Transmission Bottlenecks and the Evolution of Fitness in Rapidly

Total Page:16

File Type:pdf, Size:1020Kb

Transmission Bottlenecks and the Evolution of Fitness in Rapidly Infection, Genetics and Evolution 1 (2001) 41–48 Transmission bottlenecks and the evolution of fitness in rapidly evolving RNA viruses Santiago F. Elena∗, Rafael Sanjuán, Antonio V. Border´ıa, Paul E. Turner1 Institut Cavanilles de Biodiversitat i Biolog´ıa Evolutiva and Departament de Genètica, Universitat de València. Apartat 2085, 46071 València, Spain Received 17 November 2000; received in revised form 10 February 2001; accepted 5 March 2001 Abstract We explored the evolutionary importance of two factors in the adaptation of RNA viruses to their cellular hosts, size of viral inoculum used to initiate a new infection, and mode of transmission (horizontal versus vertical). Transmission bottlenecks should occur in natural populations of viruses and their profound effects on viral adaptation have been previously documented. However, the role of transmission mode has not received the same attention. Here we used a factorial experimental design to test the combined effects of inoculum (bottleneck) size and mode of transmission in evolution of vesicular stomatitis virus (VSV) in tissue culture, and compared our results to the predictions of a recent theoretical model. Our data were in accord with basic genetic principles concerning the balance between mutation, selection and genetic drift. In particular, attenuation of vertically transmitted viruses was a consequence of the random accumulation of deleterious mutations, whereas horizontally transmitted viruses experiencing similar bottlenecks did not suffer the same fitness losses because effective bottleneck size was actually determined by the number of host individuals. In addition, high levels of viral fitness in horizontally transmitted populations were explained by competition among viral variants. © 2001 Elsevier Science B.V. All rights reserved. Keywords: Beneficial mutations; Deleterious mutations; Experimental evolution; Fitness; Horizontal transmission; Vertical transmission; Vesicular stomatitis virus 1. Introduction Ewald (1987) suggests that virulence should decrease under vertical transmission because pathogen fitness is lim- Evolution of parasite fitness is governed by competition ited by host reproduction, a parasite that harms its host at two different levels, intrahost replication and interhost too much will reduce its own reproductive success (Chao transmission (Levin and Svanborg Éden, 1990; Bull, 1994; et al. (2000) for a different prediction when interference Ewald, 1994; Chao et al., 2000). Despite extensive theoreti- competition occurs between parasites within the host). cal work exploring the role of transmission mode in pathogen In contrast, vertical transmission of viral pathogens via evolution (Anderson and May, 1986; Lenski and May, 1994; plaque-to-plaque serial transfer in the laboratory is shown Lipsitch et al., 1996; Frank, 1996; Boots and Sasaki, 1999), to reduce virulence through the accumulation of deleterious relatively little empirical support exists for these models mutations (Domingo and Holland, 1997). In bottlenecked or their underlying assumptions (Bull et al., 1991; Herre, lineages harmful mutations will accumulate over time, caus- 1993; Turner et al., 1998; Messenger et al., 1999). Vertical ing the mean fitness of the population to decline; a process transmission of parasites occurs within a single host lineage analogous to Muller’s ratchet (Muller, 1964). Thus, parasite (between an infected parent and its offspring), but horizontal fitness can decrease through direct genetic consequences of transmission allows a parasite to reach any susceptible host the transmission process, rather than through a parasite’s in the population regardless of descent. Therefore, compe- effects on host fitness. tition between vertically transmitted parasites occurs only Recently, Bergstrom et al. (1999) discussed several con- at the intrahost level, while that between horizontally trans- sequences of transmission bottlenecks for the evolution of mitted parasites takes place at the interhost level as well. rapidly evolving pathogens, such as RNA viruses. (i) When inoculum size is large (absence of severe bottlenecks), changes in genotype frequency caused by sampling effects ∗ + + Corresponding author. Tel.: 34-963-983-666; fax: 34-963-983-670. become insignificant. Under vertical transmission, genotype E-mail address: [email protected] (S.F. Elena). 