Reassessing the phylogeny of Cyphophthalmi with phylogenomics: A UCE-based phylogeny of mite harvesters (Opiliones).

Cyphophthalmi (the mite harvesters) are a group of Opiliones with broad interest due to their species being classic examples of short-range endemics and displaying model biogeographical patterns for poor dispersers. Cyphophthalmi phylogeny has received attention using morphology, Sanger-based sequencing data, or transcriptomics. Here we turn to a new type of data, ultraconserved elements (UCEs) and provide a first phylogeny for the entire suborder Cyphophthalmi using such data and including representatives from 36 of the 46 currently recognized genera. Phylogenetic analysis of four occupancy matrices (50%, 75%, 90% and 95%), for a total of 840, 567, 129, and 23 loci, respectively, yielded a well resolved phylogeny with monophyly of Pettalidae, Parasironidae, Stylocellidae and Troglosironidae. However, Neogoveidae appeared paraphyletic with respect to Ogoveidae in all datasets and to Troglosironidae in some, and the traditional Sironidae, which was monophyletic, now appeared paraphyletic with respect to the recently erected family Parasironidae. Our phylogenomic results using UCE data resolve the position of several problematic genera (e.g., Pettalus) and add support to other parts of the tree that received low support in Sanger-based phylogenies. Our work also stresses the possibility to add museum samples to phylogenies although methods for optimizing DNA yield from such small-bodied specimens need further improvement. Finally, this backbone phylogeny demonstrates the feasibility of an all-species phylogeny using UCEs for Cyphophthalmi, and by extension, for all Opiliones.

Out of the desert: Paleoclimatic changes drove the diversification of arid-adapted Ocymyrmex ants in southern Africa.

A highly endemic ant fauna is found in the arid regions of southern Africa, including species in the genus Ocymyrmex. This genus of ants has higher species richness in the western arid regions of southern Africa compared to tropical and subtropical parts of the continent. The processes that have produced these patterns of diversity and distribution of arid adapted ants in southern Africa have never been investigated. The diversification of many other taxa in the region has been associated with past climate fluctuations that occurred during the Miocene epoch. In this study, the nature and timing of historical processes that may have led to the diversification within Ocymyrmex were assessed. We hypothesized that past climate oscillations, characterized by long periods of aridification, have driven the current distribution of Ocymyrmex species that resulted in the highest species richness of the genus in the Deserts & xeric shrublands biome in southern Africa. Ninety-four Ocymyrmex worker specimens from Botswana, Kenya, Namibia, South Africa, Tanzania and Zimbabwe, representing 21 currently described species and six morphospecies, were included in a phylogenomic analysis. Phylogenies for the genus, based on next generation sequencing data from ultraconserved elements, were inferred using Maximum Likelihood, and a dating analysis was performed using secondary age estimates as calibration points. A distribution database of Ocymyrmex records was used to assign species ranges, which were then coded according to major biomes in southern Africa and used as input for biogeographical analysis. We explored the phylogenomic relationships of Ocymyrmex and analysed these within a biogeographical and paleoclimatic framework to disentangle the potential processes responsible for diversification in this group. Dating analyses estimated that the crown age of Ocymyrmex dates to the Oligocene, around 32 Ma. Diversification within this group occurred between the mid-Miocene (∼12.5 Ma) and Pleistocene (∼2 Ma). Our biogeographic analyses suggest that Ocymyrmex species originated in the south-western region of southern Africa, which is now part of the Deserts & xeric shrublands biome and diversified into eastern subtropical areas during the Pliocene. Paleoclimatic changes resulting in increased aridity during the Miocene likely drove the diversification of the genus Ocymyrmex. It is most likely that the diversification of grasslands, because of historical climate change, facilitated the diversification of these ants to the eastern parts of southern Africa when open grasslands replaced forests during the early Miocene.

Phylogenomic analysis of Syngnathidae reveals novel relationships, origins of endemic diversity and variable diversification rates.

