Biology Commons^™

Life In Groups: The Roles Of Oxytocin In Mammalian Sociality, Allison M.J. Anacker, Annaliese K. Beery

Psychology: Faculty Publications

In recent decades, scientific understanding of the many roles of oxytocin (OT) in social behavior has advanced tremendously. The focus of this research has been on maternal attachments and reproductive pair-bonds, and much less is known about the substrates of sociality outside of reproductive contexts. It is now apparent that OT influences many aspects of social behavior including recognition, trust, empathy, and other components of the behavioral repertoire of social species. This review provides a comparative perspective on the contributions of OT to life in mammalian social groups. We provide background on the functions of OT in maternal attachments and …

Zebrafish Ciliopathy Screen Plus Human Mutational Analysis Identifies C21orf59 And Ccdc65 Defects As Causing Primary Ciliary Dyskinesia, Christina Austin-Tse, Jan Halbritter, Maimoona A. Zariwala, Renée M. Gilberti, Heon Yung Gee, Nathan Hellman, Narendra Pathak, Yan Liu, Jennifer R. Panizzi, Ramila S. Patel-King, Douglas Tritschler, Raqual Bower, Eileen O'Toole, Jonathan D. Porath, Toby W. Hurd, Moumita Chaki, Katrina A. Diaz, Stefan Kohl, Svjetlana Lovric, Daw Yang Hwang, Daniela A. Braun, Markus Schueler, Rannar Airik, Edgar A. Otto, Margaret W. Leigh, Peadar G. Noone, Johnny L. Carson, Stephanie D. Davis, Jessica E. Pittman, Thomas W. Ferkol, Jeffry J. Atkinson, Kenneth N. Olivier

Neuroscience: Faculty Publications

Primary ciliary dyskinesia (PCD) is caused when defects of motile cilia lead to chronic airway infections, male infertility, and situs abnormalities. Multiple causative PCD mutations account for only 65% of cases, suggesting that many genes essential for cilia function remain to be discovered. By using zebrafish morpholino knockdown of PCD candidate genes as an in vivo screening platform, we identified c21orf59, ccdc65, and c15orf26 as critical for cilia motility. c21orf59 and c15orf26 knockdown in zebrafish and planaria blocked outer dynein arm assembly, and ccdc65 knockdown altered cilia beat pattern. Biochemical analysis in Chlamydomonas revealed that the C21orf59 ortholog FBB18 is …

Identification And Characterization Of A Nacl Responsive Genetic Locus Involved In 2 Survival During Desiccation In Sinorhizobium Meliloti, Jan A.C. Vriezen, Frans J. De Bruijn, Klaus R. Nüsslein

Biological Sciences: Faculty Publications

The Rhizobiaceae are a bacterial family of enormous agricultural importance due to the ability of its members to fix atmospheric nitrogen in an intimate relationship with plants. Their survival as naturally occurring soil bacteria in agricultural soils as well as popular seed inocula is affected directly by drought and salinity. Survival after desiccation in the presence of NaCl is enabled by underlying genetic mechanisms in the model organism Sinorhizobium meliloti 1021. Since salt stress parallels a loss in water activity, the identification of NaCl-responsive loci may identify loci involved in survival during desiccation. This approach enabled identification of the loci …

Lost Branches On The Tree Of Life, Bryan T. Drew, Romina Gazis, Patricia Cabezas, Kristen S. Swithers, Jiabin Deng, Roseana Rodriguez, Laura A. Katz, Keith A. Crandall, David S. Hibbett, Douglas E. Soltis

Biological Sciences: Faculty Publications

No abstract provided.

Failed Species, Innominate Forms, And The Vain Search For Species Limits: Cryptic Diversity In Dusky Salamanders (Desmognathus) Of Eastern Tennessee, Stephen G. Tilley, Joseph Bernardo, Laura A. Katz, Lizmarie López, J. Devon Roll, Renáe L. Eriksen, Justin Kratovil, Noëlle K.J. Bittner, Keith A. Crandall

Biological Sciences: Faculty Publications

Cytochrome B sequences and allozymes reveal complex patterns of molecular variation in dusky salamander (Desmognathus) populations in eastern Tennessee. One group of allozymically distinctive populations, which we refer to as the Sinking Creek form (SCF), combines morphological attributes of Desmognathus fuscus with cytB sequences characteristic of Desmognathus carolinensis. This form is abruptly replaced by D. fuscus just north of Johnson City, TN with no evidence of either sympatry or gene exchange. To the south, allozymic markers indicate a broad zone of admixture with populations characterized by distinct cytB sequences and that may or may not be ultimately referable to Desmognathus …

