Red dotted line shows a normal distribution
Blue line shows the distribution after a selection has occurred

the size of the male salmon anatomy used to be around medium sized, however, since the small males have snuck into the territory and interbred with the females, the distribution of salmon sizes has expanded to small, medium, and large sizes. This is different than the initial weight span because before the small salmon snuck in, the span of weight for the male salmon wouldn't really go into the small or large category, they would stay mostly at medium.

"a.) well–developed vascular system."

igneous rocks which formed by the crystallization of magma at the surface of the earth called extrusive rocks. they are characterized by fine-grained textures because the rapid cooling at or near the surface did not provide enough time for large crystals to grow.