BACKGROUND: Seahorses, seadragons, pygmy pipehorses, and pipefishes (Syngnathidae, Syngnathiformes) are among the most recognizable groups of fishes because of their derived morphology, unusual life history, and worldwide distribution. Despite previous phylogenetic studies and recent new species descriptions of syngnathids, the evolutionary relationships among several major groups within this family remain unresolved. RESULTS: Here, we provide a reconstruction of syngnathid phylogeny based on genome-wide sampling of 1314 ultraconserved elements (UCEs) and expanded taxon sampling to assess the current taxonomy and as a basis for macroevolutionary insights. We sequenced a total of 244 new specimens across 117 species and combined with published UCE data for a total of 183 species of Syngnathidae, about 62% of the described species diversity, to compile the most data-rich phylogeny to date. We estimated divergence times using 14 syngnathiform fossils, including nine fossils with newly proposed phylogenetic affinities, to better characterize current and historical biogeographical patterns, and to reconstruct diversification through time. We present a phylogenetic hypothesis that is well-supported and provides several notable insights into syngnathid evolution. We found nine non-monophyletic genera, evidence for seven cryptic species, five potentially invalid synonyms, and identified a novel sister group to the seahorses, the Indo-Pacific pipefishes Halicampus macrorhynchus and H. punctatus. In addition, the morphologically distinct southwest Pacific seahorse Hippocampus jugumus was recovered as the sister to all other non-pygmy seahorses. As found in many other groups, a high proportion of syngnathid lineages appear to have originated in the Central Indo-Pacific and subsequently dispersed to adjoining regions. Conversely, we also found an unusually high subsequent return of lineages from southern Australasia to the Central Indo-Pacific. Diversification rates rose abruptly during the Middle Miocene Climate Transition and peaked after the closure of the Tethys Sea. CONCLUSIONS: Our results reveal a previously underappreciated diversity of syngnathid lineages. The observed biogeographic patterns suggest a significant role of the southern Australasian region as a source and sink of lineages. Shifts in diversification rates imply possible links to declining global temperatures, the separation of the Atlantic and Pacific faunas, and the environmental changes associated with these events.

Partitioned Gene-Tree Analyses and Gene-Based Topology Testing Help Resolve Incongruence in a Phylogenomic Study of Host-Specialist Bees (Apidae: Eucerinae).

Incongruence among phylogenetic results has become a common occurrence in analyses of genome-scale data sets. Incongruence originates from uncertainty in underlying evolutionary processes (e.g., incomplete lineage sorting) and from difficulties in determining the best analytical approaches for each situation. To overcome these difficulties, more studies are needed that identify incongruences and demonstrate practical ways to confidently resolve them. Here, we present results of a phylogenomic study based on the analysis 197 taxa and 2,526 ultraconserved element (UCE) loci. We investigate evolutionary relationships of Eucerinae, a diverse subfamily of apid bees (relatives of honey bees and bumble bees) with >1,200 species. We sampled representatives of all tribes within the group and >80% of genera, including two mysterious South American genera, Chilimalopsis and Teratognatha. Initial analysis of the UCE data revealed two conflicting hypotheses for relationships among tribes. To resolve the incongruence, we tested concatenation and species tree approaches and used a variety of additional strategies including locus filtering, partitioned gene-trees searches, and gene-based topological tests. We show that within-locus partitioning improves gene tree and subsequent species-tree estimation, and that this approach, confidently resolves the incongruence observed in our data set. After exploring our proposed analytical strategy on eucerine bees, we validated its efficacy to resolve hard phylogenetic problems by implementing it on a published UCE data set of Adephaga (Insecta: Coleoptera). Our results provide a robust phylogenetic hypothesis for Eucerinae and demonstrate a practical strategy for resolving incongruence in other phylogenomic data sets.

Delimiting the cryptic diversity and host preferences of Sycophila parasitoid wasps associated with oak galls using phylogenomic data.

Cryptic species diversity is a major challenge regarding the species-rich community of parasitoids attacking oak gall wasps due to a high degree of sexual dimorphism, morphological plasticity, small size and poorly known biology. As such, we know very little about the number of species present, nor the evolutionary forces responsible for generating this diversity. One hypothesis is that trait diversity in the gall wasps, including the morphology of the galls they induce, has evolved in response to selection imposed by the parasitoid community, with reciprocal selection driving diversification of the parasitoids. Using a rare, continental-scale data set of Sycophila parasitoid wasps reared from 44 species of cynipid galls from 18 species of oak across the USA, we combined mitochondrial DNA barcodes, ultraconserved elements (UCEs), morphological and natural history data to delimit putative species. Using these results, we generate the first large-scale assessment of ecological specialization and host association in this species-rich group, with implications for evolutionary ecology and biocontrol. We find most Sycophila target specific subsets of available cynipid host galls with similar morphologies, and generally attack larger galls. Our results suggest that parasitoid wasps such as Sycophila have adaptations allowing them to exploit particular host trait combinations, while hosts with contrasting traits are resistant to attack. These findings support the tritrophic niche concept for the structuring of plant-herbivore-parasitoid communities.