Rethinking The Composition Of A Rational Antibiotic Arsenal For The 21st Century, Margaret A. Riley, Sandra M. Robinson, Christopher M. Roy, Robert L. Dorit

Biological Sciences: Faculty Publications

The importance of the human microbiome in health may be the single most valuable development in our conception of the microbial world since Pasteur's germ theory of the 1860s. Its implications for our understanding of health and pathogenesis are profound. Coupled with the revolution in diagnostics that we are now witnessing - a revolution that changes medicine from a science of symptoms to a science of causes - we cannot continue to develop antibiotics as we have for the past 80 years. Instead, we need to usher in a new conception of the role of antibiotics in treatment: away from …

The Evolutionary Histories Of Clinical And Environmental Shv Β-Lactamases Are Intertwined, Robert L. Dorit, Christopher M. Roy, Sandra M. Robinson, Margaret A. Riley

Biological Sciences: Faculty Publications

The rise of antibiotic-resistant pathogens focuses our attention on the source of antibiotic resistance genes, on the existence of these genes in environments exposed to little or no antibiotics, and on the relationship between resistance genes found in the clinic and those encountered in non-clinical settings. Here, we address the evolutionary history of a class of resistance genes, the SHV β-lactamases. We focus on bla SHV genes isolated both from clinical and non-clinical sources and show that clinically important resistance determinants arise repeatedly from within a diverse pool of bla SHV genes present in the environment. While our results argue …

Pheromone Exposure Influences Preoptic Arginine Vasotocin Gene Expression And Inhibits Social Approach Behavior In Response To Rivals But Not Potential Mates, Lisa A. Mangiamele, Alex D.T. Keeney, Erin N. D'Agostino, Richmond R. Thompson

Biological Sciences: Faculty Publications

The nonapeptides arginine vasotocin (AVT) and vasopressin mediate a variety of social behaviors in vertebrates. However, the effects of these peptides on behavior can vary considerably both between and within species. AVT, in particular, stimulates aggressive and courtship responses typical of dominant males in several species, although it can also inhibit social interactions in some cases. Such differential effects may depend upon AVT influences within brain circuits that differ among species or between males that adopt alternative reproductive phenotypes and/or upon the differential activation of those circuits in different social contexts. However, to date, very little is known about how …

No Control Genes Required: Bayesian Analysis Of Qrt-Pcr Data., Mikhail V. Matz, Rachel M. Wright, James G. Scott

Biological Sciences: Faculty Publications

Model-based analysis of data from quantitative reverse-transcription PCR (qRT-PCR) is potentially more powerful and versatile than traditional methods. Yet existing model-based approaches cannot properly deal with the higher sampling variances associated with low-abundant targets, nor do they provide a natural way to incorporate assumptions about the stability of control genes directly into the model-fitting process. In our method, raw qPCR data are represented as molecule counts, and described using generalized linear mixed models under Poisson-lognormal error. A Markov Chain Monte Carlo (MCMC) algorithm is used to sample from the joint posterior distribution over all model parameters, thereby estimating the effects …

Chronic Stress Elevates Telomerase Activity In Rats, Annaliese K. Beery, Jue Lin, Joshua S. Biddle, Darlene D. Francis, Elizabeth H. Blackburn, Elissa S. Epel

Neuroscience: Faculty Publications

The enzyme telomerase lengthens telomeres—protective structures containing repetitive DNA sequences at chromosome ends. Telomere shortening is associated with diseases of ageing in mammals. Chronic stress has been related to shorter immune-cell telomeres, but telomerase activity under stress may be low, permitting telomere loss, or high, partially attenuating it. We developed an experimental model to examine the impacts of extended unpredictable stress on telomerase activity in male rats. Telomerase activity was 54 per cent higher in stressed rats than in controls, and associated with stress-related physiological and behavioural outcomes. This significant increase suggests a potential mechanism for resilience to stress-related replicative …

Morphological Description Of Telaepolella Tubasferens N. G. N. Sp., Isolate Atcc©50593™, A Filose Amoeba In The Gracilipodida, Amoebozoa, Daniel J.G. Lahr, Gabriela M. Kubik, Anastasia L. Gant, Jessica Grant, O. Roger Anderson, Laura A. Katz

