scholarly journals Adaptive evolution of olfactory degeneration in recently flightless insects

2020 ◽  
Author(s):  
Stefanie Neupert ◽  
Graham A. McCulloch ◽  
Brodie J. Foster ◽  
Jonathan M. Waters ◽  
Paul Szyszka
Keyword(s):  
Natural Selection ◽  
Selective Pressure ◽  
Temporal Structure ◽  
Parallel Evolution ◽  
Sensory Systems ◽  
Olfactory Acuity ◽  
Flying Insects ◽  
Processing Ability ◽  
Olfactory Processing ◽  
Sensory Ability

AbstractFast-moving animals need fast-acting sensory systems. Flying insects have thus evolved exceptionally quick visual (1) and olfactory processing ability (2). For example, flighted insects can track the temporal structure of turbulent odor plumes at rates above 100 Hz (3). The evolutionary lability of such sensory systems, however, remains unknown. We test for rapid evolutionary shifts in olfactory processing speed associated with flight loss, through neurobiological comparisons of sympatric flighted versus flightless lineages within a wing-polymorphic stonefly species. Our analyses of sensory responses reveal that recently-evolved flightless lineages have substantially degraded olfactory acuity. By comparing flighted versus flightless ecotypes with similar genetic backgrounds (4), we eliminate other confounding factors that might have affected the evolution of their olfactory reception mechanisms. Our detection of different patterns of degraded olfactory sensitivity and speed in independently wing-reduced lineages highlights parallel evolution of sensory degeneration. These reductions in sensory ability also echo the rapid vestigialization of wings themselves (4, 5), and represent a neurobiological parallel to the convergent phenotypic shifts seen under sharp selective gradients in other systems (e.g. parallel loss of vision in diverse cave fauna (6)). Our study provides the first direct evidence for the hypothesis that flight poses a selective pressure on the speed of olfactory receptor neurons. Our findings also emphasize the energetic costs of rapid olfaction, and the key role of natural selection in shaping dramatic neurobiological shifts.Significance StatementFlying insects move fast and have therefore evolved exceptionally quick-acting sensory systems. The speed with which such neurobiological shifts can evolve, however, remains unclear. Under the ‘use it or lose it’ hypothesis, loss of flight should lead to degradation of this fast sensory processing ability. We test for evolutionary reductions in olfactory acuity linked to flight loss, through neurobiological comparisons of flightless versus flighted lineages within a wing-polymorphic insect. Our analyses reveal that newly wing-reduced populations have substantially degraded olfactory acuity, with parallel reductions in this sensory ability detected in independently flightless lineages. These findings reveal that flight poses strong selective pressure for rapid olfaction, and highlight the potential of natural selection in rapidly shaping adaptive shifts in animal sensory systems.

When Temporal Certainty Doesn't Help

2020 ◽  
Vol 32 (2) ◽  
pp. 315-325
Author(s):  
Flor Kusnir ◽  
Slav Pesin ◽  
Gal Moscona ◽  
Ayelet N. Landau
Keyword(s):  
Sensory Input ◽  
Temporal Structure ◽  
Sensory Systems ◽  
The Other ◽  
Target Onset ◽  
Detection Thresholds ◽  
Tactile Target ◽  
Temporal Predictability ◽  
Future Events ◽  
The Impact

In a dynamically changing environment, the ability to capture regularities in our sensory input helps us generate predictions about future events. In most sensory systems, the basic finding is clear: Knowing when something will happen improves performance on it [Nobre, A. C., & van Ede, F. (2017). Anticipated moments: Temporal structure in attention. Nature Reviews Neuroscience, 19, 34–48, 2017]. We here examined the impact of temporal predictions on a less-explored modality: touch. Participants were instructed to detect a brief target embedded in an ongoing vibrotactile stimulus. Unbeknownst to them, the experiment had two timing conditions: In one part, the time of target onset was fixed and thus temporally predictable, whereas in the other, it could appear at a random time within the ongoing stimulation. We found a clear modulation of detection thresholds due to temporal predictability: Contrary to other sensory systems, detecting a predictable tactile target was worse relative to unpredictable targets. We discuss our findings within the framework of tactile suppression.

scholarly journals Molecular Footprint of Drug-Selective Pressure in a Human Immunodeficiency Virus Transmission Chain

