# evol: viruses as a facilitator / driver of horizontal gene transfer among eukaryotes

<< Gene exchange between viruses and their hosts acts as a key facilitator of horizontal gene transfer and is hypothesized to be a major driver of evolutionary change. Our understanding of this process comes primarily from bacteria and phage co-evolution, but the mode and functional importance of gene transfers between eukaryotes and their viruses remain anecdotal. >>

AA << systematically characterized viral–eukaryotic gene exchange across eukaryotic and viral diversity, identifying thousands of transfers and revealing their frequency, taxonomic distribution and projected functions. Eukaryote-derived viral genes, abundant in the Nucleocytoviricota, highlighted common strategies for viral host-manipulation, including metabolic reprogramming, proteolytic degradation and extracellular modification. Furthermore, viral-derived eukaryotic genes implicate genetic exchange in the early evolution and diversification of eukaryotes, particularly through viral-derived glycosyltransferases, which have impacted structures as diverse as algal cell walls, trypanosome mitochondria and animal tissues. These findings illuminate the nature of viral–eukaryotic gene exchange and its impact on the evolution of viruses and their eukaryotic hosts. >>️

Irwin, N.A.T., Pittis, A.A., Richards, T.A. et al. Systematic evaluation of horizontal gene transfer between eukaryotes and viruses. Nat Microbiol. doi: 10.1038/ s41564-021-01026-3. Dec 31, 2021. 

https://www.nature.com/articles/s41564-021-01026-3

<< We knew from individual examples that viral genes have played a role in the evolution of eukaryotes. Even humans have viral genes, which are important for our development and brain function, (..)  We wanted to understand more broadly how HGT (horizontal gene transfer) has affected viruses and eukaryotes from across the tree of life. >> Nicholas Irwin. ️

<< We were interested to find that certain groups of viruses, especially those that infect single-celled eukaryotes, acquire a lot of genes from their hosts, (..)  By studying the function of these genes we were able to make predictions about how these viruses affect their hosts during infection. >> Patrick Keeling.

<< Many of these viral-derived genes appear to have repeatedly affected the structure and form of different organisms, from the cell walls of algae to the tissues of animals, (..) This suggests that host-virus interactions may have played an important role in driving the diversity of life we see today. >> Nicholas Irwin. ️

<< These transfers not only have evolutionary consequences for both virus and host, but could have important health implications, >> Patrick Keeling.️

<< we think that this work serves as an interesting reminder that viruses have also contributed to the evolution of life on Earth, >>️ Nicholas Irwin. 

️

New research shows gene exchange between viruses and hosts drives evolution. University of British Columbia. Jan 5, 2022.

https://phys.org/news/2022-01-gene-exchange-viruses-hosts-evolution.html

Also

Nonlinear effects in shaping human evolution, the role of viruses. Jan 15, 2019. 

https://flashontrack.blogspot.com/2019/01/evol-nonlinear-effects-in-shaping-human.html

keyword 'evolution'  in FonT

https://flashontrack.blogspot.com/search?q=evolution

keyword 'evolution' | 'evoluzione'  in Notes (quasi-stochastic poetry)

https://inkpi.blogspot.com/search?q=evolution

https://inkpi.blogspot.com/search?q=evoluzione

Keywords: evolution, virus, gene exchange, horizontal gene transfer, HGT

# gst: apropos of transitions, disordered systems mimic genetic evolution.

<< A bacterial genome’s evolution under changing drug concentrations displays effects of memory formation and mimics how disordered solids respond to external forces. >>️

AA << simulate the effect on adaptation of an environment that is constantly changing. Using a model that describes how slow-moving disordered systems respond to external forces, (they) find that microbe evolution in changing drug concentrations exhibits hysteresis and memory formation. They use analytical methods and numerical simulations to connect these statistical physics concepts to bacterial drug resistance. >>️

AA << find that this behavior mimics that of disordered systems driven by external forces, such as ferromagnetic materials subjected to magnetic fields or amorphous materials subjected to a shearing force. They say that while their approach focuses on the evolution of drug resistance, the framework can be adapted to other problems in evolutionary biology that involve changing environmental parameters. >>

