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The Origin of a Species

Speciation is the evolutionary process that results in new species. Understanding speciation allows scientists to understand how the tree of life developed over time. This lesson set features the speciation of squamates – scaled reptiles like lizards and snakes. Students investigate the genetic and environmental factors that led to limb reduction and examine how one suborder of this group, the Serpentes, flourished thanks to this adaptation.

This lesson set was updated June 1, 2022.

Age Level
Grades 9-12
Duration
4-6 50 minute classes

NGSS Standards

DCIs (Disciplinary Core Ideas)

HS-LS4.A: Evidence of Common Ancestry and Diversity

  • A1. Genetic information, like the fossil record, provides evidence of evolution. DNA sequences vary among species, but there are many overlaps; in fact, the ongoing branching that produces multiple lines of descent can be inferred by comparing the DNA sequences of different organisms. Such information is also derivable from the similarities and differences in amino acid sequences and from anatomical and embryological evidence.

HS-LS4.C: Adaptation 

  • C4. Changes in the physical environment, whether naturally occurring or human induced, have thus contributed to the expansion of some species, the emergence of new distinct species as populations diverge under different conditions, and the decline–and sometimes the extinction–of some species.
  • C5. Species become extinct because they can no longer survive and reproduce in their altered environment. If members cannot adjust to change that is too fast or drastic, the opportunity for the species’ evolution is lost.

Performance Expectations

  • HS-LS4-1. Communicate scientific information that common ancestry and biological evolution are supported by multiple lines of empirical evidence.
  • HS-LS4-5. Evaluate the evidence supporting claims that changes in environmental conditions may result in (1) increases in the number of individuals of some species, (2) the emergence of new species over time, and (3) the extinction of other species.

Other Relevant NGSS References:

  1. NGSS Appendix F (pdf): Science and Engineering Practices in the NGSS
  2. NGSS Appendix G (pdf): Crosscutting Concepts
  3. NGSS Appendix H (pdf): Understanding the Scientific Enterprise: The Nature of Science in the Next Generation Science Standards
  4. NGSS Appendix J (pdf): Science, Technology, Society and the Environment

This is a beta version of Lesson Set One.