István Zachar

István Zachar
Centre for Ecological Research · Institute of Evolution

PhD

About

46
Publications
14,856
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
329
Citations
Citations since 2017
21 Research Items
276 Citations
20172018201920202021202220230102030405060
20172018201920202021202220230102030405060
20172018201920202021202220230102030405060
20172018201920202021202220230102030405060
Introduction
István Zachar currently works at the MTA ÖK Centre for Ecological Research. István does research in Ecology, Systems Biology and Evolutionary Biology. His current project is the origin of eukaryotes.
Additional affiliations
October 2017 - present
MTA Centre for Ecological Research
Position
  • Senior Researcher
October 2017 - present
MTA
Position
  • Researcher
October 2014 - October 2016
Eötvös Loránd University
Position
  • Research Assistant
Education
September 2004 - June 2007
Eötvös Loránd University
Field of study
  • Evolutionary biology, ecology
September 1999 - June 2004
Eötvös Loránd University
Field of study
  • Biology

Publications

Publications (46)
Article
Full-text available
The origin of mitochondria was a major evolutionary transition leading to eukaryotes, and is a hotly debated issue. It is unknown whether mitochondria were acquired early or late, and whether it was captured via phagocytosis or syntrophic integration. We present dynamical models to directly simulate the emergence of mitochondria in an ecoevolutiona...
Article
Full-text available
The origin of mitochondria is a unique and hard evolutionary problem, embedded within the origin of eukaryotes. The puzzle is challenging due to the egalitarian nature of the transition where lower-level units took over energy metabolism. Contending theories widely disagree on ancestral partners, initial conditions and unfolding of events. There ar...
Article
Full-text available
Replicators are the crucial entities in evolution. The notion of a replicator, however, is far less exact than the weight of its importance. Without identifying and classifying multiplying entities exactly, their dynamics cannot be determined appropriately. Therefore, it is importance to decide the nature and characteristics of any multiplying enti...
Article
Full-text available
The simulation of complex biochemical systems, consisting of intertwined subsystems, is a challenging task in computational biology. The complex biochemical organization of the cell is effectively modeled by the minimal cell model called chemoton, proposed by Gánti. Since the chemoton is a system consisting of a large but fixed number of interactin...
Article
Full-text available
As of today, the most credible scientific paradigm pertaining to the origin of life on Earth is undoubtedly the RNA World scenario. It is built on the assumption that catalytically active replicators (most probably RNA-like macromolecules) may have been responsible for booting up life almost four billion years ago. The many different incarnations o...
Article
Full-text available
Syntrophic cooperation among prokaryotes is ubiquitous and diverse. It relies on unilateral or mutual aid that may be both catalytic and metabolic in nature. Hypotheses of eukaryotic origins claim that mitochondrial endosymbiosis emerged from mutually beneficial syntrophy of archaeal and bacterial partners. However, there are no other examples of p...
Article
Full-text available
Background Signal reliability poses a central problem for explaining the evolution of communication. According to Zahavi’s Handicap Principle, signals are honest only if they are costly at the evolutionary equilibrium; otherwise, deception becomes common and communication breaks down. Theoretical signalling games have proved to be useful for unders...
Article
A modelling study suggests that the proposed energetic barrier between prokaryotes and eukaryotes may not be relevant to the complexity gap between the two domains. The energetic advantage of early mitochondria was probably small, and eukaryotes likely emerged without the help of an endosymbiont.
Preprint
Full-text available
Explaining signal reliability poses a central problem in animal communication. According to Zahavi’s Handicap Principle (HP), signals are honest only when they are costly at the evolutionary equilibrium – hence the term ‘handicap’; otherwise, deception evolves, and communication breaks down. The HP has no theoretical or empirical support, despite c...
Article
Full-text available
Metabolic cooperation is widespread, and it seems to be a ubiquitous and easily evolvable interaction in the microbial domain. Mutual metabolic cooperation, like syntrophy, is thought to have a crucial role in stabilizing interactions and communities, for example biofilms. Furthermore, cooperation is expected to feed back positively to the communit...
Article
Full-text available
Endosymbiosis and organellogenesis are virtually unknown among prokaryotes. The single presumed example is the endosymbiogenetic origin of mitochondria, which is hidden behind the event horizon of the last eukaryotic common ancestor. While eukaryotes are monophyletic, it is unlikely that during billions of years, there were no other prokaryote–prok...
Article
Full-text available
Complexity of life forms on the Earth has increased tremendously, primarily driven by subsequent evolutionary transitions in individuality, a mechanism in which units formerly being capable of independent replication combine to form higher-level evolutionary units. Although this process has been likened to the recursive combination of pre-adapted s...
Preprint
Full-text available
A wide variety of human and non-human behavior is computationally well accounted for by probabilistic generative models, formalized consistently in a Bayesian framework. Recently, it has been suggested that another family of adaptive systems, namely, those governed by Darwinian evolutionary dynamics, are capable of implementing building blocks of B...
Article
Full-text available
The “cost of begging” is a prominent prediction of costly signalling theory, suggesting that offspring begging has to be costly in order to be honest. Seminal signalling models predict that there is a unique equilibrium cost function for the offspring that results in honest signalling and this cost function must be proportional to parent’s fitness...
Data
Video of interactive figure. (MP4)
Data
Interactive figure as Mathematica notebook. (NB)
Article
Sexual reproduction is widespread in nature despite the different kinds of cost that it entails. We do not know exactly when the first sexual process took place and especially why it was beneficial at first. It is clearer why sex is advantageous for the prokaryotes and eukaryotes but the benefit of sex for protocells with individually replicating r...