1 Present address: Laboratory of Clinical Investigation, National Institutes frequencies in the independently evolving lineages will of Health, Bethesda, MD 20892-1888, USA. converge on an equilibrium distribution of viral phenotypes 1567-1348/01/$ – see front matter © 2001 Elsevier Science B.V. All rights reserved. PII: S1567-1348(01)00006-5 42 S.F. Elena et al. / Infection, Genetics and Evolution 1 (2001) 41–48 present in the individual transmitting the infection. Thus, low Comer et al., 1990). Therefore, both modes of transmission genetic variance and similar levels of mean fitness are ex- are a natural component of VSV biology. pected among the viral populations. By a similar argument, Here we used VSV and eukaryotic cells in tissue cul- horizontally transmitted viruses that share a common gene ture to answer three questions. Under severe bottlenecks, pool will converge on an equilibrium phenotypic distribu- can horizontally transmitted viruses better combat the mu- tion (and hence the same genetic variability and fitness). But tational load and achieve greater fitness? With increased horizontal transfer allows fitter strains to export their greater inoculum size, does the fitness of vertically transmitted productivity to other host lineages, and selection should viruses approach that of their horizontally transmitted coun- maintain high fitness in horizontally transmitted viruses. terparts? Do smaller bottlenecks lead to greater genetic This effect of transmission mode on fitness is expected even variance in fitness among replicate populations regardless when the host population contains as few as five individuals. of transmission mode? (ii) When inoculum size is small (severe bottlenecks), sam- pling error causes the genotype frequency distribution in a newly infected host to deviate from that in the transmitting 2. Material and methods host and, presumably, mean fitness should decline. The evolutionary dynamics of horizontally and vertically 2.1. Viral clones, cells and culture conditions transmitted viruses should differ in two ways. First, under vertical transmission alone the viruses in each individual Viruses used in this study were originally derived from the host compose an evolutionarily separate population from Mudd-Summer strain of the VSV Indiana serotype, hereafter those in every other host. Therefore, vertically transmitted referred to as wild-type (wt). MARM C is a mutant derived → viruses from different hosts at time t = 0 will never share from wt. Both genotypes only differ on an Asp259 Ala a common host at time t>0. In contrast, horizontally substitution in the G surface protein, a mutation that allows transmitted viruses from separate hosts at t = 0 may share growth under I1-monoclonal antibody (I1-mAb) concentra- a common host at t>0. The result is that vertically trans- tions that completely neutralize wt (Lefrancois and Lyles, mitted viruses are separated into n subpopulations passing 1982; Vandepol et al., 1986). This amino acid substitution through a bottleneck of size b at each transmission event, do not have any effect on MARM C fitness and both clones whereas horizontally transmitted pathogens form a single can be considered as effectively neutrals (Holland et al., population passing through a bottleneck of size nb. Sec- 1991; Miralles et al., 1999, 2000). MARM C served as the ond, horizontally transmitted viral populations feature a common competitor in our fitness assays (see Section 2.2). greater potential for growth rate differences to counteract Baby hamster kidney (BHK) cells were grown as mono- mutational load. Under horizontal transmission a novel mu- layers under Dulbecco modified Eagle’s minimum essential tation will continue competing with its progenitor to infect medium (DMEM) supplemented with 5% newborn calf the same set of hosts until one is lost to extinction. But serum and 0.06% proteose peptone 3. Cells were grown to with vertical transmission the two mutations can compete a density of ∼ 3 × 105 cells/cm2 in 25 cm2 plastic flasks for only as long as they reside in the same individual, and infections, or in 100 cm2 plates for routine maintenance. To selection has less time to combat deleterious mutations. produce I1-mAb, hybridoma cells were grown in DMEM Thus, smaller bottleneck size and relatively weak selection containing 20% foetal bovine serum, 2 ␮g/ml thymidine, allow mutations to more severely reduce fitness in verti- 0.1 mg/ml glycine, 14 ␮g/ml hypoxanthine and 1.3 ␮l/ml of cally transmitted viruses than in horizontally transmitted Opti-mAb (GibcoBRL). All cell lines were maintained in ◦ ones. incubators at 37 C, 5% CO2 atmosphere, and 95% relative Vesicular stomatitis virus (VSV) is a typical member humidity. of the Vesiculovirus genus (family Rhabdoviridae, order Mononegavirales), and provides an excellent model to test 2.2. Experimental design predictions similar to those above. VSV and other RNA viruses feature extremely high rates of spontaneous muta- Our experimental design (Fig. 1) mimicked virus evo- tion (orders of magnitude larger than DNA genomes) that lution in a population of multicellular hosts reproduc- distinguish them from other parasites (Drake and Holland,
