scholarly journals Conflict and cooperation in eukaryogenesis: implications for the timing of endosymbiosis and the evolution of sex

2015 ◽  
Author(s):  
Arunas L Radzvilavicius ◽  
Neil W Blackstone
Keyword(s):  
Cell Fusion ◽  
Mitochondrial Gene ◽  
Evolutionary Process ◽  
Eukaryotic Cell ◽  
Evolutionary Transition ◽  
Evolutionary Transitions ◽  
Conflict And Cooperation ◽  
Conflict Mediation ◽  
Considerable Debate ◽  
History Of

The complex eukaryotic cell is a result of an ancient endosymbiosis and one of the major evolutionary transitions. The timing of key eukaryotic innovations relative to the acquisition of mitochondria remains subject to considerable debate, yet the evolutionary process itself might constrain the order of these events. Endosymbiosis entailed levels-of-selection conflicts, and mechanisms of conflict mediation had to evolve for eukaryogenesis to proceed. The initial mechanisms of conflict mediation were based on the pathways inherited from prokaryotic symbionts and led to metabolic homeostasis in the eukaryotic cell, while later mechanisms (e.g., mitochondrial gene transfer) contributed to the expansion of the eukaryotic genome. Perhaps the greatest opportunity for conflict arose with the emergence of sex involving whole-cell fusion. While early evolution of cell fusion may have affected symbiont acquisition, sex together with the competitive symbiont behaviour would have destabilised the emerging higher-level unit. Cytoplasmic mixing, on the other hand, would have been beneficial for selfish endosymbionts, capable of using their own metabolism to manipulate the life history of the host. Given the results of our mathematical modelling, we argue that sex represents a rather late proto- eukaryotic innovation, allowing for the growth of the chimeric nucleus and contributing to the successful completion of the evolutionary transition.

scholarly journals Conflict and cooperation in eukaryogenesis: implications for the timing of endosymbiosis and the evolution of sex

2015 ◽  
Vol 12 (111) ◽  
pp. 20150584 ◽  
Author(s):  
Arunas L. Radzvilavicius ◽  
Neil W. Blackstone
Keyword(s):  
Gene Loss ◽  
Adenine Nucleotide ◽  
Mitochondrial Gene ◽  
Evolutionary Process ◽  
Eukaryotic Cell ◽  
Evolution Of Sex ◽  
Conflict And Cooperation ◽  
Conflict Mediation ◽  
Considerable Debate ◽  
History Of

Roughly 1.5–2.0 Gya, the eukaryotic cell evolved from an endosymbiosis of an archaeal host and proteobacterial symbionts. The timing of this endosymbiosis relative to the evolution of eukaryotic features remains subject to considerable debate, yet the evolutionary process itself constrains the timing of these events. Endosymbiosis entailed levels-of-selection conflicts, and mechanisms of conflict mediation had to evolve for eukaryogenesis to proceed. The initial mechanisms of conflict mediation (e.g. signalling with calcium and soluble adenylyl cyclase, substrate carriers, adenine nucleotide translocase, uncouplers) led to metabolic homeostasis in the eukaryotic cell. Later mechanisms (e.g. mitochondrial gene loss) contributed to the chimeric eukaryotic genome. These integral features of eukaryotes were derived because of, and therefore subsequent to, endosymbiosis. Perhaps the greatest opportunity for conflict arose with the emergence of eukaryotic sex, involving whole-cell fusion. A simple model demonstrates that competition on the lower level severely hinders the evolution of sex. Cytoplasmic mixing, however, is beneficial for non-cooperative endosymbionts, which could have used their aerobic metabolism to manipulate the life history of the host. While early evolution of sex may have facilitated symbiont acquisition, sex would have also destabilized the subsequent endosymbiosis. More plausibly, the evolution of sex and the true nucleus concluded the transition.

scholarly journals Eukaryogenesis, how special really?

2015 ◽  
Vol 112 (33) ◽  
pp. 10278-10285 ◽  
Author(s):  
Austin Booth ◽  
W. Ford Doolittle
Keyword(s):  
Eukaryotic Cell ◽  
Evolutionary Transition ◽  
Evolutionary Potential ◽  
Evolutionary Transitions ◽  
History Of Research ◽  
Evolution Of Life ◽  
Widespread Acceptance ◽  
Statistical Support ◽  
History Of ◽  
Rhetorical Value