Biological Sciences: Faculty Publications

We describe the amoeboid isolate ATCC©50593™ as a new taxon, Telaepolella tubasferens n. g. n. sp. This multinucleated amoeba has filose pseudopods and is superficially similar to members of the vampyrellids (Rhizaria) such as Arachnula impatiens Cienkowski, 1876, which was the original identification upon deposition. However, previous multigene analyses place this taxon within the Gracilipodida Lahr and Katz 2011 in the Amoebozoa. Here, we document the morphology of this organism at multiple life history stages and provide data underlying the description as a new taxon. We demonstrate that T. tubasferens is distinct from Arachnula and other rhizarians (Theratromyxa, Leptophrys) in …

Resistance Is Futile: The Bacteriocin Model For Addressing The Antibiotic Resistance Challenge, Margaret A. Riley, Sandra M. Robinson, Christopher M. Roy, Morgan Dennis, Vivian Liu, Robert Dorit

Biological Sciences: Faculty Publications

Pathogenic bacteria resistant to many or all antibiotics already exist. With the decline in microbiological research at pharmaceutical companies, the high rate at which resistance has evolved and spread has demanded a novel approach to addressing this critical human health issue. In the present paper, we propose a new paradigm in antibiotic discovery and development, one that applies ecological and evolutionary theory to design antimicrobial drugs that are more difficult and/or more costly to resist. In essence, we propose to simply adopt the strategies invented and applied by bacteria for hundreds of millions of years. Our research focuses on bacteriocins, …

Engineered, Harnessed, And Hijacked: Synthetic Uses For Cytoskeletal Systems, Brian S. Goodman, Nathan D. Derr, Samara L. Reck-Peterson

Biological Sciences: Faculty Publications

Synthetic biology re-imagines existing biological systems by designing and constructing new biological parts, devices, and systems. In the arena of cytoskeleton-based transport, synthetic approaches are currently used in two broad ways. First, molecular motors are harnessed for non-physiological functions in cells. Second, transport systems are engineered in vitro to determine the biophysical rules that govern motility. These rules are then applied to synthetic nanotechnological systems. We review recent advances in both of these areas and conclude by discussing future directions in engineering the cytoskeleton and its motors for transport.

Tug-Of-War In Motor Protein Ensembles Revealed With A Programmable Dna Origami Scaffold, N. D. Derr, B. S. Goodman, R. Jungmann, A. E. Leschziner, W. M. Shih, S. L. Reck-Peterson

Biological Sciences: Faculty Publications

Cytoplasmic dynein and kinesin-1 are microtubule-based motors with opposite polarity that transport a wide variety of cargo in eukaryotic cells. Many cellular cargos demonstrate bidirectional movement due to the presence of ensembles of dynein and kinesin, but are ultimately sorted with spatial and temporal precision. To investigate the mechanisms that coordinate motor ensemble behavior, we built a programmable synthetic cargo using three-dimensional DNA origami to which varying numbers of DNA oligonucleotide-linked motors could be attached, allowing for control of motor type, number, spacing, and orientation in vitro. In ensembles of one to seven identical-polarity motors, motor number had minimal affect …

Congruence And Indifference Between Two Molecular Markers For Understanding Oral Evolution In The Marynidae Sensu Lato (Ciliophora, Colpodea), Micah Dunthorn, Laura A. Katz, Thorsten Stoeck, Wilhelm Foissner

Biological Sciences: Faculty Publications

Our understanding of the evolution of oral structures within the Colpodida is confounded by the low number of morphological characters that can be used in constructing hypotheses, and by the low taxon and character sampling in molecular phylogenetic analyses designed to assess these hypotheses. Here we increase character sampling by sequencing the mitochondrial SSU-rDNA locus for three isolates of the Marynidae sensu lato. We show that the inferred mitochondrial and nuclear SSU-rDNA trees, as well as concatenated and constrained analyses, are congruent in not recovering a monophyletic Marynidae. However, due to low node support, the trees are indifferent to whether …

Analyses Of Chromosome Copy Number And Expression Level Of Four Genes In The Ciliate Chilodonella Uncinata Reveal A Complex Pattern That Suggests Epigenetic Regulation, Laure Bellec, Laura A. Katz

