scholarly journals Superinfection and the evolution of an initial asymptomatic stage

2021 ◽  
Vol 8 (1) ◽  
pp. 202212
Author(s):  
Chadi M. Saad-Roy ◽  
Bryan T. Grenfell ◽  
Simon A. Levin ◽  
Lorenzo Pellis ◽  
Helena B. Stage ◽  
...  
Keyword(s):  
Evolutionary Dynamics ◽  
Host Immunity ◽  
Infected Host ◽  
Life History Strategies ◽  
Evolutionary Transitions ◽  
Initial Stage ◽  
Branching Point ◽  
Asymptomatic Stage ◽  
Infection Stage ◽  
New Framework

Pathogens have evolved a variety of life-history strategies. An important strategy consists of successful transmission by an infected host before the appearance of symptoms, that is, while the host is still partially or fully asymptomatic. During this initial stage of infection, it is possible for another pathogen to superinfect an already infected host and replace the previously infecting pathogen. Here, we study the effect of superinfection during the first stage of an infection on the evolutionary dynamics of the degree to which the host is asymptomatic (host latency) in that same stage. We find that superinfection can lead to major differences in evolutionary behaviour. Most strikingly, the duration of immunity following infection can significantly influence pathogen evolutionary dynamics, whereas without superinfection the outcomes are independent of host immunity. For example, changes in host immunity can drive evolutionary transitions from a fully symptomatic to a fully asymptomatic first infection stage. Additionally, if superinfection relative to susceptible infection is strong enough, evolution can lead to a unique strategy of latency that corresponds to a local fitness minimum, and is therefore invasible by nearby mutants. Thus, this strategy is a branching point, and can lead to coexistence of pathogens with different latencies. Furthermore, in this new framework with superinfection, we also find that there can exist two interior singular strategies. Overall, new evolutionary outcomes can cascade from superinfection.

scholarly journals Synthesizing within-host and population-level selective pressures on viral populations: the impact of adaptive immunity on viral immune escape

2010 ◽  
Vol 7 (50) ◽  
pp. 1311-1318 ◽  
Author(s):  
Igor Volkov ◽  
Kim M. Pepin ◽  
James O. Lloyd-Smith ◽  
Jayanth R. Banavar ◽  
Bryan T. Grenfell
Keyword(s):  
Evolutionary Dynamics ◽  
Immune Escape ◽  
Adaptive Immune Response ◽  
Population Level ◽  
Analytical Framework ◽  
Host Population ◽  
Host Immunity ◽  
Host Cells ◽  
Susceptible Host ◽  
The Impact

The evolution of viruses to escape prevailing host immunity involves selection at multiple integrative scales, from within-host viral and immune kinetics to the host population level. In order to understand how viral immune escape occurs, we develop an analytical framework that links the dynamical nature of immunity and viral variation across these scales. Our epidemiological model incorporates within-host viral evolutionary dynamics for a virus that causes acute infections (e.g. influenza and norovirus) with changes in host immunity in response to genetic changes in the virus population. We use a deterministic description of the within-host replication dynamics of the virus, the pool of susceptible host cells and the host adaptive immune response. We find that viral immune escape is most effective at intermediate values of immune strength. At very low levels of immunity, selection is too weak to drive immune escape in recovered hosts, while very high levels of immunity impose such strong selection that viral subpopulations go extinct before acquiring enough genetic diversity to escape host immunity. This result echoes the predictions of simpler models, but our formulation allows us to dissect the combination of within-host and transmission-level processes that drive immune escape.

scholarly journals Late Ordovician (Hirnantian) diploporitan fauna of Anticosti Island, Quebec, Canada: implications for evolutionary and biogeographic patterns

2018 ◽  
Vol 55 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Sarah L. Sheffield ◽  
William I. Ausich ◽  
Colin D. Sumrall
Keyword(s):  
Evolutionary Dynamics ◽  
Late Ordovician ◽  
Upper Ordovician ◽  
Evolutionary Transitions ◽  
Biogeographic Patterns ◽  
Critical Data ◽  
New Localities ◽  
Reefal Facies ◽  
Anticosti Island ◽  
Fossil Data

