Evolution or Natural Selection fam ;)
If all else fails, moms spaghetti
The main difference is that organisms that have similar characteristics could be in the same species or have common ancestors
The one that is caused by the modification of density-independent factors is : parasitic wasp invade cocoons, killing caterpillars
Density independent factors refer to occurrences that limit the number of a specific population
hope this helps
This isn't always the case and there is no reason it should be .Whether or not a trait is common has to do with how many copies of that gene version (or allele) are in the population. It has little or nothing to do with whether the trait is dominant or recessive. Let's take eye color as an example.