️

Rachel Berkowitz. Disordered Systems Mimic Genetic Evolution. Physics 15, s118. Sep 20, 2022. 

https://physics.aps.org/articles/v15/s118

Suman G. Das, Joachim Krug, Muhittin Mungan. Driven Disordered Systems Approach to Biological Evolution in Changing Environments. Phys. Rev. X 12, 031040. Sep 20, 2022.

https://journals.aps.org/prx/abstract/10.1103/PhysRevX.12.031040

Also

keyword 'disorder' in FonT

https://flashontrack.blogspot.com/search?q=disorder

keyword 'disordine' in Notes

(quasi-stochastic poetry)

https://inkpi.blogspot.com/search?q=disordine

Keywords: gst, disorder, disordered systems, evolution, genetic evolution 

# behav: social isolation vs. evolutionary dynamics

<< For some animals—such as beetles, ants, toads, and primates—short-term social isolation can be just as vital as social interaction to development and long-term evolution. In a review published July 17 in the journal Trends in Ecology & Evolution, two evolutionary biologists describe approaches for testing how an animal's isolation might impact natural selection and evolution. >>

Social isolation: Animals that break away from the pack can influence evolution. Cell Press. Jul 17, 2018.

https://m.phys.org/news/2018-07-social-isolation-animals-evolution.html

AA << suggest that the 'index of social isolation', the mismatch between actual and optimal social interaction experienced by individuals within a population, may play a key role in releasing cryptic genetic variation, adaptation rates, diversification patterns, and ecosystem-level processes. Evolutionary dynamics arising from social isolation could have significant impacts in applied settings such as conservation, animal breeding, control of biological invasions, and evolutionary resilience to anthropogenic change. >>

Nathan W. Bailey, Allen J. Moore.  Evolutionary Consequences of Social Isolation. Trends in Ecology & Evolution. doi: 10.1016/j.tree.2018.05.008. Jul 17, 2018.

https://www.cell.com/trends/ecology-evolution/abstract/S0169-5347(18)30120-4

# evol: the hypothesis of quasi-stochastic 'jazzy' metamechanics of biological evolution (in Arabidopsis thaliana)

<< Mutations occur when DNA is damaged and left unrepaired, creating a new variation. The scientists wanted to know if mutation was purely random or something deeper. What they found was unexpected. >>️

<< We always thought of mutation as basically random across the genome, (..) It turns out that mutation is very non-random and it's non-random in a way that benefits the plant. It's a totally new way of thinking about mutation. >> Grey Monroe. ️

Study challenges evolutionary theory that DNA mutations are random. UC Davis. Jan 12, 2022.

https://phys.org/news/2022-01-evolutionary-theory-dna-mutations-random.html

Monroe JG, Srikant T, et al. Mutation bias reflects natural selection in Arabidopsis thaliana. Nature. doi: 10.1038/ s41586-021-04269-6. Jan 12, 2022.

https://www.nature.com/articles/s41586-021-04269-6

FonT 

for a long time I have developed the suspicion that the small plant cared for by grandmother on the windowsill could be a not trivial image of (r)evolution ... 

The three ways of the plastoquinone inside the photosystem II complex. May 23, 2017.

https://flashontrack.blogspot.com/2017/05/s-phyto-three-ways-of-plastoquinone.html

Also

keyword 'evolution'  in FonT

https://flashontrack.blogspot.com/search?q=evolution

keyword 'evolution' | 'evoluzione'  in Notes (quasi-stochastic poetry)

https://inkpi.blogspot.com/search?q=evolution

https://inkpi.blogspot.com/search?q=evoluzione

keyword 'jazz' in FonT

https://flashontrack.blogspot.com/search?q=jazz

keyword 'jazz' in Notes (quasi-stochastic poetry):

https://inkpi.blogspot.com/search?q=jazz

keywords: evol, dna, mutations, randomness, quasi-stochasticity, jazz

# evol: an irrefutable evidence that they rose from the dead by an 'iterative evolution' process

<< the last surviving flightless species of bird, a type of rail, in the Indian Ocean had previously gone extinct but rose from the dead thanks to a rare process called 'iterative evolution'. >>

<< This is the first time that iterative evolution (the repeated evolution of similar or parallel structures from the same ancestor but at different times) has been seen in rails and one of the most significant in bird records. >>

The bird that came back from the dead. University of Portsmouth. May 9, 2019.

https://m.phys.org/news/2019-05-bird-dead.html

<< Fossil evidence presented here is unique for Rallidae and epitomizes the ability of birds from this clade to successfully colonize isolated islands and evolve flightlessness on multiple occasions. >>

Julian P Hume, David Martill. Repeated evolution of flightlessness in Dryolimnas rails (Aves: Rallidae) after extinction and recolonization on Aldabra. Zoological Journal of the Linnean Society, zlz018.  doi: 10.1093/zoolinnean/zlz018. May 8, 2019.

https://academic.oup.com/zoolinnean/advance-article-abstract/doi/10.1093/zoolinnean/zlz018/5487031

# evol: nonlinear effects in shaping human evolution, the role of viruses

<< Human evolution used to be depicted as a straight line, gradually progressing from an ape-like ancestor to modern Homo sapiens. But thanks to next-generation sequencing, findings in recent years have shown that it wasn’t quite so orderly. Now, a new study is reporting new details about the role of viruses in shaping evolution, in particular, viral interactions between modern humans and Neanderthals. >>

<< Many Neanderthal sequences have been lost in modern humans, but some stayed and appear to have quickly increased to high frequencies at the time of contact, suggestive of their selective benefits at that time, >> Dmitri Petrov

New study reports the role of viruses in shaping evolution. Oct 5, 2018.

https://thesurg.com/virus-shaping-evolution

AA << hypothesized that interbreeding between Neanderthals and modern humans led to (1) the exposure of each species to novel viruses and (2) the exchange of adaptive alleles that provided resistance against these viruses. >>

David Enard, Dmitri A. Petrov. Evidence that RNA Viruses Drove Adaptive Introgression between Neanderthals and Modern Humans. Cell. 175 (2) P360-371.E13 Oct 4, 2018.

https://www.cell.com/cell/fulltext/S0092-8674(18)31095-X 

# evol: hanging by a rope off a cliff, the vibrant pigments of bird feathers to trace the mechanics of evolution

<< All organisms depend on input of exogenous compounds that cannot be internally produced. Gain and loss of such dependencies structure ecological communities and drive species’ evolution, yet the evolution of mechanisms that accommodate these variable dependencies remain elusive. (AA) show that historical cycles of gains and losses of external dependencies in avian carotenoid-producing networks are linked to their evolutionary diversification. >>

Alexander V. Badyaev, Alexander B. Posner, et al. Cycles of external dependency drive evolution of avian carotenoid networks. Nature Communications volume 10, Article number: 1596 Apr 8, 2019.

https://www.nature.com/articles/s41467-019-09579-y

<< Think about hanging by a rope off a cliff. With one rope, if it disappears, you die. If you have two and one fails, you get to live. But having a third safety rope allows enough stability that you can make something out of the first two - like a ladder - and thus take control of your trajectory while the stability lasts, >> Alexander Badyaev.

What the vibrant pigments of bird feathers can teach us about how evolution works. University of Arizona. Apr 24, 2019.

https://www.eurekalert.org/pub_releases/2019-04/uoa-wtv042419.php

# evol-ethno: the fuzzy dispersal and interaction dynamics of ancient (early) nomads

AA << evaluate single versus multiple dispersal models and southern versus the northern dispersal routes across the Asian continent. They also review behavioral and environmental variability and how these may have affected modern human dispersals and interactions with indigenous populations >>

