Saber-toothed cats (Machairodontinae) are among the most widely recognized representatives of the now largely extinct Pleistocene megafauna. However, many aspects of their ecology, evolution, and extinction remain uncertain. Although ancient-DNA studies have led to huge advances in our knowledge of these aspects of many other megafauna species (e.g., mammoths and cave bears), relatively few ancient-DNA studies have focused on saber-toothed cats [ 1–3 ], and they have been restricted to short fragments of mitochondrial DNA. Here we investigate the evolutionary history of two lineages of saber-toothed cats (Smilodon and Homotherium) in relation to living carnivores and find that the Machairodontinae form a well-supported clade that is distinct from all living felids. We present partial mitochondrial genomes from one S. populator sample and three Homotherium sp. samples, including the only Late Pleistocene Homotherium sample from Eurasia [ 4 ]. We confirm the identification of the unique Late Pleistocene European fossil through ancient-DNA analyses, thus strengthening the evidence that Homotherium occurred in Europe over 200,000 years later than previously believed. This in turn forces a re-evaluation of its demography and extinction dynamics. Within the Machairodontinae, we find a deep divergence between Smilodon and Homotherium (∼18 million years) but limited diversity between the American and European Homotherium specimens. The genetic data support the hypothesis that all Late Pleistocene (or post-Villafrancian) Homotherium should be considered a single species, H. latidens, which was previously proposed based on morphological data [ 5, 6 ].

Summary Situated at the furthest northeastern edge of Canada, the island of Newfoundland (approximately 110,000 km2) and Labrador (approximately 295,000 km2) today constitute a province characterized by abundant natural resources but low population density. Both landmasses were covered by the Laurentide ice sheet during the Last Glacial Maximum (18,000 years before present [YBP]); after the glacier retreated, ice patches remained on the island until ca. 9,000 calibrated (cal) YBP [1]. Nevertheless, indigenous peoples, whose ancestors had trekked some 5,000 km from the west coast, arrived approximately 10,000 cal YBP in Labrador and ca. 6,000 cal YBP in Newfoundland [2, 3]. Differential features in material culture indicate at least three settlement episodes by distinct cultural groups, including the Maritime Archaic, Palaeoeskimo, and Beothuk. Newfoundland has remained home to indigenous peoples until present day with only one apparent hiatus (3,400–2,800 YBP). This record suggests abandonment, severe constriction, or local extinction followed by subsequent immigrations from single or multiple source populations, but the specific dynamics and the cultural and biological relationships, if any, among these successive peoples remain enigmatic [4]. By examining the mitochondrial genome diversity and isotopic ratios of 74 ancient remains in conjunction with the archaeological record, we have provided definitive evidence for the genetic discontinuity between the maternal lineages of these populations. This northeastern margin of North America appears to have been populated multiple times by distinct groups that did not share a recent common ancestry, but rather one much deeper in time at the entry point into the continent.

The curse of ancient Egyptian DNA was lifted by a recent study which sequenced the mitochondrial genomes (mtGenome) of 90 ancient Egyptians from the archaeological site of Abusir el-Meleq. Surprisingly, these ancient inhabitants were more closely related to those from the Near East than to contemporary Egyptians. It has been accepted that the timeless highway of the Nile River seeded Egypt with African genetic influence, well before pre-Dynastic times. Here we report on the successful recovery and analysis of the complete mtGenome from a burial recovered from a remote Romano–Christian cemetery, Kellis 2 (K2). K2 serviced the ancient municipality of Kellis, a village located in the Dakhleh Oasis in the southwest desert in Egypt. The data were obtained by high throughput sequencing (HTS) performed independently at two ancient DNA facilities (Armed Forces DNA Identification Laboratory, Dover, DE, USA and Carl R. Woese Institute for Genomic Biology, University of Illinois Urbana-Champaign, Urbana, IL, USA). These efforts produced concordant haplotypes representing a U1a1a haplogroup lineage. This result indicates that Near Eastern maternal influence previously identified at Abusir el-Meleq was also present further south, in ancient Kellis during the Romano–Christian period.

