Chapter 4: Forces of Evolution
- Page ID
- 177572
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- 4.1: The Modern Synthesis and Population Genetics
- It’s hard for us to imagine all the way back, 3.8 billion years ago, to the origins of life. Scientists still study and debate how life came into being and whether it originated on Earth or in some other region of the universe. What we do know is that a living single-celled organism was present on Earth during the early stages of our planet’s existence. Today’s genetic and genomic technologies work to determine the relationships between all of today’s living organisms.
- 4.2: The Forces of Evolution
- Today, we recognize that evolution takes place through a combination of mechanisms: mutation, genetic drift, gene flow, and natural selection. These mechanisms are called the “forces of evolution” and together they can account for all the genotypic variation observed in the world today. Keep in mind that each of these forces was first defined and then tested—and re-tested—through the experimental work of the many scientists who contributed to the Modern Synthesis.
- 4.3: Studying Evolution in Action
- This chapter has introduced you to the mechanisms by which evolution occurs, known as the forces of evolution. But, how do we detect and study evolution in real time? One tool scientists use is the Hardy-Weinberg Equilibrium formula: a mathematical formula that allows the estimation of the number and distribution of dominant and recessive alleles in a population. It’s important to note that the Hardy-Weinberg formula only gives us an estimate based on the data for a snapshot in time.
- 4.4: End of Chapter Review
- Discussion questions and key term definitions.
Acknowledgment
Many thanks to Dr. Vincent M. Riccardi for sharing his vast knowledge of neurofibromatosis and for encouraging me to explore it from an anthropological perspective.