Species that reproduce sexually have greater genetic diversity than species that reproduce asexually. why is this the case

We want most cells to be even in and out which is called

Fossils can only be formed when? if mud, silt or tar is in the area to preserve the fossil ierosion does not occur and allows the fossil to form oxygen and microorganisms cannot decay the bones the area is dry and does not contain mud or silt

Can someone i have no idea of how to do this.