These photos are in part collected here for my own records, but I hope they can also be educational when others are pondering the changes they may see between chick fluff and adult feathers. They grow up so quickly...
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Born on St. Paddy's Day, I was very tempted to keep this little one, my first successful 2020 hatchling.
LEARN ABOUT SHETLANDS
and the care and breeding of sheep
Fundamentals of Mendelian Genetics
An Overview
Andrea deCarlo
Mendelian genetics, founded on the principles established by Gregor Mendel in the 19th century, forms the basis of classical inheritance patterns. Through controlled breeding experiments with pea plants, Mendel identified fundamental laws of inheritance, including the concepts of dominant and recessive traits. These principles apply broadly across the biological world, including in domesticated livestock such as sheep. One of the most illustrative examples of simple Mendelian inheritance in sheep is white vs. non-white wool color, which follows a pattern of simple dominance.
Mendel’s Laws and Simple Dominance
Mendel’s first law, the Law of Segregation, states that an organism carries two alleles for each trait, one inherited from each parent, and these alleles separate during gamete formation. His second law, the Law of Independent Assortment, explains how different traits are inherited independently of one another, provided they are on different chromosomes. Simple dominance occurs when one allele masks the expression of another, with the dominant allele determining the phenotype in heterozygous individuals.
Sheep Coat Color: A Mendelian Example
In sheep, coat color is often governed by Mendelian principles. A well-known example is the black versus white coat color determined by a single gene. The allele for white coat color (W) is dominant, while the allele for non-white coat color (w) is recessive. This means that a sheep inheriting at least one dominant allele (WW or Ww) will have a white coat, whereas only those inheriting two recessive alleles (ww) will be non-white.
Conclusion
Mendelian genetics provides a straightforward framework for understanding inheritance, particularly through traits that follow simple dominance. The inheritance of coat color in sheep exemplifies these principles, reinforcing the foundational nature of Mendel’s laws in biological inheritance. While real-world genetics can be influenced by additional factors such as polygenic traits and environmental interactions, simple dominance remains a fundamental concept in the study of genetics