Christopher J. Bae, Katerina Douka, Michael D. Petraglia. On the origin of modern humans: Asian perspectives. Science. 2017; 358 (6368): eaai9067
doi: 10.1126/science.aai9067. Dec 8, 2017

http://science.sciencemag.org/content/358/6368/eaai9067

<< Homo sapiens reached distant parts of the Asian continent, as well as Near Oceania, much earlier than previously thought. Additionally, evidence that modern humans interbred with other hominins already present in Asia, such as Neanderthals and Denisovans, complicates the evolutionary history of our species >>

Revising the story of the dispersal of modern humans across Eurasia. Technological advances and multidisciplinary research teams are reshaping our understanding of when and how humans left Africa - and who they met along the way. Dec 7, 2017

http://www.shh.mpg.de/742617/human-dispersals-africa

https://www.sciencedaily.com/releases/2017/12/171207141724.htm

<< Climate is a key factor determining the types of vegetation that can grow in an ecosystem. By recreating the plant foods and habitat available at a given time, it is possible to learn about changes that occurred during important transitions in the evolution of humans >>

Marie DeNoia Aronsohn. The Way We Were: Climate and Human Evolution. Dec 1, 2017.

https://m.phys.org/news/2017-12-wereclimate-human-evolution.html 

http://blogs.ei.columbia.edu/2017/12/01/the-way-we-were-climate-and-human-evolution/

# evol: echolocation, a prime example of convergent evolution

<< Echolocation is a prime example of convergent evolution, the independent gain of similar features in species of different lineages. >>

<< Distantly related species entering similar biological niches often adapt by evolving similar morphological and physiological characters. How much genomic molecular convergence (particularly of highly constrained coding sequence) contributes to convergent phenotypic evolution, such as echolocation in bats and whales, is a long-standing fundamental question.  >>

AA << find that the gene set most overrepresented (q-value = 2.2e-3) with convergent substitutions in echolocators, affecting 18 genes, regulates development of the cochlear ganglion, a structure with empirically supported relevance to echolocation. >>

Amir Marcovitz, Yatish Turakhia, et al. A functional enrichment test for molecular convergent evolution finds a clear protein-coding signal in echolocating bats and whales.
PNAS doi: 10.1073/pnas.1818532116   Sep 30, 2019    https://www.pnas.org/content/early/2019/09/27/1818532116 

Krista Conger. Scientists uncover genetic similarities among species that use sound to navigate. Stanford University Medical Center. Oct 4, 2019.   https://m.phys.org/news/2019-10-scientists-uncover-genetic-similarities-species.html

# s-evol: the role of Ediacarans on the evolution of others

<< The fossil group called the Ediacaran biota have been troubling researchers for a long time >>

In this study  the Ediacaran biota  << played an enabling role in bilaterian evolution similar to that proposed for the Savannah environment for human evolution and bipedality >>

http://www.alphagalileo.org/ViewItem.aspx?ItemId=159128&CultureCode=en

Graham E. Budd, Soren Jensen. The origin of the animals and a ‘Savannah’ hypothesis for early bilaterian evolution. Biological Reviews, 2015; DOI: 10.1111/brv.12239

http://onlinelibrary.wiley.com/doi/10.1111/brv.12239/abstract

# life; a hypothetical externalization of knowledge effects; humans are thought to have decreased in brain volume since the end of the last ice age (3,000 y.ago)

<< Human brain size nearly quadrupled in the six million years since Homo last shared a common ancestor with chimpanzees, but human brains are thought to have decreased in volume since the end of the last Ice Age. The timing and reason for this decrease is enigmatic. Here (AA) use change-point analysis to estimate the timing of changes in the rate of hominin brain evolution. (They) find that hominin brains experienced positive rate changes at 2.1 and 1.5 million years ago, coincident with the early evolution of Homo and technological innovations evident in the archeological record. But (AA) also find that human brain size reduction was surprisingly recent, occurring in the last 3,000 years. >>

Jeremy M. DeSilva, James F. A. Traniello, et al. When and Why Did Human Brains Decrease in Size? A New Change-Point Analysis and Insights From Brain Evolution in Ants. Front. Ecol. Evol.,  doi: 10.3389/ fevo.2021.742639. Oct 22, 2021. 

