Article

Speciation collapse and invasive species dynamics during the Late Devonian “Mass Extinction”

GSA Today 01/2012; 22(1):4-9. DOI: 10.1130/g128a.1

ABSTRACT

The Late Devonian (Frasnian-Famennian) interval includes one of the most dramatic intervals of biotic turnover in the Phanerozoic. Statistical evaluation of diversity change reveals that the primary cause of biodiversity decline was reduced speciation during the crisis interval, not elevated extinction rates. Although various hypotheses have been proposed to explain extinction increase during the Late Devonian, potential causes for reduced speciation have previously been largely unaddressed. Recent analyses focusing on biogeographic and phylogenetic patterns of species in shallow marine ecosystems of Laurentia indicate that a dramatic increase in interbasinal species invasions, facilitated by transgressive pulses, fundamentally affected biodiversity by enabling range expansion of ecological generalists and eliminating vicariance, the primary pathway by which new species typically form. Modern species invasions may result in similar speciation loss, exacerbating the current biodiversity crisis.

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Available from: Alycia L Stigall
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    • "75% brachiopod genera (McGhee, 1996), and extinction of 60% ammonoid families at the event horizon and origination of most new families in the Famennian (Becker and House, 2000). However, Alroy (2008) and Stigall (2012) concluded that the main cause of biodiversity decline during the F–F boundary interval was not elevated extinction rates but reduced speciation rates, therefore this event should be defined as the F–F Biodiversity Crisis. In this paper, the term mass extinction (or biotic crisis) is still used as it seems more applicable to the situation in South China. "
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    ABSTRACT: The Frasnian–Famennian (F–F) event may be recognized in various facies areas in South China. In the pelagic cherty basin facies, both Lower and Upper Kellwasser events can seemingly be recognized. In the deeper water carbonate facies, the F–F event level is well controlled in light of conodont biostratigraphy. In the shallow water carbonate and mixed carbonate-shale facies, the F–F boundary may be defined by clear taxonomic distinction in benthic fossils (articulate brachiopods and corals) as well as evidence from minor pelagic fossils. Post-extinction recovery rate of benthic organisms differs in different facies settings and different taxonomic groups. In open shallow water platform to inter-platform depression areas, brachiopods seem to recover quickly, probably in the Middle Pa. triangularis Zone; benthic ostracodes seem to recover at a later stage; recovery of rugose corals did not happen until the uppermost Famennian. Three steps of the F–F mass extinction are postulated: 1) extinction of diverse brachiopods (including most atrypids); 2) extinction of pelagic conodonts; 3) extinction of both benthic faunas (very abundant and diverse rugose corals and ostracodes) and pelagic conodonts. Evidence of an end-Frasnian regression in South China is clear, particularly in shallow water settings. However, in deeper water settings, the picture is complicated, with evidence of both sea level rise and fall in the latest Frasnian. It may be assumed from overall data so far known that crustal evolution itself and associated multiple volcanic/hydrothermal activities may have mainly caused frequent and rapid climatically warming-cooling alterations and sea level changes as well as marine ecologic collapse (eutrophication, microbial blooming, seawater acidification, and anoxia), which may explain the F–F extinction pattern in South China.
    Full-text · Article · Nov 2015 · Palaeogeography Palaeoclimatology Palaeoecology
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    • "It is bracketed by two oceanic anoxia events that are associated with major mass extinctions. The Kellwasser Event at the Frasnian– Famennian (F–F) boundary decimated coral reef and other benthic marine communities (Copper, 1994) while slightly older extinctions decimated terrestrial ecosystems (Stigall, 2012 and McGhee, 2013). In contrast, the Hangenberg Event at the Devonian–Carboniferous (D–C) boundary primarily affected pelagic marine communities including fish (Sallan and Coates, 2010) and cephalopods (Becker, 1993 and Zong et al., 2014). "
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    ABSTRACT: Sedimentary petrology and trace element geochemistry indicate that the Late Devonian to Early Carboniferous Heishantou Formation near Boulongour Reservoir (NW Xinjiang, China) was deposited on a steep slope, mid-latitude accreting island arc complex in an open oceanic system. Bulk 87Sr/86Sr ratios show excursion patterns that are consistent with excursions at the Devonian-Carboniferous (D-C) boundary in epicontinental margin sediments. Sedimentation rates for the Boulongour Reservoir sediments show highly variable rates that range from 0.5 cm/ky to 10 cm/ky, consistent with other Late Devonian sections and modern arc environments. Multiple whole rock geochemical proxies for anoxia and the size and distribution of pyrite framboids suggest the presence of the Hangenberg Event in the sediments associated with the D-C boundary, despite the lack of visible black shale. The presence of anoxia in an open ocean, island arc environment cannot be explained by upwelling of anoxic bottom waters at this paleolatitude, but can be explained by the global infliction of oceanic shallow water eutrophication on to a climate system in distress.
    Full-text · Article · Mar 2015 · Gondwana Research
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    • "claim that widespread forest fires and massive soil erosion took place during the Frasnian–Famennian event, leading to eutrophication, the development of anoxic/euxinic conditions in the water column, and in consequence mass extinction (more correctly, biodiversity crisis; Stigall, 2012) of marine biota. Although this scenario is novel and intriguing, it does, in our opinion lack sufficient evidence. "
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    ABSTRACT: Kaiho et al. (2013, Palaeogeography, Palaeoclimatology, Palaeoecology 392 (2013): 272–280) interpreted the occurrence of elevated concentrations of high molecular weight polycyclic aromatic hydrocarbons and dibenzofuran as indicators of wildfires and enhanced run-off near the Frasnian-Famennian (F-F) boundary. We argue that other processes, including weathering or hydrothermal oxidation (not discussed by Kaiho et al.) lead to the observed increase in the concentration of these compounds and also change their distribution. Kaiho et al.’s evidence for soil erosion and eutrophication-induced euxinia is also weak in the case of the investigated Belgian sections. Finally, Kaiho et al. rather unfortunately omitted a great wealth of important data published elsewhere, choosing instead to include only those which support their ideas and interpretations.
    Full-text · Article · Jan 2015 · Palaeogeography Palaeoclimatology Palaeoecology
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