Ch 22 Descent with Modification There are no direct measurements in evolution like cosmology Evolution has several misconceptions Species evolve into higher beings ex human thought Star Trek Any kind of dramatic mutations are possible causing the evolution of a new race of beings ex X Men An organism can evolve during its lifetime ex Pok mon An organism can influence the evolution of its own structures ex Dilbert Evolution is the process of change in organisms throughout the earth s history It is Not by choice Not in the lifetime of the individual Limited by genetic material and the history of the organism Darwin did not spontaneously discover evolution on his own Historical context Antiquity through the 1600s o Plato thought that there were ideal forms of each species deviations from the ideal form were lesser He taught his student Aristotle this o Aristotle categorized the fixed ideal species by features He created the Scala Naturae or Scale of Nature Plants were the lowest and humans were the highest o Biblical Creation fit with Aristotle s form Early Christians added the angels and God to his system and created the Great Chain of Being They also thought that the earth was not that old only a few thousand years 1700s o Newton published Principia and began the Age of Enlightenment and the Age of Reason o Carolus Linnaeus was a Swedish naturalist that developed a nested classification system of organisms o Le Comte de Buffon was a French naturalist who wrote about fossils and rocks He proposed that the earth was very old and that at least six epic changes had happened in its history o Erasmus Darwin Grandfather was a natural philosopher He wrote Zoonomia where he speculates as to the origin of life The Temple of Nature 1802 is a poem exploring the possibilities of the origin of life Early 1800s o George Curvier was a French naturalist and paleontologist He interpreted the living context of fossils It was originally thought that fossils were an ancient form of art he saw living creatures and inferred where they lived He also inferred that strata in the rocks were caused by floods and favored catastrophism o Charles Lyell was a Scottish geologist and the father of modern geology He wrote Principles of geology which gave evidence for gradualism He inferred that changes were uniform in time and rate i e 1 inch of sand 32 years of accumulation These rates held true today and in the past he then inferred that the Earth is very old He later became a mentor to Darwin o Jean Baptiste de Lamarck was a French naturalist He proposed that present life descended from earlier extinct life i e evolution He proposed evolution was due to adaptations of species to the environment His proposed Mechanism the inheritance of acquired characteristics was wrong and focused on use and disuse Epigenetic variation in a phenotype outside of the genotype that MAY be passed down o Thomas Robert Malthus was an English economist He published an essay on human population growth which shows the potential for exponential population growth He saw in very poor areas that even though humans produced more offspring than the environment could support growth was restrained When there are limited resources there is competition and the weakest and poorest suffer the most Darwin born Feb 12 1809 same day as Lincoln He was the son of a physician and an amateur naturalist as a young man His father wanted him to go to medical school but Darwin hated it and dropped out He got a degree in theology to become a clergyman He married his wealthy cousin Emma They had ten kids two of which died in early childhood and three of which became famous scientists He died at the age of 73 Voyage He set sail on the HMS Beagle in 1831 1836 at the age of 22 He was the companion of the ship s captain and paid his own way He collected plants animals fossils and shipped them to England and studied them when he got back Theory He fully developed the theory in 1844 but hesitated to publish it In 1858 he received a letter form Alfred Wallace which proposed the same idea He published Origin of Species in 18959 Thomas Huxley was one of his biggest supporters Darwin Darwin s Theory 2 parts Part 1 All present life is related through descent with modification from a common ancestor in the past Linnaeus classification system reflected the relatedness EVOLUTION Part 2 Natural selection is the mechanism for evolution These parts were based on observations and inferences Observation 1 o All species tend to produce more offspring than the environment can support Limiting resources keep the population in check Observation 2 o There is heritable individual variation within a species Inference 1 o Individuals with certain heritable traits will tend to leave more offspring than others Unequal reproductive success is the result of the ability to survive AND reproduce Inference 2 o These heritable favorable traits accumulate over time leading to adaptation to the environment Adaptation the traits that enhance the survival and reproductive success of and individual It ultimately leads to new species Different adaptations are favored in different environments Not explained in Darwin s Theory Origin of life How variation arises didn t know about Mendel How inheritance works Why variation still exists Sudden changes in the fossil record The source of totally new characteristics Evidence in support of Darwin s Theory Direct observation of Natural Selection soapberry bug drug resistant bacteria The fossil record o Older rocks lack present day groups o 3 5 BYA only prokaryotes 428MYA only fish no amphibians o Older rocks have many extinct species o Evidence of transition of form to a new major group horses to whales Homology Convergence Biogeography Homology similarity in form as a result of common ancestry Homologous structure mammalian forelimb is a common ancestral form with similar structure Evolution trees are based on shared homologous forms Vestigial structures are remnants of structures that are no longer adaptive bling cave salamanders have eyes Developmental HS are homologous structures that appear during the development of offspring Molecular Cell H are genetic code Convergence is when unrelated species have similar adaptations analogous structures caused by similar natural selection torpedo shape in ocean animals wings thick stems and thorns in deserts tree gliding Biogeography is the study of the distribution of species It reflects geologic history Suggests