Katy E. Klymus

AFLP markers resolve intra-specific relationships and infer genetic structure among lineages of the canyon treefrog, Hyla arenicolor

The canyon treefrog, Hyla arenicolor, is a wide-ranging hylid found from southwestern US into southern Mexico. Recent studies have shown this species to have a complex evolutionary history, with several phylogeographically distinct lineages, a probable cryptic species, and multiple episodes of mitochondrial introgression with the sister group, the H. eximia complex. We aimed to use genome wide AFLP markers to better resolve relationships within this group. As in other studies, our inferred phylogeny not only provides evidence for repeated mitochondrial introgression between H. arenicolor lineages and H. eximia/H. wrightorum, but it also affords more resolution within the main H. arenicolor clade than was previously achieved with sequence data. However, as with a previous study, the placement of a lineage of H. arenicolor whose distribution is centered in the Balsas Basin of Mexico remains poorly resolved, perhaps due to past hybridization with the H. eximia complex. Furthermore, the AFLP data set shows no differentiation among lineages from the Grand Canyon and Colorado Plateau despite their large mitochondrial sequence divergence. Finally, our results infer a well-supported sister relationship between this combined Colorado Plateau/Grand Canyon lineage and the Sonoran Desert lineage, a relationship that strongly contradicts conclusions drawn from the mtDNA evidence. Our study provides a basis for further behavioral and ecological speciation studies of this system and highlights the importance of multi-taxon (species) sampling in phylogenetic and phylogeographic studies.

Behavioral and phylogenetic differentiation in a potential cryptic species complex, the canyon treefrog

Detection of genetic and behavioral diversity within morphologically similar species has led to the discovery of cryptic species complexes. We tested the hypothesis that the canyon treefrog (Hyla arenicolor) may consist of cryptic species by examining mate-attraction signals among highly divergent lineages defined by mitochondrial DNA (mtDNA). Unexpectedly, calls exhibited little variation among the three U.S. lineages despite large mtDNA sequence divergences. We re-analyzed intraspecific and interspecific phylogenetic relationships by sequencing both mitochondrial and nuclear genetic markers among populations and a closely related, but morphologically and behaviorally different species, the Arizona treefrog (H. wrightorum). Discordance between mitochondrial and nuclear datasets suggests multiple instances of introgression of H. wrightorums mitochondrial genome into populations of H. arenicolor. Furthermore, intraspecific population structure based on nuclear markers shows better congruence with patterns...