Recommended publications
  • Cultural Macroevolution and the Transmission of Traits
    UC Davis UC Davis Previously Published Works Title Cultural macroevolution and the transmission of traits Permalink https://escholarship.org/uc/item/92n9t9q0 Journal Evolutionary Anthropology, 15(2) ISSN 1060-1538 Authors Borgerhoff Mulder, Monique Nunn, C L Towner, M. C. Publication Date 2006-03-01 Peer reviewed eScholarship.org Powered by the California Digital Library University of California Borgerhoff Mulder, Nunn and Towner 2005 1/4/2007 Page 1 of 38 CULTURAL MACROEVOLUTION AND THE TRANSMISSION OF TRAITS Monique Borgerhoff Mulder University of California Department of Anthropology Davis, CA 95616 USA email: [email protected] Charles L. Nunn University of California Department of Integrative Biology Berkeley, CA 94720-3140 USA Max Planck Institute for Evolutionary Anthropology Leipzig, Germany email: [email protected] Mary C. Towner University of California Department of Anthropology Davis, CA 95616 USA email: [email protected] Monique Borgerhoff Mulder is at the Department of Anthropology (UC Davis) and also a member of the Center for Population Biology and the Graduate Group in Ecology. Charles Nunn is a scientist at the Max Planck Institute for Evolutionary Anthropology and in the Department of Integrative Biology at UC Berkeley. Mary Towner is a post doctoral fellow in the Department of Anthropology at UC Davis Word Count: 7668 (including 4 boxes) 7 figures 100 refs Revised for Evolutionary Anthropology p. 1 Borgerhoff Mulder, Nunn and Towner 2005 1/4/2007 Page 2 of 38 Cultural traits are distributed across human societies in a patterned way. Study of the mechanisms whereby cultural traits persist and change over time is key to understanding human cultural diversity.
    [Show full text]
  • Parents with Periodontitis Impact the Subgingival Colonization of Their Ofspring Mabelle Freitas Monteiro1, Khaled Altabtbaei2, Purnima S
    www.nature.com/scientificreports OPEN Parents with periodontitis impact the subgingival colonization of their ofspring Mabelle Freitas Monteiro1, Khaled Altabtbaei2, Purnima S. Kumar3,4*, Márcio Zafalon Casati1, Karina Gonzales Silverio Ruiz1, Enilson Antonio Sallum1, Francisco Humberto Nociti‑Junior1 & Renato Corrêa Viana Casarin1,4 Early acquisition of a pathogenic microbiota and the presence of dysbiosis in childhood is associated with susceptibility to and the familial aggregation of periodontitis. This longitudinal interventional case–control study aimed to evaluate the impact of parental periodontal disease on the acquisition of oral pathogens in their ofspring. Subgingival plaque and clinical periodontal metrics were collected from 18 parents with a history of generalized aggressive periodontitis and their children (6–12 years of age), and 18 periodontally healthy parents and their parents at baseline and following professional oral prophylaxis. 16S rRNA amplicon sequencing revealed that parents were the primary source of the child’s microbiome, afecting their microbial acquisition and diversity. Children of periodontitis parents were preferentially colonized by Filifactor alocis, Porphyromonas gingivalis, Aggregatibacter actinomycetemcomitans, Streptococcus parasanguinis, Fusobacterium nucleatum and several species belonging to the genus Selenomonas even in the absence of periodontitis, and these species controlled inter‑bacterial interactions. These pathogens also emerged as robust discriminators of the microbial signatures of children of parents with periodontitis. Plaque control did not modulate this pathogenic pattern, attesting to the microbiome’s resistance to change once it has been established. This study highlights the critical role played by parental disease in microbial colonization patterns in their ofspring and the early acquisition of periodontitis‑related species and underscores the need for greater surveillance and preventive measures in families of periodontitis patients.