https://www.frontiersin.org/articles/10.3389/fevo.2021.742639/full

When and why did human brains decrease in size 3,000 years ago? Ants may hold clues. Frontiers. Oct 22, 2021.

https://phys.org/news/2021-10-human-brains-decrease-size-years.html

Also

keyword 'nomade' | 'nomad' | 'nomads' | 'nomadic' | 'hunter-gatherers' in FonT

https://flashontrack.blogspot.com/search?q=nomade

https://flashontrack.blogspot.com/search?q=nomad

https://flashontrack.blogspot.com/search?q=nomads

https://flashontrack.blogspot.com/search?q=nomadic

https://flashontrack.blogspot.com/search?q=hunter-gatherers

keyword 'nomade' | 'nomadi' in Notes (quasi-stochastic poetry)

https://inkpi.blogspot.com/search?q=nomade

https://inkpi.blogspot.com/search?q=nomadi

keyword 'ctz' entities in FonT

https://flashontrack.blogspot.com/search?q=ctz

keywords: evolution, brain, brain size, nomads, post-nomads, sociocultural effects

# evol: dry, chaotic environment in the transition to modern (nomadic) humans

<< A progressively drying climate punctuated by variable wetter episodes may have precipitated the transition from our hominin ancestors to anatomically modern humans >>

Dryer, less predictable environment may have spurred human evolution. University of Arizona. Oct 8, 2018.

https://m.phys.org/news/2018-10-dryer-environment-spurred-human-evolution.html

R. Bernhart Owen, Veronica M. Muiruri, et al. Progressive aridification in East Africa over the last half million years and implications for human evolution. PNAS Oct 8, 2018 doi: 10.1073/pnas.1801357115 

http://www.pnas.org/content/early/2018/10/03/1801357115

# phys: trace the birth and evolution of a quasiparticle entity

<< The idea of quasiparticles was first introduced in the 1930s by physicist Lev Landau, who was trying to gain a better understanding of complex quantum systems. >>

<< Over the past decades, physicists worldwide have been trying to gain a better understanding of non-equilibrium dynamics in quantum many-body systems. Some studies investigated what are known as quasiparticles, disturbances or entities in physical systems that exhibit behavior similar to that of particles. >>

In this study AA << observed three distinct regimes of impurity evolution marked by dynamic transitions. These regimes then link initial few-body and later many-body physical dynamics. >>

Ingrid Fadelli. Observing the birth of a quasiparticle. Mar 11, 2021.

https://phys.org/news/2021-03-birth-quasiparticle.html

<<  These results offer a systematic picture of polaron formation from weak to strong impurity interactions. They reveal three distinct regimes of evolution with dynamical transitions that provide a link between few-body processes and many-body dynamics. Our measurements reveal universal dynamical behaviour in interacting many-body systems and demonstrate new pathways to study non-equilibrium quantum phenomena. >>

Magnus G. Skou, Thomas G. Skov, et al. Non-equilibrium quantum dynamics and formation of the Bose polaron. 

Nat. Phys. (2021). doi: 10.1038/ s41567-021-01184-5. Feb 25, 2021.

https://www.nature.com/articles/s41567-021-01184-5

"three distinct regimes"  

https://www.nature.com/articles/s41567-021-01184-5.epdf?no_publisher_access=1&r3_referer=nature

# gst: evolution of survivors compared to discrete vs continuous noise

<< Environmental variations can significantly influence how populations compete for resources, and hence shape their evolution. Here, (AA) study population dynamics subject to a fluctuating environment modeled by a varying carrying capacity changing continuously in time according to either binary random switches, or by being driven by a noise of continuous range. >>

<< the slow strain fixation probability can be greatly enhanced for a continuously varying environment compared to binary switches, even when the first two moments of the carrying capacity coincide. >>️

Ami Taitelbaum, Robert West, et al. Evolutionary dynamics in a varying environment: Continuous versus discrete noise. Phys. Rev. Research 5, L022004. April 4, 2023. 