Accurate time-calibrated phylogenies are the centerpiece of many macroevolutionary studies, and the relationship between the size and scale of molecular data sets and the density and accuracy of fossil calibrations is a key element of time tree studies. Here, we develop a target capture array specifically for living turtles, compare its efficiency to an ultraconserved element (UCE) dataset, and present a time-calibrated molecular phylogeny based on 539 nuclear loci sequenced from 26 species representing the breadth of living turtle diversity plus outgroups. Our gene array, based on three fully sequenced turtle genomes, is 2.4 times more variable across turtles than a recently published UCE data set for an identical subset of 13 species, confirming that taxon-specific arrays return more informative data per sequencing effort than UCEs. We used our genomic data to estimate the ages of living turtle clades including a mid-late Triassic origin for crown turtles and a mid-Carboniferous split of turtles from their sister group, Archosauria. By specifically excluding several of the earliest potential crown turtle fossils and limiting the age of fossil calibration points to the unambiguous crown lineage Caribemys oxfordiensis from the Late Jurassic (Oxfordian, 163.5–157.3Ma) we corroborate a relatively ancient age for living turtles. We also provide novel age estimates for five of the ten testudine families containing more than a single species, as well as several intrafamilial clades. Most of the diversity of crown turtles appears to date to the Paleogene, well after the Cretaceous-Paleogene mass extinction 66mya.

The taxonomy of American deer has been established almost entirely on the basis of morphological data and without the use of explicit phylogenetic methods; hence, phylogenetic analyses including data for all of the currently recognized species, even if based on a single gene, might improve current understanding of their taxonomy. We tested the monophyly of the morphology-defined genera and species of New World deer (Odocoileini) with phylogenetic analyses of mitochondrial DNA sequences. This is the first such test conducted using extensive geographic and taxonomic sampling. Our results do not support the monophyly of Mazama, Odocoileus, Pudu, M. americana, M. nemorivaga, Od. hemionus, and Od. virginianus. Mazama contains species that belong to other genera. We found a novel sister-taxon relationship between “Mazama” pandora and a clade formed by Od. hemionus columbianus and Od. h. sitkensis, and transfer pandora to Odocoileus. The clade formed by Od. h. columbianus and Od. h. sitkensis may represent a valid species, whereas the remaining subspecies of Od. hemionus appear closer to Od. virginianus. Pudu (Pudu) puda was not found sister to Pudu (Pudella) mephistophiles. If confirmed, this result will prompt the recognition of the monotypic Pudella as a distinct genus. We provide evidence for the existence of an undescribed species now confused with Mazama americana, and identify other instances of cryptic, taxonomically unrecognized species-level diversity among populations here regarded as Mazama temama, “Mazama” nemorivaga, and Hippocamelus antisensis. Noteworthy records that substantially extend the known distributions of M. temama and “M.” gouazoubira are provided, and we unveil a surprising ambiguity regarding the distribution of “M.” nemorivaga, as it is described in the literature. The study of deer of the tribe Odocoileini has been hampered by the paucity of information regarding voucher specimens and the provenance of sequences deposited in GenBank. We pinpoint priorities for future systematic research on the tribe Odocoileini., The taxonomy of American deer has been established almost entirely on the basis of morphological data and without the use of explicit phylogenetic methods; hence, phylogenetic analyses including data for all of the currently recognized species, even if based on a single gene, might improve current understanding of their taxonomy. We tested the monophyly of the morphology-defined genera and species of New World deer (Odocoileini) with phylogenetic analyses of mitochondrial DNA sequences. This is the first such test conducted using extensive geographic and taxonomic sampling. Our results do not support the monophyly of Mazama, Odocoileus, Pudu, M. americana, M. nemorivaga, Od. hemionus, and Od. virginianus. Mazama contains species that belong to other genera. We found a novel sister-taxon relationship between “Mazama” pandora and a clade formed by Od. hemionus columbianus and Od. h. sitkensis, and transfer pandora to Odocoileus. The clade formed by Od. h. columbianus and Od. h. sitkensis may represent a valid species, whereas the remaining subspecies of Od. hemionus appear closer to Od. virginianus. Pudu (Pudu) puda was not found sister to Pudu (Pudella) mephistophiles. If confirmed, this result will prompt the recognition of the monotypic Pudella as a distinct genus. We provide evidence for the existence of an undescribed species now confused with Mazama americana, and identify other instances of cryptic, taxonomically unrecognized species-level diversity among populations here regarded as Mazama temama, “Mazama” nemorivaga, and Hippocamelus antisensis. Noteworthy records that substantially extend the known distributions of M. temama and “M.” gouazoubira are provided, and we unveil a surprising ambiguity regarding the distribution of “M.” nemorivaga, as it is described in the literature. The study of deer of the tribe Odocoileini has been hampered by the paucity of information regarding voucher specimens and the provenance of sequences deposited in GenBank. We pinpoint priorities for future systematic research on the tribe Odocoileini.

