An isolated population of wild turkeys has adult males that weigh an average of 18 pounds and females that weigh an average of 10 pounds

Question

Another isolated population living 100 miles north has a population where adult males weigh 13 pounds and females 8 pounds on average. Both populations have a very low phenotypic variance. How could you determine genetic contributions to the weight differences between the populations?

Answer 1

The phenotypic variation (VP) is dependent on genotypic variation (VG) plus environmental variation (VE) and gene-environment interactions (2COVG,E + VG × E). To isolate VG members of both populations could be captured and bred in captivity under identical circumstances. After a few generations, environmental influences, including VM, should have equalized. If the separate populations have achieved identical VP then VG contributions are limited. If the separate populations maintain a significant size difference, the populations could be crossed. If the F1s are intermediate in weight and the F2s are average but have a much wider variance, then quantitative genetic factors are more important and narrow-sense heritability can be measured as H = VA/VP. If, instead, the F1s have one parental type and the F2s are of that type and of the other parental type, a single gene with a dominant and recessive phenotype could cause the size difference. A number of other possibilities exist depending on one or two other genes that might have incompletely dominant or additive alleles.