One fundamental lesson taught at the junior high level is the idea of dominant and recessive genes. Living systems, including humans, possess two copies of each gene. One genetic trait can be dominant to a recessive trait and is observed when one or both gene copies are dominant. Both recessive copies of the pair must be present for a recessive trait to be observed. Gregory Mendel first discovered dominant and recessive traits by simple cross-pollination of pea plants during the 19th century. It is one of the first lessons taught in genetic science and a force that drives evolutionary change. Students can examine identifiable traits within their families using observable phenotypes such as hair and eye color. Students can record these traits for parents, siblings, aunts, uncles and possibly grandparents. Constructing a family genetic tree is an interesting project, allowing students to formulate conclusions concerning possible recessive and dominant traits.
Evolution is a gradual change caused by small alterations, mutations, in genetic material. Favorable mutations improve the chance of survival in a process Charles Darwin termed "survival of the fittest." However, migration and isolation of smaller groups can provide an alternative habitat that favors different traits from the norm. The process is called allopatric speciation. Students in junior high and high school can research recent speciation for an excellent project topic. Isolation in a new environment can favor traits different from the original species. Eventually a new species may develop. Students can test speciation in a laboratory setting by dividing a group of flies or similar insects into two different environments. The insects will grow and reproduce in isolation from each other. Eventually dominant traits will surface after several generations, favoring each laboratory-created environment.
Evolutionary genetics is a field also concerned with genomic discovery in extinct species. It brings questions whether genetic material can be isolated from frozen or mummified remains. Researchers have had complications finding complete genetic material from animals that disappeared thousands of years ago. However, hair samples provide an alternative to genomic DNA. Animal cells have developed a partnership with some bacteria. In theory, bacteria infected animal cells and changed into the energy-producing subcellular organelle called mitochondria, forming a mutual relationship with the cell. High school students can work together on a project researching mitochondrial DNA and the difference with respect to cellular DNA, answering such questions as why mtDNA is better preserved. Students can also present research into projects where ancient mtDNA has been analyzed. In one example, mtDNA isolated from mammoth remains have shown relative similarity in mtDNA even from isolated groups. Although it is a complex issue for high school students, project development can help students grasp basic ideas.
One important aspect of evolutionary genetics junior high school, high school and college students can explore is the human factor in evolution. Humans have a profound effect on evolution. Well-known examples include antibiotic-resistant bacteria and insects resistant to pesticides. From a genetic perspective, a few bacteria cells and insects had some genetic alteration from the norm that provided a trait for survival. These species survive and reproduce, giving the trait to future generations. This is an excellent research topic idea as well as a topic for classroom discussion. Students can research pollution, migration, isolation and direct human contact that all influence evolution and speciation. One example is a species of Pacific Island finches identified by Darwin that appear to show reverse evolution due to human introduction of different food plants. Farming is another aspect of human presence leading to increased isolation by reducing habitat areas.