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86 results for “evolutionary tree”
Supplementary videos to the article "The first arctic strain of Rhizochromulina: morphology, ultrastructure, and position in the evolutionary tree of the order Rhizochromulinales (Ochrophyta, Dictyochophyceae)"
<p>Supplementary videos to the article "The first arctic strain of Rhizochromulina: morphology, ultrastructure, and position in the evolutionary tree of the order Rhizochromulinales (Ochrophyta, Dictyochophyceae)"</p>
Data from: Phylogenetic relationships within the lizard clade Xantusiidae: using trees and divergence times to address evolutionary questions at multiple levels
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Data from: Relative impacts of environmental variation and evolutionary history on the nestedness and modularity of tree-herbivore networks.
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Data from: Comparing evolutionary rates between trees, clades, & traits
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Data from: Evaluating evolutionary history in the face of high gene tree discordance in Australian Gehyra (Reptilia: Gekkonidae)
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Data from: Evolutionary history of almond tree domestication in the Mediterranean basin
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Data from: Evolutionary melting pots: a biodiversity hotspot shaped by ring diversifications around the Black Sea in the Eastern tree frog (Hyla orientalis)
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Introgression across evolutionary scales suggests reticulation contributes to Amazonian tree diversity
<p>Hybridisation has the potential to generate or homogenize biodiversity and is a particularly common phenomenon in plants, with an estimated 25% of plant species undergoing inter-specific gene flow. However, hybridisation in Amazonia's megadiverse tree flora was assumed to be extremely rare despite extensive sympatry between closely related species, and its role in diversification remains enigmatic because it has not yet been examined empirically. Using members of a dominant Amazonian tree family (<i>Brownea</i>, Fabaceae) as a model to address this knowledge gap, our study recovered extensive evidence of hybridisation among multiple lineages across phylogenetic scales. More specifically, using targeted sequence capture our results uncovered several historical introgression events between <i>Brownea </i>lineages and indicated that gene tree incongruence in <i>Brownea</i> is best explained by reticulation, rather than solely by incomplete lineage sorting. Furthermore, investigation of recent hybridisation using ~19,000 ddRAD loci recovered a high degree of shared variation between two <i>Brownea </i>species that co-occur in the Ecuadorian Amazon.</p> <p>Our analyses also showed that these sympatric lineages exhibit homogeneous rates of introgression among loci relative to the genome-wide average, implying a lack of selection against hybrid genotypes and persistent hybridisation. Our results demonstrate that gene flow between multiple Amazonian tree species has occurred across temporal scales, and contrasts with the prevailing view of hybridisation's rarity in Amazonia. Overall, our results provide novel evidence that reticulate evolution influenced diversification in part of the Amazonian tree flora, which is the most diverse on Earth.</p>
Evolutionary rate and genetic load in an emblematic Mediterranean tree following an ancient and prolonged population collapse
Severe bottlenecks significantly diminish the amount of genetic diversity and the speed at which it accumulates (i.e. evolutionary rate). They further compromise the efficiency of natural selection to eliminate deleterious variants, which may reach fixation in the surviving populations. Consequently, expanding and adapting to new environments may pose a significant challenge when strong bottlenecks result in genetic pauperization. Herein, we surveyed the patterns of nucleotide diversity, molecular adaptation and genetic load across hundreds of loci in a circum-Mediterranean conifer (<i>Pinus pinea</i> L.) that represents one of the most extreme cases of genetic pauperization in widespread outbreeding taxa. We found very little genetic variation in both hypervariable non-coding (nuSSRs) and gene-coding loci, which translated into genetic diversity estimates one order of magnitude lower than those previously reported for pines. Such values were consistent with a strong population decline that began some ~1Ma. Comparisons with the related and partially parapatric maritime pine revealed reduced rates of adaptive evolution (<i>α</i> and <i>ω</i><sub>a</sub>) and a significant accumulation of genetic load. These did not appear to result from differences in mutation rates or linkage disequilibrium between the two species; instead they are the likely outcome of contrasting demographic histories affecting both the speed at which these taxa accumulate genetic diversity, and the global efficacy of selection. Future studies, and programs for conservation and management, should thus start testing for the effects of genetic load on fitness and integrating such effects into predictive models.
Data from: The phylogeny of Rickettsia using different evolutionary signatures: how tree-like is bacterial evolution?
