Data from: Genotype predicts quantitative song variety in a chickadee hybrid zone despite limited sampling

In the avian sub-order Passeri (the songbirds), song develops according to
both a flexible neural template and auditory input from conspecifics,
making innately-constrained characters of song difficult to isolate. In a
hybridizing population of Black-capped Chickadees (Poecile atricapillus)
and Carolina Chickadees (Poecile carolinensis), we found that genetic
ancestry was weakly predictive of a multidimensional measure of song
variety (a continuously distributed quantitative alternative to
categorical song repertoire size) but did not successfully predict
one-dimensional song variety. We used species-diagnostic autosomal markers
to genotype 55 individuals inside and outside of the Black-capped
Chickadee/Carolina Chickadee hybrid zone in Missouri and Kansas. Using
active recording methods, we then obtained high-volume, high-quality song
recordings of 10 genotyped chickadees from a single hybrid zone population
on a small, lake-bounded peninsula in west-central Missouri. We extracted
acoustic data from these recordings to generate measurements of song
variety across one, two and three dimensions of multivariate acoustic
space for each individual. We tested how well, and in what direction,
genetic ancestry predicted song variety for each of these
dimensionalities, after predicting that song variety would increase with
Carolina Chickadee ancestry. Linear models predicting song variety in two
and three dimensions from genetic ancestry ranging from carolinensis-like
backcrosses to pure carolinensis explained 41% and 43% of the variation
respectively, with slope values in the predicted direction. A linear model
predicting song variety in one dimension from genetic ancestry explained
12% of the variation. Our results are suggestive but not conclusive of
genetic predispositions for song variety. Our findings provide support for
the continued use of multidimensional song variety measurements and offer
future directions for tackling the question of the genotype-song
relationship in hybrid zones between species with vocal learning.