Vocal Dialect Recognition and Population Genetic Consequences

SYNOPSIS. On the basis of male territorial song, a system ofdiscrete dialects is described in a population of White-crownedSparrows in central, coastal California. Four of these dialectsare genetically differentiated from one another. Inbreedingcoefficients calculated from electrophoretic alleles indicatethat individuals in a dialect are inbred due to isolation ofthe dialect not because of inbreeding with close relatives.Males react more aggressively to male song from an adjacentdialect than to song from another member of their own dialectbut react only weakly to song from a distant dialect. This indicatesthat male-male interactions may have a role in maintaining dialectpopulations. Females of the Mountain White-crowned Sparrow havebeen tested in dialect experiments in the laboratory and foundto respond with precopulatory sexual posturing almost exclusivelyto song from the home dialect in comparison to song from analien dialect. This indicates that female choice of mate mayalso play a role in maintaining dialect populations.