Mating is rarely random. many organisms choose a mate for specific reasons - body size, coloration, antler size, feather length, etc. changes in allelic frequencies due to this non-randomness of mating is called question 3 options: hardy-weinberg equilibrium. natural selection. genetic drift. gene flow.

Natural selection

Explanation:

Sexual selection refers to the natural selection where the allele frequencies of a population are changed due to nonrandom mating between the individuals. Certain preferences for the mate by organisms result in sexual selection. It is mostly exhibited by females.

For example, peahen prefers the peacocks with elaborate tail features as their mate. The sexual selection also occurs when there is competition among the members of the same sex for a mate. This type of sexual selection is mostly exhibited by males and results in fighting and display.

answer: the blood-brain barrier is a layer of specialized membranes and cell processes designed to keep undesirable substances from passing from the bloodstream into the precious tissues of the brain. while the blood-brain barrier does keep most bad things out of the central nervous system, it is not impermeable.

explanation: