Selfish Replicators Research Articles

Are viruses alive? The replicator paradigm sheds decisive light on an old but misguided question

The question whether or not “viruses are alive” has caused considerable debate over many years. Yet, the question is effectively without substance because the answer depends entirely on the definition of life or the state of “being alive” that is bound to be arbitrary. In contrast, the status of viruses among biological entities is readily defined within the replicator paradigm. All biological replicators form a continuum along the selfishness-cooperativity axis, from the completely selfish to fully cooperative forms. Within this range, typical, lytic viruses represent the selfish extreme whereas temperate viruses and various mobile elements occupy positions closer to the middle of the range. Selfish replicators not only belong to the biological realm but are intrinsic to any evolving system of replicators. No such system can evolve without the emergence of parasites, and moreover, parasites drive the evolution of biological complexity at multiple levels. The history of life is a story of parasite-host coevolution that includes both the incessant arms race and various forms of cooperation. All organisms are communities of interacting, coevolving replicators of different classes. A complete theory of replicator coevolution remains to be developed, but it appears likely that not only the differentiation between selfish and cooperative replicators but the emergence of the entire range of replication strategies, from selfish to cooperative, is intrinsic to biological evolution.

Selfish intracellular replicators: a two-level selection minimalist mathematical model

A mathematical model of the interaction between two levels of selection (intracellular and cellular) is presented. The paradigm is that of a selfish intracellular replicator, such as a strand of selfish DNA, that reproduces itself at the expense of the efficiency of the structure of the cell. A mathematical analysis is conducted and conditions for the survival of the selfish replicators are obtained explicitly. Our results indicate that, if reproduction is asexual, mechanisms of horizontal transfer of genes are essential for the fixation of such replicators in the population and also that less harmful replicators have a better chance of infecting a whole population, while aggressive ones will usually successfully infect only a part of it.

Tag-Mediated Altruism is Contingent on How Cheaters Are Defined

Cooperation is essential for complex biological and social systems and explaining its evolutionary origins remains a central question in several disciplines. Tag systems are a class of models demonstrating the evolution of cooperation between selfish replicators. A number of previous models have been presented but they have not been widely explored. Though previous researchers have concentrated on the effects of one or several parameters of tag models, exploring exactly what is meant by cheating in a tag system has received little attention. Here we re-implement three previous models of tag-mediated altruism and introduce four definitions of cheaters. Previous models have used what we consider weaker versions of cheaters that may not exploit cooperators to the degree possible, or to the degree observed in natural systems. We find that the level of altruism that evolves in a population is highly contingent on how cheaters are defined. In particular when cheaters are defined as agents that display an appropriate tag but have no mechanism for participating in altruistic acts themselves, a population is quickly invaded by cheaters and all altruism collapses. Even in the intermediate case where cheaters may revert back to a tag-tolerance mode of interaction, only minimal levels of altruism evolve. Our results suggest that models of tag-mediated altruism using stronger types of cheaters may require additional mechanisms, such as punishment strategies or multi-level selection, to evolve meaningful levels of altruism.

Through a generation darkly: small RNAs in the gametophyte

The various classes of small non-coding RNAs are a fundamentally important component of the transcriptome. These molecules have roles in many essential processes such as regulation of gene expression at the transcriptional and post-transcriptional levels, guidance of DNA methylation and defence against selfish replicators such as transposons. Their diversity and functions in the sporophytic generation of angiosperms is well explored compared with the gametophytic generation, where little is known about them. Recent progress in understanding their abundance, diversity and function in the gametophyte is reviewed.

Memetics in Neurosurgery and Neuroscience

Imitation is a powerful means of spreading culture that teaches people to speak languages, children to play, and surgeons to operate. The basic unit of imitation is a replicator called meme which, like genes, carries information and spreads it. The concepts of memes and the science of memetics were introduced by the biologist Richard Dawkins in 1976 and, since then, memes have been found everywhere, and used to explain both social and scientific phenomena. Memes are ideas, tunes, fashions, and ways of saying things; they are also surgical techniques, because these too have the replicating power to jump from brain to brain via the process of imitation. Like surgery in general, neurosurgery is a complex set of memes: the neuroscientific concepts and surgical techniques shared by neuroscientists and neurosurgeons by means of congresses, articles and the imitation of others’ actions in operating theatres. The spread of neural memes is guaranteed by bridges that interconnect the individual elements of the general network, in the same way as fashions or infections. Over the last few decades, neurophysiological discoveries such as mirror neurons have revealed the presence of a neural network that is very important in the process of imitation, and studying memetics should be considered as important as studying genetics because both involve selfish replicators (memes and genes) whose co-evolution is fundamental to understanding the evolution of mankind and culture. The study of memetics and its applications in the fields of neurosurgery and neuroscience can offer a new perspective for understanding the mechanisms of both neural and social networks, thus providing a holistic view of neuroscience and the social sciences that will lead to further insights into the science of the mind.

The Evolutionary Dynamics of Selfish Replicators: a Two-level Selection Model

The aim of the present paper is to study the evolutionary dynamics of selfish replicators in a constant genetic background. Selfish replicators are viewed at a single locus, having a pleiotropic effect. Infinitely many alleles are possible; they act on individual fitness and have various levels of ability to distort segregation. This results in a two-level process of selection, including inter-individual selection (effect on individual fitness) and intra-individual selection (ability to distort segregation). The model takes other parameters into account, such as dominance, inbreeding and inbreeding depression. The system can have two different behaviours. (1) In some cases, evolutionary cycles are possible. The cycles correspond to an alternation of phases with predominant inter-individual selection, corresponding to major-effect mutations, and phases with predominant intra-individual selection, corresponding to small-effect mutations. (2) For other values of the parameters, a synthetic fitness can be defined: this absolute allelic fitness is estimated as a function of one's fitness due to both inter-individual and intra-individual selection. During the course of evolution, the synthetic fitness increases. The optimisation of a synthetic fitness is the most general process. The optimised value is essentially homologous to the value optimised for resource allocation to male and female function in hermaphrodites (female function being homologous to the effect on individual fitness, and male function being homologous to distortion ability). The relative importance of both behaviours is discussed. It is argued that repeated sequences causing some human degenerative hereditary diseases may follow a two-step evolutionary process: a progressive increase in number of sequences accompanied by a decrease of the individual fitness would be followed by massive elimination of such sequences. But in general the optimisation of the synthetic fitness seems to be more likely.

Why are organelles uniparentally inherited?

Restricted accessMoreSectionsView PDF ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmail Cite this article Godelle B. and Reboud X. 1995Why are organelles uniparentally inherited?Proc. R. Soc. Lond. B.25927–33http://doi.org/10.1098/rspb.1995.0005SectionRestricted accessArticleWhy are organelles uniparentally inherited? B. Godelle Google Scholar Find this author on PubMed Search for more papers by this author and X. Reboud Google Scholar Find this author on PubMed Search for more papers by this author B. Godelle Google Scholar Find this author on PubMed Search for more papers by this author and X. Reboud Google Scholar Find this author on PubMed Search for more papers by this author Published:23 January 1995https://doi.org/10.1098/rspb.1995.0005AbstractUniparental inheritance of organelles is a very common trait but one that has received few attempts at evolutionary explanation. The most commonly adopted theory emphasizes the potentially deleterious behaviour of selfish cytoplasmic replicators and considers uniparental inheritance as a character whereby nuclear genes may avoid the spread of these cytoplasmic replicators. Here, the autonomous evolution of cytoplasmic genes is considered and an alternative evolutionary pathway to uniparental inheritance is described. The process involves specialization of organelles to cell lines, with invasion of the cytoplasm by cytoplasmic replicators specialized to replicate in the female germ-line. As a result, the nature of selection is modified and other cytoplasmic genes (especially selfish replicators) cannot spread: uniparental inheritance appears, then, to be a stable mode of inheritance. The conditions that lead to this evolutionary process are studied; it appears that the constraints caused by the evolution of anisogamy are of great importance and that the distribution of mutations can cause major differences in the evolutionary outcome.FootnotesThis text was harvested from a scanned image of the original document using optical character recognition (OCR) software. As such, it may contain errors. Please contact the Royal Society if you find an error you would like to see corrected. Mathematical notations produced through Infty OCR. Previous ArticleNext Article VIEW FULL TEXT DOWNLOAD PDF FiguresRelatedReferencesDetailsCited by Tilquin A, Christie J and Kokko H (2018) Mitochondrial complementation: a possible neglected factor behind early eukaryotic sex, Journal of Evolutionary Biology, 10.1111/jeb.13293, 31:8, (1152-1164), Online publication date: 1-Aug-2018. Chacón Sánchez M (2017) Organelle Genomes in Phaseolus Beans and Their Use in Evolutionary Studies The Common Bean Genome, 10.1007/978-3-319-63526-2_7, (147-166), . Ferdy J and Godelle B (2005) Diversification of Transmission Modes and the Evolution of Mutualism, The American Naturalist, 10.1086/491799, 166:5, (613-627), Online publication date: 1-Nov-2005. Korpelainen H (2004) The evolutionary processes of mitochondrial and chloroplast genomes differ from those of nuclear genomes, Naturwissenschaften, 10.1007/s00114-004-0571-3, 91:11, (505-518), Online publication date: 1-Nov-2004. Silliker M, Liles J and Monroe J (2017) Patterns of mitochondrial inheritance in the myxogastrid Didymium iridis , Mycologia, 10.1080/15572536.2003.11833152, 94:6, (939-946), Online publication date: 1-Nov-2002. Hastings (2008) The costs of sex due to deleterious intracellular parasites, Journal of Evolutionary Biology, 10.1046/j.1420-9101.1999.00019.x, 12:1, (177-183), Online publication date: 1-Jan-1999. Herrick G and Seger J (1999) Imprinting and Paternal Genome Elimination in Insects Genomic Imprinting, 10.1007/978-3-540-69111-2_3, (41-71), . Kondrashov A (1997) Evolutionary Genetics of Life Cycles, Annual Review of Ecology and Systematics, 10.1146/annurev.ecolsys.28.1.391, 28:1, (391-435), Online publication date: 1-Nov-1997. Waage J (1997) Parental Investment—Minding the Kids or Keeping Control? Feminism and Evolutionary Biology, 10.1007/978-1-4615-5985-6_24, (527-553), . Hurst L (1997) Cytoplasmic genetics under inbreeding and outbreeding, Proceedings of the Royal Society of London. Series B: Biological Sciences, 258:1353, (287-298), Online publication date: 22-Dec-1994. This Issue23 January 1995Volume 259Issue 1354 Article InformationDOI:https://doi.org/10.1098/rspb.1995.0005Published by:Royal SocietyPrint ISSN:0962-8452Online ISSN:1471-2954History: Manuscript received16/09/1994Manuscript accepted13/10/1994Published online01/01/1997Published in print23/01/1995 License:Scanned images copyright © 2017, Royal Society Citations and impact Large datasets are available through Proceedings B's partnership with Dryad

COMMENTS ON GEORGE WILLIAMS'S ESSAY ON MORALITY AND NATURE

Abstract. Although there is no questioning the heroism of those who “rebel against the selfish replicators” their task seems very nearly insurmountable. I question whether anyone can formulate a broadly acceptable moral system that will not in some respects be constrained by the legacy of generations spent as selfish and kin‐selected replicators.