Short tandem repeat (STR) variants are highly polymorphic markers that facilitate powerful population genetic analyses. STRs are especially valuable in conservation and ecological genetic research, yielding detailed information on population structure and short-term demographic fluctuations. Massively parallel sequencing has not previously been leveraged for scalable, efficient STR recovery. Here, we present a pipeline for developing STR markers directly from high-throughput shotgun sequencing data without a reference genome, and an approach for highly parallel target STR recovery. We employed our approach to capture a panel of 5000 STRs from a test group of diademed sifakas (Propithecus diadema, n = 3), endangered Malagasy rainforest lemurs, and we report extremely efficient recovery of targeted loci—97.3–99.6% of STRs characterized with ≥10x non-redundant sequence coverage. We then tested our STR capture strategy on P. diadema fecal DNA, and report robust initial results and suggestions for future implementations. In addition to STR targets, this approach also generates large, genome-wide single nucleotide polymorphism (SNP) panels from flanking regions. Our method provides a cost-effective and scalable solution for rapid recovery of large STR and SNP datasets in any species without needing a reference genome, and can be used even with suboptimal DNA more easily acquired in conservation and ecological studies.

Escherichia coli cell-free transcription-translation (TXTL) systems offer versatile platforms for advanced biomanufacturing and for prototyping synthetic biological parts and devices. Production and testing could be accelerated with the use of linear DNA, which can be rapidly and cheaply synthesized. However, linear DNA is efficiently degraded in TXTL preparations from E. coli. Here, we show that double-stranded DNA encoding χ sites-eight base-pair sequences preferentially bound by the RecBCD recombination machinery-stabilizes linear DNA and greatly enhances the TXTL-based expression and activity of a fluorescent reporter gene, simple regulatory cascades, and T7 bacteriophage particles. The χ-site DNA and the DNA-binding λ protein Gam yielded similar enhancements, and DNA with as few as four χ sites was sufficient to ensure robust gene expression in TXTL. Given the affordability and scalability of producing the short χ-site DNA, this generalized strategy is expected to advance the broad use of TXTL systems across its many applications. Biotechnol. Bioeng. 2017;114: 2137-2141. © 2017 Wiley Periodicals, Inc.

Adaptive radiations could often occur in discrete stages. For instance, the species flock of ∼1000 species of Lake Malawi cichlid fishes might have only diverged once between rocky and sandy environments during the initial stage of their diversification. All further diversification within the rock-dwelling (mbuna) or sand-dwelling (utaka) cichlids would have occurred during a subsequent second stage of extensive trophic evolution that was followed by a third stage of sexual trait divergence. We provide an improved phylogenetic framework for Malawi cichlids to test this three-stage hypothesis based on newly reconstructed phylogenetic relationships among 32 taxonomically disparate Malawi cichlids species. Using several reconstruction methods and 1037 ultra-conserved element (UCE) markers, we recovered a molecular phylogeny that confidently resolved relationships among most of the Malawi lineages sampled when a bifurcating framework was enforced. These bifurcating reconstructions also indicated that the sand-dwelling species Cyathochromis obliquidens was well-nested within the primarily rock-dwelling radiation known as the mbuna. In contrast to predictions from the three-stage model of vertebrate diversification, the recovered phylogeny reveals an initial colonization of rocky reefs, followed by substantial diversification of rock-dwelling lineages, and then at least one instance of subsequent evolution back into sandy habitats. This repeated evolution into major habitat types provides further evidence that the three-stage model of Malawi cichlid diversification has numerous exceptions.