Hirnantian (latest Ordovician) localities containing echinoderm fossils are rare; the few that have been discovered primarily contain disarticulated crinoid ossicles. Therefore, relatively little is known about echinoderm evolutionary dynamics across the Late Ordovician – early Silurian boundary, especially noncrinoid echinoderms. New diploporitan echinoderms, Holocystites salmoensis and an unidentified holocystitid, from reefal facies of the Upper Ordovician Ellis Bay Formation of Anticosti Island provide a critical data point concerning diploporitan biogeography and evolutionary pathways undertaken during the Ordovician and Silurian. These fossils also provide a crucial link in understanding the ancestry of the Silurian Holocystites Fauna, an unusual diploporitan fauna from the middle Silurian of North America, whose origination dates back at least 15 million years earlier than previously thought with the discovery of taxa described here. New fossil data such as these stress the importance of uncovering new localities from underrepresented times and places in Earth’s history, so that these evolutionary transitions can be better understood.

scholarly journals Effects of in situ climate warming on monarch caterpillar (Danaus plexippus) development

2015 ◽  
Author(s):  
Nathan P Lemoine ◽  
Jillian N Capdevielle ◽  
John D Parker
Keyword(s):  
Climate Warming ◽  
Host Plants ◽  
Evolutionary Dynamics ◽  
Danaus Plexippus ◽  
Developmental Rate ◽  
Life History Strategies ◽  
Lepidopteran Larvae ◽  
The Impact ◽  
Pupal Mass

Climate warming will fundamentally alter basic life history strategies of many ectothermic insects. In the lab, rising temperatures increase growth rates of lepidopteran larvae, but also reduce final pupal mass and increase mortality. Using in situ field warming experiments on their natural host plants, we assessed the impact of climate warming on development of monarch (Danaus plexippus) larvae. Monarchs were reared on Asclepias tuberosa grown under ‘Ambient’ and ‘Warmed’ conditions. We quantified time to pupation, final pupal mass, and survivorship. Warming significantly decreased time to pupation, such that an increase of 1˚ C corresponded to a 0.5 day decrease in pupation time. In contrast, survivorship and pupal mass were not affected by warming. Our results indicate that climate warming will speed the developmental rate of monarchs, influencing their ecological and evolutionary dynamics. However, the effects of climate warming on larval development in other monarch populations and at different times of year should be investigated.

scholarly journals A Laurasian origin for a pantropical bird radiation is supported by genomic and fossil data (Aves: Coraciiformes)

2019 ◽  
Vol 286 (1910) ◽  
pp. 20190122 ◽  
Author(s):  
Jenna M. McCullough ◽  
Robert G. Moyle ◽  
Brian T. Smith ◽  
Michael J. Andersen
Keyword(s):  
Evolutionary Dynamics ◽  
Species Tree ◽  
Old World ◽  
Avian Order ◽  
History Of ◽  
The Tropics ◽  
Fossil Data ◽  
Old World Tropics ◽  
New Framework

The evolution of pantropically distributed clades has puzzled palaeo- and neontologists for decades regarding the different hypotheses about where they originated. In this study, we explored how a pantropical distribution arose in a diverse clade with a rich fossil history: the avian order Coraciiformes. This group has played a central role in the debate of the biogeographical history of Neoaves. However, the order lacked a coherent species tree to inform study of its evolutionary dynamics. Here, we present the first complete species tree of Coraciiformes, produced with 4858 ultraconserved elements, which supports two clades: (1) Old World-restricted bee-eaters, rollers and ground-rollers; and (2) New World todies and motmots, and cosmopolitan kingfishers. Our results indicated two pulses of diversification: (1) major lineages of Coraciiformes arose in Laurasia approximately 57 Ma, followed by independent dispersals into equatorial regions, possibly due to tracking tropical habitat into the lower latitudes—the Coracii (Coraciidae + Brachypteraciidae) into the Afrotropics, bee-eaters throughout the Old World tropics, and kingfishers into the Australasian tropics; and (2) diversification of genera in the tropics during the Miocene and Pliocene. Our study supports the important role of Laurasia as the geographical origin of a major pantropical lineage and provides a new framework for comparative analyses in this charismatic bird radiation.

