Hi!
The answer would be sexual selection.
Sexual Selection is a process that is a for of natural selection in which certain individuals of a species have an advantage over other individuals of the same sex of the species in competition for mating with the opposite sex.
For instance, genes that encode bright feathers give an advantage to the male peacocks over other males which do not have an equally bright assortment of feathers, increasing the individual's reproductive success. This results in the advantageous genes (such as of bright feathers) recurring over the generations and remaining a part of the gene pool.
Hope this helps!