Phylogeography and population genetics of a widespread cold-adapted ant, Prenolepis imparis.

As species arise, evolve and diverge, they are shaped by forces that unfold across short and long timescales and at both local and vast geographical scales. It is rare, however, to be able document this history across broad sweeps of time and space in a single species. Here, we report the results of a continental-scale phylogenomic analysis across the entire range of a widespread species. We analysed sequences of 1402 orthologous ultraconserved element (UCE) loci from 75 individuals to identify population genetic structure and historical demographic patterns across the continent-wide range of a cold-adapted ant, the winter ant, Prenolepis imparis. We recovered five well-supported, genetically isolated clades representing lineages that diverged from 8.2-2.2 million years ago. These include: (i) an early diverging lineage located in Florida, (ii) a lineage that spans the southern United States, (iii) populations that extend across the midwestern and northeastern United States, (iv) populations from the western United States and (v) populations in southwestern Arizona and Mexico. Population genetic analyses revealed little or no gene flow among these lineages, but patterns consistent with more recent gene flow among populations within lineages, and localized structure with migration in the western United States. High support for five major geographical lineages and lack of evidence of contemporary gene flow indicate in situ diversification across the species' range, producing relatively ancient lineages that persisted through subsequent climate change and glaciation during the Quaternary.

A phylogenomic perspective on the evolutionary history of the stonefly genus Suwallia (Plecoptera: Chloroperlidae) revealed by ultraconserved genomic elements.

Evolutionary biologists have long sought to disentangle phylogenetic relationships among taxa spanning the tree of life, an increasingly important task as anthropogenic influences accelerate population declines and species extinctions, particularly in insects. Phylogenetic analyses are commonly used to identify unique evolutionary lineages, to clarify taxonomic designations of the focal taxa, and to inform conservation decisions. Advances in DNA sequencing techniques have increasingly facilitated the ability of researchers to apply genomic methods to phylogenetic analyses, even for non-model organisms. Stoneflies are non-model insects that are important bioindicators of the quality of freshwater habitats and landscape disturbance as they spend the immature stages of their life cycles in fresh water, and the adult stages in terrestrial environments. Phylogenetic relationships within the stonefly genus Suwallia (Insecta: Plecoptera: Chloroperlidae) are poorly understood, and have never been assessed using molecular data. We used DNA sequence data from genome-wide ultraconserved element loci to generate the first molecular phylogeny for the group and assess its monophyly. We found that Palearctic and Nearctic Suwallia do not form reciprocally monophyletic clades, and that a biogeographic history including dispersal, vicariance, and founder event speciation via jump dispersal best explains the geographic distribution of this group. Our results also strongly suggest that Neaviperla forcipata (Neave, 1929) is nested within Suwallia, and the concept of the genus Suwallia should be revised to include it. Thus, we formally propose a new taxonomic combination wherein Neaviperla forcipata (Neave, 1929) is reclassified as Suwallia forcipata (Neave, 1929). Moreover, some Suwallia species (e.g., S. amoenacolens, S. kerzhneri, S. marginata, S. pallidula, and S. starki) exhibit pronounced cryptic diversity that is worthy of further investigation. These findings provide a first glimpse into the evolutionary history of Suwallia, improve our understanding of stonefly diversity in the tribe Suwallini, and highlight areas where additional research is needed.

Historical specimens and the limits of subspecies phylogenomics in the New World quails (Odontophoridae).