Eukaryogenesis is widely viewed as an improbable evolutionary transition uniquely affecting the evolution of life on this planet. However, scientific and popular rhetoric extolling this event as a singularity lacks rigorous evidential and statistical support. Here, we question several of the usual claims about the specialness of eukaryogenesis, focusing on both eukaryogenesis as a process and its outcome, the eukaryotic cell. We argue in favor of four ideas. First, the criteria by which we judge eukaryogenesis to have required a genuinely unlikely series of events 2 billion years in the making are being eroded by discoveries that fill in the gaps of the prokaryote:eukaryote “discontinuity.” Second, eukaryogenesis confronts evolutionary theory in ways not different from other evolutionary transitions in individuality; parallel systems can be found at several hierarchical levels. Third, identifying which of several complex cellular features confer on eukaryotes a putative richer evolutionary potential remains an area of speculation: various keys to success have been proposed and rejected over the five-decade history of research in this area. Fourth, and perhaps most importantly, it is difficult and may be impossible to eliminate eukaryocentric bias from the measures by which eukaryotes as a whole are judged to have achieved greater success than prokaryotes as a whole. Overall, we question whether premises of existing theories about the uniqueness of eukaryogenesis and the greater evolutionary potential of eukaryotes have been objectively formulated and whether, despite widespread acceptance that eukaryogenesis was “special,” any such notion has more than rhetorical value.

scholarly journals The order of trait emergence in the evolution of cyanobacterial multicellularity

2019 ◽  
Author(s):  
Katrin Hammerschmidt ◽  
Giddy Landan ◽  
Fernando Domingues Kümmel Tria ◽  
Jaime Alcorta ◽  
Tal Dagan
Keyword(s):  
Division Of Labor ◽  
Phenotypic Trait ◽  
Evolutionary Transition ◽  
Evolutionary Transitions ◽  
Differentiated Cells ◽  
Labor Theory ◽  
Significant Events ◽  
Reproductive Life ◽  
History Of ◽  
Multicellular Organisms

AbstractThe transition from unicellular to multicellular organisms is one of the most significant events in the history of life. Key to this process is the emergence of Darwinian individuality at the higher level: groups must become single entities capable of reproduction for selection to shape their evolution. Evolutionary transitions in individuality are characterized by cooperation between the lower level entities and by division of labor. Theory suggests that division of labor may drive the transition to multicellularity by eliminating the trade-off between two incompatible processes that cannot be performed simultaneously in one cell. Here we examine the evolution of the most ancient multicellular transition known today, that of cyanobacteria, where we reconstruct the sequence of ecological and phenotypic trait evolution. Our results show that the prime driver of multicellularity in cyanobacteria was the expansion in metabolic capacity offered by nitrogen fixation, which was accompanied by the emergence of the filamentous morphology and succeeded by a reproductive life cycle. This was followed by the progression of multicellularity into higher complexity in the form of differentiated cells and patterned multicellularity.Significance StatementThe emergence of multicellularity is a major evolutionary transition. The oldest transition, that of cyanobacteria, happened more than 3 to 3.5 billion years ago. We find N2 fixation to be the prime driver of multicellularity in cyanobacteria. This innovation faced the challenge of incompatible metabolic processes since the N2 fixing enzyme (nitrogenase) is sensitive to oxygen, which is abundantly found in cyanobacteria cells performing photosynthesis. At the same time, N2-fixation conferred an adaptive benefit to the filamentous morphology as cells could divide their labour into performing either N2-fixation or photosynthesis. This was followed by the culmination of complex multicellularity in the form of differentiated cells and patterned multicellularity.

scholarly journals Horizontal gene flow from Eubacteria to Archaebacteria and what it means for our understanding of eukaryogenesis

2015 ◽  
Vol 370 (1678) ◽  
pp. 20140337 ◽  
Author(s):  
Wasiu A. Akanni ◽  
Karen Siu-Ting ◽  
Christopher J. Creevey ◽  
James O. McInerney ◽  
Mark Wilkinson ◽  
...  
Keyword(s):  
Large Scale ◽  
Eukaryotic Cell ◽  
Current Evidence ◽  
Evolutionary Transitions ◽  
Genomic Dataset ◽  
Large Numbers ◽  
Supertree Method ◽  
Eukaryotic Origin ◽  
History Of ◽  
Host Nucleus

The origin of the eukaryotic cell is considered one of the major evolutionary transitions in the history of life. Current evidence strongly supports a scenario of eukaryotic origin in which two prokaryotes, an archaebacterial host and an α -proteobacterium (the free-living ancestor of the mitochondrion), entered a stable symbiotic relationship. The establishment of this relationship was associated with a process of chimerization, whereby a large number of genes from the α-proteobacterial symbiont were transferred to the host nucleus. A general framework allowing the conceptualization of eukaryogenesis from a genomic perspective has long been lacking. Recent studies suggest that the origins of several archaebacterial phyla were coincident with massive imports of eubacterial genes. Although this does not indicate that these phyla originated through the same process that led to the origin of Eukaryota, it suggests that Archaebacteria might have had a general propensity to integrate into their genomes large amounts of eubacterial DNA. We suggest that this propensity provides a framework in which eukaryogenesis can be understood and studied in the light of archaebacterial ecology. We applied a recently developed supertree method to a genomic dataset composed of 392 eubacterial and 51 archaebacterial genera to test whether large numbers of genes flowing from Eubacteria are indeed coincident with the origin of major archaebacterial clades. In addition, we identified two potential large-scale transfers of uncertain directionality at the base of the archaebacterial tree. Our results are consistent with previous findings and seem to indicate that eubacterial gene imports (particularly from δ - Proteobacteria, Clostridia and Actinobacteria) were an important factor in archaebacterial history. Archaebacteria seem to have long relied on Eubacteria as a source of genetic diversity, and while the precise mechanism that allowed these imports is unknown, we suggest that our results support the view that processes comparable to those through which eukaryotes emerged might have been common in archaebacterial history.

