Dominant Role of Sexually Antagonistic Effects in Drosophila Genomic Evolution

The evolution of new genes is a general process across organisms. New genes often have adaptive functions that underlie evolutionary novelties, as suggested by strong signals of positive selection. We review new evidence for a pervasive role of sex-dependent effects in new gene evolution. Recent studies in Drosophila have revealed that intralocus sexual conflict (IASC) is prevalent in the evolution of both new and old genes. Large-scale knockdown experiments in somatic tissues have revealed that most new genes benefit males but harm females, while germline knockdowns have shown that less than half of new genes benefit both sexes. New experimental approaches demonstrate that new genes expressing IASC have become fixed in natural populations and have evolved new reproductive functions. Here, we review recent literature to discuss how IASC, sexual antagonism, germline–soma conflict, and natural selection together drive new gene evolution. We discuss patterns of sequence and functional divergence between new and old genes that underlie broad patterns of genome evolution.