Diversification of a polyploid complex: the biogeography and acoustic communication evolution of North American gray treefrogs throughout the Quaternary

Polyploid speciation and whole genome duplications are major drivers of
biological diversity. After polyploid species are formed, the interactions
between diploid and polyploid lineages may generate additional diversity
in novel cytotypes and phenotypes. In anurans, mate choice by acoustic
communication is the primary method by which individuals identify their
own species and assess suitable mates. As such, the evolution of acoustic
signals is an important mechanism for contributing to reproductive
isolation and diversification in this group. The North American gray
treefrog complex, consisting of the diploid Hyla chrysoscelis and
the tetraploid Hyla versicolor, has long been used to study reproductive
isolation and research on this system has consistently driven this field
forward. Here, we estimate the biogeographic history of this group,
focusing specifically on the geographic origin of whole genome duplication
and the expansion of lineages out of refugia following climate
oscillations and retreats of the Laurentide ice sheet. We then test for
lineage-specific differences in mating signals by applying comparative
methods to a large acoustic data set collected over 52 years that includes
>1500 individual frogs. Finally, we expand upon our results in
light of recent estimates of the complex’s genomic evolution to describe
the history of diversification in gray treefrogs throughout the
Quaternary.