Deep drilling reveals massive shifts in evolutionary dynamics after formation of ancient ecosystem
Ontology highlight
ABSTRACT:
SUBMITTER: Wilke T
PROVIDER: S-EPMC7527215 | biostudies-literature | 2020 Sep
REPOSITORIES: biostudies-literature
Similar Datasets
Project description:Loss of complex characters is thought to be irreversible (Dollo's law). However, hypotheses of irreversible evolution are remarkably difficult to test, especially when character transitions are frequent. In such cases, inference of ancestral states, in the absence of fossil evidence, is uncertain and represents the single greatest constraint for reconstructing the evolutionary history of characters. Breeding system character transitions are of particular interest because they affect the amount and distribution of genetic variation within species. Transitions from obligate outcrossing to partial or predominant self-fertilization are thought to represent one of the most common trends in flowering plants. We use the unique molecular genetic properties (manifested as deep persistent polymorphisms) of the locus that enforces outcrossing to demonstrate that its loss is irreversible in the plant family Solanaceae. We argue that current phylogenetic methods of reconstruction are potentially inadequate in cases where ancestral state information is inferred by using only the phylogeny and the distribution of character states in extant taxa. This study shows in a statistical framework that a particular character transition is irreversible, consistent with Dollo's law.
| S-EPMC1360522 | biostudies-literature
Project description:Diptera is often considered to be the richest insect group due to its great species diversity and broad ecological versatility. However, data on dipteran diversity from subtropical ecosystems have hitherto been scarce, due to the lack of studies conducted at an appropriate large scale. We investigated the diversity and composition of Diptera communities on Tianmu Mountain, Zhejiang, China, using DNA metabarcoding technology, and evaluated their dynamic responses to the effects of slope aspect, season, and altitudinal zone. A total of 5,092 operational taxonomic units (OTUs) were discovered and tentatively assigned to 72 dipteran families, including 2 family records new for China and 30 family records new for the locality. Cecidomyiidae, Sciaridae, and Phoridae were the predominant families, representing 53.6% of total OTUs, while 52 families include >95% unidentified and presumed undescribed species. We found that the community structure of Diptera was significantly affected by aspect, seasonality (month) and elevation, with richer diversity harbored in north-facing than south-facing slopes, and seasonality a more profound driver of community structure and diversity than elevation. Overall, massive species diversity of Diptera communities was discovered in this subtropical ecosystem of east China. The huge diversity of potentially undescribed species only revealed by metabarcoding now requires more detailed taxonomic study, as a step toward an evolutionary integration that accumulates information on species' geographic ranges, ecological traits, functional roles, and species interactions, and thus places the local communities in the context of the growing knowledge base of global biodiversity and its response to environmental change.
| S-EPMC8796913 | biostudies-literature
Project description:DNA-based snapshots of ancient vegetation have shown that the composition of high-latitude plant communities changed considerably during the late Quaternary. However, parallel changes in biotic interactions remain largely uninvestigated. Here we show how mutualisms involving plants and heterotrophic organisms varied during the last 50,000 years. During 50-25 ka BP, a cool period featuring stadial-interstadial fluctuations, arbuscular mycorrhizal and non-N-fixing plants predominated. During 25-15 ka BP, a cold, dry interval, the representation of ectomycorrhizal, non-mycorrhizal and facultatively mycorrhizal plants increased, while that of N-fixing plants decreased further. From 15 ka BP, which marks the transition to and establishment of the Holocene interglaciation, representation of arbuscular mycorrhizal plants decreased further, while that of ectomycorrhizal, non-mycorrhizal, N-fixing and wind-pollinated plants increased. These changes in the mutualist trait structure of vegetation may reflect responses to historical environmental conditions that are without current analogue, or biogeographic processes, such as spatial decoupling of mutualist partners.
