In ancient cultures without a writing system, it is difficult to infer the basis of status and rank. Here the authors analyse ancient DNA from nine presumed elite individuals buried successively over a 300-year period at Chaco Canyon, and show evidence of matrilineal rela…

Mutations in mtDNA lead to muscular and neurological diseases and are linked to aging. The most frequent aberrancy is the “common deletion” that involves a 4,977-bp region flanked by 13-bp repeats. To investigate the basis of this deletion, we developed a single-molecule mtDNA combing method. The analysis of replicating mtDNA molecules provided in vivo evidence in support of the asymmetric mode of replication. Furthermore, we observed frequent fork stalling at the junction of the common deletion, suggesting that impaired replication triggers the formation of this toxic lesion. In parallel experiments, we employed mito-TALENs to induce breaks in distinct loci of the mitochondrial genome and found that breaks adjacent to the 5′ repeat trigger the common deletion. Interestingly, this process was mediated by the mitochondrial replisome independent of canonical DSB repair. Altogether, our data underscore a unique replication-dependent repair pathway that leads to the mitochondrial common deletion.

Although hybridisation through genome duplication is well known, hybridisation without genome duplication (homoploid hybrid speciation, HHS) is not. Few well-documented cases have been reported. A possible instance of HHS in Medicago prostrata Jacq. was suggested previously, based on only two genes and one individual. We tested whether this species was formed through HHS by sampling eight nuclear loci and 22 individuals, with additional individuals from related species, using gene capture and Illumina sequencing. Phylogenetic inference and coalescent simulations were performed to infer the causes of gene tree incongruence. We found no evidence that phylogenetic differences among M. prostrata individuals were the result of HHS. Instead, an autopolyploid origin of tetraploids with introgression from tetraploids of the M. sativa complex is likely. We argue that tetraploid M. prostrata individuals constitute a new species, characterised by a partially non-overlapping distribution and distinctive alleles (from the M. sativa complex). No gene flow from tetraploid to diploid M. prostrata is apparent, suggesting partial reproductive isolation. Thus, speciation via autopolyploidy appears to have been reinforced by introgression. This raises the intriguing possibility that introgressed alleles may be responsible for the increased range exploited by tetraploid M. prostrata with respect to that of the diploids.

The microhylid frog genus Kaloula is an adaptive radiation spanning the edge of the Asian mainland and multiple adjacent island archipelagos, with much of the clade’s diversity associated with an endemic Philippine radiation. Relationships among clades from the Philippines, however, remain unresolved. With ultraconserved element (UCE) and mitogenomic data, we identified highly supported differences in topology and areas of poor resolution, for each marker set. Using the UCE data, we then identified possible instances of contemporary hybridization, past introgression, and incomplete lineage sorting (ILS) within the Philippine Kaloula. Using a simulation approach, and an estimate of the Philippine Kaloula clade origin (12.7—21.0 mya), we demonstrate that an evolutionary history including inferred instances of hybridization, introgression, and ILS leads to phylogenetic reconstructions that show concordance with results from the observed mitogenome and UCE data. In the process of validating a complex evolutionary scenario in the Philippine Kaloula, we provide the first demonstration of the efficacy of UCE data for phylogenomic studies of anuran amphibians.

The Adelaide geosyncline, a mountainous region in central southern Australia, is purported to be an important continental refugium for Mediterranean and semi-arid Australian biota, yet few population genetic studies have been conducted to test this theory. Here, we focus on a plant species distributed widely throughout the region, the narrow-leaf hopbush, Dodonaea viscosa ssp. angustissima, and examine its genetic diversity and population structure. We used a hybrid-capture target enrichment technique to selectively sequence over 700 genes from 89 individuals across 17 sampling locations. We compared 815 single nucleotide polymorphisms among individuals and populations to investigate population genetic structure. Three distinct genetic clusters were identified; a Flinders/Gammon ranges cluster, an Eastern cluster, and a Kangaroo Island cluster. Higher genetic diversity was identified in the Flinders/Gammon Ranges cluster, indicating that this area is likely to have acted as a refugium during past climate oscillations. We discuss these findings and consider the historical range dynamics of these populations. We also provide methodological considerations for population genomics studies that aim to use novel genomic approaches (such as target capture methods) on non-model systems. The application of our findings to restoration of this species across the region are also considered.

