# Selection and evolution

**In this chapter, you will learn to:**

* Explain how both genetic and environmental factors contribute to variation in phenotypes.
* Distinguish between continuous and discontinuous variation.
* Describe the process of natural selection, including how antibiotic resistance develops in bacteria.
* Explain the differences among stabilizing, disruptive, and directional selection.
* Describe how the founder effect and genetic drift can influence allele frequencies in populations.
* Apply the Hardy–Weinberg equations to genetic problems.
* Outline the principles of selective breeding with relevant examples.
* Summarize the theory of evolution as changes in gene pools over time.
* Discuss how DNA sequencing is used to determine evolutionary relationships between species.
* Explain the formation of new species through allopatric and sympatric speciation processes.