As phylogenomics focuses on comprehensive taxon sampling at the species and population/subspecies levels, incorporating genomic data from historical specimens has become increasingly common. While historical samples can fill critical gaps in our understanding of the evolutionary history of diverse groups, they also introduce additional sources of phylogenomic uncertainty, making it difficult to discern novel evolutionary relationships from artifacts caused by sample quality issues. These problems highlight the need for improved strategies to disentangle artifactual patterns from true biological signal as historical specimens become more prevalent in phylogenomic datasets. Here, we tested the limits of historical specimen-driven phylogenomics to resolve subspecies-level relationships within a highly polytypic family, the New World quails (Odontophoridae), using thousands of ultraconserved elements (UCEs). We found that relationships at and above the species-level were well-resolved and highly supported across all analyses, with the exception of discordant relationships within the two most polytypic genera which included many historical specimens. We examined the causes of discordance and found that inferring phylogenies from subsets of taxa resolved the disagreements, suggesting that analyzing subclades can help remove artifactual causes of discordance in datasets that include historical samples. At the subspecies-level, we found well-resolved geographic structure within the two most polytypic genera, including the most polytypic species in this family, Northern Bobwhites (Colinus virginianus), demonstrating that variable sites within UCEs are capable of resolving phylogenetic structure below the species level. Our results highlight the importance of complete taxonomic sampling for resolving relationships among polytypic species, often through the inclusion of historical specimens, and we propose an integrative strategy for understanding and addressing the uncertainty that historical samples sometimes introduce to phylogenetic analyses.

Phylogenomic analysis of evolutionary relationships in Ranitomeya poison frogs (Family Dendrobatidae) using ultraconserved elements.

The use of genome-scale data in phylogenetics has enabled recent strides in determining the relationships between taxa that are taxonomically problematic because of extensive morphological variation. Here, we employ a phylogenomic approach to infer evolutionary relationships within Ranitomeya (Anura: Dendrobatidae), an Amazonian lineage of poison frogs consisting of 16 species with remarkable diversity in color pattern, range size, and parental care behavior. We infer phylogenies with all described species of Ranitomeya from ultraconserved nuclear genomic elements (UCEs) and also estimate divergence times. Our results differ from previous analyses regarding interspecific relationships. Notably, we find that R. toraro and R. defleri are not sister species but rather distantly related, contrary to previous analyses based on smaller genetic datasets. We recover R. uakarii as paraphyletic, designate certain populations formerly assigned to R. fantastica from Peru as R. summersi, and transfer the French Guianan and eastern Brazilian R. amazonica populations to R. variabilis. By clarifying both inter- and intraspecific relationships within Ranitomeya, our study paves the way for future tests of hypotheses on color pattern evolution and historical biogeography.

Evolutionary relationships of anglerfishes (Lophiiformes) reconstructed using ultraconserved elements.

The macroevolutionary consequences of evolving in the deep-sea remain poorly understood and are compounded by the fact that convergent adaptations for living in this environment makes elucidating phylogenetic relationships difficult. Lophiiform anglerfishes exhibit extreme habitat and predatory specializations, including the use of a fin-spine system as a luring device and unique reproductive strategies where parasitic males attach and fuse to females. Despite their notoriety for these odd characteristics, evolutionary relationships among these fishes remain unclear. We sought to clarify the evolutionary history of Lophiiformes using data from 1000 ultraconserved elements and phylogenomic inference methods with particular interest paid to the Ceratioidei (deep-sea anglerfishes) and Antennarioidei (frogfishes and handfishes). At the suborder level, we recovered similar topologies in separate phylogenomic analyses: The Lophioidei (monkfishes) are the sister group to the rest of the Lophiiformes, Ogcocephaloidei (batfishes) and Antennarioidei (frogfishes) form a sister group, and Chaunacioidei (coffinfishes) and Ceratioidei (deep-sea anglerfishes) form a clade. The relationships we recover within the ceratioids disagree with most previous phylogenetic investigations, which used legacy phylogenetic markers or morphology. We recovered non-monophyletic relationships in the Antennarioidei and proposed three new families based on molecular and morphological evidence: Histiophrynidae, Rhycheridae, and Tathicarpidae. Antennariidae was re-evaluated to include what was known as Antennariinae, but not Histiophryninae. Non-bifurcating signal in splits network analysis indicated reticulations among and within suborders, supporting the complicated history of the Lophiiformes previously found with morphological data. Although we resolve relationships within Antennarioidei, Ceratioidei relationships remain somewhat unclear without better taxonomic sampling.

A phylogeny of white-eyes based on ultraconserved elements.

White-eyes are an iconic radiation of passerine birds that have been the subject of studies in evolutionary biology, biogeography, and speciation theory. Zosterops white-eyes in particular are thought to have radiated rapidly across continental and insular regions of the Afro- and Indo-Pacific tropics, yet their phylogenetic history remains equivocal. Here, we sampled 77% of the genera and 47% of known white-eye species and sequenced thousands of ultraconserved elements to infer the phylogeny of the avian family Zosteropidae. We used concatenated maximum likelihood and species tree methods and found strong support for seven clades of white-eyes and three clades within the species-rich Zosterops radiation.

