ALBERT

Description: Grasslands in southern South America are extensive ecosystems which harbor a unique biodiversity; however, studies on the evolution of their taxa are scarce. Here we studied the phylogeography and population history of the Correndera Pipit (Anthus correndera), a grassland specialist bird with a large breeding distribution in southern South America, with the goals of investigating its phylogeographic history and relate it to the historical development of South American grasslands. The mitochondrial NADH dehydrogenase subunit II gene (ND2) was sequenced in 66 individuals from 19 localities and the intron 9 of the sex-linked gene for aconitase (ACOI9) was sequenced from a subset of those individuals, including all five subspecies of A. correndera, as well as the closely related A. antarcticus. Phylogenetic analysis revealed two distinct lineages within the complex: the first (A) corresponding to Andean subspecies A. c. calcaratus and A. c. catamarcae and the second (B) including birds traditionally assigned to A. c. correndera, A. c. chilensis, A. c. grayi and some individuals of A. c. catamarcae. A. antarcticus is nested within this second lineage. These results were also supported by evidence of niche divergence for variables associated with precipitation. The oldest split between clade A and B was estimated at c. 0.37 Mya, during the middle Pleistocene. Species distribution models for the present and the Last Glacial Maximum (LGM) suggest that grassland areas in southern South America remained relatively stable, in contrast to the general view of a reduction in grassland cover in South America since the LGM. Recent divergences and low phylogeographic structure (for lowland vs. highland geographic groups, intra-population genetic variance was greater than inter-groups; e.g., for ACOI9: 95.47% and ND2: 51.51% respectively), suggest widespread gene flow between lowland populations.

Description: The ground beetle genus Ceroglossus contains co-distributed species that show pronounced intraspecific diversity in the form of geographical colour morphs. While colour morphs among different species appear to match in some geographical regions, in others, there is little apparent colour matching. Mimicry is a potential explanation for covariation in colour patterns, but it is not clear whether the degree of sympatric colour matching is higher than expected by chance given the obvious mismatches among morphs in some regions. Here, we used reflectance spectrometry to quantify elytral coloration from the perspective of an avian predator to test whether colour similarity between species is, indeed, higher in sympatry. After finding no significant phylogenetic signal in the colour data, analyses showed strong statistical support for sympatric colour similarity between species despite the apparent lack of colour matching in some areas. We hypothesize Müllerian mimicry as the responsible mechanism for sympatric colour similarity in Ceroglossus and discuss potential explanations and future directions to elucidate why mimicry has not developed similar levels of interspecific colour resemblance across space.

Description: The Antarctic Circumpolar Current (ACC) dominates the open-ocean circulation of the Southern Ocean, and both isolates and connects the Southern Ocean biodiversity. However, the impact on biological processes of other Southern Ocean currents is less clear. Adjacent to the West Antarctic Peninsula (WAP), the ACC flows offshore in a northeastward direction, whereas the Antarctic Peninsula Coastal Current (APCC) follows a complex circulation pattern along the coast, with topographically influenced deflections depending on the area. Using genomic data, we estimated genetic structure and migration rates between populations of the benthic bivalve Aequiyoldia eightsii from the shallows of southern South America and the WAP to test the role of the ACC and the APCC in its dispersal. We found strong genetic structure across the ACC (between southern South America and Antarctica) and moderate structure between populations of the WAP. Migration rates along the WAP were consistent with the APCC being important for species dispersal. Along with supporting current knowledge about ocean circulation models at the WAP, migration from the tip of the Antarctic Peninsula to the Bellingshausen Sea highlights the complexities of Southern Ocean circulation. This study provides novel biological evidence of a role of the APCC as a driver of species dispersal and highlights the power of genomic data for aiding in the understanding of the influence of complex oceanographic processes in shaping the population structure of marine species.

Description: Advances in phylogenomics contribute toward resolving long-standing evolutionary questions. Notwithstanding, genetic diversity contained within more than a billion biological specimens deposited in natural history museums remains recalcitrant to analysis owing to challenges posed by its intrinsically degraded nature. Yet that tantalizing resource could be critical in overcoming taxon sampling constraints hindering our ability to address major evolutionary questions. We addressed this impediment by developing phyloHyRAD, a new bioinformatic pipeline enabling locus recovery at a broad evolutionary scale from HyRAD-X exome capture of museum specimens of low DNA integrity using a benchtop RAD-derived exome-complexity-reduction probe set developed from high DNA integrity specimens. Our new pipeline can also successfully align raw RNAseq transcriptomic and ultraconserved element reads with the RAD-derived probe catalog. Using this method, we generated a robust timetree for Carabinae beetles, the lack of which had precluded study of macroevolutionary trends pertaining to their biogeography and wing-morphology evolution. We successfully recovered up to 2,945 loci with a mean of 1,788 loci across the exome of specimens of varying age. Coverage was not significantly linked to specimen age, demonstrating the wide exploitability of museum specimens. We also recovered fragmentary mitogenomes compatible with Sanger-sequenced mtDNA. Our phylogenomic timetree revealed a Lower Cretaceous origin for crown group Carabinae, with the extinct Aplothorax Waterhouse, 1841 nested within the genus Calosoma Weber, 1801 demonstrating the junior synonymy of Aplothorax syn. nov., resulting in the new combination Calosomaburchellii (Waterhouse, 1841) comb. nov. This study compellingly illustrates that HyRAD-X and phyloHyRAD efficiently provide genomic-level data sets informative at deep evolutionary scales.