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
Natural selection wikipedia , lookup
Symbiogenesis wikipedia , lookup
Organisms at high altitude wikipedia , lookup
Catholic Church and evolution wikipedia , lookup
Evolutionary developmental biology wikipedia , lookup
Inclusive fitness wikipedia , lookup
State switching wikipedia , lookup
Hologenome theory of evolution wikipedia , lookup
Punctuated equilibrium wikipedia , lookup
Theistic evolution wikipedia , lookup
MODERN EVOLUTIONARY THEORY WHAT HAPPENED AFTER DARWIN? PROBLEMS WITH DARWIN’S THEORY 1. Why is there variation within a species? 2. How are traits passed from one generation to another? http://4.bp.blogspot.com/EmedhzGoq4U/Tl14PpYybRI/AAAAAAAAgT0/nzHhIdibNw8/s800/101%2Bdalmatians%2Bposter.jpg WATSON AND CRICK’S MODEL OF DNA STRUCTURE Central Dogma of Molecular Biology DNA RNA protein • genes – portions of the DNA that code for a specific protein • proteins – amino acid sequences that are workhorses of living systems http://www.chemheritage.org/Images/Main-Images250x290/Discover/Themes/Biomolecules/watsoncrick1.jpg DISCOVERY OF THE GENETIC CODE series of instructions that shows how proteins are made based on DNA/RNA http://4.bp.blogspot.com/-v3WGNk6Pps/TxgT9DFFntI/AAAAAAAAGgA/U2ZMO0Qzjc/s1600/Dna%2Bgenetic%2Bcode%2BUnseen%2BR are.jpg SOURCES OF INHERITABLE VARIATION 1. Mutation • any change in DNA sequence • due to • • mistakes in DNA replication environmental factors http://www.brooklyn.cuny.edu/bc/ahp/BioInfo/MUT/Mut.Mutation.html, http://static.ddmcdn.com/gif/evolution-fly.gif SOURCES OF INHERITABLE VARIATION 2. Gene shuffling • independent chromosome movement during gamete formation (223~8.4 million gene combinations) • sexual reproduction causes variation within populations • members of a population interbreed and are acted on in similar ways by the environment; they evolve together http://1.bp.blogspot.com/_bAYLalavZ6w/TPtJ5s9xlZI/AAAAAAAAAD0/6KPTjLGRM8g/s1 600/meiosis.gif, http://local.brookings.k12.sd.us/biology/Mitosis.htm EVOLUTION AS GENETIC CHANGE Natural selection on single-gene traits http://www.brainbeau.com/cihs/Evolution/Genes_Variation_Genetic _Change_files/slide0066_image020.jpg Change in allele frequency Evolution EVOLUTION AS GENETIC CHANGE Natural selection on polygenic traits Change in distribution of phenotypes Evolution http://www.citruscollege.edu/lc/archive/biology/PublishingImages/0306l.jpg EVOLUTION AS GENETIC CHANGE • Natural selection is NOT always necessary for genetic change to occur • Genetic drift • • when an allele becomes common in a population by chance not all characteristics of an organism contribute to its fitness http://biology.unm.edu/ccouncil/Biology_203/Images/PopGen/bottleneck.gif SPECIATION Formation of a new species • species group of organisms that interbreed and produce fertile offspring • reproductive isolation • • • behavioral isolation geographic isolation temporal isolation Evolution Reproductive isolation Separation of gene pools Different responses to natural selection and genetic drift http://csmith1974.files.wordpress.com/2010/11/behavioral-isolation-1.jpg, http://bioweb.cs.earlham.edu/912/formation/IMAGES/fish.jpg, http://biology-forums.com/gallery/33_14_07_11_5_59_19.jpeg EXPERIMENTAL EVOLUTION Darwin’s Hypothesis http://4.bp.blogspot.com/-KhUhy5HCFNk/TVb-KjAZtGI/AAAAAAAAAew/f4iTxy9qSE4/s1600/Galapagos-finches.jpg EXPERIMENTAL EVOLUTION Grant Experiment Enough inheritable variation in beak size and shape Differences in beak size and shape differences in fitness Identify and measure as many birds as possible on one island Observe survival of different birds when resources are scarce Many of the characteristics appeared in bell-shaped distributions Birds with differently-sized beaks had different chances of surviving a drought There is great variation of inheritable traits among finches Big-beaked birds had higher chances of surviving during a drought SPECIATION IN DARWIN’S FINCHES Founders arrive Separation of populations on different islands Natural selection changes in the gene pool Continued evolution Ecological competition Reproductive isolation MACROEVOLUTION Large-scale evolutionary changes that occur over long periods of time MASS EXTINCTIONS • Disappearances of huge numbers of species • Asteroids, geological activity • Disappearance of dominant species allowed other species to take over ADAPTIVE RADIATION • A single group of species evolved into different forms that live in different ways • Produces great diversity http://mindblowingscience.com/science-by-numbers/the-5-major-mass-extinction-events/ MACROEVOLUTION Large-scale evolutionary changes that occur over long periods of time CONVERGENT EVOLUTION • Unrelated organisms resemble one another • Due to similar environmental conditions COEVOLUTION • When organisms that interact closely with one another evolve together http://students.washington.edu/kjbyers/coursework.html MACROEVOLUTION Large-scale evolutionary changes that occur over long periods of time PUNCTUATED EQUILIBRIUM CHANGES IN DEVELOPMENTAL GENES • Rapid evolution may occur after long stable periods • Usually occurs because of genetic drift or together with adaptive radiation • Similar hox genes are present in diverse organisms • These dictate the basic body plan of the organism • Major evolutionary changes may have occurred through these genes http://withfriendship.com/images/i/42351/Punctuated-equilibrium-picture.jpg, http://sciphu.files.wordpress.com/2008/02/punctuated-equilibrium.jpg