https://journals.aps.org/prresearch/abstract/10.1103/PhysRevResearch.5.L022004

Also: noise, in https://www.inkgmr.net/kwrds.html

Keywords: gst, evolution, noise, discrete vs continuous noise

# ecol: when a predator could help his prey to adapt to an uncertain future (among the fly Iteomyia salicisverruca) ...

<< The loss of biodiversity is rewiring the web of life; however, it is uncertain how this will affect the ability of remaining populations to evolve and adapt to future environments. >>

AA << conducted a field experiment that either maintained a natural community of predators or removed all but one of the predators that was able to impose selection on a common prey. (They) found that the loss of predators acted to constrain prey evolution toward a particular combination of traits. Moreover, (they) found that the loss of predators could make it more difficult for prey to adapt to uncertain future environments. Taken together, (these) results suggest that the simplification of the web of life may constrain the adaptive potential of remaining populations. >>

Matthew A. Barbour, Christopher J. Greyson‐Gaito, et al. Loss of consumers constrains phenotypic evolution in the resulting food web. Evolution Letters. doi: 10.1002/ evl3.170. Apr 20, 2020. 

https://onlinelibrary.wiley.com/doi/full/10.1002/evl3.170

<< Thinking about the big picture, our study hints at a potential insidious side effect of extinctions, (..) The extinction of natural enemies may compromise the ability of remaining species to adapt and persist in an uncertain and changing world. If this is true, this would put many ecosystems at even greater risk than we currently realize. >> Matthew A. Barbour.

Predators help prey adapt to an uncertain future. University of Zurich. 

 May 4, 2020

https://phys.org/news/2020-05-predators-prey-uncertain-future.html

# evol: ancient photosynthesis could be as old as life itself

<< the earliest bacteria had the tools to perform a crucial step in photosynthesis,  (..) The finding also challenges expectations for how life might have evolved on other planets. >>️

<< Photosystem II show patterns of evolution that are usually only attributed to the oldest known enzymes, which were crucial for life itself to evolve >> Tanai Cardona.️

<< enzymes capable of performing the key process in oxygenic photosynthesis -- splitting water into hydrogen and oxygen -- could actually have been present in some of the earliest bacteria. The earliest evidence for life on Earth is over 3.4 billion years old and some studies have suggested that the earliest life could well be older than 4.0 billion years old.  Like the evolution of the eye, the first version of oxygenic photosynthesis may have been very simple and inefficient; as the earliest eyes sensed only light, the earliest photosynthesis may have been very inefficient and slow. (..) that oxygen production was present at all so early on means in other environments, such as on other planets, the transition to complex life could have taken much less time. >>️

Photosynthesis could be as old as life itself. Imperial College London. Mar 24, 2021. 

https://www.sciencedaily.com/releases/2021/03/210324142839.htm

Thomas Olivera, Patricia Sanchez-Baracaldo, et al. Time-resolved comparative molecular evolution of oxygenic photosynthesis.Biochimica et Biophysica Acta (BBA) - Bioenergetics, 2021; 1862 (6): 148400. doi: 10.1016/ j.bbabio.2021.148400. Jun 1,  2021.

https://www.sciencedirect.com/science/article/pii/S0005272821000335

Also

Lewis M. Ward, Patrick M. Shih. Granick revisited: Synthesizing evolutionary and ecological evidence for the late origin of bacteriochlorophyll via ghost  lineages and horizontal gene transfer. PLoS ONE 16(1): e0239248. doi:10.1371/journal.pone.0239248. 

Jan 28, 2021. 

https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0239248

# evol: adaptability by genome duplications (A. kamchatica)

<< "With these results, we have demonstrated on a molecular-genetic level that genome duplications can positively affect the adaptability of organisms," says plant scientist Timothy Paape. The multiple gene copies enable the plant to assume advantageous mutations while keeping an original copy of important genes. >>

Genome duplication drives evolution of species. University of Zurich. Sep 25, 2018.

https://m.phys.org/news/2018-09-genome-duplication-evolution-species.html

Timothy Paape, Roman V. Briskine, et al. Patterns of polymorphism and selection in the subgenomes of the allopolyploid Arabidopsis kamchatica.
Nature Comm 9 3909 Sep 25, 2018

https://www.nature.com/articles/s41467-018-06108-1

# gst: adhesive performances (sticky approaches): a single type of toe pad (with lots of friction) vs multi functional "drunken stumbles"