2005 ◽  
Vol 79 (18) ◽  
pp. 11981-11989 ◽  
Author(s):  
Philippe Lemey ◽  
Inge Derdelinckx ◽  
Andrew Rambaut ◽  
Kristel Van Laethem ◽  
Stephanie Dumont ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Selective Pressure ◽  
Phylogenetic Analyses ◽  
Parallel Evolution ◽  
Multidrug Resistant ◽  
Resistance Mutations ◽  
Fixation Rate ◽  
Codon Substitution ◽  
Transmission Chain ◽  
Immunodeficiency Virus

ABSTRACT Known human immunodeficiency virus (HIV) transmission histories are invaluable models for investigating the evolutionary and transmission dynamics of the virus and to assess the accuracy of phylogenetic reconstructions. Here we have characterized an HIV-1 transmission chain consisting of nine infected patients, almost all of whom were treated with antiviral drugs at later stages of infection. Partial pol and env gp41 regions of the HIV genome were directly sequenced from plasma viral RNA for at least one sample from each patient. Phylogenetic analyses in pol using likelihood methods inferred an evolutionary history not fully compatible with the known transmission history. This could be attributed to parallel evolution of drug resistance mutations resulting in the incorrect clustering of multidrug-resistant virus. On the other hand, a fully compatible phylogenetic tree was reconstructed from the env sequences. We were able to identify and quantify the molecular footprint of drug-selective pressure in pol using maximum likelihood inference under different codon substitution models. An increased fixation rate of mutations in the HIV population of the multidrug-resistant patient was demonstrated using molecular clock modeling. We show that molecular evolutionary analyses, guided by a known transmission history, can reveal the presence of confounding factors like natural selection and caution should be taken when accurate descriptions of HIV evolution are required.

scholarly journals Adaptive strategies of the candidate probioticE. coliNissle in the mammalian gut

2018 ◽  
Author(s):  
Nathan Crook ◽  
Aura Ferreiro ◽  
Andrew J. Gasparrini ◽  
Mitchell Pesesky ◽  
Molly K. Gibson ◽  
...  
Keyword(s):  
Natural Selection ◽  
Gastrointestinal Tract ◽  
Selective Pressure ◽  
Adaptive Strategies ◽  
Species Competition ◽  
E Coli ◽  
Genetic Function ◽  
Probiotic Strains ◽  
Therapeutic Properties ◽  
Serum Phenylalanine

SummaryProbiotics are living microorganisms that are increasingly used as gastrointestinal therapeutics by virtue of their innate or engineered genetic function. Unlike abiotic therapeutics, probiotics can replicate in their intended site, subjecting their genomes and therapeutic properties to natural selection. By exposing the candidate probioticE. coliNissle (EcN) to the mouse gastrointestinal tract over several weeks, we uncovered the consequences of gut transit, inter-species competition, antibiotic pressure, and engineered genetic function on the processes under selective pressure during both within-genome and horizontal evolutionary modes. We then show the utility of EcN as a chassis for engineered function by achieving the highest reported reduction in serum phenylalanine levels in a mouse model of phenylketonuria using an engineered probiotic. Collectively, we demonstrate a generalizable pipeline which can be applied to other probiotic strains to better understand their safety and engineering potential.

scholarly journals Why sloths defecate on the ground: rejection of the mutualistic model

2021 ◽  
Vol 13 (1) ◽  
pp. 4
Author(s):  
Julian Monge Nájera
Keyword(s):  
Natural Selection ◽  
Selective Pressure ◽  
Current Knowledge ◽  
Published Data ◽  
Risk Of Predation ◽  
New Hypothesis

 Introduction: Sloths are arboreal mammals that defecate on the ground, increasing the risk of predation. There are several hypotheses that try to explain why they undergo this risk. Objective: To critically review all the hypotheses and to propose a new hypothesis that is compatible with all known data. Methods: I verified the assumptions and implications of five hypotheses against the literature available February, 2021. Results: Previous hypotheses either lack reliable supporting data, or are contradicted by published data. Here I propose that defecation on the ground is an ancestral behavior that persists in all sloth species because there has not been enough natural selection against it. Conclusions: Current knowledge of sloth biology is compatible with the hypothesis that there has not been enough selective pressure for sloths to abandon defecation on the ground. 

