An official website of the United States government
Abstract AimThe Neotropics constitute the most biodiverse region of the world, yet its patterns of diversification and speciation differ among Neotropical areas and are not equally well understood. Particularly, avian evolutionary processes are understudied in the open habitats of temperate South America, where the role of glacial cycles is not clear. We analysed the evolutionary history of a Neotropical widespread bird species as a case study to evaluate its continental‐scale patterns and processes of diversification, with a focus on Patagonia. LocationOpen habitats of the Neotropics. TaxonVanellus chilensis(Aves, Charadriiformes). MethodsWe obtained reduced representation genomic and mitochondrial data from the four subspecies ofV. chilensisto perform a phylogenetic/phylogeographical analysis and study the evolutionary history of the species. We complemented these analyses with the study of vocalizations, a reproductive signal in birds. ResultsThe initial diversification event withinV. chilensis, approximately 600,000 years ago, split a Patagonian lineage from one containing individuals from the rest of the Neotropics. We found considerable gene flow between these two lineages and a contact zone in northern Patagonia, and showed that genomic admixture extends to northwestern Argentina. Shallower divergence was detected between the two non‐Patagonian subspecies, which are separated by the Amazon River. Vocalizations were significantly different between the two main lineages and were intermediate in their temporal and frequency characteristics in the contact zone. Main ConclusionsPatagonian populations ofV. chilensisare clearly differentiated from those of the rest of the Neotropics, possibly as a consequence of Pleistocene glaciations. A secondary contact zone in northern Patagonia with extensive gene flow among lineages appears to be the consequence of post‐glacial, northward expansion of the Patagonian populations. Future analyses focused on the dynamics of the contact zone will allow us to establish whether the species continues to diverge or is homogenizing.
more »
« less
This content will become publicly available on August 29, 2025
Genetic and phenotypic differentiation in Thamnophilus ruficapillus , a Neotropical passerine with disjunct distribution in the Andean and Atlantic forests
The Andean and Atlantic forests are separated by the open vegetation corridor, which acts as a geographic barrier. However, these forests experienced cycles of connection and isolation in the past, which shaped the phylogeographic patterns of their biotas. We analysed the evolutionary history of the rufous‐capped antshrikeThamnophilus ruficapillus, a species with a disjunct distribution in the Atlantic and Andean forests and thus an appropriate model to study the effect of the open vegetation corridor and the Andes on the diversification of the Neotropical avifauna. We performed a phylogenetic/phylogeographic analysis, including the five subspecies, using mitochondrial and nuclear genomic DNA, and studied their differences in vocalizations and plumage coloration. Both the mitochondrial and nuclear DNA evidenced a marked phylogeographic structure with three differentiated lineages that diverged without signs of gene flow in the Pleistocene (1.0–1.7 million years ago): one in the Atlantic Forest and two in the Andean forest. However, the two Andean lineages do not coincide with the two disjunct areas of distribution of the species in the Andes. Vocalizations were significantly different between most subspecies, but their pattern of differentiation was discordant with that of the nuclear and mitochondrial DNA. In fact, we did not find song differentiation between the subspecies of the Atlantic Forest and that of the northwestern Bolivian Andes, even though they differ genetically and belong to different lineages. Consistently, no differences were found in plumage coloration between the subspecies of the Atlantic Forest and that of the southern Andes. Our results suggest a complex evolutionary history in this species, which differentiated both due to dispersion across the open vegetation corridor, likely during a period of connection between the Andean and Atlantic forests, and the effect of the Bolivian Altiplano as a geographic barrier. In both cases, Pleistocene climatic oscillations appear to have influenced the species diversification.
