Final answer:
Non-Mendelian inheritance includes incomplete dominance, codominance, and polygenic inheritance, where phenotypes may blend, express both alleles fully, or involve multiple genes. These patterns, along with environmental influences, can complicate inheritance studies beyond simple Mendelian genetics.
Step-by-step explanation:
Patterns of Inheritance Beyond Mendelian Genetics
​Mendelian genetics provides a foundation for understanding inheritance; however, not all inherited traits follow the simple dominant-recessive patterns that Mendel described. There are various types of non-Mendelian inheritance patterns, including incomplete dominance, codominance, and polygenic inheritance. In incomplete dominance, the heterozygous phenotype is a blend of the two homozygous phenotypes. An example is seen in snapdragons, where crossing red (RR) and white (rr) flowers results in pink (Rr) offspring. Codominance occurs when both alleles in the heterozygote are fully expressed, such as in human blood types AB, where both A and B antigens are present. Polygenic inheritance involves multiple genes contributing to the phenotype, leading to a wide range of variations, as seen in human skin color, height, and eye color.
These non-Mendelian patterns show that inheritance can be more complex than a single gene with two alleles determining a trait. Environmental factors can also influence phenotypic expression, further complicating the understanding of inheritance patterns. Therefore, some inheritance patterns cannot be solely explained by Mendelian genetics.