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The Making of the Fittest: Natural Selection and Adaption


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This 10-minute film describes the research of Dr. Michael Nachman and colleagues, whose work in the field and in the lab has documented and quantified physical and genetic evolutionary changes in rock pocket mouse populations.

Howard Hughes Medical Institute

Grade level:

10 minutes

Teaching tips:
HHMI provides a variety of teacher resources to accompany this video: an in-depth film guide, student quiz, and lessons on allele and phenotype frequencies, molecular genetics of color mutations, biochemistry and cell signaling and color variation over time.

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

  • There is a fit between organisms and their environments, though not always a perfect fit. (LS4.C)

  • Evolution results from selection acting upon genetic variation within a population. (LS4.B)

  • New heritable traits can result from recombinations of existing genes or from genetic mutations in reproductive cells. (LS3.B)

  • Mutations are random.

  • Traits that confer an advantage may persist in the population and are called adaptations. (LS4.B, LS4.C)

  • Inherited characteristics affect the likelihood of an organism's survival and reproduction. (LS4.B, LS4.C)

  • Depending on environmental conditions, inherited characteristics may be advantageous, neutral, or detrimental.

  • The amount of genetic variation within a population may affect the likelihood of survival of the population; the less the available diversity, the less likely the population will be able to survive environmental change.

  • Natural selection acts on the variation that exists in a population. (LS4.B, LS4.C)

  • Natural selection acts on phenotype as an expression of genotype.

  • Organisms cannot intentionally produce adaptive mutations in response to environmental influences.

  • Populations, not individuals, evolve.

  • Over time, the proportion of individuals with advantageous characteristics may increase (and the proportion with disadvantageous characteristics may decrease) due to their likelihood of surviving and reproducing. (LS4.B, LS4.C)

  • A hallmark of science is exposing ideas to testing. (P3, P4, P6, P7)

  • Scientists use multiple research methods (experiments, observational research, comparative research, and modeling) to collect data. (P2, P3, P4, NOS1)

  • There is variation within a population. (LS3.B)

  • The number of offspring that survive to reproduce successfully is limited by environmental factors. (LS4.B, LS4.C)

  • Natural selection is dependent on environmental conditions.

  • Environmental changes may provide opportunities that can influence natural selection. (LS4.B, LS4.C)

  • Fitness is reproductive success - the number of viable offspring produced by an individual in comparison to other individuals in a population/species.

  • There is a fit between the form of a trait and its function, though not always a perfect fit.

Teacher background:

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