Answer:
Decreased variation in the shades of red because no form of the trait is advantageous.
Step-by-step explanation:
Natural selection may be defined as the differential reproduction and survival of the individual due to their differences in the phenotype. Natural selection acts as the main driving force for evolution.
The male cardinal red color gets change or may show variation as it is no longer used by them to attract the females. The red shade variation get decreases and may get changed over time. The red color trait is non advantageous and get extinct with time.