    [Show full text]
  • The Human Gut Microbiota: a Dynamic Interplay with the Host from Birth to Senescence Settled During Childhood
    Review nature publishing group The human gut microbiota: a dynamic interplay with the host from birth to senescence settled during childhood Lorenza Putignani1, Federica Del Chierico2, Andrea Petrucca2,3, Pamela Vernocchi2,4 and Bruno Dallapiccola5 The microbiota “organ” is the central bioreactor of the gastroin- producing immunological memory (2). Indeed, the intestinal testinal tract, populated by a total of 1014 bacteria and charac- epithelium at the interface between microbiota and lymphoid terized by a genomic content (microbiome), which represents tissue plays a crucial role in the mucosa immune response more than 100 times the human genome. The microbiota (2). The IS ability to coevolve with the microbiota during the plays an important role in child health by acting as a barrier perinatal life allows the host and the microbiota to coexist in a against pathogens and their invasion with a highly dynamic relationship of mutual benefit, which consists in dispensing, in modality, exerting metabolic multistep functions and stimu- a highly coordinated way, specific immune responses toward lating the development of the host immune system, through the biomass of foreign antigens, and in discriminating false well-­organized programming, which influences all of the alarms triggered by benign antigens (2). The failure to obtain growth and aging processes. The advent of “omics” technolo- or maintain this complex homeostasis has a negative impact gies (genomics, proteomics, metabolomics), characterized by on the intestinal and systemic health (2). Once the balance complex technological platforms and advanced analytical and fails, the “disturbance” causes the disease, triggering an abnor- computational procedures, has opened new avenues to the mal inflammatory response as it happens, for example, for the knowledge of the gut microbiota ecosystem, clarifying some inflammatory bowel diseases in newborns (2).
    [Show full text]
  • Studying Vertical Microbiome Transmission from Mothers to Infants by Strain-Level Metagenomic Profiling
    bioRxiv preprint doi: https://doi.org/10.1101/081828; this version posted October 21, 2016. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-NC 4.0 International license. 1 Studying vertical microbiome transmission from mothers to infants by strain-level metagenomic profiling Francesco Asnicar*,1, Serena Manara*,1, Moreno Zolfo1, Duy Tin Truong1, Matthias Scholz1, Federica Armanini1, Pamela Ferretti1, Valentina Gorfer2, Anna Pedrotti2, Adrian Tett1,#, Nicola Segata1,# * Equal contribution # Corresponding authors: [email protected], [email protected] 1 Centre for Integrative Biology, University of Trento, Italy 2 Azienda Provinciale per i Servizi Sanitari, Trento, Italy Abstract The gut microbiome starts to be shaped in the first days of life and continues to increase its diversity during the first months. Several investigations are assessing the link between the configuration of the infant gut microbiome and infant health, but a comprehensive strain-level assessment of vertically transmitted microbes from mother to infant is still missing. We longitudinally collected fecal and breast milk samples from multiple mother-infant pairs during the first year of life, and applied shotgun metagenomic sequencing followed by strain-level profiling. We observed several specific strains including those from Bifidobacterium bifidum, Coprococcus comes, and Ruminococcus bromii, that were present in samples from the same mother-infant pair, while being clearly distinct from those carried by other pairs, which is indicative of vertical transmission. We further applied metatranscriptomics to study the in vivo expression of vertically transmitted microbes, for example Bacteroides vulgatus and Bifidobacterium spp., thus suggesting that transmitted strains are functionally active in the two rather different environments of the adult and infant guts.
    [Show full text]
  • Evolution of Vertical and Oblique Transmission Under Fluctuating
    Evolution of vertical and oblique transmission under PNAS PLUS fluctuating selection Yoav Rama, Uri Libermanb, and Marcus W. Feldmana,1 aDepartment of Biology, Stanford University, Stanford, CA 94305-5020; and bSchool of Mathematical Sciences, Tel Aviv University, Tel Aviv 69978, Israel Contributed by Marcus W. Feldman, December 22, 2017 (sent for review November 2, 2017; reviewed by Hamish G. Spencer and Mark M. Tanaka) The evolution and maintenance of social learning, in competition symbionts from the parental cohort may be transmitted obliquely with individual learning, under fluctuating selection have been to younger individuals (18). In such cases, fluctuations in the well-studied in the theory of cultural evolution. Here, we study resource type or availability may have fitness effects that depend competition between vertical and oblique cultural transmission on features of the transmitted microbiome. This ecological per- of a dichotomous phenotype under constant, periodically cycling, spective on community transmission is stressed by van Opstal and and randomly fluctuating selection. Conditions are derived for Bordenstein (19), who emphasize the “need to consider the rel- the existence of a stable polymorphism in a periodically cycling ative roles of vertical and horizontal transmission of microbial selection regime. Under such a selection regime, the fate of a communities.” genetic modifier of the rate of vertical transmission depends on Another perspective on the evolutionary consequences of fluc- the length of the cycle and the strength of selection. In gen- tuating environments (and as a result, fluctuating selection) eral, the evolutionarily stable rate of vertical transmission differs derives from the phenomenon of phenotypic switching (20–25).
