Final answer:
High realized heritability in phlox may be due to strong selection pressure, such as bees preferring red over blue flowers, which affects the frequency of the visible phenotypes despite blue color being a dominant trait over the red color.
Step-by-step explanation:
The observation that realized heritability in phlox is relatively high can be attributed to several factors. One key factor is selection pressure. For example, if bees preferentially pollinate red flowers over blue ones, there's a strong selection for the red flower phenotype. Additionally, if blue flower color is dominant to red, the genetic structure may not directly reflect the selection pressure visible in phenotype frequencies.
With 600 blue flowers and 200 red flowers, the expected allele frequencies for color could be calculated using the Hardy-Weinberg formula, considering the proportions of homozygous dominant, heterozygous, and homozygous recessive individuals.