A polyvalent and universal tool for genomic studies in gastropod molluscs (Heterobranchia).

Molluscs are the second most diverse animal phylum and heterobranch gastropods present ~ 44,000 species. These comprise fascinating creatures with huge morphological and ecological disparity. Such great diversity comes with even larger phylogenetic uncertainty and many taxa have been largely neglected in molecular assessments. Genomic tools have provided resolution to deep cladogenic events but generating large numbers of transcriptomes/genomes is expensive and usually requires fresh material. Here we leverage a target enrichment approach to design and synthesize a probe set based on available genomes and transcriptomes across Heterobranchia. Our probe set contains 57,606 70mer baits and targets a total of 2,259 ultra-conserved elements (UCEs). Post-sequencing capture efficiency was tested against 31 marine heterobranchs from major groups, including Acochlidia, Acteonoidea, Aplysiida, Cephalaspidea, Pleurobranchida, Pteropoda, Runcinida, Sacoglossa, and Umbraculida. The combined Trinity and Velvet assemblies recovered up to 2,211 UCEs in Tectipleura, up to 1,978 in Nudipleura, and up to 1,927 in Acteonoidea, the latter two being the most distantly related taxa to our core study group. Total alignment length was 525,599 bp and contained 52% informative sites and 21% missing data. Maximum-likelihood and Bayesian inference approaches recovered the monophyly of all orders tested as well as the larger clades Nudipleura, Panpulmonata, and Euopisthobranchia. The successful enrichment of diversely preserved material and DNA concentrations demonstrate the polyvalent nature of UCEs, and the universality of the probe set designed. We believe this probe set will enable multiple, interesting lines of research, that will benefit from an inexpensive and largely informative tool that will, additionally, benefit from the access to museum collections to gather genomic data.

Divergence, gene flow, and speciation in eight lineages of trans-Beringian birds.

Determining how genetic diversity is structured between populations that span the divergence continuum from populations to biological species is key to understanding the generation and maintenance of biodiversity. We investigated genetic divergence and gene flow in eight lineages of birds with a trans-Beringian distribution, where Asian and North American populations have likely been split and reunited through multiple Pleistocene glacial cycles. Our study transects the speciation process, including eight pairwise comparisons in three orders (ducks, shorebirds and passerines) at population, subspecies and species levels. Using ultraconserved elements (UCEs), we found that these lineages represent conditions from slightly differentiated populations to full biological species. Although allopatric speciation is considered the predominant mode of divergence in birds, all of our best divergence models included gene flow, supporting speciation with gene flow as the predominant mode in Beringia. In our eight lineages, three were best described by a split-migration model (divergence with gene flow), three best fit a secondary contact scenario (isolation followed by gene flow), and two showed support for both models. The lineages were not evenly distributed across a divergence space defined by gene flow (M) and differentiation (FST ), instead forming two discontinuous groups: one with relatively shallow divergence, no fixed single nucleotide polymorphisms (SNPs), and high rates of gene flow between populations; and the second with relatively deeply divergent lineages, multiple fixed SNPs, and low gene flow. Our results highlight the important role that gene flow plays in avian divergence in Beringia.

Phylogenetic relationships and systematics of the Amazonian poison frog genus Ameerega using ultraconserved genomic elements.

The Amazonian poison frog genus Ameerega is one of the largest yet most understudied of the brightly colored genera in the anuran family Dendrobatidae, with 30 described species ranging throughout tropical South America. Phylogenetic analyses of Ameerega are highly discordant, lacking consistency due to variation in data types and methods, and often with limited coverage of species diversity in the genus. Here, we present a comprehensive phylogenomic reconstruction of Ameerega, utilizing state-of-the-art sequence capture techniques and phylogenetic methods. We sequenced thousands of ultraconserved elements from over 100 tissue samples, representing almost every described Ameerega species, as well as undescribed cryptic diversity. We generated topologies using maximum likelihood and coalescent methods and compared the use of maximum likelihood and Bayesian methods for estimating divergence times. Our phylogenetic inference diverged strongly from those of previous studies, and we recommend steps to bring Ameerega taxonomy in line with the new phylogeny. We place several species in a phylogeny for the first time, as well as provide evidence for six potential candidate species. We estimate that Ameerega experienced a rapid radiation approximately 7-11 million years ago and that the ancestor of all Ameerega was likely an aposematic, montane species. This study underscores the utility of phylogenomic data in improving our understanding of the phylogeny of understudied clades and making novel inferences about their evolution.

