The white-striped and tan-striped morphs of the white-throated sparrow.
From Genes to Behavior
The evolution of behavior relies on changes at the level of the genome; yet the ability to attribute a behavioral change to a specific, naturally occurring genetic change is rare in vertebrates. In white-throated sparrows, a genetic polymorphism segregates with a behavioral phenotype. Males and females of the white-striped (WS) morph are heterozygous for a rearranged chromosome 2, called ZAL2m, and respond to a simulated territorial intrusion with high levels of aggressive singing. Birds of the tan-striped (TS) morph are homozygous for the standard arrangement (ZAL2) and respond with relatively little or no singing. In addition to the difference in aggression, TS males engage in more parental behavior than WS males. Because of its association with aggressive and parental phenotypes, the ZAL2m chromosome represents a powerful target for studying the genes involved in these behaviors. We are using complementary approaches to identify genes that contribute to the behavioral phenotypes.
Emory University School of Medicine
NISC, National Human Genome Research Institute, NIH
Georgia Institute of Technology
Diagram: The ZAL2m chromosome (far right) differs from the ZAL2 (left) by two pericentric inversions. The middle arrangement represents a hypothetical ancestral or intermediate version.