Biology subjects

Bauernfeind, S. M.

Publications and source records attributed to Bauernfeind, S. M..

3 recordsLinked to original sources

bioRxiv2026

Asymmetric gene flow across a desert contact zone in a riparian songbird

Secondary contact is a key point in the speciation process, and fine-scale geography can shape its outcomes. This is especially true for species restricted to fragmented habitats, such as riparian corridors through arid regions. Here we examine the role of disjunct riparian habitat in shaping secondary contact in Bells Vireo (Vireo bellii), a North American songbird species that contains distinct eastern and western forms. We recovered a unique, discontinuous contact zone along the Rio Grande in New Mexico, where two populations with greater nuclear and mitochondrial genetic affinity for the eastern lineage are separated by a population with an affinity for the western lineage. This point of primarily western ancestry on the Rio Grande corresponded with a stretch where several intermittently flowing tributaries join from the west and may have acted as gene flow corridors. Using a combination of empirical analyses of divergence and diversity across the genome and population genetic simulations, we uncovered evidence of neutral, genome-wide admixture driving the genomic architecture of divergence, rather than evidence for local adaptation or selective sweeps. In sum, this genomic study showed us how fine-scale dispersal corridors can cause idiosyncratic patterns of admixture when habitat is limiting in zones of secondary contact.

evolutionary biology↗

bioRxiv2024

Taxonomy and nomenclature of the giant hummingbirds (Patagona spp.) (Aves: Trochilidae)

Giant hummingbirds (Patagona spp.) are extraordinarily large hummingbirds whose taxonomy has been muddled for two centuries. Patagona systematics were recently redefined in a study of migration, physiology, and genomics, revealing two species: the Southern Giant Hummingbird and Northern Giant Hummingbird. Here, we re-evaluate taxonomy and nomenclature of the genus in light of its newly-clarified biology and species limits, analyzing data from 608 specimens and wild-caught individuals spanning 1864-2023. The forms gigas and peruviana were both described based on multiple syntypes. No adequate syntypes for P. gigas are extant, so we designate a neotype for this taxon. We then critically consider the identity and usage of gigas and peruviana, respectively, and examine identification challenges that have fostered taxonomic uncertainty. We endorse the names Patagona gigas for the Southern Giant Hummingbird and P. peruviana for the Northern Giant Hummingbird. The genetic identity of the peruviana lectotype remains untested, but its plumage appears to match the northern species. We found that [~]33% of Patagona gigas specimens in major museum collections are misidentified as peruviana; we provide this list to correct the historical record. To facilitate identification and future study of these two cryptic species, we provide comprehensive information on plumage, measurements, and seasonal ranges.

zoology↗

bioRxiv2020

Detecting turnover among complex communities using null models: A case study with sky-island haemosporidian parasites

Turnover in species composition between sites, or beta diversity, is a critical component of species diversity that is typically influenced by geography, environment, and biotic interactions. Quantifying turnover is particularly challenging, however, in multi-host, multi-parasite assemblages where undersampling is unavoidable, resulting in inflated estimates of turnover and uncertainty about its spatial scale. We developed and implemented a framework using null models to test for community turnover in avian haemosporidian communities of three sky islands in the southwestern United States. We screened 776 birds for haemosporidian parasites from three genera (Parahaemoproteus, Plasmodium, and Leucocytozoon) by amplifying and sequencing a mitochondrial DNA barcode. We detected infections in 280 birds (36.1%), sequenced 357 infections, and found a total of 99 parasite haplotypes. When compared to communities simulated from a regional pool, we observed more unique, single-mountain haplotypes and fewer haplotypes shared among three mountain ranges than expected, indicating that haemosporidian communities differ to some degree among adjacent mountain ranges. These results were robust even after pruning datasets to include only identical sets of host species, and they were consistent for two of the three haemosporidian genera. The two more distant mountain ranges were more similar to each other than the one located centrally, suggesting that the differences we detected were due to stochastic colonization-extirpation dynamics. These results demonstrate that avian haemosporidian communities of temperate-zone forests differ on relatively fine spatial scales associated with adjacent sky-islands. Null models are essential tools for detecting turnover in complex, undersampled, and poorly known systems.

ecology↗