AA << shows how different groups of lizards – geckos and anoles – took two completely different evolutionary paths to developing the beneficial trait of sticky toe pads >>

<< anoles seemed to commit to a single type of toe pad, one that generates lots of friction. As a group, they were able to develop sticky toe pads early. Geckos, meanwhile, opted for an evolutionary “drunken stumble,” and seemingly didn’t commit to a single approach, instead evolving toe pads that generate plenty of friction in some species and others that excel at sticking directly to a surface >>

Layne Cameron, Travis Hagey. An evolving sticky situation. Oct 12, 2017

http://msutoday.msu.edu/news/2017/an-evolving-sticky-situation/

https://www.sciencedaily.com/releases/2017/10/171012123031.htm

Travis J. Hagey, Josef C. Uyeda, et al. Tempo and mode of performance evolution across multiple independent origins of adhesive toe pads in lizards. Evolution.  2017; 71 (10): 2344–58 doi: 10.1111/evo.13318 Sep 13, 2017

http://onlinelibrary.wiley.com/doi/10.1111/evo.13318/abstract

# gst: how small particles could reshape an asteroid

<< In January 2019, NASA's OSIRIS-REx spacecraft was orbiting asteroid Bennu when the spacecraft's cameras caught something unexpected: Thousands of tiny bits of material, some just the size of marbles, began to bounce off the surface of the asteroid—like a game of ping-pong in space. Since then, many such particle ejection events have been observed at Bennu's surface. >>

AA have been studying << asteroids for a long time, and no one had ever seen this phenomenon before—these little particles getting shot off of the surface  (..) such seemingly small occurrences may add up over time—perhaps even helping to give the asteroid its telltale shape, which is often compared to a spinning top. >>

<< basic orbital calculations suggest that all of these particles should do one of two things: Jump off the surface and fall right back down or escape from Bennu's gravity and never come back. >>

<< When particles eventually land on Bennu's surface, many appear to disproportionately fall near its equator where the asteroid has a distinct bulge. As a result, these events could be reshaping the asteroid over thousands or millions of years by moving mass from its north and south to its middle. >>

Daniel Strain. How small particles could reshape Bennu and other asteroids. University of Colorado at Boulder. Sep 9, 2020.

https://phys.org/news/2020-09-small-particles-reshape-bennu-asteroids.html 

McMahon Jay W, Scheeres Daniel J, et al. Dynamical Evolution of Simulated Particles Ejected From Asteroid Bennu. J Geophys Res: Planets. 125 (8). doi: 10.1029/ 2019JE006229. May 18, 2020.

https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2019JE006229 

Scheeres Daniel J, McMahon Jay W, et al. Particle Ejection Contributions to the Rotational Acceleration and Orbit Evolution of Asteroid (101955) Bennu. 

J Geophys Res: Planets. 125 (3). doi: 10.1029/ 2019JE006284. March 11, 2020. 

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2019JE006284

# evol: the rare art of surviving: the case of Actinopterygians ray-finned fishes

<< Actinopterygians (ray-finned fishes) successfully passed through four of the big five mass extinction events of the Phanerozoic >>

<< Many researchers have assumed that the Permo-Triassic mass extinction (..) and end-Triassic extinction (..) had little impact on actinopterygians, despite devastating many other groups. >>

Fiann M. Smithwick, Thomas L. Stubbs. Phanerozoic survivors: Actinopterygian evolution through the Permo-Triassic and Triassic-Jurassic mass extinction events.  Evolution. 2018; 72 (2): 348 - 62. doi: 10.1111/evo.13421. Feb 2, 2018

http://onlinelibrary.wiley.com/doi/10.1111/evo.13421/abstract

University of Bristol. The resilience of ray-finned fishes. Feb 5, 2018.

https://m.phys.org/news/2018-02-resilience-ray-finned-fishes.html