The portion of a muzzle-loader rifle that fits against your shoulder is the - BUTT.
A muzzle-loader is a firearm in which the projectile and usually the propellant charge is loaded from the muzzle of the gun. This is distinct from the more popular modern designs of breech-loading firearms. That portion of a muzzle-loader rifle that fits against ones shoulder is called the butt.
Plasticity is most adaptive when the environment change <u>Slowly and predictably </u>throughout an organism's life.
The ability of individual genotypes to create various phenotypes when exposed to various environmental situations is known as phenotypic plasticity. Here, the emphasis is on the role of plasticity in evolution rather than the evolution of plasticity itself, i.e., the evolution of phenotypic traits and organismal variety through plasticity. Phenotypic plasticity is a crucial characteristic of developmental systems that enables the organism to deal with environmental variability and/or unpredictability, although its significance for adaptive evolution is still debated.
Learn more about Phenotypic Plasticity here-
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