more »
« less
- Award ID(s):
- 2232929
- PAR ID:
- 10548882
- Publisher / Repository:
- Wiley
- Date Published:
- Journal Name:
- Journal of Avian Biology
- ISSN:
- 0908-8857
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Chaetodipus nelsoni occurs on rocky substrates across the Mexican Altiplano. We investigated phylogeographic diversity within the species using morphologic, karyotypic, and molecular data. Data from nuclear (AFLP) and mitochondrial DNA support three distinct genetic groups with minimal substructuring coincident with biogeographic barriers previously identified in the Chihuahuan Desert and drainage basins of the Altiplano. We examined the morphological and karyotypic data in light of the molecular data. The results support recognition of three species within the currently accepted widespread C. nelsoni: 1) C. nelsoni restricted to a distribution centered on the El Salado River Basin; 2) elevation of C. n. collis to species, with two subspecies: one centered on Trans-Pecos Texas, the other on the Mapimí Basin (new subspecies); and 3) recognition of a new species, C. durangae, centered on the Nazas Basin and upper Río Mezquital drainage.more » « less
-
Lozier, Jeffrey (Ed.)Abstract Coloration is an important phenotypic trait for taxonomic studies and has been widely used for identifying insect species and populations. However, coloration can be a poor diagnostic character for insect species that exhibit high polymorphism in this trait, which can lead to over-splitting of taxonomic units. In orchid bees, color variation has been interpreted by different taxonomists as either polymorphism associated with Müllerian mimicry complexes or diagnostic traits for species identification. Despite this uncertainty, integrative approaches that incorporate multiple independent datasets to test the validity of hair coloration as a character that identifies independent evolutionary units have not been used. Here, we use phylogenomic data from Ultraconserved Elements (UCEs) to explore whether color phenotypes in the widespread orchid bee species complexes Eulaema meriana and Eulaema bombiformis (Hymenoptera: Apidae: Euglossini) correspond to independent lineages or polymorphic trait variation within species. We find that lineages within both species are structured according to geography and that color morphs are generally unassociated with evolutionarily independent groups except for populations located in the Atlantic Forest of Brazil. We conclude that there is compelling evidence that E. atleticana and E. niveofasciata are subspecies of E. meriana and E. bombiformis, respectively, and not different species as previously suggested. Therefore, we recognize Eulaema meriana atleticanacomb. n. and Eulaema bombiformis niveofasciatacomb. n. and discuss their morphological characteristics. We make recommendations on the use of color traits for orchid bee taxonomy and discuss the significance of subspecies as evolutionary units relevant for conservation efforts.more » « less
-
The impacts of the interdecadal variability of the Pacific and the Atlantic Oceans on precipitation over the Central Andes during the austral summer (December-January-February, DJF) are investigated for the 1921–2010 period based on monthly gridded precipitation data and low-pass filtered time series of the Niño 4 index (IN4), the Niño 1 + 2 index with Niño 3.4 index removed (IN1+2 * ), Atlantic Multidecadal Oscillation (AMO), and Interdecadal Pacific Oscillation (IPO) indices, and the three first rotated principal components of the interdecadal component of the sea surface temperature (SST) anomalies over the Atlantic Ocean. A rotated empirical orthogonal function (REOF) analysis of precipitation in the Central Andes (10°S–30°S) yields two leading modes, RPC1 and RPC2, which represent 40.4% and 18.6% of the total variance, respectively. REOF1 features a precipitation dipole between the northern Bolivian and the Chilean Altiplano. REOF2 also features a precipitation dipole, with highest negative loading over the southern Peruvian Andes. The REOF1 positive phase is associated with moisture transport from the lowlands toward the Bolivian Altiplano, induced by upper-level easterly wind anomalies over the Central Andes. At the same time conditions tend to be dry over the southern Peruvian Andes. The positive phase of REOF2 is related to weakened moisture transport, induced by upper-level westerly wind anomalies over Peru. The IPO warm phase induces significant dry anomalies over the Bolivian Altiplano, albeit weaker than during the IN4 warm phase, via upper-level westerly wind anomalies over the Central Andes. No significant relationship was found between Central Andean precipitation and the AMO on interdecadal timescales.more » « less
-
Abstract The South American Dry Diagonal, also called the Diagonal of Open Formations, is a large region of seasonally dry vegetation extending from northeastern Brazil to northern Argentina, comprising the Caatinga, Cerrado, and Chaco subregions. A growing body of phylogeography literature has determined that a complex history of climatic changes coupled with more ancient geological events has produced a diverse and endemic‐rich Dry Diagonal biota. However, the exact drivers are still under investigation, and their relative strengths and effects are controversial. Pleistocene climatic fluctuations structured lineages via vegetation shifts, refugium formation, and corridors between the Amazon and Atlantic forests. In some taxa, older geological events, such as the reconfiguration of the São Francisco River, uplift of the Central Brazilian Plateau, or the Miocene inundation of the Chaco by marine incursions, were more important. Here, we review the Dry Diagonal phylogeography literature, discussing each hypothesized driver of diversification and assessing degree of support. Few studies statistically test these hypotheses, with most support drawn from associating encountered phylogeographic patterns such as population structure with the timing of ancient geoclimatic events. Across statistical studies, most hypotheses are well supported, with the exception of the Pleistocene Arc Hypothesis. However, taxonomic and regional biases persist, such as a proportional overabundance of herpetofauna studies, and the under‐representation of Chaco studies. Overall, both Pleistocene climate change and Neogene geological events shaped the evolution of the Dry Diagonal biota, though the precise effects are regionally and taxonomically varied. We encourage further use of model‐based analyses to test evolutionary scenarios, as well as interdisciplinary collaborations to progress the field beyond its current focus on the traditional set of geoclimatic hypotheses.more » « less
