Transcript Evolution
Evolution • Evolution- change in allele frequency in a population over time (decent with modification) • Population- Group of individuals of a single species that occupy the same general area • Allele- an alternative version of a gene • Gene- a discrete unit of hereditary information consisting of a specific nucleotide sequence in DNA, codes for a protein that leads to a physical characteristic Types of Evolution • Microevolution- evolution within a species • Macroevolution- evolution that produces a new species • Origins of life according to evolution Lamarckian Evolution Lamarck’s theory is incorrect 3 concepts •Theory of need •Theory of use and disuse •Theory of inheritance of acquired characteristics Charles Darwin • • • • Naturalist on the HMS Beagle Surveying ship 5 year voyage beginning in 1831 Made observations and collected specimens along the way, many from the Galapagos Islands • Returned to England and began to develop his theory of Evolution •Galapagos finches that Darwin observed have different beaks based on the food that they eat •Darwin believed the differences in their beaks were due to evolution •He believed the different species of finches adapted to different environments at different times, so they could get the food that was available there •Darwin believed they evolved from a common ancestor Artificial Selection Species definitely have the ability to change over time to become very different than what they once were Charles Darwin • Published “On the Origin of Species by Means of Natural Selection” in 1859 • Published “The Descent of Man” in 1871 Evolution by Natural Selection • Mechanism of evolution- evolution is what happens, natural selection is how it happens • Individuals whose inherited traits give them a higher probability of surviving and reproducing in a given environment tend to have more offspring than other individuals which leads to the accumulation of favorable traits in a population over generations Evolution by Natural Selection • Traits must be genetically based • Genes must lead to a reproductive advantage • Causes the allele frequency in the population to change • Takes many generations • Remember: favorable traits are based on the environment Survival of the fittest • Somewhat misleading • Does not necessarily mean physical strength • It means better adapted to the current environment What leads to natural selection? • Environmental change- an allele that was once not an advantage becomes an advantage because the environment is different. • Immigration (gene flow)- individuals with more advantageous genes join a population. • Genetic drift- random selection of a gene because of an event that significantly decreases population size and eliminates all or most individuals with a particular gene. • Mutation- altering of the nucleotide sequence can make a gene more advantageous. Microevolution • Pests and pesticides • Bacterial resistance to antibiotics • Selection to avoid predation Microevolution- evolution within a species