As an overview for Mendelian experiments, students can select a set of traits for the selected species, define the initial genotype for the parents, and cross these parents to produce the first generation of offspring. For the first generation offspring, specific or random crosses of the offspring can then be performed to produce subsequent generations. For each generation a summary is provided showing the frequencies of each of the phenotype combinations, and students can also view the phenotypes of each of the individual offspring. The goal is to allow students to observe how the selected traits get expressed as a function of generation, and then from these observations determine and understand the genetic model governing expression of these traits. Given below is an outline of the general steps involved in performing a Mendelian experiment.
- The first step is to select a species in the species menu. Depending on the species selected, the laboratory will change to reflect the type of species chosen. The default room is for plant species.
After selecting a species, open the Setup menu and make sure the Mendelian option is selected. A list of traits for that species will be listed. Select one or more of the traits you wish to follow as crosses are performed. Use Ctl-click (Windows) or Cmd-click (Mac) to select multiple traits simultaneously.
For plant species, self-crosses are allowed. Select whether there will be one or two parents for the cross.
After the traits have been selected, the genotypes for each parent must be defined. This can be done randomly by clicking on the Randomize button, or the genotype can be defined manually using the dropdown list for each allele. Note that some traits are defined by multiple loci and for some presets the genotypes of the parents could be hidden.
Now the number of offspring per cross must be defined. In most cases, you will use the default number, but the number of offspring that can be produced from each cross can be changed within a range of values that is typical for the selected species.
Finally, click on the Cross button to perform the cross for the defined parents. The results will show in the Live Data display. In many cases, you will need to perform multiple crosses to generate enough offspring to obtain some reasonable statistics. Just return to the Setup menu and click Cross again.
After producing the desired population size, subsequent generations of offspring can be produced by clicking on the Next Generation button. The Setup displaywill be reconfigured to allow you to select the parents that will produce the next generation of offspring. The parents can be selected manually from the list of offspring or randomly.