Rickettsia is a genus of intracellular bacteria whose hosts and transmission strategies are both impressively diverse, and this is reflected in a highly dynamic genome. Some previous studies have described the evolutionary history of Rickettsia as non-tree-like, due to incongruity between phylogenetic reconstructions using different portions of the genome. Here, we reconstruct the Rickettsia phylogeny using whole-genome data, including two new genomes from previously unsampled host groups. We find that a single topology, which is supported by multiple sources of phylogenetic signal, well describes the evolutionary history of the core genome. We do observe extensive incongruence between individual gene trees, but analyses of simulations over a single topology and interspersed partitions of sites show that this is more plausibly attributed to systematic error than to horizontal gene transfer. Some conflicting placements also result from phylogenetic analyses of accessory genome content (i.e. gene presence/absence), but we argue that these are also due to systematic error, stemming from convergent genome reduction, which cannot be accommodated by existing phylogenetic methods. Our results show that, even within a single genus, tests for gene exchange based on phylogenetic incongruence may be susceptible to false positives.
Data from: Diversity, disparity, and evolutionary rate estimation for unresolved Yule trees
The branching structure of biological evolution confers statistical dependencies on phenotypic trait values in related organisms. For this reason, comparative macroevolutionary studies usually begin with an inferred phylogeny that describes the evolutionary relationships of the organisms of interest. The probability of the observed trait data can be computed by assuming a model for trait evolution, such as Brownian motion, over the branches of this fixed tree. However, the phylogenetic tree itself contributes statistical uncertainty to estimates of other evolutionary quantities, and many comparative evolutionary biologists regard the tree as a nuisance parameter. In this paper, we present a framework for analytically integrating over unknown phylogenetic trees in comparative evolutionary studies by assuming that the tree arises from a continuous-time Markov branching model called the Yule process. To do this, we derive a closed-form expression for the distribution of phylogenetic diversity, which is the sum of branch lengths connecting a set of taxa. We then present a generalization of phylogenetic diversity which is equivalent to the expected trait disparity in a set of taxa whose evolutionary relationships are generated by a Yule process and whose traits evolve by Brownian motion. We derive expressions for the distribution of expected trait disparity under a Yule tree. Given one or more observations of trait disparity in a clade, we perform fast likelihood-based estimation of the Brownian variance for unresolved clades. Our method does not require simulation or a fixed phylogenetic tree. We conclude with a brief example illustrating Brownian rate estimation for thirteen taxonomic families in order Carnivora, in which the phylogenetic tree for each family is unresolved.
Data from: Organellar phylogenomics inform systematics in the green algal family Hydrodictyaceae (Chlorophyceae) and provide clues to the complex evolutionary history of plastid genomes in the green algal Tree of Life.
Premise of the study: Phylogenomic analyses across the green algae are resolving relationships at the class, order and family levels, and highlighting dynamic patterns of evolution in organellar genomes. Here we present a within-family phylogenomic study to resolve genera and species relationships in the family Hydrodictyaceae (Chlorophyceae), for which poor resolution in previous phylogenetic studies, along with divergent morphological traits, have precluded taxonomic revisions. Methods: Complete plastome sequences and mitochondrial protein-coding gene sequences were acquired from representatives of the Hydrodictyaceae using Next-Generation sequencing methods. Plastomes were characterized and gene order and content were compared with plastomes spanning the Sphaeropleales. Single-gene and concatenated-gene phylogenetic analyses of plastid and mitochondrial genes were performed. Key results: The Hydrodictyaceae contain the largest sphaeroplealean plastomes thus far fully sequenced. Conservation of plastome gene order within Hydrodictyaceae is striking compared with more dynamic patterns revealed across Sphaeropleales. Phylogenetic analyses resolve Hydrodictyon sister to a monophyletic Pediastrum, though the morphologically distinct P. angulosum and P. duplex continue to be polyphyletic. Analyses of plastid data supported the neochloridacean genus Chlorotetraëdron as sister to Hydrodictyaceae, while conflicting signal was found in the mitochondrial data. Conclusions: A phylogenomic approach resolved within-family relationships not obtainable with previous phylogenetic analyses. Denser taxon sampling across Sphaeropleales is necessary to capture patterns in plastome evolution, and further taxa and studies are needed to fully resolve sister lineage to Hydrodictyaceae and polyphyly of Pediastrum angulosum and P. duplex.
