scholarly journals Differential human impact on the survival of genetically distinct avian lineages

1999 ◽  
Vol 9 (2) ◽  
pp. 147-154 ◽  
Author(s):  
Austin L. Hughes
Keyword(s):  
Human Impact ◽  
Physical Environment ◽  
Mass Extinction ◽  
The Earth ◽  
Biotic Diversity ◽  
Extinction Event ◽  
Mass Extinction Event ◽  
Extinction Events ◽  
The Impact ◽  
Mass Extinction Events

SummaryAt the present time the earth is facing an anthropogenic (human-caused) mass extinction event that may eventually rival previous mass extinction events caused by drastic changes i n the physical environment; however, the impact of this event on the earth's biotic diversity remains difficult to predict. Patterns of extinction and endangerment in birds, one of the best known taxonomically among major groups of organisms, showed that the distribution of human impact has been non-uniform relative to phylogenetic relationships. Fifteen major avian lineages differed over 35-fold with respect to the frequency of historical extinction and over threefold with respect to frequency of current threat; and overall rates of both extinction and threat were significantly higher in non-passerine orders than in passerines. Moreover, among both passerines and non-passerines, the rate of historic extinction has been significantly higher for species in monotypic genera than for other species; and in passerines, the rate of current threat is significantly higher for species in monotypic genera than for other species. Thus, the anthropogenic extinction and threat to avian species has specifically targeted species that are phylogenetically and thus, presumably genetically, unique.

Testing for a mass extinction without selecting taxa

Paleobiology ◽  
2000 ◽  
Vol 26 (4) ◽  
pp. 647-650 ◽  
Author(s):  
Andrew R. Solow ◽  
Woollcott K. Smith
Keyword(s):  
Statistical Inference ◽  
Mass Extinction ◽  
Extinction Event ◽  
Mass Extinction Event ◽  
Extinction Events ◽  
Mass Extinction Events ◽  
Stratigraphic Height ◽  
Selection Of

Statistical inference about mass extinction events is commonly based on the pattern of fossil finds among a group of taxa. An important issue for existing methods is the selection of taxa for inclusion in the analysis. A common approach is to select taxa on the basis of the stratigraphic height of their uppermost finds. This approach creates a bias in favor of detecting a mass extinction event. This paper describes and illustrates an approach that avoids this problem.

scholarly journals Dead clades walking are a pervasive macroevolutionary pattern

2021 ◽  
Vol 118 (15) ◽  
pp. e2019208118
Author(s):  
B. Davis Barnes ◽  
Judith A. Sclafani ◽  
Andrew Zaffos
Keyword(s):  
Mass Extinction ◽  
Bayesian Method ◽  
Marine Invertebrate ◽  
Mass Extinctions ◽  
Extinction Event ◽  
Genus Richness ◽  
Mass Extinction Event ◽  
Extinction Events ◽  
Mass Extinction Events

D. Jablonski [Proc. Natl. Acad. Sci. U.S.A. 99, 8139–8144 (2002)] coined the term “dead clades walking” (DCWs) to describe marine fossil orders that experience significant drops in genus richness during mass extinction events and never rediversify to previous levels. This phenomenon is generally interpreted as further evidence that the macroevolutionary consequences of mass extinctions can continue well past the formal boundary. It is unclear, however, exactly how long DCWs are expected to persist after extinction events and to what degree they impact broader trends in Phanerozoic biodiversity. Here we analyze the fossil occurrences of 134 skeletonized marine invertebrate orders in the Paleobiology Database (paleobiodb.org) using a Bayesian method to identify significant change points in genus richness. Our analysis identifies 70 orders that experience major diversity losses without recovery. Most of these taxa, however, do not fit the popular conception of DCWs as clades that narrowly survive a mass extinction event and linger for only a few stages before succumbing to extinction. The median postdrop duration of these DCW orders is long (>30 Myr), suggesting that previous studies may have underestimated the long-term taxonomic impact of mass extinction events. More importantly, many drops in diversity without recovery are not associated with mass extinction events and occur during background extinction stages. The prevalence of DCW orders throughout both mass and background extinction intervals and across phyla (>50% of all marine invertebrate orders) suggests that the DCW pattern is a major component of macroevolutionary turnover.

Rapid macrobenthic diversification and stabilization after the end-Cretaceous mass extinction event

Geology ◽  
2020 ◽  
Vol 48 (11) ◽  
pp. 1048-1052
Author(s):  
Francisco J. Rodríguez-Tovar ◽  
Christopher M. Lowery ◽  
Timothy J. Bralower ◽  
Sean P.S. Gulick ◽  
Heather L. Jones
Keyword(s):  
Mass Extinction ◽  
Rapid Recovery ◽  
Community Recovery ◽  
Scientific Drilling ◽  
Extinction Event ◽  
Chicxulub Impact Crater ◽  
Mass Extinction Event ◽  
International Ocean Discovery Program ◽  
Extinction Events ◽  
The Impact

