Vocal Dialect Recognition and Population Genetic Consequences

Abstract

SYNOPSIS. On the basis of male territorial song, a system of discrete dialects is described in a population of White-crowned Sparrows in central, coastal California. Four of these dialects are genetically differentiated from one another. Inbreeding coefficients calculated from electrophoretic alleles indicate that individuals in a dialect are inbred due to isolation of the dialect not because of inbreeding with close relatives. Males react more aggressively to male song from an adjacent dialect than to song from another member of their own dialect but react only weakly to song from a distant dialect. This indicates that male-male interactions may have a role in maintaining dialect populations. Females of the Mountain White-crowned Sparrow have been tested in dialect experiments in the laboratory and found to respond with precopulatory sexual posturing almost exclusively to song from the home dialect in comparison to song from an alien dialect. This indicates that female choice of mate may also play a role in maintaining dialect populations.