The Geographic Dynamics of Coevolution

2001 ◽  
Author(s):  
John N. Thompson
Keyword(s):  
Species Interactions ◽  
Evolutionary Ecology ◽  
Empirical Studies ◽  
Evolutionary Process ◽  
Eukaryotic Cell ◽  
Geographic Ranges ◽  
Interacting Species ◽  
Local Populations ◽  
History Of ◽  
Phylogenetic Lineages

Coevolution is reciprocal evolutionary change in interacting species driven by natural selection. It is a pervasive evolutionary process that has shaped many of the major events in the history of life, including the origin of the eukaryotic cell, the origin of plants, the evolution of coral reefs, and the formation of lichens, mycorrhizae, and rhizobia, all of which are crucial in the development of terrestrial communities. Just as important, evidence is increasing that Coevolution is an important ongoing ecological process, continually shaping and reshaping interactions among species, sometimes over time spans of only a few decades. This chapter is an evaluation of coevolution as an ongoing process shaped by the geographic structure of interactions among species. It is an analysis of what we have learned recently as we have taken a broader geographic view of how coevolution continually remolds the relationships among taxa. The first mathematical models of geographically structured coevolution were developed only in the past few years, and there are still fewer than a dozen empirical studies that have analyzed any aspects of coevolutionary structure and dynamics across geographic landscapes. Nevertheless, these theoretical and empirical studies have together suggested that coevolution is very likely a much more dynamic process than suggested by the previous several decades of study in evolutionary ecology. Coevolution is a hierarchical process. Local populations of species interact with one another and sometimes coevolve. These local populations are in turn connected through gene flow to populations in other communities, and this geographic structuring adds another level to the coevolutionary process. Local geographic clusters of populations may show metapopulation dynamics, and yet broader geographic groupings of populations may show considerable genetic differentiation in the traits of interacting species. Only a subset of locally or regionally coevolving traits will eventually sweep through all populations. Hence, coevolution as seen in comparisons of interacting phylogenetic lineages will show only a small fraction of the Coevolutionary dynamics found at the population, metapopulation, and broader geographic scales. Within this hierarchical structure of coevolution, many of the dynamics may occur above the level of local populations and below the level of the fixed traits of species for three reasons: Many species are collections of genetically differentiated populations, the outcomes of species interactions commonly differ among communities, and interacting species often do not have identical geographic ranges.

scholarly journals The role of public goods in planetary evolution

2017 ◽  
Vol 375 (2109) ◽  
pp. 20160359 ◽  
Author(s):  
James O. McInerney ◽  
Douglas H. Erwin
Keyword(s):  
Public Goods ◽  
Phylogenetic Signal ◽  
Eukaryotic Cell ◽  
Early History ◽  
Evolutionary Transition ◽  
Direct Graph ◽  
Planetary Evolution ◽  
History Of ◽  
Life On Earth

Biological public goods are broadly shared within an ecosystem and readily available. They appear to be widespread and may have played important roles in the history of life on Earth. Of particular importance to events in the early history of life are the roles of public goods in the merging of genomes, protein domains and even cells. We suggest that public goods facilitated the origin of the eukaryotic cell, a classic major evolutionary transition. The recognition of genomic public goods challenges advocates of a direct graph view of phylogeny, and those who deny that any useful phylogenetic signal persists in modern genomes. Ecological spillovers generate public goods that provide new ecological opportunities. This article is part of the themed issue ‘Reconceptualizing the origins of life’.

scholarly journals Why did eukaryotes evolve only once? Genetic and energetic aspects of conflict and conflict mediation

2013 ◽  
Vol 368 (1622) ◽  
pp. 20120266 ◽  
Author(s):  
Neil W. Blackstone
Keyword(s):  
Metabolic Regulation ◽  
Protein Import ◽  
De Novo ◽  
Heritable Variation ◽  
Evolutionary Transitions ◽  
Metabolic Signalling ◽  
Emergent Feature ◽  
Conflict Mediation ◽  
History Of ◽  
Origin Of Eukaryotes