Data from: Tree imbalance causes a bias in phylogenetic estimation of evolutionary timescales using heterochronous sequences
Phylogenetic estimation of evolutionary timescales has become routine in biology, forming the basis of a wide range of evolutionary and ecological studies. However, there are various sources of bias that can affect these estimates. We investigated whether tree imbalance, a property that is commonly observed in phylogenetic trees, can lead to reduced accuracy or precision of phylogenetic timescale estimates. We analysed simulated data sets with calibrations at internal nodes and at the tips, taking into consideration different calibration schemes and levels of tree imbalance. We also investigated the effect of tree imbalance on two empirical data sets: mitogenomes from primates and serial samples of the African swine fever virus. In analyses calibrated using dated, heterochronous tips, we found that tree imbalance had a detrimental impact on precision and produced a bias in which the overall timescale was underestimated. A pronounced effect was observed in analyses with shallow calibrations. The greatest decreases in accuracy usually occurred in the age estimates for medium and deep nodes of the tree. In contrast, analyses calibrated at internal nodes did not display a reduction in estimation accuracy or precision due to tree imbalance. Our results suggest that molecular-clock analyses can be improved by increasing taxon sampling, with the specific aims of including deeper calibrations, breaking up long branches and reducing tree imbalance.
Long evolutionary history of an emerging fungal pathogen of diverse tree species in eastern Asia, Australia, and the Pacific Islands
<p>Emerging plant pathogens have been increasing exponentially over the last century. To address this issue, it is critical to determine whether these pathogens are native to ecosystems or have been recently introduced. Understanding the ecological and evolutionary processes fostering emergence can help to manage their spread and predict epidemics/epiphytotics. Using restriction site-associated DNA sequencing data, we studied genetic relationships, pathways of spread, and evolutionary history of <em>Phellinus noxius</em>, an emerging root-rotting fungus of unknown origin, in eastern Asia, Australia, and the Pacific Islands. We analyzed patterns of genetic variation using Bayesian inference, maximum likelihood phylogeny, populations splits and mixtures measuring correlations in allele frequencies and genetic drift, and finally applied coalescent based theory using Approximate Bayesian computation (ABC) with supervised machine learning. Population structure analyses revealed five genetic groups with signatures of complex recent and ancient migration histories. The most probable scenario of ancient pathogen spread is movement from an unsampled population to Malaysia and the Pacific Islands, with subsequent spread to Taiwan and Australia. Furthermore, ABC analyses indicate <em>P. noxius</em> spread occurred thousands of generations ago, contradicting previous assumptions that this pathogen was recently introduced to multiple geographic regions. Our results suggest that recent emergence of <em>P. noxius</em>in eastern Asia, Australia, and the Pacific Islands is likely driven by anthropogenic and natural disturbances, such as deforestation, land-use change, severe weather events, and/or introduction of exotic plants. This study provides a novel example of applying genome-wide allele frequency data to unravel dynamics of pathogen emergence under changing ecosystem conditions.</p>
Supplementary material 1 from: Venegas PJ, García-Ayachi LA, Toral E, Malqui J, Ron SR (2023) A new species of spiny-backed tree frog, genus Osteocephalus (Anura, Hylidae), from the Yanachaga Chemillén National Park in central Peru. Evolutionary Systematics 7(2): 237-251. https://doi.org/10.3897/evolsyst.7.102360
Additional specimens examined
Data from: Organellar phylogenomics inform systematics in the green algal family Hydrodictyaceae (Chlorophyceae) and provide clues to the complex evolutionary history of plastid genomes in the green algal Tree of Life.
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Data from: Diversity, disparity, and evolutionary rate estimation for unresolved Yule trees
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Data from: Congruence, fossils, and the evolutionary tree of rodents and lagomorphs
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Evolutionary rate and genetic load in an emblematic Mediterranean tree following an ancient and prolonged population collapse
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Data from: The phylogeny of Rickettsia using different evolutionary signatures: how tree-like is bacterial evolution?
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Allen Brain Atlas
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DANDI Archive for NWB datasets
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International Brain Laboratory public data
The International Brain Laboratory public data releases expose standardized mouse decision-making experiments, including Neuropixels recordings, widefield calcium imaging, behavior, and session metadata accessed through the ONE API.
OpenNeuro
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