Abstract Previous ichnological analysis at the Chicxulub impact crater, Yucatán Peninsula, México (International Ocean Discovery Program [IODP]/International Continental Scientific Drilling Program [ICDP] Site M0077), showed a surprisingly rapid initial tracemaker community recovery after the end-Cretaceous (Cretaceous-Paleogene [K-Pg]) mass extinction event. Here, we found that full recovery was also rapid, with the establishment of a well-developed tiered community within ∼700 k.y. Several stages of recovery were observed, with distinct phases of stabilization and diversification, ending in the development of a trace fossil assemblage mainly consisting of abundant Zoophycos, Chondrites, and Planolites, assigned to the Zoophycos ichnofacies. The increase in diversity is associated with higher abundance, larger forms, and a deeper and more complex tiering structure. Such rapid recovery suggests that favorable paleoenvironmental conditions were quickly reestablished within the impact basin, enabling colonization of the substrate. Comparison with the end-Permian extinction reveals similarities during recovery, yet postextinction recovery was significantly faster after the K-Pg event. The rapid recovery has significant implications for the evolution of macrobenthic biota after the K-Pg event. Our results have relevance in understanding how communities recovered after the K-Pg impact and how this event differed from other mass extinction events.

scholarly journals The Sixth Species Extinction Event by Humans

2015 ◽  
Vol 5 (1) ◽  
pp. 61-72
Author(s):  
Victor John Nazarevich
Keyword(s):  
Mass Extinction ◽  
Recent Literature ◽  
Theoretical Research ◽  
Future Research ◽  
The Earth ◽  
Unknown Species ◽  
Extinction Event ◽  
Extinction Events ◽  
The Impact ◽  
The Relationship

The number of species becoming extinct has drawn a significant deal of attention from scientists and non-scientists alike. This research reviews recent literature citing evidence for the impact humans have had on our planet and how our biological systems are affected in both known species of flora and fauna as well as unknown species of flora and fauna, the latter lacking documentation as well as sightings by humans. Theoretical research is derived from previous research investigating the impacts of humankind’s use of the land as well as population increases. Though there are many different definitions of what a mass extinction is and gradations of extinction intensity, a conservative approach is used to assess the seriousness of the current ongoing extinction crisis, setting the highest level of recognition for mass extinction, in extreme diversity loss associated with the Big Five extinction events (Barnosky, 2011). Understanding the relationship between extinction and functional diversity over time will be critical for making conservation work (Boyer & Jetz, 2014). If another mass extinction is allowed to progress, it would mean the end of biodiversity as we know it and would also mean that greater pressure would be placed on both humans and flora and fauna to survive in a world completely changed by the Anthropocene. Over the course of 8,000-10,000 years, humans grew in population and changed the landscape of the Earth (Foley, 2013). The research concludes that focus should be on preserving the environment and future research should be performed on the study of unknown species.

scholarly journals The impact of the Cretaceous–Paleogene (K–Pg) mass extinction event on the global sulfur cycle: Evidence from Seymour Island, Antarctica

2018 ◽  
Vol 230 ◽  
pp. 17-45 ◽  
Author(s):  
James D. Witts ◽  
Robert J. Newton ◽  
Benjamin J.W. Mills ◽  
Paul B. Wignall ◽  
Simon H. Bottrell ◽  
...  
Keyword(s):  
Mass Extinction ◽  
Sulfur Cycle ◽  
Extinction Event ◽  
Mass Extinction Event ◽  
The Impact ◽  
Seymour Island

scholarly journals Identifying the most surprising victims of mass extinction events: an example using Late Ordovician brachiopods

2017 ◽  
Vol 13 (9) ◽  
pp. 20170400 ◽  
Author(s):  
Seth Finnegan ◽  
Christian M. Ø. Rasmussen ◽  
David A. T. Harper
Keyword(s):  
Deep Water ◽  
Mass Extinction ◽  
Late Ordovician ◽  
Extinction Rate ◽  
Simple Method ◽  
Training Models ◽  
Extinction Event ◽  
Extinction Events ◽  
Mass Extinction Events

Mass extinction events are recognized by increases in extinction rate and magnitude and, often, by changes in the selectivity of extinction. When considering the selective fingerprint of a particular event, not all taxon extinctions are equally informative: some would be expected even under a ‘background’ selectivity regime, whereas others would not and thus require special explanation. When evaluating possible drivers for the extinction event, the latter group is of particular interest. Here, we introduce a simple method for identifying these most surprising victims of extinction events by training models on background extinction intervals and using these models to make per-taxon assessments of ‘expected’ risk during the extinction interval. As an example, we examine brachiopod genus extinctions during the Late Ordovician Mass Extinction and show that extinction of genera in the deep-water ‘ Foliomena fauna’ was particularly unexpected given preceding Late Ordovician extinction patterns.

scholarly journals Evidence for fungal proliferation following the Cretaceous/Paleogene mass-extinction event, based on chemostratigraphy in the Raton and Powder River basins, western North America

