IntroBio-13-Evolution

IntroBio-13-Evolution - Evolution 1 Evolution • Change in...

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Unformatted text preview: Evolution 1 Evolution • Change in allele frequencies in a population over time 2 Evolution explains: • Origin of species • Diversity of organisms and their relationships • Similarities and differences among species • Adaptation to the environment 3 History of Evolutionary Theory 4 Aristotle – “Scale of Nature” • Classified objects and living organisms from simplest to the most complex forms • Each form of life was perfect and permanent 5 Renaissance • All organisms had been created by God • Species could never change, arise or become extinct 6 Carolus Linneaus • Science of taxonomy - binomial system of naming organisms according to genus and species 7 Georges Cuvier • Paleontology- study of fossils • Catastrophism : changes between geological strata marked an extinction event due to a dramatic change in environment • Each layer of fossils represented the remains of organisms that died in a catastrophe 8 Jean Baptiste Lamarck 1. Use and disuse principle : body parts grow in proportion to how much they are used 2. Inheritance of acquired characteristics principle : changes an animal acquires during its lifetime are inherited by its offspring 9 Charles Lyell • Uniformitarianism : geological processes that formed the Earth’s surface over long periods of time are operating today and at the same rate 10 Charles Darwin (1809 – 1882) 11 Charles Darwin • 1859 – “On the Origin of Species by Means of Natural Selection” • Organisms are des cended with modifications from a common ancestor • Mechanism ( natural selection ) to explain how evolution takes place 12 Natural selection is based on 5 observations: 1. If all individuals in a population reproduced successfully, the population size would increase exponentially 2. But population size tends to remain stable 13 3. Natural resources are limited 4. Members of a population vary in their characteristics 5. Much of this variation between individuals is heritable 14 Conclusions: • There is a differential success in reproduction • Organisms produce more offspring than the resources available to them can support • This leads to a struggle for existence among the individuals of a population 15 • Survival depends in part on inherited characteristics • Individuals whose inherited traits give them a high probability of surviving and reproducing in a given environment have higher fitness and are likely to leave more offspring then less fit individuals 16 Fitness • “Survival of the fittest” • Genetic contribution of an individual to the gene pool of the next generation 17 Heritable traits • Expression of genes that are passed on to offspring during reproduction 18 Adaptation • Heritable trait that allows organisms to survive and reproduce better under existing environmental conditions 19 •...
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IntroBio-13-Evolution - Evolution 1 Evolution • Change in...

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