scholarly journals Overlapping Risky Decision-Making and Olfactory Processing Ability in HIV-Infected Individuals

2017 ◽  
Vol 03 (03) ◽  
Author(s):  
Christopher Jackson ◽  
Narayan Rai ◽  
Charlee K McLean ◽  
Maria Mananita S Hipolito ◽  
Flora Terrell Hamilton ◽  
...  
Keyword(s):  
Decision Making ◽  
Risky Decision Making ◽  
Risky Decision ◽  
Processing Ability ◽  
Olfactory Processing

Constraints in cancer evolution

2017 ◽  
Vol 45 (1) ◽  
pp. 1-13 ◽  
Author(s):  
Subramanian Venkatesan ◽  
Nicolai J. Birkbak ◽  
Charles Swanton
Keyword(s):  
Natural Selection ◽  
Genome Sequencing ◽  
Convergent Evolution ◽  
Parallel Evolution ◽  
Survival Outcomes ◽  
Next Generation ◽  
Cancer Evolution ◽  
Therapeutic Approaches ◽  
Biological Impact ◽  
Intratumour Heterogeneity

Next-generation deep genome sequencing has only recently allowed us to quantitatively dissect the extent of heterogeneity within a tumour, resolving patterns of cancer evolution. Intratumour heterogeneity and natural selection contribute to resistance to anticancer therapies in the advanced setting. Recent evidence has also revealed that cancer evolution might be constrained. In this review, we discuss the origins of intratumour heterogeneity and subsequently focus on constraints imposed upon cancer evolution. The presence of (1) parallel evolution, (2) convergent evolution and (3) the biological impact of acquiring mutations in specific orders suggest that cancer evolution may be exploitable. These constraints on cancer evolution may help us identify cancer evolutionary rule books, which could eventually inform both diagnostic and therapeutic approaches to improve survival outcomes.

scholarly journals Translational readthrough goes unseen by natural selection

2019 ◽  
Author(s):  
April Snofrid Kleppe ◽  
Erich Bornberg-Bauer
Keyword(s):  
Protein Synthesis ◽  
Natural Selection ◽  
Selective Pressure ◽  
Evolutionary Rate ◽  
Stop Codon ◽  
Gc Content ◽  
Ribosome Profiling ◽  
Protein Isoforms ◽  
Common Error ◽  
Translational Readthrough

AbstractOccasionally during protein synthesis, the ribosome bypasses the stop codon and continues translation to the next stop codon in frame. This error is called translational readthrough (TR). Earlier research suggest that TR is a relatively common error, in several taxa, yet the evolutionary relevance of this translational error is still unclear. By analysing ribosome profiling data, we have conducted species comparisons between yeasts to infer conservation of TR between orthologs. Moreover, we infer the evolutionary rate of error prone and canonically translated proteins to deduct differential selective pressure. We find that about 40% of error prone proteins in Schizosaccharomyces pombe do not have any orthologs in Saccharomyces cerevisiae, but that 60% of error prone proteins in S. pombe are undergoing canonical translation in S. cerevisiae. Error prone proteins tend to have a higher GC-content in the 3’-UTR, unlike their canonically translated ortholog. We do not find the same trends for GC-content of the CDS. We discuss the role of 3’-UTR and GC-content regarding translational readthrough. Moreover, we find that there is neither selective pressure against or for TR. We suggest that TR is a near-neutral error that goes unseen by natural selection. We speculate that TR yield neutral protein isoforms that are not being purged. We suggest that isoforms, yielded by TR, increase proteomic diversity in the cell, which is readily available upon sudden environmental shifts and which therefore may become adaptive.Author SummaryThere is an evolutionary balance act between adaptation and selection against change. Any system needs to be able to adapt facing novel environmental conditions. Simultaneously, biological systems are under selection to maintain fitness and thus undergo selection against mutations. Phenotypic mutations - translational errors during protein synthesis - have been suggested to play a role in protein evolvability by enabling quick assessment of viable phenotypes and thus enable quick adaptation. Here we test this hypothesis, by inferring evolutionary rate of proteins prone to a specific case of phenotypic mutations: translational readthrough (TR). By making use of publicly available data of yeasts, we find that TR goes unseen by natural selection and appear as a neutral event. We suggest that TR goes unseen by selection and occurs as “permissive wallflowers”, which may become relevant and yield adaptive benefits. This work highlights that stochastic processes are not necessarily under stringent selection but may prevail. In conclusion, we suggest that TR is a neutral non-adaptive process that can yield adaptive benefits.

