Answer:
It will contain a larger proportion of flies that lay eggs in sap because the trait results in a higher chance of reproducing successfully and passing on the gene
Step-by-step explanation:
Over the years the population of flies that lays egg in the rotten bark will reduce this is because of the low chance of reproducing and there will be an increase in the population of flies that lays egg in the sap because the flies have a higher chance of reproducing successfully leading to an increase in the population and the ability of the gene to be passed on successfully to their offspring in next generation.