New sequencing technologies are providing a large-scale proliferation of sequence data, including complete mitochondrial genomes as a side effect of target capture methods. In this study, we use massively parallel sequencing to provide the nearly complete mitochondrial genome of the ant Octostruma stenognatha. The annotation of the genome revealed an interesting pattern that agrees with a recent deep reorganization in the systematics within the Formicidae family. This is the first mitogenome for the genus in a lineage, where the scarcity of mitochondrial information has restricted our understanding of its evolutionary history. This is a valuable example of the power and velocity with which products from new sequencing technologies can increase our capacity to understand evolutionary biology, especially in non-model species.

Understanding both the role of selection in driving phenotypic change and its underlying genetic basis remain major challenges in evolutionary biology. Here, we use modern tools to revisit a classic system of local adaptation in the North American deer mouse, Peromyscus maniculatus, which occupies two main habitat types: prairie and forest. Using historical collections, we find that forest-dwelling mice have longer tails than those from nonforested habitat, even when we account for individual and population relatedness. Using genome-wide SNP data, we show that mice from forested habitats in the eastern and western parts of their range form separate clades, suggesting that increased tail length evolved independently. We find that forest mice in the east and west have both more and longer caudal vertebrae, but not trunk vertebrae, than nearby prairie forms. By intercrossing prairie and forest mice, we show that the number and length of caudal vertebrae are not correlated in this recombinant population, indicating that variation in these traits is controlled by separate genetic loci. Together, these results demonstrate convergent evolution of the long-tailed forest phenotype through two distinct genetic mechanisms, affecting number and length of vertebrae, and suggest that these morphological changes—either independently or together—are adaptive.

Museum specimens provide a wealth of information to biologists, but obtaining genetic data from formalin-fixed and fluid-preserved specimens remains challenging. While DNA sequences have been recovered from such specimens, most approaches are time-consuming and produce low data quality and quantity. Here, we use a modified DNA extraction protocol combined with high-throughput sequencing to recover DNA from formalin-fixed and fluid-preserved snakes that were collected over a century ago and for which little or no modern genetic materials exist in public collections. We successfully extracted DNA and sequenced ultraconserved elements (x¯ = 2318 loci) from 10 fluid-preserved snakes and included them in a phylogeny with modern samples. This phylogeny demonstrates the general use of such specimens in phylogenomic studies and provides evidence for the placement of enigmatic snakes, such as the rare and never-before sequenced Indian Xylophis stenorhynchus. Our study emphasizes the relevance of museum collections in modern research and simultaneously provides a protocol that may prove useful for specimens that have been previously intractable for DNA sequencing.

Cell-free transcription-translationplatforms havebeen widely utilized to express soluble proteins in basic synthetic biological circuit prototyping. From asynthetic biology point of view, it is critical to express membrane proteins in cell-freetranscription-translationsystems, and use them directly in biocircuits,considering the fact that histidine kinases, G-protein coupled receptors (GPCRs) and other important biosensors are all membraneproteins.Previous studies have expressed membrane proteins in cell-free systems with the help of detergents, liposomes or nanodiscs, but have not demonstrated the ability to prototype circuit behavior for the purpose of testing more complex circuit functions involving membrane-bound proteins. Built on previous efforts, in this work we demonstrated that we could co-translationally express solubilizedand activemembrane proteins in our cell-free TX-TL platform with membrane-like materials. Wefirsttested the expression ofseveral constructs with β1 and β2 adrenergicreceptorsin TX-TL and observed significantinsoluble membraneprotein production.The addition ofnanodiscs to the cell free expression system enabled solubilization of membrane proteins. Nanodisc is lipoprotein-based membrane-like material. The activity of β2 adrenergicreceptor was tested withboth fluorescence and Surface Plasmon Resonance (SPR) binding assays by monitoring the specific binding response ofsmall-molecule binders, carazolol and norepinephrine.Our results suggest that it is promisingto use cell-free expression systems to prototype synthetic biocircuits involvingsingle chain membrane proteinswithout extra procedures. This data made us one step closer to testingcomplex membrane protein circuits in cell-free environment.

Standard phylogenetic methods produce conflicting results for several parts of the tree of life. Here, a new phylogenomic method is presented, which resolves controversial relationships within the Otophysi freshwater fish and several other recalcitrant groups.