Apatch of wildlife area may have different climate conditions around its perimeter. this is known as (edge effect, habitat fragmentation).

I believe it's the edge effect

Codominance is when alleles have the same amount of dominance and both are expressed in a heterozygous individual(ab blood type, roan cow). in a heterozygote with incomplete dominance, the phenotype seen is an intermediate of the dominant and recessive phenotype.(pink flowers when the dominant form is red snd recessive form is white)