UV-B radiation was the Devonian-Carboniferous boundary terrestrial extinction kill mechanism

Marshall, J.; Lakin, Jon; Troth, Ian; Wallace-Johnson, Sarah M.

doi:10.1126/sciadv.aba0768

Cited by 76 publications

(67 citation statements)

References 63 publications

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“…Ref. (5) argues that a period of exceptional and sustained warming would lead to the loss of the protective ozone layer via this mechanism.…”

Section: Heating Mechanism For Ozone Depletionmentioning

confidence: 99%

“…Refs. (5,9,11) also report the discovery of spores from this episode with distinct morphologies including malformed spines and dark pigmented walls, features consistent with severely deteriorating environmental conditions, and UV-B damage following destruction of the ozone layer (11). However, more quantitative data are needed to study their variation during quiescent times in the fossil record.…”

mentioning

confidence: 98%

“…Previous work has not considered astrophysical sources of ionizing radiation, which are known to be possible causes of ozone depletion and concomitant UV-B increase that could trigger elevated extinction levels (see, e.g., (8)), as well as direct genetic damage. Here we consider whether astrophysical sources could account for the data in (5), and whether any additional evidence could test for their occurrence.…”

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confidence: 99%

“…The Late Devonian biodiversity crisis is characterized by a protracted decline in speciation rate occurring over millions of years ( 1 , 2 ), punctuated by an extinction pulse (Kellwasser event) followed

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My later by a more moderate extinction (Hangenberg event) around the Devonian–Carboniferous boundary (DCB)

359

My ago ( 3 , 4 ). Marshall et al ( 5 ) recently suggested that the Hangenberg event was associated with ozone depletion (see also ref. 6 ), in light of evidence such as malformations persisting in palynological assemblages on the order of many thousands of years.…”

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confidence: 99%

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Supernova triggers for end-Devonian extinctions

Fields

Melott

Ellis

et al. 2020

Proc. Natl. Acad. Sci. U.S.A.

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The Late Devonian was a protracted period of low speciation resulting in biodiversity decline, culminating in extinction events near the Devonian–Carboniferous boundary. Recent evidence indicates that the final extinction event may have coincided with a dramatic drop in stratospheric ozone, possibly due to a global temperature rise. Here we study an alternative possible cause for the postulated ozone drop: a nearby supernova explosion that could inflict damage by accelerating cosmic rays that can deliver ionizing radiation for up to ∼100 ky. We therefore propose that the end-Devonian extinctions were triggered by supernova explosions at ∼20 pc, somewhat beyond the “kill distance” that would have precipitated a full mass extinction. Such nearby supernovae are likely due to core collapses of massive stars; these are concentrated in the thin Galactic disk where the Sun resides. Detecting either of the long-lived radioisotopes Sm146 or Pu244 in one or more end-Devonian extinction strata would confirm a supernova origin, point to the core-collapse explosion of a massive star, and probe supernova nucleosynthesis. Other possible tests of the supernova hypothesis are discussed.

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“…Ref. (5) argues that a period of exceptional and sustained warming would lead to the loss of the protective ozone layer via this mechanism.…”

Section: Heating Mechanism For Ozone Depletionmentioning

confidence: 99%

mentioning

confidence: 98%

mentioning

confidence: 99%

10

My later by a more moderate extinction (Hangenberg event) around the Devonian–Carboniferous boundary (DCB)

359

mentioning

confidence: 99%

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Supernova triggers for end-Devonian extinctions

Fields

Melott

Ellis

et al. 2020

Proc. Natl. Acad. Sci. U.S.A.

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“…A prominent environmental stressor is UV radiation, which has been related with some extinctions as in the Devonian-Carboniferous boundary period (Marshall et al, 2020).…”

Section: Accepted Articlementioning

confidence: 99%

Interspecific hybrids show a reduced adaptive potential under DNA damaging conditions

Bautista

Marsit

Landry

2020

Evolutionary Applications

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Hybridization may increase the probability of adaptation to extreme stresses. This advantage could be caused by an increased genome plasticity in hybrids, which could accelerate the search for adaptive mutations. High ultraviolet (UV) radiation is a particular challenge in terms of adaptation because it affects the viability of organisms by directly damaging DNA, while also challenging future generations by increasing mutation rate. Here we test if hybridization accelerates adaptive evolution in response to DNA damage, using yeast as a model. We exposed 180 populations of hybrids between species (Saccharomyces cerevisiae and Saccharomyces paradoxus) and their parental strains to UV mimetic and control conditions for approximately 100 generations. Although we found that adaptation occurs in both hybrids and parents, hybrids achieved a lower rate of adaptation, contrary to our expectations. Adaptation to DNA damage conditions comes with a large and similar cost for parents and hybrids, suggesting that this cost is not responsible for the lower adaptability of hybrids. We suggest that the lower Accepted Article This article is protected by copyright. All rights reserved adaptive potential of hybrids in this condition may result from the interaction between DNA damage and the inherent genetic instability of hybrids.

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