Answer:
If bird song promotes an individual's ability to attract a mate and reproduce, then the song has an function
Step-by-step explanation:
Within a community, certain novel traits are fixed because they impart beneficial adaptations on an individual in their ecosystem (like mate attraction). Such modifications enable such individuals to live longer than their peers, and breed over time to produce more offspring who also exhibit these traits.
Natural selection takes place and is determined by the fitness of an individual , it contributes to evolutionary change as individuals with certain traits reproduce, the traits become fixed and prevalent within the population.