Gene duplication and alternative splicing (AS) are the two major evolutionary mechanisms that can bring the functional variation by increasing gene diversification. The purpose of this research is to understand the evolutionary relationship between these two different mechanisms, utilizing available data resources. We found the proportion of AS loci and the average number of AS isoforms per locus to be larger in duplicated genes compared to those in singleton genes. However we also found that small gene families have larger proportion of AS loci and larger average number of AS isoforms per locus than large gene families. These results suggest that gene duplication allows for more alternative splicing events to occur on newly duplicated copies than on singletons, probably due to the reduced functional constraint on the duplicates. Smaller average number of AS isoforms in the larger gene families can be explained by the decreased possibility for new useful function to be created via a new alternative splicing event.