Data from: Elements of male song performance and complexity are associated with reduced risk of paternity loss in a South American passerine

Many passerines have elaborated songs hypothesized to have evolved through
sexual selection. Extra-pair mating can be a contributing factor in the
evolution of complex songs by increasing the variance in male fitness. We
investigated this by quantifying the relationship between male song
performance and complexity and levels of paternity loss through extra-pair
mating by their female mates in the Grass Wren (Cistothorus platensis), a
socially monogamous passerine with elaborate songs. We conducted fieldwork
in the Uspallata Valley, Mendoza, Argentina, over two breeding seasons and
recorded the songs of 30 focal males during the egg-laying stage of their
social mate. We collected blood samples from adults and nestlings and used
ddRAD sequencing SNP data to determine parentage. We assessed extra-pair
mating behaviour of females by measuring paternity loss of their social
partner and examined whether variation in paternity loss was associated
with structural characteristics of that male’s songs. We found
relationships between paternity loss and song duration, syllable
diversity, and duty cycle. Our findings indicate that some specific traits
of male song are associated with lower levels of paternity loss and,
therefore, potentially higher fitness. Future studies should determine
whether this relationship is a result of female preference (intersexual
selection), effective male mate guarding or territory defence (intrasexual
selection), or both.