| S-EPMC5762924 | biostudies-literature
Project description:Ancient DNA (aDNA) has played a major role in our understanding of the past. Important advances in the sequencing and analysis of aDNA from a range of organisms have enabled a detailed understanding of processes such as past demography, introgression, domestication, adaptation and speciation. However, to date and with the notable exception of microbiomes and sediments, most aDNA studies have focused on single taxa or taxonomic groups, making the study of changes at the community level challenging. This is rather surprising because current sequencing and analytical approaches allow us to obtain and analyse aDNA from multiple source materials. When combined, these data can enable the simultaneous study of multiple taxa through space and time, and could thus provide a more comprehensive understanding of ecosystem-wide changes. It is therefore timely to develop an integrative approach to aDNA studies by combining data from multiple taxa and substrates. In this review, we discuss the various applications, associated challenges and future prospects of such an approach.
| S-EPMC8385357 | biostudies-literature
Project description:The widespread identification of genes without detectable homology in related taxa is a hallmark of genome sequencing projects in animals, together with the abundance of gene duplications. Such genes have been called novel, young, taxon-restricted, or orphans, but little is known about the mechanisms accounting for their origin, age, and mode of evolution. Phylogenomic studies relying on deep and systematic taxon sampling and using the comparative method can provide insight into the evolutionary dynamics acting on novel genes. We used a phylogenomic approach for the nematode model organism Pristionchus pacificus and sequenced six additional Pristionchus and two outgroup species. This resulted in 10 genomes with a ladder-like phylogeny, sequenced in one laboratory using the same platform and analyzed by the same bioinformatic procedures. Our analysis revealed that 68%-81% of genes are assignable to orthologous gene families, the majority of which defined nine age classes with presence/absence patterns that can be explained by single evolutionary events. Contrasting different age classes, we find that older age classes are concentrated at chromosome centers, whereas novel gene families preferentially arise at the periphery, are weakly expressed, evolve rapidly, and have a high propensity of being lost. Over time, they increase in expression and become more constrained. Thus, the detailed phylogenetic resolution allowed a comprehensive characterization of the evolutionary dynamics of Pristionchus genomes indicating that distribution of age classes and their associated differences shape chromosomal divergence. This study establishes the Pristionchus system for future research on the mechanisms that drive the formation of novel genes.
| S-EPMC6211646 | biostudies-literature
Project description:Since the late eighteenth century, fossils of bizarre extinct creatures have been described from the Americas, revealing a previously unimagined chapter in the history of mammals. The most bizarre of these are the 'native' South American ungulates thought to represent a group of mammals that evolved in relative isolation on South America, but with an uncertain affinity to any particular placental lineage. Many authors have considered them descended from Laurasian 'condylarths', which also includes the probable ancestors of perissodactyls and artiodactyls, whereas others have placed them either closer to the uniquely South American xenarthrans (anteaters, armadillos and sloths) or the basal afrotherians (e.g. elephants and hyraxes). These hypotheses have been debated owing to conflicting morphological characteristics and the hitherto inability to retrieve molecular information. Of the 'native' South American mammals, only the toxodonts and litopterns persisted until the Late Pleistocene-Early Holocene. Owing to known difficulties in retrieving ancient DNA (aDNA) from specimens from warm climates, this research presents a molecular phylogeny for both Macrauchenia patachonica (Litopterna) and Toxodon platensis (Notoungulata) recovered using proteomics-based (liquid chromatography-tandem mass spectrometry) sequencing analyses of bone collagen. The results place both taxa in a clade that is monophyletic with the perissodactyls, which today are represented by horses, rhinoceroses and tapirs.
| S-EPMC4426609 | biostudies-literature
Project description:Nelumbo nucifera is an evolutionary relic from the Late Cretaceous period. Sequencing the N. nucifera mitochondrial genome is important for elucidating the evolutionary characteristics of basal eudicots. Here, the N. nucifera mitochondrial genome was sequenced using single molecule real-time sequencing technology (SMRT), and the mitochondrial genome map was constructed after de novo assembly and annotation. The results showed that the 524,797-bp N. nucifera mitochondrial genome has a total of 63 genes, including 40 protein-coding genes, three rRNA genes and 20 tRNA genes. Fifteen collinear gene clusters were conserved across different plant species. Approximately 700 RNA editing sites in the protein-coding genes were identified. Positively selected genes were identified with selection pressure analysis. Nineteen chloroplast-derived fragments were identified, and seven tRNAs were derived from the chloroplast. These results suggest that the N. nucifera mitochondrial genome retains evolutionarily conserved characteristics, including ancient gene content and gene clusters, high levels of RNA editing, and low levels of chloroplast-derived fragment insertions. As the first publicly available basal eudicot mitochondrial genome, the N. nucifera mitochondrial genome facilitates further analysis of the characteristics of basal eudicots and provides clues of the evolutionary trajectory from basal angiosperms to advanced eudicots.
