Q.Explain stabilizing, directional and disruptive selection with examples.

Natural selection acts on a population's existing phenotypic variation in three characteristic patterns. Stabilising selection operates in a stable environment, favouring average phenotypes and removing both extremes, narrowing the population's variation without producing new species (e.g. sparrows surviving a storm clustering around the mean body size). Directional selection operates as the environment changes gradually, shifting the population's phenotype distribution progressively toward one end of the range (e.g. sex-linked body-weight differences in sparrows). Disruptive selection (centrifugal selection) operates when a uniform environment becomes heterogeneous, favouring both extreme phenotypes over the intermediate one — a comparatively …