Biological Sciences: Faculty Publications

Chilodonella uncinata, like all ciliates, contains two distinct nuclei in every cell: a germline micronucleus and a somatic macronucleus. The macronucleus develops from the zygotic nucleus through a series of chromosomal rearrangements. Macronuclear development in C. uncinata yields a nucleus with highly amplified gene-sized chromosomes. The macronucleus is transcriptionally active during vegetative growth while there is no expression in the micronucleus except during a brief period following conjugation. Gene family evolution in ciliates occurs through complex processes including gene duplication and an alternative processing of scrambled genes. Here we use quantitative PCR to compare relative expression levels of eight genes …

Mechanical Stretch And Pi3k Signaling Link Cell Migration And Proliferation To Coordinate Epithelial Tubule Morphogenesis In The Zebrafish Pronephros, Aleksandr Vasilyev, Yan Liu, Nathan Hellman, Narendra Pathak, Iain A. Drummond

Neuroscience: Faculty Publications

Organ development leads to the emergence of organ function, which in turn can impact developmental processes. Here we show that fluid flow-induced collective epithelial migration during kidney nephron morphogenesis induces cell stretch that in turn signals epithelial proliferation. Increased cell proliferation was dependent on PI3K signaling. Inhibiting epithelial proliferation by blocking PI3K or CDK4/Cyclin D1 activity arrested cell migration prematurely and caused a marked overstretching of the distal nephron tubule. Computational modeling of the involved cell processes predicted major morphological and kinetic outcomes observed experimentally under a variety of conditions. Overall, our findings suggest that kidney development is a recursive …

Assessing Whether Alpha-Tubulin Sequences Are Suitable For Phylogenetic Reconstruction Of Ciliophora With Insights Into Its Evolution In Euplotids, Zhenzhen Yi, Laura A. Katz, Weibo Song

Biological Sciences: Faculty Publications

The current understanding of ciliate phylogeny is mainly based on analyses of a single gene, the small subunit ribosomal RNA (SSU-rDNA). However, phylogenetic trees based on single gene sequence are not reliable estimators of species trees, and SSU-rDNA genealogies are not useful for resolution of some branches within Ciliophora. Since congruence between multiple loci is the best tool to determine evolutionary history, we assessed the usefulness of alpha-tubulin gene, a protein-coding gene that is frequently sequenced, for ciliate phylogeny. Here, we generate alpha-tubulin gene sequences of 12 genera and 30 species within the order Euplotida, one of the most frequently …

Turning The Crown Upside Down: Gene Tree Parsimony Roots The Eukaryotic Tree Of Life, Laura A. Katz, Jessica R. Grant, Laura Wegener Parfrey, J. Gordon Burleigh

Biological Sciences: Faculty Publications

The first analyses of gene sequence data indicated that the eukaryotic tree of life consisted of a long stem of microbial groups topped by a crown-containing plants, animals, and fungi and their microbial relatives. Although more recent multigene concatenated analyses have refined the relationships among the many branches of eukaryotes, the root of the eukaryotic tree of life has remained elusive. Inferring the root of extant eukaryotes is challenging because of the age of the group (∼1.7-2.1 billion years old), tremendous heterogeneity in rates of evolution among lineages, and lack of obvious outgroups for many genes. Here, we reconstruct a …

Transcendental Thermodynamics, Richard E. Morel, George Fleck

Kahn Institute Projects

Thermodynamics is often viewed as a narrow, introspective discipline, trapped by its origins in the 18th and 19th centuries. By dramatic contrast, we show that the Fourth Law of Thermodynamics provides explanations and interpretations of all natural events, extending across artificial boundaries of tradition- al academic disciplines. The Fourth Law of Thermodynamics states that far-from-equilibrium systems increase entropy at the maximum rate available to them. This broadly inclusive paradigm applies to systems from molecules, to organisms, to the biosphere. The Fourth Law is the Law of Evolution. All systems that communicate with their environment exhibit self-organization and self-optimization, enabling the …

Macondo Crude Oil From The Deepwater Horizon Oil Spill Disrupts Specific Developmental Processes During Zebrafish Embryogenesis, T. Yvanka De Soysa, Allison Ulrich, Timo Friedrich, Danielle Pite, Shannon L. Compton, Deborah Ok, Rebecca L. Bernardos, Gerald B. Downes, Shizuka Hsieh, Rachael Stein, M. Caterina Lagdameo, Katherine Halvorsen, Lydia Rose Kesich, Michael J.F. Barresi

