Why do individuals of the same species vary in how they look, function, and behave?
The information passed from parents to offspring is coded in the DNA molecules that form the chromosomes. In sexual reproduction, chromosomes can sometimes swap sections during the process of meiosis (cell division), thereby creating new genetic combinations and thus more genetic variation. Although DNA replication is tightly regulated and remarkably accurate, errors do occur and result in mutations, which are also a source of genetic variation. Environmental factors can also cause mutations in genes, and viable mutations are inherited. Environmental factors also affect expression of traits, and hence affect the probability of occurrences of traits in a population. Thus the variation and distribution of traits observed depend on both genetic and environmental factors.
Topic Summary:
Variation among individuals of the same species can be explained by both genetic and environmental factors. Individuals within a species have similar but not identical genes. In sexual reproduction, variations in traits between parent and offspring arise from the particular set of chromosomes (and their respective multiple genes) inherited, with each parent contributing half of each chromosome pair. More rarely, such variations result from mutations, which are changes in the information that genes carry. Although genes control the general traits of any given organism, other parts of the DNA and external environmental factors can modify an individual’s specific development, appearance, behavior, and likelihood of producing offspring. The set of variations of genes present, together with the interactions of genes with their environment, determines the distribution of variation of traits in a population.
✓ MASTERY CHECK
COLLEGE & CAREERS
YOU CAN APPLY THESE SKILLS BY:
- Interpreting information to learn how a genetic disease is transmitted.
- Follow a career as a genetic counselor, helping families understand and evaluate the likelihood that a gene will be expressed.
National Research Council 2012. A Framework for K-12 Science Education: Practices, Crosscutting Concepts, and Core Ideas. Washington, DC: The National Academies Press. https://doi.org/10.17226/13165
This site contains original content that may not be authorized for use by the creator and is legally used under the fair use principles section 107 of the Copyright Act of 1986 (17 U.S. Code § 107)
The official NGSS website. https://www.nextgenscience.org
This site contains original content that may not be authorized for use by the creator and is legally used under the fair use principles section 107 of the Copyright Act of 1986 (17 U.S. Code § 107)
The official NGSS website. https://www.nextgenscience.org