    [Show full text]
  • A Symbiont's Guide to the Germline Authors:​Shelbi L Russell, Laura
    Preprints (www.preprints.org) | NOT PEER-REVIEWED | Posted: 15 January 2019 Title: ​A symbiont’s guide to the germline Authors:​ Shelbi L Russell, Laura Chappell, and William Sullivan Affiliations: Department of Molecular, Cell, and Developmental Biology. University of California Santa Cruz. Santa Cruz, California, United States of America. To whom correspondence should be addressed: Email: ​[email protected] 1 © 2019 by the author(s). Distributed under a Creative Commons CC BY license. Preprints (www.preprints.org) | NOT PEER-REVIEWED | Posted: 15 January 2019 Abstract: Microbial symbioses exhibit astounding adaptations, yet all symbionts face the problem of how to reliably associate with host offspring every generation. A common strategy is vertical transmission, in which symbionts are directly transmitted from the female to her offspring. The diversity of symbionts and vertical transmission mechanisms is as expansive as the diversity of eukaryotic host taxa that house them. However, there are several common themes among these mechanisms based on the degree to which symbionts associate with the host germline during transmission. In this review, we detail three distinct vertical transmission strategies, starting with associations that are transmitted from host somatic cells to offspring somatic cells, either due to lacking a germline or avoiding it. A second strategy involves somatically-localized symbionts that migrate into the germline during host development. The third strategy we discuss is one in which the symbiont maintains continuous association with the germline throughout development. Unexpectedly, the vast majority of documented vertically inherited symbionts rely on the second strategy: soma-to-germline migration. Given that not all eukaryotes contain a sequestered germline and instead produce offspring from somatic stem cell lineages, this soma-to-germline migration is discussed in the context of multicellular evolution.
    [Show full text]
  • The Role of Multilevel Selection in Host Microbiome Evolution
    The role of multilevel selection in host microbiome evolution Simon van Vlieta,1 and Michael Doebelia,b aDepartment of Zoology, University of British Columbia, Vancouver, BC V6T 1Z4, Canada; and bDepartment of Mathematics, University of British Columbia, Vancouver, BC V6T 1Z2, Canada Edited by W. Ford Doolittle, Dalhousie University, Halifax, Canada, and approved August 28, 2019 (received for review June 7, 2019) Animals are associated with a microbiome that can affect selection at the holobiont level is unlikely to play a major role in their reproductive success. It is, therefore, important to under- nature (13, 14, 17–19). stand how a host and its microbiome coevolve. According to the The strength of the association between a host and its micro- hologenome concept, hosts and their microbiome form an inte- biome is thus expected to depend on the relative importance grated evolutionary entity, a holobiont, on which selection can of vertical and horizontal transmission, and recent studies have potentially act directly. However, this view is controversial, and shown that organisms can vary strongly in this regard (11, 15). there is an active debate on whether the association between This raises the question for what organisms and under what hosts and their microbiomes is strong enough to allow for selec- conditions selection can act at the level of the holobiont. This tion at the holobiont level. Much of this debate is based on verbal question has been actively debated in the recent literature; how- arguments, but a quantitative framework is needed to investi- ever, most of this debate is based on verbal arguments (7–10, 13, gate the conditions under which selection can act at the holobiont 17, 18).