An enhanced target-enrichment bait set for Hexacorallia provides phylogenomic resolution of the staghorn corals (Acroporidae) and close relatives.

Targeted enrichment of genomic DNA can profoundly increase the phylogenetic resolution of clades and inform taxonomy. Here, we redesign a custom bait set previously developed for the cnidarian class Anthozoa to more efficiently target and capture ultraconserved elements (UCEs) and exonic loci within the subclass Hexacorallia. We test this enhanced bait set (targeting 2476 loci) on 99 specimens of scleractinian corals spanning both the "complex" (Acroporidae, Agariciidae) and "robust" (Fungiidae) clades. Focused sampling in the staghorn corals (genus Acropora) highlights the ability of sequence capture to inform the taxonomy of a clade previously deficient in molecular resolution. A mean of 1850 (±298) loci were captured per taxon (955 UCEs, 894 exons), and a 75% complete concatenated alignment of 96 samples included 1792 loci (991 UCE, 801 exons) and ~1.87 million base pairs. Maximum likelihood and Bayesian analyses recovered robust molecular relationships and revealed that species-level relationships within the Acropora are incongruent with traditional morphological groupings. Both UCE and exon datasets delineated six well-supported clades within Acropora. The enhanced bait set will facilitate investigations of the evolutionary history of many important groups of reef corals, particularly where previous molecular marker development has been unsuccessful.

Resolving Deep Nodes in an Ancient Radiation of Neotropical Fishes in the Presence of Conflicting Signals from Incomplete Lineage Sorting.

Resolving patterns of ancient and rapid diversifications is one of the most challenging tasks in evolutionary biology. These difficulties arise from confusing phylogenetic signals that are associated with the interplay of incomplete lineage sorting (ILS) and homoplasy. Phylogenomic analyses of hundreds, or even thousands, of loci offer the potential to resolve such contentious relationships. Yet, how much useful phylogenetic information these large data sets contain remains uncertain and often goes untested. Here, we assess the utility of different data filtering approaches to maximize phylogenetic information and minimize noise when reconstructing an ancient radiation of Neotropical electric knifefishes (Order Gymnotiformes) using ultraconserved elements. We found two contrasting hypotheses of gymnotiform evolutionary relationships depending on whether phylogenetic inferences were based on concatenation or coalescent methods. In the first case, all analyses inferred a previously-and commonly-proposed hypothesis, where the family Apteronotidae was found as the sister group to all other gymnotiform families. In contrast, coalescent-based analyses suggested a novel hypothesis where families producing pulse-type (viz., Gymnotidae, Hypopomidae, and Rhamphichthyidae) and wave-type electric signals (viz., Apteronotidae, Sternopygidae) were reciprocally monophyletic. Nodal support for this second hypothesis increased when analyzing loci with the highest phylogenetic information content and further increased when data were pruned using targeted filtering methods that maximized phylogenetic informativeness at the deepest nodes of the Gymnotiformes. Bayesian concordance analyses and topology tests of individual gene genealogies demonstrated that the difficulty of resolving this radiation was likely due to high gene-tree incongruences that resulted from ILS. We show that data filtering reduces gene-tree heterogeneity and increases nodal support and consistency of species trees using coalescent methods; however, we failed to observe the same effect when using concatenation methods. Furthermore, the targeted filtering strategies applied here support the use of "gene data interrogation" rather than "gene genealogy interrogation" approaches in phylogenomic analyses, to extract phylogenetic signal from intractable portions of the Tree of Life.

Long non-coding RNA in stem cell pluripotency and lineage commitment: functions and evolutionary conservation.

LncRNAs have recently emerged as new and fundamental transcriptional and post-transcriptional regulators acting at multiple levels of gene expression. Indeed, lncRNAs participate in a wide variety of stem cell and developmental processes, acting in cis and/or in trans in the nuclear and/or in the cytoplasmic compartments, and generating an intricate network of interactions with RNAs, enhancers, and chromatin-modifier complexes. Given the versatility of these molecules to operate in different subcellular compartments, via different modes of action and with different target specificity, the interest in this research field is rapidly growing. Here, we review recent progress in defining the functional role of lncRNAs in stem cell biology with a specific focus on the underlying mechanisms. We also discuss recent findings on a new family of evolutionary conserved lncRNAs transcribed from ultraconserved elements, which show perfect conservation between human, mouse, and rat genomes, and that are emerging as new player in this complex scenario.