According to multi-level theory, evolutionary transitions require mediating conflicts between lower-level units in favour of the higher-level unit. By this view, the origin of eukaryotes and the origin of multicellularity would seem largely equivalent. Yet, eukaryotes evolved only once in the history of life, whereas multicellular eukaryotes have evolved many times. Examining conflicts between evolutionary units and mechanisms that mediate these conflicts can illuminate these differences. Energy-converting endosymbionts that allow eukaryotes to transcend surface-to-volume constraints also can allocate energy into their own selfish replication. This principal conflict in the origin of eukaryotes can be mediated by genetic or energetic mechanisms. Genome transfer diminishes the heritable variation of the symbiont, but requires the de novo evolution of the protein-import apparatus and was opposed by selection for selfish symbionts. By contrast, metabolic signalling is a shared primitive feature of all cells. Redox state of the cytosol is an emergent feature that cannot be subverted by an individual symbiont. Hypothetical scenarios illustrate how metabolic regulation may have mediated the conflicts inherent at different stages in the origin of eukaryotes. Aspects of metabolic regulation may have subsequently been coopted from within-cell to between-cell pathways, allowing multicellularity to emerge repeatedly.

scholarly journals Biological Transmission of Arboviruses: Reexamination of and New Insights into Components, Mechanisms, and Unique Traits as Well as Their Evolutionary Trends

2005 ◽  
Vol 18 (4) ◽  
pp. 608-637 ◽  
Author(s):  
Goro Kuno ◽  
Gwong-Jen J. Chang
Keyword(s):  
Biological Sciences ◽  
Host Range ◽  
Disease Transmission ◽  
Evolutionary Process ◽  
Field Research ◽  
Diverse Range ◽  
Unique Mode ◽  
History Of ◽  
Mode Of Transmission ◽  
Available Information

SUMMARY Among animal viruses, arboviruses are unique in that they depend on arthropod vectors for transmission. Field research and laboratory investigations related to the three components of this unique mode of transmission, virus, vector, and vertebrate host, have produced an enormous amount of valuable information that may be found in numerous publications. However, despite many reviews on specific viruses, diseases, or interests, a systematic approach to organizing the available information on all facets of biological transmission and then to interpret it in the context of the evolutionary process has not been attempted before. Such an attempt in this review clearly demonstrates tremendous progress made worldwide to characterize the viruses, to comprehend disease transmission and pathogenesis, and to understand the biology of vectors and their role in transmission. The rapid progress in molecular biologic techniques also helped resolve many virologic puzzles and yielded highly valuable data hitherto unavailable, such as characterization of virus receptors, the genetic basis of vertebrate resistance to viral infection, and phylogenetic evidence of the history of host range shifts in arboviruses. However, glaring gaps in knowledge of many critical subjects, such as the mechanism of viral persistence and the existence of vertebrate reservoirs, are still evident. Furthermore, with the accumulated data, new questions were raised, such as evolutionary directions of virus virulence and of host range. Although many fundamental questions on the evolution of this unique mode of transmission remained unresolved in the absence of a fossil record, available observations for arboviruses and the information derived from studies in other fields of the biological sciences suggested convergent evolution as a plausible process. Overall, discussion of the diverse range of theories proposed and observations made by many investigators was found to be highly valuable for sorting out the possible mechanism(s) of the emergence of arboviral diseases.

scholarly journals Memahami Sensionalisme dalam Berita Televisi: Perspektif Evolusi Biologi

2020 ◽  
Vol 16 (2) ◽  
Author(s):  
Gentur Agustinus Naru
Keyword(s):  
Human Brain ◽  
Evolutionary Biology ◽  
Evolutionary Process ◽  
Time Difference ◽  
Evolutionary Perspective ◽  
History Of ◽  
The Relationship

Although there have been many studies regarding sensationalism on television, there have not been enough studies to explain why sensational news always attracts viewers' attention regardless of space or time difference. Encouraged by this background, this research tries to answer the question, "What makes sensational news interesting to television viewers?" Inspired by a biological evolutionary perspective, this article formulates a hypothesis that reads, "Sensationalism can draw the attention of the audience because sensational news arouses the most basic instincts of humans, namely the mode of survival (Gurven, 2017)". In this view, the model has become inherent in humans as a result of the evolutionary process. In other words, this hypothesis also believes that audience interest in sensational news is universal rather than contextual.   This article explores a variety of literature in biology, psychology, and communication to try to answer that hypothesis. In order to that, this article is divided into three main sections. We will first explore the history of sensational journalism on television to show the historicity of sensational topics and techniques on television. Second, we will demonstrate the philosophical roots of an evolutionary biology view that explains the relationship between information stimuli and the workings of the human brain and the basic instincts we have carried since evolution thousands of years ago. Finally, we will show studies that prove empirically how news patterns (both sensational topics and production formats) impact viewing interest.

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