    [Show full text]
  • Thresholds and Transitions in Hominin Cultural Evolution
    philosophies Article The Encultured Primate: Thresholds and Transitions in Hominin Cultural Evolution Chris Buskes Department of Philosophy, Radboud University, 6500 HD Nijmegen, The Netherlands; [email protected] Received: 30 November 2018; Accepted: 28 January 2019; Published: 1 February 2019 Abstract: This article tries to shed light on the mystery of human culture. Human beings are the only extant species with cumulative, evolving cultures. Many animal species do have cultural traditions in the form of socially transmitted practices but they typically lack cumulative culture. Why is that? This discrepancy between humans and animals is even more puzzling if one realizes that culture seems highly advantageous. Thanks to their accumulated knowledge and techniques our early ancestors were able to leave their cradle in Africa and swarm out across the planet, thereby adjusting themselves to a whole range of new environments. Without culture this would have been impossible. So we may ask once again: if cumulative culture is so useful, why don’t other animals have it? In order to explain this mystery I won’t appeal to the major transitions in human evolution—like walking upright, crafting stone tools and controlling fire, etc.—because that would be question begging. Instead I try to unearth the mechanisms that caused those evolutionary turning points to occur in the first place. It seems that unlike other animals, humans are predisposed to efficiently acquire, store and transmit cultural information in such ways that our cultures can genuinely evolve. Keywords: cultural evolution; cumulative culture; gene–culture coevolution; dual inheritance; universal Darwinism; memetics 1. Introduction Why is Homo sapiens the only species on our planet with cumulative culture? This issue is a profound mystery because it is obvious that culture has many merits.
    [Show full text]
  • Within-Host Diversity and Vertical Transmission of Group B Streptococcus Among
    bioRxiv preprint doi: https://doi.org/10.1101/760512; this version posted September 6, 2019. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY 4.0 International license. Within-Host Diversity and Vertical Transmission of Group B Streptococcus Among Mother-infant Dyads in The Gambia Ebenezer Foster-Nyarko1,2, Madikay Senghore1, Brenda A. Kwambana-Adams1, Nabil- Fareed Alikhan2, Anuradha Ravi2, James Jafali1,4, Kaddijatou Jawneh1, Amara Jah1, Maimuna Jarju1, Fatima Ceesay1, Sainabou Bojang1, Archibald Worwui1, Aderonke Odutola1, Ezra Ogundare1, Mark J. Pallen2, Martin Ota1,3, Martin Antonio1,5† 1Medical Research Council Unit The Gambia at the London School of Hygiene and Tropical Medicine, Atlantic Boulevard Road, Fajara, The Gambia 2Quadram Institute, Norwich Research Park, Norwich, Norfolk, United Kingdom 3GSK, 20 Avenue Fleming, 1300 Wavre, Belgium 4Pathogen Biology Research Group, Malawi-Liverpool-Wellcome Trust Clinical Research Programme, Chichiri, Blantyre 3, Malawi 5Microbiology and Infection Unit, Warwick Medical School, University of Warwick, Coventry, United Kingdom †Corresponding author: Professor Martin Antonio, Medical Research Council Unit The Gambia at the London School of Hygiene and Tropical Medicine, Atlantic Road, Fajara, The Gambia. Email: [email protected] bioRxiv preprint doi: https://doi.org/10.1101/760512; this version posted September 6, 2019. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY 4.0 International license.
    [Show full text]
  • Symbiote Transmission and Maintenance of Extra-Genomic Associations
    ORIGINAL RESEARCH ARTICLE published: 24 February 2014 doi: 10.3389/fmicb.2014.00046 Symbiote transmission and maintenance of extra-genomic associations Benjamin M. Fitzpatrick* Department of Ecology and Evolutionary Biology, University of Tennessee, Knoxville, TN, USA Edited by: Symbiotes can be transmitted from parents to offspring or horizontally from unrelated Monica Medina, Pennsylvania State hosts or the environment. A key question is whether symbiote transmission is similar University, USA enough to Mendelian gene transmission to generate and maintain coevolutionary Reviewed by: associations between host and symbiote genes. Recent papers come to opposite Carl J. Yeoman, Montana State University, USA conclusions, with some suggesting that any horizontal transmission eliminates genetic Martin Zimmer, Universität Salzburg, association. These studies are hard to compare owing to arbitrary differences in modeling Austria approach, parameter values, and assumptions about selection. I show that associations *Correspondence: between host and symbiote genes (extra-genomic associations) can be described by the Benjamin M. Fitzpatrick, same dynamic model as conventional linkage disequilibria between genes in the same Department of Ecology and Evolutionary Biology, University of genome. Thus, covariance between host and symbiote genomes depends on population Tennessee, 569 Dabney, Knoxville, history, geographic structure, selection, and co-transmission rate, just as covariance TN 37996, USA between genes within a genome. The conclusion that horizontal transmission rapidly e-mail: benfi[email protected] erodes extra-genomic associations is equivalent to the conclusion that recombination rapidly erodes associations between genes within a genome. The conclusion is correct in the absence of population structure or selection. However, population structure can maintain spatial associations between host and symbiote traits, and non-additive selection (interspecific epistasis) can generate covariances between host and symbiote genotypes.
