1) Variation: there needs to be a difference in the individuals within a population
2) Inheritance: These variable traits must be able to be passed down genetically
3) Growth rate: There needs to be a growth rate that requires a struggle for resources
4) Survival rate: There needs to be a difference in survival rate for the different variation types... certain variations will live
Cold air will underlie warmer air at higher altitudes. :^)
Hope this helps!
There are 75% chances that their offsprings will be checkered.
Explanation:
The gene version allele is received by an individual and if they are different then the gene of the parent which is dominating is expressed in the offspring. However, in the case of co dominance the offspring gets the trait of both parent alleles.
So, in this case the mating of checkered rooster and checkered hen with co-dominance in their trait of genes will produce checkered offspring with a chance of 75 percent as can be calculated by the punnet square. The result will be 3 out of 4 checkered offspring.