The frequency of a certain trait in a population of beetles will increase over time if what?

If the beetle with that trait benefits from it or survives more than other beetles with another trait.

Explanation:

if there is a green beetle and a blue beetle birds are probably going to spot the blue beetle first and eat it but if its a green one it can hide in a leaf and survive more than the beetles with blue color

when the displaced particles are perpendicular to the direction the wave travels, is called a transverse wave, whereas in longitudinal wave the displace practices are parallel to the direction of the wave.

in the given image:

first image shows - longitudinal wave

second image shows - transverse wave

third image shows - longitudinal wave

fourth image shows - longitudinal wave

not necessarily. higher fitness requires the organism to be reproductive successful. for example, an organism at age 10 with 15 offspring is much more fit than an organism at age 15 with only 5 offspring.