A McKinsey 7S Model-Based Framework for ERP Readiness Assessment

2011 ◽  
Vol 7 (4) ◽  
pp. 23-63 ◽  
Author(s):  
Payam Hanafizadeh ◽  
Ahad Zare Ravasan
Keyword(s):  
Enterprise Resource Planning ◽  
Resource Planning ◽  
Erp Systems ◽  
Erp Implementation ◽  
Readiness Assessment ◽  
Initial Stage ◽  
Confirmatory Factor ◽  
Superordinate Goals ◽  
Expensive Process ◽  
New Framework

Implementing Enterprise Resource Planning (ERP) systems is a complex, lengthy and expensive process which usually faces serious challenges and failures. Thus, it is necessary to perform a readiness assessment at the initial stage of an ERP implementation project to identify weakness areas which may encounter the project with failure. This paper proposes a new framework for assessing readiness of an organization to implement the ERP project on the basis of McKinsey 7S model using confirmatory factor analysis. Through this method, the construct of ERP readiness is proposed based on 7 dimensions namely “structure”, “strategy”, “systems”, “skills”, “style/culture”, “staff”, and “shared values/ superordinate goals”. Using the framework, the current situation of the organization can be determined and necessary changes can be made prior to system implementation. The proposed framework is then applied to 2 real Iranian banking cases and the advantages of the framework over available frameworks are illustrated.

scholarly journals Effects ofin situclimate warming on monarch caterpillar (Danaus plexippus) development

PeerJ ◽  
2015 ◽  
Vol 3 ◽  
pp. e1293 ◽  
Author(s):  
Nathan P. Lemoine ◽  
Jillian N. Capdevielle ◽  
John D. Parker
Keyword(s):  
Climate Warming ◽  
Host Plants ◽  
Evolutionary Dynamics ◽  
Danaus Plexippus ◽  
Developmental Rate ◽  
Life History Strategies ◽  
Lepidopteran Larvae ◽  
The Impact ◽  
Pupal Mass

Climate warming will fundamentally alter basic life history strategies of many ectothermic insects. In the lab, rising temperatures increase growth rates of lepidopteran larvae but also reduce final pupal mass and increase mortality. Usingin situfield warming experiments on their natural host plants, we assessed the impact of climate warming on development of monarch (Danaus plexippus) larvae. Monarchs were reared onAsclepias tuberosagrown under ‘Ambient’ and ‘Warmed’ conditions. We quantified time to pupation, final pupal mass, and survivorship. Warming significantly decreased time to pupation, such that an increase of 1 °C corresponded to a 0.5 day decrease in pupation time. In contrast, survivorship and pupal mass were not affected by warming. Our results indicate that climate warming will speed the developmental rate of monarchs, influencing their ecological and evolutionary dynamics. However, the effects of climate warming on larval development in other monarch populations and at different times of year should be investigated.

scholarly journals Assortment of flowering time and immunity alleles in natural Arabidopsis thaliana populations suggests immunity and vegetative lifespan strategies coevolve

2017 ◽  
Author(s):  
Shirin Glander ◽  
Fei He ◽  
Gregor Schmitz ◽  
Anika Witten ◽  
Arndt Telschow ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Flowering Time ◽  
Evolutionary Dynamics ◽  
Natural Populations ◽  
Optimal Investment ◽  
Host Immunity ◽  
Host Defenses ◽  
Immunity Genes ◽  
Pleiotropic Action ◽  
The Impact

ABSTRACTThe selective impact of pathogen epidemics on host defenses can be strong but remains transient. By contrast, life-history shifts can durably and continuously modify the balance between costs and benefits of immunity, which arbitrates the evolution of host defenses. Their impact on the evolutionary dynamics of host immunity, however, has seldom been documented. Optimal investment into immunity is expected to decrease with shortening lifespan, because a shorter life decreases the probability to encounter pathogens or enemies. Here, we document that in natural populations of Arabidopsis thaliana, the expression levels of immunity genes correlate positively with flowering time, which in annual species is a proxy for lifespan. Using a novel genetic strategy based on bulk-segregants, we partitioned flowering time-dependent from – independent immunity genes and could demonstrate that this positive co-variation can be genetically separated. It is therefore not explained by the pleiotropic action of some major regulatory genes controlling both immunity and lifespan. Moreover, we find that immunity genes containing variants reported to impact fitness in natural field conditions are among the genes whose expression co-varies most strongly with flowering time. Taken together, these analyses reveal that natural selection has likely assorted alleles promoting lower expression of immunity genes with alleles that decrease the duration of vegetative lifespan in A. thaliana and vice versa. This is the first study documenting a pattern of variation consistent with the impact that selection on flowering time is predicted to have on diversity in host immunity.

