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
Precambrian body plans wikipedia , lookup
Natural selection wikipedia , lookup
Inclusive fitness wikipedia , lookup
Microbial cooperation wikipedia , lookup
Paleontology wikipedia , lookup
Genetics and the Origin of Species wikipedia , lookup
The eclipse of Darwinism wikipedia , lookup
High-altitude adaptation in humans wikipedia , lookup
Evolution of sexual reproduction wikipedia , lookup
• EVOLUTION – CHANGE OVER TIME • • NATURAL SELECTION - INDIVIDUALS BETTER ADAPTED TO THE ENVIRONMENT ARE ABLE TO SURVIVE & REPRODUCE. – A.K.A. “SURVIVAL OF THE FITTEST” – POPULATION – GROUP OF INDIVIDUALS OF SAME SPECIES THAT INTERBREED • GENE POOL – COMMON GROUP OF ALL GENES PRESENT IN A POPULATION 2 special processes can assist with change in these populations: Mutations change in DNA sequence in the population Genetic Recombination (Sexual Reproduction). Allows for new combinations of alleles and gene shuffling. Genetic Drift may change populations through “random” changes of allele frequency. A normal distribution of a population, based on average size. Stabilizing selection causes a move toward a middle, or stable, condition. Disruptive Selection occurs when those individuals in the middle are less fit than those on the extreme ends. Directional Selection occurs when a specific trait on one side of the spectrum or the other is selected for. • • • • • • • • • • • • • • • Founder Effect: a cause of genetic drift attributable to colonization by a limited number of individuals from a parent population (example – if you pull 10 colored balls from a trash can, and you only pull out red ones, even through other colors are there, you end up with a new population with only the red trait) Gene Flow: genetic exchange due to the migration of fertile individuals or gametes between populations (reduces differences between populations) (in human circles, think of the joining of families). Nonrandom mating: inbreeding and assortive mating (both shift frequencies of different genotypes) – selective breeding for a trait we desire) – big, red apples, or heavy beef. Natural Selection: differential success in reproduction; only form of microevolution that adapts a population to its environment How natural selection microevolution works Resistance to antibacterial soap Generation 1: 1.00 not resistant 0.00 resistant Generation 2: 0.96 not resistant 0.04 resistant Generation 3: 0.76 not resistant 0.24 resistant Sexual Selection – mate selection based on Bling • Generation 4: 0.12 not resistant 0.88 resistant Sexual dimorphism: secondary sex characteristic distinction (males and females look different to attract members of the opposite sex). • Sexual selection: selection towards secondary sex characteristics that leads to sexual dimorphism (ie – the bling pays off ) THE FORMATION OF NEW SPECIES • AS NEW SPECIES EVOLVE, POPULATIONS BECOME REPRODUCTIVELY ISOLATED • REPRODUCTIVE ISOLATION – MEMBERS OF 2 POPULATIONS CANNOT INTERBREED & PRODUCE FERTILE OFFSPRING. • • BEHAVIORAL ISOLATION- CAPABLE OF BREEDING BUT HAVE DIFFERENCES IN COURTSHIP RITUALS (EX. MEADOWLARKS) • GEOGRAPHICAL ISOLATION – SEPARATED BY GEOGRAPHIC BARRIERS LIKE RIVERS, MOUNTAINS, OR BODIES OF WATER (EX. SQUIRREL) • TEMPORAL ISOLATION – 2 OR MORE SPECIES REPRODUCE AT DIFFERENT TIMES. SPECIATION IN THE GALAPAGOS FINCHES OCCURRED BY: An example of adaptive radiation – these species all diverged from a common ancestor (founder species) FOUNDING OF A NEW POPULATION, • GEOGRAPHIC ISOLATION which led to -- REPRODUCTIVE ISOLATION and • • CHANGES IN THE NEW POPULATION’S GENE POOL due to COMPETITION. Evidence for Evolution • Fossil Record: Fossil Record provides evidence that living things have evolved. Fossils show the history of life on earth and how different groups of organisms have changed over time • Geographic Distribution of Living Species: Separation by a large body of water, or land, that does not allow species to come back into contact with each other for continued gene flow. • Homologous Body Structures • Similarities in Embryology • Relative dating says the newest rocks will have the youngest fossils. As the rocks are deeper in the earth, they will have older fossils from farther back in Earth’s history. Absolute age will utilize various measures of radioactive decay of materials, including Carbon, to determine the actual age of fossils. Early Atmosphere – the beginnings of Earth Earth was Hot!! Little or no oxygen Gasses in atmosphere: Hydrogen cyanide (poison to you!) Hydrogen sulfide Carbon dioxide Carbon monoxide Nitrogen water Where did Oxygen come from? Some of that oxygen was generated by photosynthetic cyanobacteria Some came from the chemical separation of water molecules into oxygen and hydrogen. Oxygen drove some life forms to extinction Others evolved ways of using oxygen for respiration Miller and Urey’s Experiment Passed sparks through a mixture of hydrogen methane ammonia and water This produced amino acids – the building blocks of life Where did Oxygen come from? Some of that oxygen was generated by photosynthetic cyanobacteria Some came from the chemical separation of water molecules into oxygen and hydrogen. Oxygen drove some life forms to extinction Others evolved ways of using oxygen for respiration So how does the formation of amino acids make cells? Formation of microspheres Large organic molecules can sometimes form tiny proteinoid microspheres Store and release energy, selectively permeable membranes, may have acquired more characteristics of living cells Endosymbiotic theory eukaryotic cells arose from living communities formed by prokaryotic organisms Ancient prokaryotes entered primitive eukaryotic cells and remained there as organelles