scholarly journals Ecology and genomic background shape the probability of parallel adaptation to climate

2021 ◽  
Author(s):  
Samridhi Chaturvedi ◽  
Zachariah Gompert ◽  
Jeffrey Feder ◽  
Owen Osborne ◽  
Moritz Muschick ◽  
...  
Keyword(s):  
Natural Selection ◽  
Bayesian Modeling ◽  
Parallel Evolution ◽  
Cuticular Hydrocarbon ◽  
Randomization Tests ◽  
Phenotypic Data ◽  
Standing Variation ◽  
Stick Insects ◽  
Shed Light ◽  
Genomic Similarity

Abstract Evolution can repeat itself, resulting in parallel adaptations in independent lineages occupying similar environments. Moreover, parallel evolution sometimes, but not always, uses the same genes. Two main hypotheses have been put forth to explain the probability and extent of parallel evolution. First, parallel evolution is more likely when shared ecologies result in similar patterns of natural selection in different taxa. Second, parallelism is more likely when genomes are similar, because of shared standing variation and similar mutational effects in closely related genomes. Here we combine ecological, genomic, experimental, and phenotypic data with randomization tests and Bayesian modeling to quantify the degree of parallelism and study its relationship with ecology and genetics. Our results show that the probability of parallel adaptation to climate among species of Timema stick insects is shaped collectively by shared ecology and genomic background. Specifically, the probability of genetic parallelism decays with divergence in climatic (i.e., ecological) conditions and genomic similarity. Moreover, we find that climate-associated loci are likely subject to selection in a field experiment, overlap with genetic regions associated with cuticular hydrocarbon traits, and are not strongly shaped by introgression between species. Our findings shed light on when evolution is most expected to repeat itself.

Effects of Relaxed Natural Selection on the Evolution of Behavior

1999 ◽  
Author(s):  
Richard G. Coss
Keyword(s):  
Natural Selection ◽  
Related Species ◽  
Empirical Test ◽  
Parallel Evolution ◽  
Phylogenetic Reconstruction ◽  
Evolutionary Process ◽  
Behavioral Differences ◽  
Relaxed Selection ◽  
Herbert Spencer ◽  
Habitat Properties

Theoretical discussion of the role of natural selection in shaping behavioral variation in different habitats has been an integral part of the study of animal behavior since the late 19th century. Herbert Spencer (1888) was among the first to argue that migrating populations that fail to adjust to environmental circumstances “are the first to disappear.” A common rationale for comparing populations or related species is the desire to identify behavioral differences that correspond with habitat properties providing different patterns of selection (Tuomi 1981, Riechert 1993, this volume). Behavioral similarities are often ignored or are treated as less interesting because the thrust of the research program emphasizes behavioral differences as an empirical test of the theory of natural selection. Nevertheless, these similarities can be as revealing of evolutionary process as are differences when they reflect behavioral convergence or slow disintegration of behavior under relaxed selection (Coss and Goldthwaite 1995). When populations invade novel habitats, they not only experience new selective regimes; they can also experience relaxed selection on specific behavioral phenotypes. This is particularly common when the new habitat is missing a class of predators that was abundant in the ancestral habitat (e.g., Curio 1975, Pressley 1981). Under relaxed selection, characters may disintegrate, presumably because mutations that result in loss of the phenotype are not at a selective disadvantage. Disintegration is not always observed, however. Instead, behavioral characters are sometimes retained for long periods of time after selection has been relaxed (Coss 1991b, Kaneshiro 1989). Inferring relaxed selection requires that the history of the contrasted populations be relatively well known. Both ancestral selective regimes and behavioral characters must be known if character polarity is to be established. Character polarity must be established to distinguish disintegration from parallel evolution of novel behavior patterns. This often is a problem in population contrasts because differentiation is usually too recent to have resulted in the evolution of enough derived characters for the use of standard cladistic methods of phylogenetic reconstruction, although recent advances in statistical and molecular techniques are promising (Foster 1994, Foster and Cameron 1996). Instead, inference of character polarity has typically relied on geological evidence and comparison with closely related species.

Sign in / Sign up

Export Citation Format

Share Document