| S-EPMC4957087 | biostudies-literature
Project description:Stochasticity in gene regulation has been characterized extensively, but how it affects cellular growth and fitness is less clear. We study the growth of E. coli cells as they shift from glucose to lactose metabolism, which is characterized by an obligatory growth arrest in bulk experiments that is termed the lag phase. Here, we follow the growth dynamics of individual cells at minute-resolution using a single-cell assay in a microfluidic device during this shift, while also monitoring lac expression. Mirroring the bulk results, the majority of cells displays a growth arrest upon glucose exhaustion, and resume when triggered by stochastic lac expression events. However, a significant fraction of cells maintains a high rate of elongation and displays no detectable growth lag during the shift. This ability to suppress the growth lag should provide important selective advantages when nutrients are scarce. Trajectories of individual cells display a highly non-linear relation between lac expression and growth, with only a fraction of fully induced levels being sufficient for achieving near maximal growth. A stochastic molecular model together with measured dependencies between nutrient concentration, lac expression level, and growth accurately reproduces the observed switching distributions. The results show that a growth arrest is not obligatory in the classic diauxic shift, and underscore that regulatory stochasticity ought to be considered in terms of its impact on growth and survival.
| S-EPMC3640066 | biostudies-literature
Project description:The influence of biophysical relationships on rates of morphological evolution is a cornerstone of evolutionary theory. Mechanical sensitivity-the correlation strength between mechanical output and the system's underlying morphological components-is thought to impact the evolutionary dynamics of form-function relationships, yet has rarely been examined. Here, we compare the evolutionary rates of the mechanical components of the four-bar linkage system in the raptorial appendage of mantis shrimp (Order Stomatopoda). This system's mechanical output (kinematic transmission (KT)) is highly sensitive to variation in its output link, and less sensitive to its input and coupler links. We found that differential mechanical sensitivity is associated with variation in evolutionary rate: KT and the output link exhibit faster rates of evolution than the input and coupler links to which KT is less sensitive. Furthermore, for KT and, to a lesser extent, the output link, rates of evolution were faster in 'spearing' stomatopods than 'smashers', indicating that mechanical sensitivity may influence trait-dependent diversification. Our results suggest that mechanical sensitivity can impact morphological evolution and guide the process of phenotypic diversification. The connection between mechanical sensitivity and evolutionary rates provides a window into the interaction between physical rules and the evolutionary dynamics of morphological diversification.
| S-EPMC5310036 | biostudies-literature
Project description:A hallmark of the human immunodeficiency virus 1 (HIV-1) is its rapid rate of evolution within and among its various subtypes. Two complementary hypotheses are suggested to explain the sequence variability among HIV-1 subtypes. The first suggests that the functional constraints at each site remain the same across all subtypes, and the differences among subtypes are a direct reflection of random substitutions, which have occurred during the time elapsed since their divergence. The alternative hypothesis suggests that the functional constraints themselves have evolved, and thus sequence differences among subtypes in some sites reflect shifts in function. To determine the contribution of each of these two alternatives to HIV-1 subtype evolution, we have developed a novel Bayesian method for testing and detecting site-specific rate shifts. The RAte Shift EstimatoR (RASER) method determines whether or not site-specific functional shifts characterize the evolution of a protein and, if so, points to the specific sites and lineages in which these shifts have most likely occurred. Applying RASER to a dataset composed of large samples of HIV-1 sequences from different group M subtypes, we reveal rampant evolutionary shifts throughout the HIV-1 proteome. Most of these rate shifts have occurred during the divergence of the major subtypes, establishing that subtype divergence occurred together with functional diversification. We report further evidence for the emergence of a new sub-subtype, characterized by abundant rate-shifting sites. When focusing on the rate-shifting sites detected, we find that many are associated with known function relating to viral life cycle and drug resistance. Finally, we discuss mechanisms of covariation of rate-shifting sites.
| S-EPMC2566816 | biostudies-literature