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EVOLUTION. SBI3U Ms. Papaiconomou & Ms. Lorenowicz. What is Evolution?. Evolution is the relative change in the characteristics of populations that occurs over successive generations. Diversity of Life. Diversity is the cornerstone of evolutionary biology
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EVOLUTION SBI3U Ms. Papaiconomou & Ms. Lorenowicz
What is Evolution? • Evolution is the relative change in the characteristics of populationsthat occurs over successive generations
Diversity of Life • Diversity is the cornerstone of evolutionary biology • Not all individuals of a species are exactly alike • Differences between individuals are not always immediately visible • Diversity is important for the long term survival of a species
Biodiversity • Differences in characteristics between individuals may be: • Advantageous • Harmful • Neutral • Characteristic may not give an individual an advantage now, but may become critical for survival later if the environment changes
What controls the characteristics of individuals? • Genes!! • There are different versions of genes, known as alleles, in a population which is the basis of biodiversity. • Gene pool – total of all genes in a population
What is Evolution? • Evolution is • the relative change in the characteristics of populations that occurs over successive generations • any shift in the gene pool of a population • ratio of characteristics in a population change over successive generations
Who can evolve? • Individuals cannot evolve! • Individuals cannot change their genes. • Populations are the smallest unit that can evolve. • Populations can have a shift in their gene pool.
Why would populations evolve? • So that a population becomes better suited to its habitats. • Increased survival • Better chance of passing on characteristics to offspring. • Takes place over many generations.
How does a population evolve? • A shift in the gene pool so that a higher ratio of individuals have a particular adaptation. • Adaptation • a particular structure, physiology or behaviour that helps an organism survive and reproduce in a particular environment. • e.g. camouflage, superb sense of smell, bill shape
Example of a population that evolved:Peppered moths in England