Phylogenomic species delimitation in microendemic frogs of the Brazilian Atlantic Forest.

The advent of next-generation sequencing allows researchers to use large-scale datasets for species delimitation analyses, yet one can envision an inflection point where the added accuracy of including more loci does not offset the increased computational burden. One alternative to including all loci could be to prioritize the analysis of loci for which there is an expectation of high informativeness. Here, we explore the issue of species delimitation and locus selection with montane species from two anuran genera that have been isolated in sky islands across the southern Brazilian Atlantic Forest: Melanophryniscus (Bufonidae) and Brachycephalus (Brachycephalidae). To delimit species, we obtained genetic data using target enrichment of ultraconserved elements from 32 populations (13 for Melanophryniscus and 19 for Brachycephalus), and we were able to create datasets that included over 800 loci with no missing data. We ranked loci according to their number of parsimony-informative sites, and we performed species delimitation analyses using BPP with the most informative 10, 20, 40, 80, 160, 320, and 640 loci. We identified three types of phylogenetic node: nodes with either consistently high or low support regardless of the number of loci or their informativeness and nodes that were initially poorly supported where support became stronger as we included more data. When viewed across all sensitivity analyses, our results suggest that the current species richness in both genera is likely underestimated. In addition, our results show the effects of different sampling strategies on species delimitation using phylogenomic datasets.

Combining transcriptomes and ultraconserved elements to illuminate the phylogeny of Apidae.

Two increasingly popular approaches to reconstruct the Tree of Life involve whole transcriptome sequencing and the target capture of ultraconserved elements (UCEs). Both methods can be used to generate large, multigene datasets for analysis of phylogenetic relationships in non-model organisms. While targeted exon sequencing across divergent lineages is now a standard method, it is still not clear if UCE data can be readily combined with published transcriptomes. In this study, we evaluate the combination of UCEs and transcriptomes in a single analysis using genome-, transcriptome-, and UCE data for 79 bees in the largest and most biologically diverse bee family, Apidae. Using existing tools, we first developed a workflow to assemble phylogenomic data from different sources and produced two large nucleotide matrices of combined data. We then reconstructed the phylogeny of the Apidae using concatenation- and coalescent-based methods, and critically evaluated the resulting phylogenies in the context of previously published genetic, genomic, and morphological data sets. Our estimated phylogenetic trees are robustly supported and largely congruent with previous molecular hypotheses, from deep nodes to shallow species-level phylogenies. Moreover, the combined approach allows us to resolve controversial nodes of the apid Tree of Life, by clarifying the relationships among the genera of orchid bees (Euglossini) and the monophyly of the Centridini. Additionally, we present novel phylogenetic evidence supporting the monophyly of the diverse clade of cleptoparasitic Apidae and the placement of two enigmatic, oil-collecting genera (Ctenoplectra and Tetrapedia). Lastly, we propose a revised classification of the family Apidae that reflects our improved understanding of apid higher-level relationships.

Genomic data resolve gene tree discordance in spiderhunters (Nectariniidae, Arachnothera).

Reduced representation genomic sequencing methods efficiently gather sequence data from thousands of loci throughout the genome. These data can be used to test previous phylogenetic hypotheses produced from limited numbers of mitochondrial and nuclear loci that often reveal intriguing, but conflicting, results. In this paper, we use phylogenomic data to revisit recent molecular phylogenetic work that clarified many taxonomic relationships within spiderhunters, but also questioned the monophyly of this distinctive genus of sunbirds (AVES: Nectariniidae; Arachnothera). DNA sequence data were produced by target-capture sequencing of ultraconserved elements (UCEs) to infer the evolutionary history of 11 species of Arachnothera and six outgroups, including the Purple-naped Sunbird (Hypogramma hypogrammicum), which previous work suggested might lie within Arachnothera. Although we recovered many different gene tree topologies, concatenated and coalescent methods of analysis converged on a species tree that strongly supports the monophyly of Arachnothera, with Hypogramma as its sister taxon.