Biological Sciences: Faculty Publications

Background: The Deepwater Horizon disaster was the largest marine oil spill in history, and total vertical exposure of oil to the water column suggests it could impact an enormous diversity of ecosystems. The most vulnerable organisms are those encountering these pollutants during their early life stages. Water-soluble components of crude oil and specific polycyclic aromatic hydrocarbons have been shown to cause defects in cardiovascular and craniofacial development in a variety of teleost species, but the developmental origins of these defects have yet to be determined. We have adopted zebrafish, Danio rerio, as a model to test whether water accumulated fractions …

By Any Other Name: Heterologous Replacement Of The Escherichia Coli Rnase P Protein Subunit Has In Vivo Fitness Consequences, Paula C.G. Turrini, Jasmine L. Loveland, Robert L. Dorit

Biological Sciences: Faculty Publications

Bacterial RNase P is an essential ribonucleoprotein composed of a catalytic RNA component (encoded by the rnpB gene) and an associated protein moiety (encoded by rnpA). We construct a system that allows for the deletion of the essential endogenous rnpA copy and for its simultaneous replacement by a heterologous version of the gene. Using growth rate as a proxy, we explore the effects on fitness of heterologous replacement by increasingly divergent versions of the RNase P protein. All of the heterologs tested complement the loss of the endogenous rnpA gene, suggesting that all existing bacterial versions of the rnpA …

Vincristine And Bortezomib Cause Axon Outgrowth And Behavioral Defects In Larval Zebrafish, Tahsin M. Khan, Nathan Benaich, Clare F. Malone, Rebecca L. Bernardos, Amy R. Russell, Gerald B. Downes, Michael J. Barresi, Lara D. Hutson

Biological Sciences: Faculty Publications

Peripheral neuropathy is a common side effect of a number of pharmaceutical compounds, including several chemotherapy drugs. Among these are vincristine sulfate, a mitotic inhibitor used to treat a variety of leukemias, lymphomas, and other cancers, and bortezomib, a 26S proteasome inhibitor used primarily to treat relapsed multiple myeloma and mantle cell lymphoma. To gain insight into the mechanisms by which these compounds act, we tested their effects in zebrafish. Vincristine or bortezomib given during late embryonic development caused significant defects at both behavioral and cellular levels. Intriguingly, the effects of the two drugs appear to be distinct. Vincristine causes …

Dynein Achieves Processive Motion Using Both Stochastic And Coordinated Stepping, Weihong Qiu, Nathan D. Derr, Brian S. Goodman, Elizabeth Villa, David Wu, William Shih, Samara L. Reck-Peterson

Biological Sciences: Faculty Publications

Processivity, the ability of single molecules to move continuously along a track, is a fundamental requirement of cargo-transporting molecular motors. Here, we investigate how cytoplasmic dynein, a homodimeric, microtubule-based motor, achieves processive motion. To do this, we developed a versatile method for assembling Saccharomyces cerevisiae dynein heterodimers, using complementary DNA oligonucleotides covalently linked to dynein monomers labeled with different organic fluorophores. Using two-color, single-molecule microscopy and high-precision, two-dimensional tracking, we find that dynein has a highly variable stepping pattern that is distinct from all other processive cytoskeletal motors, which use 'hand-over-hand' mechanisms. Uniquely, dynein stepping is stochastic when its two …

Desiccation Induces Viable But Non-Culturable Cells In Sinorhizobium Meliloti 1021, Jan A.C. Vriezen, Frans J. De Bruijn, Klaus R. Nüsslein

Biological Sciences: Faculty Publications

Sinorhizobium meliloti is a microorganism commercially used in the production of e.g. Medicago sativa seed inocula. Many inocula are powder-based and production includes a drying step. Although S. meliloti survives drying well, the quality of the inocula is reduced during this process. In this study we determined survival during desiccation of the commercial strains 102F84 and 102F85 as well as the model strain USDA1021.

