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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
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.
- There is a fit between organisms and their environments, though not always a perfect fit.
- There is a fit between the form of a trait and its function, though not always a perfect fit.
- Evolution is often defined as a change in allele frequencies within a population.
- The Hardy-Weinberg equation describes expectations about the gene pool of a population that is not evolvingóone that is very large, mates randomly, and does not experience mutation, natural selection, or gene flow.
- Evolution results from natural selection acting upon genetic variation within a population.
- Evolution results from mutations.
- Natural selection and genetic drift act on the variation that exists in a population.
- Natural selection acts on phenotype as an expression of genotype.
- Phenotype is a product of both genotype and the organismís interactions with the environment.
- Variation of a character within a population may be discrete or continuous.
- Mutation is a random process.
- Organisms cannot intentionally produce adaptive mutations in response to environmental influences.
- Inherited characteristics affect the likelihood of an organismís survival and reproduction.
- 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.
- Traits that confer an advantage may persist in the population and are called adaptations.
- Depending on environmental conditions, inherited characteristics may be advantageous, neutral, or detrimental.
- Natural selection can act on the variation in a population in different ways.
- Natural selection may favor individuals with one extreme value for a trait, shifting the average value of that trait in one direction over the course of many generations.
- Natural selection sometimes favors heterozygotes over homozygotes at a locus.
- Heterozygote advantage preserves genetic variation at that locus (i.e., within the population, it maintains multiple alleles at that locus).
- An individualís fitness (or relative fitness) is the contribution that individual makes to the gene pool of the next generation relative to other individuals in the population.
- An organismís fitness depends on both its survival and its reproduction.
- A hallmark of science is exposing ideas to testing.
- Scientists use multiple research methods (experiments, observational research, comparative research, and modeling) to collect data.