scholarly journals Evolution of an asymptomatic first stage of infection in a heterogeneous population

2021 ◽  
Vol 18 (179) ◽  
pp. 20210175
Author(s):  
Chadi M. Saad-Roy ◽  
Bryan T. Grenfell ◽  
Simon A. Levin ◽  
P. van den Driessche ◽  
Ned S. Wingreen
Keyword(s):  
Population Structure ◽  
Life History ◽  
Evolutionary Dynamics ◽  
Population Heterogeneity ◽  
Life History Strategies ◽  
Specific Power ◽  
Central Feature ◽  
Evolutionarily Stable Strategies ◽  
Infectious Stage

Pathogens evolve different life-history strategies, which depend in part on differences in their host populations. A central feature of hosts is their population structure (e.g. spatial). Additionally, hosts themselves can exhibit different degrees of symptoms when newly infected; this latency is a key life-history property of pathogens. With an evolutionary-epidemiological model, we examine the role of population structure on the evolutionary dynamics of latency. We focus on specific power-law-like formulations for transmission and progression from the first infectious stage as a function of latency, assuming that the across-group to within-group transmission ratio increases if hosts are less symptomatic. We find that simple population heterogeneity can lead to local evolutionarily stable strategies (ESSs) at zero and infinite latency in situations where a unique ESS exists in the corresponding homogeneous case. Furthermore, there can exist more than one interior evolutionarily singular strategy. We find that this diversity of outcomes is due to the (possibly slight) advantage of across-group transmission for pathogens that produce fewer symptoms in a first infectious stage. Thus, our work reveals that allowing individuals without symptoms to travel can have important unintended evolutionary effects and is thus fundamentally problematic in view of the evolutionary dynamics of latency.

scholarly journals Compound Dynamics and Combinatorial Patterns of Amino Acid Repeats Encode a System of Evolutionary and Developmental Markers

2019 ◽  
Vol 11 (11) ◽  
pp. 3159-3178
Author(s):  
Ilaria Pelassa ◽  
Marica Cibelli ◽  
Veronica Villeri ◽  
Elena Lilliu ◽  
Serena Vaglietti ◽  
...  
Keyword(s):  
Amino Acid ◽  
Evolutionary History ◽  
Evolutionary Dynamics ◽  
Phylogenetic Signal ◽  
Regulatory System ◽  
Evolutionary Transitions ◽  
Quantitative Evidence ◽  
Amino Acid Repeats ◽  
Eukaryotic Proteomes ◽  
History Of

Abstract Homopolymeric amino acid repeats (AARs) like polyalanine (polyA) and polyglutamine (polyQ) in some developmental proteins (DPs) regulate certain aspects of organismal morphology and behavior, suggesting an evolutionary role for AARs as developmental “tuning knobs.” It is still unclear, however, whether these are occasional protein-specific phenomena or hints at the existence of a whole AAR-based regulatory system in DPs. Using novel approaches to trace their functional and evolutionary history, we find quantitative evidence supporting a generalized, combinatorial role of AARs in developmental processes with evolutionary implications. We observe nonrandom AAR distributions and combinations in HOX and other DPs, as well as in their interactomes, defining elements of a proteome-wide combinatorial functional code whereby different AARs and their combinations appear preferentially in proteins involved in the development of specific organs/systems. Such functional associations can be either static or display detectable evolutionary dynamics. These findings suggest that progressive changes in AAR occurrence/combination, by altering embryonic development, may have contributed to taxonomic divergence, leaving detectable traces in the evolutionary history of proteomes. Consistent with this hypothesis, we find that the evolutionary trajectories of the 20 AARs in eukaryotic proteomes are highly interrelated and their individual or compound dynamics can sharply mark taxonomic boundaries, or display clock-like trends, carrying overall a strong phylogenetic signal. These findings provide quantitative evidence and an interpretive framework outlining a combinatorial system of AARs whose compound dynamics mark at the same time DP functions and evolutionary transitions.

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