The survival of S. meliloti 1021 was estimated during nine weeks at 22% relative humidity. We found that after an initial rapid decline of colony forming units, the decline slowed to a steady 10-fold reduction …

A Multicenter Evaluation Of Diagnostic Tools To Define Endpoints For Programs To Eliminate Bancroftian Filariasis, Katherine Gass, Madsen V.E. Beau De Rochars, Daniel Boakye, Mark Bradley, Peter U. Fischer, John Gyapong, Makoto Itoh, Nese Ituaso-Conway, Hayley Joseph, Dominique Kyelem, Sandra J. Laney, Anne-Marie Legrand, Tilaka S. Liyanage, Wayne Melrose, Khalfan Mohammed, Nils Pilotte, Eric A. Ottesen, Catherine Plichart, Kapa Ramaiah, Ramakrishna U. Rao, Jeffrey Talbot, Gary J. Weil, Steven A. Williams, Kimberly Y. Won, Patrick J. Lammie

Biological Sciences: Faculty Publications

Successful mass drug administration (MDA) campaigns have brought several countries near the point of Lymphatic Filariasis (LF) elimination. A diagnostic tool is needed to determine when the prevalence levels have decreased to a point that MDA campaigns can be discontinued without the threat of recrudescence. A six-country study was conducted assessing the performance of seven diagnostic tests, including tests for microfilariae (blood smear, PCR), parasite antigen (ICT, Og4C3) and antifilarial antibody (Bm14, PanLF, Urine SXP). One community survey and one school survey were performed in each country. A total of 8,513 people from the six countries participated in the study, …

Heterogeneous Rates Of Molecular Evolution Among Cryptic Species Of The Ciliate Morphospecies Chilodonella Uncinata, Laura A. Katz, Jennifer Deberardinis, Meaghan S. Hall, Alexandra M. Kovner, Micah Dunthorn, Spencer V. Muse

Biological Sciences: Faculty Publications

While molecular analyses have provided insight into the phylogeny of ciliates, the few studies assessing intraspecific variation have largely relied on just a single locus [e.g., nuclear small subunit rDNA (nSSUrDNA) or mitochondrial cytochrome oxidase I]. In this study, we characterize the diversity of several nuclear protein-coding genes plus both nSSU-rDNA and mitochondrial small subunit rDNA (mtSSU-rDNA) of five isolates of the ciliate morphospecies Chilodonella uncinata. Although these isolates have nearly identical nSSU-rDNA sequences, they differ by up to 8.0% in mtSSU-rDNA. Comparative analyses of all loci, including b-tubulin paralogs, indicate a lack of recombination between strains, demonstrating that the …

The Nih-Niaid Filariasis Research Reagent Resource Center, Michelle L. Michalski, Kathryn G. Griffiths, Steven A. Williams, Ray M. Kaplan, Andrew Moorhead

Biological Sciences: Faculty Publications

Filarial worms cause a variety of tropical diseases in humans; however, they are difficult to study because they have complex life cycles that require arthropod intermediate hosts and mammalian definitive hosts. Research efforts in industrialized countries are further complicated by the fact that some filarial nematodes that cause disease in humans are restricted in host specificity to humans alone. This potentially makes the commitment to research difficult, expensive, and restrictive. Over 40 years ago, the United States National Institutes of Health–National Institute of Allergy and Infectious Diseases (NIH-NIAID) established a resource from which investigators could obtain various filarial parasite species …

Auditory Selectivity For Acoustic Features That Confer Species Recognition In The Túngara Frog, Lisa A. Mangiamele, Sabrina S. Burmeister

Biological Sciences: Faculty Publications

In anurans, recognition of species-specific acoustic signals is essential to finding a mate. In many species, behavioral tests have elucidated which acoustic features contribute to species recognition, but the mechanisms by which the brain encodes these species-specific signal components are less well understood. The túngara frog produces a 'whine' mating call that is characterized by a descending frequency sweep. However, much of the signal is unnecessary for recognition, as recognition behavior can be triggered by a descending two-tone step that mimics the frequency change in a portion of the whine. To identify the brain regions that contribute to species recognition …

Estimating The Timing Of Early Eukaryotic Diversification With Multigene Molecular Clocks, Laura Wegener Parfrey, Daniel J.G. Lahr, Andrew H. Knoll, Laura A. Katz

Biological Sciences: Faculty Publications

Although macroscopic plants, animals, and fungi are the most familiar eukaryotes, the bulk of eukaryotic diversity is microbial. Elucidating the timing of diversification among the more than 70 lineages is key to understanding the evolution of eukaryotes. Here, we use taxon-rich multigene data combined with diverse fossils and a relaxed molecular clock framework to estimate the timing of the last common ancestor of extant eukaryotes and the divergence of major clades. Overall, these analyses suggest that the last common ancestor lived between 1866 and 1679 Ma, consistent with the earliest microfossils interpreted with confidence as eukaryotic. During this interval, the …