Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Hologenome theory of evolution wikipedia , lookup
Sexual selection wikipedia , lookup
Natural selection wikipedia , lookup
Punctuated equilibrium wikipedia , lookup
Theistic evolution wikipedia , lookup
On the Origin of Species wikipedia , lookup
Genetics and the Origin of Species wikipedia , lookup
The Expression of the Emotions in Man and Animals wikipedia , lookup
Evolution By Diana L. Duckworth Rustburg High School Campbell County Two Separate Issues • Does evolution occur? – Immutability of species or transmutation of species – Did all life originate from one common ancestor? • If evolution occurs, how does it occur? Before Origin of Species • Erasmus Darwin – physician, poet – All life descended from single filament – Grew in complexity; capacity for self improvement; improvements handed down to offspring – Darwin’s grandfather http://a-evolucao-de-darwin.weblog.com.pt/arquivo/2008/02/concurso_erasmus_darwin Lamarck -Philosophie Zoologique • French – translation problems • After career of 30 years abruptly became an evolutionist (1800) – Spontaneous generation – Tend toward complexity • Explanation: – Pressures from environment – new needs – Use certain organs more; grow larger – Acquired characteristics are heritable http://bio.research.ucsc.edu/people/bernardi/Marina/public_html/Bio175/Bio175Website/Index.html Important Influences on C. Darwin http://www.lakesideschool.org/ studentweb/worldhistory/mode rnworld/ThomasRobertMalthus essay.htm http://io.uwinnipeg.ca/~simmons/16cm05/1116/16evolut.htm • Malthus – populations grow exponentially; competition for food so not all survive • Charles Lyell – professor at Cambridge; lifelong friend & advisor • First textbook of geology – Propounded uniformitarian principle instead of catastrophism – Earth history built up through small, gradual changes – Earth is very old Charles Darwin • Young man – without real direction • Obtained position on HMS Beagle as companion to captain • Voyage 1831 – 1836 • Started out believing common view – species are immutable http://nayagam.wordpress.com/2006/02/ Changing Ideas http://www.geol.umd.edu/~jmerck/galsite/research/projects/hayeslip/darw in.html http://www.mccullagh.org/image/d30-3/iguana-closeup.html • During voyage, Darwin became convinced that species do change over time – the transmutability of species • Fossil evidence from South America • Similarity of species in Galapagos to those on South American mainland Galapagos • Chance remark by governor of Galapagos – • Can tell what island a tortoise comes from by the shape of his shell Mockingbirds • Darwin recognized mockingbirds – Labeled with island of origin – • Gave them to bird expert, John Gould, on his return to London – Gould found 3 speices among specimens – Each species from a different island! http://www.hiltonpond.org/ThisWeek020501.html http://www.birddigiscoping.com/2005_10_01_archive.html http://costaricaphoto.wordpress.com/ Collected a bunch of little brown birds; based on beaks, he thought they were a mix of grosbeaks, wrens, finches & orioles; did not label collection location. http://www.avianweb.com/finchspecies.htm “Darwin’s” Finches • Gave them to John Gould – All finches – 13 species!! • Now Darwin wondered – how could 13 different, but closely related species arrive in the Galapagos? • His answer – one arrived & evolved into 13 species http://www.greenclub.bc.ca/Green_Club_Activity/GVRD_Parks_Events/gvrd_parks_events.htm Insights led to theory • Idea was fully formed by 1838 • Filled series of notebooks which contain every important concept in evolution • Done by 1844 • Yet he did not publish until 1859 http://www.shimer.edu/admissions/dialectic-natural-sciences.cfm Why the delay? • Darwin had very poor health. Long periods of inactivity. • Knew dramatic impact of his ideas & wanted to support them with more data. • Began work on barnacle classification which took 10 years & other experiments to bolster his theory. • Other considerations: • Impact on his marriage since his wife was pious Christian, distractions & responsibilities of family & community life; political climate (he was establishment, idea might encourage radicalism); did he not want to offend his friends in clergy? What prompted the publication • Competition from a young naturalist working in East Indies • Alfred Russell Wallace • Independently happened on the same idea, even calling it “natural selection” • Observed the change from Australian to Asian species in the Indonesian Islands • Darwin simply did not want to be scooped! His ego would not allow it! http://www.thebeagleproject.com/2007/03/i-am-afraid-ships-on-fire-or-why-this.html Wallace Line http://people.eku.edu/ritchisong/RITCHISO/birdbiogeography.html On the Origin of Species • Took Darwin one year to complete and publish manuscript. He could not include all of the data he had amassed in intervening years. • First half of Origin he answered the question “HOW?” – Natural Selection • Second half he presented arguments from four areas of research that supported the concept of transmutation of species & that all life had evolved from a common ancestor. – Biogeography; comparative anatomy; embryology; & paleontology (fossils) Natural Selection • Populations of a species have variability in traits & these traits are heritable. • A trait may convey a survival advantage on the individual possessing it. • These individuals survive to reproduce in greater numbers. • Advantageous trait is passed on to their offspring. • Advantageous trait increases in population. Speciation • Isolation of a population is required for natural selection to produce another species. • May be geographic isolation. • Changes in the environment produce the selective force which causes natural selection. From 1859 to 1882 • Darwin was already well known in scientific circles for his body of work • This book made him famous at all levels of society and on all continents • It quickly sold out & there were 5 more editions • Subject of much rumor; not everyone read the book & just over simplified ideas & distorted them. Single greatest misconception: • Man evolved from monkeys…. Man was not discussed in Origin but in a later book, The Descent of Man… • What Darwin said: • All life developed from a common ancestor – note that the word evolution does not appear in Origin • In other words, man and monkey had a common ancestor that was neither man, nor monkey Greatest Flaw • Darwin did not abandon some of the Lamarckian ideas • He did not know of the work of Gregor Mendel, so he did not know the reality of inheritance • Enamored of idea of use & disuse (use it or lose it) • Did not refute the idea of the inheritance of acquired traits. How does transmutation occur? • Natural Selection – survival of the fittest • Individuals with traits that give them an advantage in their environment will survive and reproduce, thus passing these advantageous traits on to the next generation. – Populations must have variable traits – These traits must be heritable