    [Show full text]
  • Is More Better? Higher Sterilization of Infected Hosts Need Not Result in Reduced Pest Population Size
    Journal of Mathematical Biology manuscript No. (will be inserted by the editor) Is more better? Higher sterilization of infected hosts need not result in reduced pest population size Daniel Maxin · LudˇekBerec · Adrienna Bingham · Denali Molitor · Julie Pattyson Received: date / Accepted: date Abstract We analyze the effect of sterilization in the infected hosts in several epidemiological models involving infectious diseases that can be transmitted both vertically and horizontally. Sterilizing pathogens can be used as pest con- trol agents by intentionally inoculating the target population, with the goal of reducing or eliminating it completely. Contrary to previous models that did not include vertical transmission we found that the population size at the endemic equilibrium may actually increase with higher levels of sterility. This effect is proved to exist for low to high efficiencies of vertical transmission. On the other hand, if the disease is sexually transmitted and the host repro- duction and disease transmission are both consistently mediated by mating, D. Maxin Department of Mathematics and Computer Science, Valparaiso University, 1900 Chapel Drive, Valparaiso, IN 46383 Tel.: +219-464-5193 Fax: +219-464-5361 E-mail: [email protected] L. Berec Department of Biosystematics and Ecology, Institute of Entomology, Biology Centre ASCR, Braniˇsovsk´a31, 37005 Cesk´eBudˇejovice,ˇ Czech Republic E-mail: [email protected] A. Bingham Department of Mathematics and Computer Science, Angelo State University, 2601 West Avenue N, San Angelo, TX 76909 E-mail: [email protected] D. Molitor Department of Mathematics and Computer Science, Colorado College, 14 East Cache La Poudre Street, Colorado Springs, CO 80903 E-mail: [email protected] J.
    [Show full text]
  • Evidence That Vertical Transmission of the Vaginal Microbiota Can Persist Into
    bioRxiv preprint doi: https://doi.org/10.1101/768598; this version posted September 16, 2019. The copyright holder for this preprint (which was not certified by peer review) is the author/funder. All rights reserved. No reuse allowed without permission. 1 Title: Evidence that vertical transmission of the vaginal microbiota can persist into 2 adolescence 3 4 Running title: Vertical transmission of the vaginal microbiota 5 6 Authors: Christine M. Bassis ([email protected])1, Kaylie A. Bullock 7 ([email protected])1, Daniel E. Sack ([email protected])1, Katie Saund 8 ([email protected])2, Ali Pirani ([email protected])2, Evan S. Snitkin 9 ([email protected])1,2, Veronica I. Alaniz ([email protected])3, 10 Elisabeth H. Quint ([email protected])3, Vincent B. Young 11 ([email protected])1,2 and Jason D. Bell ([email protected])3. 12 13 1. Division of Infectious Disease, Department of Internal Medicine 14 2. Department of Microbiology and Immunology 15 3. Department of Obstetrics and Gynecology, University of Michigan, Ann Arbor, MI 16 48109 17 18 19 Corresponding author: Christine M. Bassis ([email protected]) 20 21 22 23 bioRxiv preprint doi: https://doi.org/10.1101/768598; this version posted September 16, 2019. The copyright holder for this preprint (which was not certified by peer review) is the author/funder. All rights reserved. No reuse allowed without permission. 24 Abstract 25 Background: Factors that influence vaginal microbiota composition, including its 26 source, are not well understood. To determine if vaginal microbiota transmission from 27 mother to daughter at birth influences the human vaginal microbiota composition in 28 adolescence, we investigated the relationship between the vaginal microbiota of 13 29 mother/daughter pairs and the daughter’s birth mode.
    [Show full text]