Preprint
Full-text available
Complexity of life forms on Earth has increased tremendously, primarily driven by subsequent evolutionary transitions in individuality, a mechanism in which units formerly being capable of independent replication combine to form higher-level evolutionary units. Although this process has been likened to the recursive combination of pre-adapted sub-s...
Preprint
Full-text available
The “cost of begging” is a prominent prediction of costly signalling theory, suggesting that offspring begging has to be costly in order to be honest. More specifically, it predicts that there is a single cost function for the offspring (depending on e.g. offspring quality) that maintains honesty and it must be proportional to parent’s fitness loss...
Article
Full-text available
Background : The fact that surplus connections and neurons are pruned during development is well established. We complement this selectionist picture by a proof-of-principle model of evolutionary search in the brain, that accounts for new variations in theory space. We present a model for Darwinian evolutionary search for candidate solutions in the...
Article
Full-text available
In this paper, we show that a neurally implemented a cognitive architecture with evolutionary dynamics can solve the four-tree problem. Our model, called Darwinian Neurodynamics, assumes that the unconscious mechanism of problem solving during insight tasks is a Darwinian process. It is based on the evolution of patterns that represent candidate so...
Article
Full-text available
Background: The fact that surplus connections and neurons are pruned during development is well established. We complement this selectionist picture by a proof-of-principle model of evolutionary search in the brain, that accounts for new variations in theory space. We present a model for Darwinian evolutionary search for candidate solutions in the...
Conference Paper
Full-text available
The human brain can generate new ideas, hypotheses and candidate solutions to difficult tasks with surprising ease. We argue that this process has evolutionary dynamics, with multiplication, inheritance and variability all implemented in neural matter. This inspires our model, whose main component is a population of recurrent attractor networks wit...
Article
Full-text available
The RNA world hypothesis of the origin of life, in which RNA emerged as both enzyme and information carrier, is receiving solid experimental support. The prebiotic synthesis of biomolecules, the catalytic aid offered by mineral surfaces, and the vast enzymatic repertoire of ribozymes are only pieces of the origin of life puzzle; the full picture ca...
Data
Correlation plot of the fitness landscape as a function of Hamming distances for sequence pairs of length . (TIF)
Data
Examples of coexistence for . (XLS)
Data
Coexistence plots of pairs of double-stranded sequences of length (upper panel) and (lower panel) using two monomers (, ) in case of uniform degradation and identical elongation rate constants and non-complementary pairing. The green indicates stable coexistence, grey indicates structurally unstable coexistence, i.e. compositional identity (no coex...
Data
Examples of coexistence for . (XLS)
Data
Supporting text with sections on 1) Parameters for methods M1, M2, M3 and M4; 2) Analysis of non-complementary pairing with antiparallel polarity; 3) Analysis and analytical results of non-complementary pairing and uniform degradation rates; 4) Proofs; 5) Discussion of the fitness landscape; 6) Examples of coexistence of longer sequences. (PDF)
Data
Split plot of the coexistence of two non-complementary sequence pairs with antiparallel strand polarity (4 sequences per pair) of length . Lower left half: coexistence is marked by green, extinction of the first sequence pair by red and extinction of the second sequence pair by blue. Upper right half: stability of coexistence according to the leadi...
Data
Analysis of coexistence of non-complementary pairs of sequences of length according to method M1. Second column shows the number of scanned sequences (and the amount as a fraction of the whole combined sequence space). The third column shows the fraction of coexisting sequences in the scanned domain, i.e. the probability of coexistence of random se...
Data
Examples of coexistence for . (XLS)
Data
Analysis of coexistence of non-complementary pairs of length according to method M2. Second column shows the number of scanned sequences (and the amount as a fraction of the combined sequence space). The third column shows the fraction of coexisting sequences averaged over the scanned sequence groups and over 1000 random degradation rate sets for i...
Article
Full-text available
Models of competitive template replication, although basic for replicator dynamics and primordial evolution, have not yet taken different sequences explicitly into account, neither have they analyzed the effect of resource partitioning (feeding on different resources) on coexistence. Here we show by analytical and numerical calculations that Gause'...
Chapter
Full-text available
Here we review chemical and biological replicators that were either engineered (artificially) or evolved (either naturally or artificially). They are automata even though they need not be electro-mechanical machines or computer programs. Gánti has described the class of fluid automata (Gánti, 2003a) into which almost (but perhaps not) all biologica...
Thesis
Full-text available
Replicators are the most important objects of evolutionary biology. Their cumulative evolution lead to the emergence of complex, adaptive systems, like life. All major transitions of evolution are outcomes of the evolution of replicators. However, replication (and evolution) are universal concepts, independent of the level of biological organizatio...
Article
Full-text available
An important question in language evolution is whether segmentation as a linguistic process is able to yield compositionality. Segmentation is hypothesized to be a process to bridge the gap between holistic and compositional lexicons. However, to date no thorough analytical method has been provided to test the feasibility of segmentation. In this p...
Chapter
Full-text available
It is justified to assume that part of our genetic endowment contributes to our language skills, yet it is impossible to tell at this moment exactly how genes affect the language faculty. We complement experimental biological studies by an in silico approach in that we simulate the evolution of neuronal networks under selection for language-related...

Network

Cited By