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Lesson summary for:
A Step in Speciation

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Overview:
Students compare different subspecies of a California salamander on a grid map of California to focus on patterns of their distribution, their likely evolutionary relationships, and probable sequence of formation from the ancestral salamander.

Author/Source:
ENSI

Grade level:
13-16

Time:
Two 50-minute periods

Teaching tips:
Much of the "busy" work can be streamlined to make this an effective activity at the undergraduate student level.

Concepts:
Correspondence to the Next Generation Science Standards is indicated in parentheses after each relevant concept. See our conceptual framework for details.

  • Evolution is often defined as a change in allele frequencies within a population.

  • Natural selection and genetic drift act on the variation that exists in a population.

  • Speciation is the splitting of one ancestral lineage into two or more descendent lineages.

  • Speciation is often the result of geographic isolation.

  • Occupying new environments can provide new selection pressures and new opportunities, leading to speciation.

  • A hallmark of science is exposing ideas to testing.

  • Scientists can test ideas about events and processes long past, very distant, and not directly observable.

Teacher background:

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