believe that the more differences there are in the DNA sequence, the farther our relations go but the closer they are, the more closely related we are Scientists also look at the different amino acids in organisms and the same trend seems to be observed - less differences = closer relations Artificial Selection Humans love to stick their noses in things and change it all around to make their lives better Artificial selection is the process of humans selecting and breeding individuals with desired traits This is commonly found in the farming community Ex. pigs, corn, wheat, cows, horses, dogs, etc. Theories of Evolution A theory is a model that accounts for all the known evidence as completely as possible Remember - nothing in science is FACT - there are always new discoveries being made either supporting theories or adding doubt to them Theories of Evolution Before the 18th century, people thought that living things were fixed and stayed the way they are During the 18th century, many people began questioning this vision Georges-Louis Leclerc de Buffon proposed that a species could change over time Theories of Evolution Carl Linnaeus and Erasus Darwin put forth similar ideas Linnaeus thought that the few species created had become hybrids which led to the formation of new species Darwin (Charles Darwin’s grandfather) proposed that all life had developed from a single source These were both not widely accepted at the time Lamarck’s Theory Jean-Baptiste Pierre Antoine de Monet Chevalier de Lamarck presented the first theory of evolution that included a mechanism He thought that simple species were created by spontaneous generation (living things came from non-living matter) and became more complex over time Lamarck’s Theory He believed that organisms had a force or desire that caused them to change for the better He thought that organisms must be able to produce new parts to adapt to certain environments He thought that the use and disuse of structures were then passed on to offspring and that was how changes happened over time Lamarck’s Theory Lamarckism is now used to describe inheritance of acquired characteristics which is the false concept of inheritance of features acquired during the life of an individual Although Lamarck’s theory isn’t true, he was on to something when he postulated that the environment played a role in changing organisms Darwin’s Theory Charles Darwin came to be known as the father of evolutionary biology after sharing his theories and observations In 1831, Darwin set sail on the HMS Beagle to travel around the world and returned with a large amount of observations (now evidence) that aided his inferences later in his life Darwin’s Theory He spent a large amount of time on the Galapagos Islands and his most famous and well-known evidence for his later theories are the Galapagos finches. He noticed that there were many different beak types among these birds that each had a specific role to aide the bird - from thick seed crushing beaks to small skinny beaks good for eating insects Darwin’s Theory Darwin’s Theory Darwin became interested in artificial selection and thought that if humans could alter the appearance of organisms, why couldn’t nature? After years of observations and research, Darwin developed and published his theory of natural selection in his book ‘The Origin of Species by Means of Natural Selection or The Preservation of Favoured Races in the Struggle for Life’ Darwin’s Theory He didn’t write this whole book himself, but worked with a man named Alfred Russell Wallace who had come to many of the same conclusions as Darwin in his life of research as well The theory of natural selection is one of the major supporting arguments for evolution today Darwin’s Theory Darwin’s Theory Natural selection is the result of differential reproductive success of individuals caused by variations in their inherited characteristics https://www.youtube.com/watch?v=0SCjhI86grU