Final answer:
Non-Mendelian inheritance includes pleiotropic traits where a single gene affects multiple characteristics, differing from Mendel's simple dominant-recessive patterns. Polygenic traits, in contrast, are influenced by multiple genes and display a wide range of phenotypes, often modified by environmental factors.
Step-by-step explanation:
Non-Mendelian inheritance refers to the inheritance of traits that do not follow Mendel's laws of inheritance. Unlike the simple dominant-recessive traits that Mendel described, non-Mendelian inheritance involves more complex genetic interactions.
One type of non-Mendelian inheritance is known as pleiotropy. Pleiotropy occurs when a single gene influences multiple phenotypic traits. An example of pleiotropy is the platelet cell fragment in the blood, which affects the clotting process.
In contrast to Mendelian traits, which are influenced by one gene with two alleles and complete dominance resulting in predictable phenotypes, polygenic traits are controlled by multiple genes and each may have multiple alleles.
Polygenic traits show a range of phenotypes and are often influenced by environmental factors. Height and weight are classic examples of polygenic traits.
Understanding that some traits are polygenic or affected by pleiotropy helps explain why some phenotypes cannot be explained by simple Mendelian genetics. These complexities in genetic inheritance patterns add to the diversity and adaptability of species.