Genetic traits are determined by alleles which can be dominant or recessive.
You receive two pairs of alleles which then combine to form the geno/phenotype.
Homozygous = both alleles are the same
Heterozygous = alleles are different
There are three possibilities here:
The genotype QQ, which would give a phenotype of large claws
The genotype Qq, which would give a phenotype of medium claws
and the genotype qq, which would give a phenotype of small claws.
(In most alleles, it would seem that Qq would result in large claws because Q would be dominant over the recessive allele q. In this case, however, the two just blend together in what is called codominance.)
I can't see the statements that you're talking about, judging by the fact that you said "which," but it is easily predictable that with hardened soil, those with larger claws would survive. (natural selection) Over time it will be those with larger claws who have more offspring, and thus the trait of large claws would become more prominent.
