LIFE SCIENCE

Detailed explanation-1: -I) Directional selection occurs when natural selection favours one extreme of continuous variation. II)Disruptive selection occurs when natural selection favours both extremes of continuous variation.

Detailed explanation-2: -Directional selection: Directional selection occurs when a single phenotype is favored, causing the allele frequency to continuously shift in one direction.

Detailed explanation-3: -The directional selection theory says that an extreme phenotype (characteristics or traits) is favored over other phenotypes and this causes the allele frequency (how often the variant of a gene shows up in a population) to shift over time in favor of the extreme phenotype.

Detailed explanation-4: -Changes in weather, climate, or food availability can lead to directional selection. In a very timely example connected to climate change, sockeye salmon have recently been observed shifting the timing of their spawn run in Alaska, likely due to rising water temperatures.