2020 ◽  
pp. 134-142
Author(s):  
Keith Berry
Keyword(s):  
Amino Acid ◽  
North America ◽  
Mass Extinction ◽  
River Basins ◽  
High Energy ◽  
Western North America ◽  
Ecosystem Recovery ◽  
Extinction Event ◽  
Mass Extinction Event ◽  
The Impact

The presence of the amino acid α-aminoisobutyric acid (Aib) within Cretaceous/Paleogene (K/Pg) boundary clay in the Raton and Powder River basins in Colorado and Wyoming, respectively, has been described as compelling evidence that extraterrestrial Aib survived the high-energy Chicxulub impact. Based on contemporary experiments and simulations, however, it is highly unlikely that extraterrestrial Aib survived the impact, which had peak impact pressures and temperatures in excess of 600 GPa and 10,000 K, respectively. In other words, the amino acid signature of the carbonaceous chondritic asteroid that impacted Chicxulub was undoubtedly destroyed upon impact during formation of the vapor plume or so-called “fireball.” The only organisms known to produce Aib are the suite (more than 30 genera) of cosmopolitan saprotrophic filamentous fungi that include Trichoderma Pers., which has recently been hypothesized to have thrived during the K/Pg mass-extinction event. Therefore it is proposed that the Aib horizon in the K/Pg boundary clay in the Raton and Powder River basins correlates with the K/Pg boundary fungal spike, which thus far has only been observed in New Zealand (Southern Hemisphere). This proposition is based upon superimposing the Aib horizon on the well-known iridium and fern-spore spikes, as its stratigraphic position precisely matches that predicted by the fungal spike. If correct, this hypothesis alters the conventional perspective on the tempo and mode of terrestrial ecosystem recovery in western North America, as the heavily sampled K/Pg boundary section in the Raton Basin was instrumental in shaping the traditional narrative of the rapid recolonization of a denuded landscape by ferns via wind-blown spores in the immediate wake of regional deforestation caused by the K/Pg impact event. Perhaps more importantly, it could present an alternative to traditional palynological approaches for locating the fungal spike in other terrestrial K/Pg boundary sections and could provide additional support for the generalization that global mass-extinction events are frequently accompanied by fungal spikes.

scholarly journals A Hiatus Obscures the Early Evolution of Modern Lineages of Bony Fishes

2021 ◽  
Vol 8 ◽  
Author(s):  
Carlo Romano
Keyword(s):  
Mass Extinction ◽  
Fossil Record ◽  
Middle Triassic ◽  
Early Evolution ◽  
Early Triassic ◽  
Triassic Boundary ◽  
Bony Fishes ◽  
Extinction Event ◽  
Mass Extinction Event ◽  
The Impact

About half of all vertebrate species today are ray-finned fishes (Actinopterygii), and nearly all of them belong to the Neopterygii (modern ray-fins). The oldest unequivocal neopterygian fossils are known from the Early Triassic. They appear during a time when global fish faunas consisted of mostly cosmopolitan taxa, and contemporary bony fishes belonged mainly to non-neopterygian (“paleopterygian”) lineages. In the Middle Triassic (Pelsonian substage and later), less than 10 myrs (million years) after the Permian-Triassic boundary mass extinction event (PTBME), neopterygians were already species-rich and trophically diverse, and bony fish faunas were more regionally differentiated compared to the Early Triassic. Still little is known about the early evolution of neopterygians leading up to this first diversity peak. A major factor limiting our understanding of this “Triassic revolution” is an interval marked by a very poor fossil record, overlapping with the Spathian (late Olenekian, Early Triassic), Aegean (Early Anisian, Middle Triassic), and Bithynian (early Middle Anisian) substages. Here, I review the fossil record of Early and Middle Triassic marine bony fishes (Actinistia and Actinopterygii) at the substage-level in order to evaluate the impact of this hiatus–named herein the Spathian–Bithynian gap (SBG)–on our understanding of their diversification after the largest mass extinction event of the past. I propose three hypotheses: 1) the SSBE hypothesis, suggesting that most of the Middle Triassic diversity appeared in the aftermath of the Smithian-Spathian boundary extinction (SSBE; ∼2 myrs after the PTBME), 2) the Pelsonian explosion hypothesis, which states that most of the Middle Triassic ichthyodiversity is the result of a radiation event in the Pelsonian, and 3) the gradual replacement hypothesis, i.e. that the faunal turnover during the SBG was steady and bony fishes were not affected by extinction events subsequent to the PTBME. Based on current knowledge, hypothesis three is favored herein, but further studies are necessary to test alternative hypotheses. In light of the SBG, claims of a protracted diversification of bony fishes after the PTBME should be treated with caution.

scholarly journals Human activity is altering the world’s zoogeographical regions

2018 ◽  
Author(s):  
Rubén Bernardo-Madrid ◽  
Joaquín Calatayud ◽  
Manuela González-Suarez ◽  
Martin Rosvall ◽  
Pablo M. Lucas ◽  
...  
Keyword(s):  
Species Composition ◽  
Human Activity ◽  
Human Activities ◽  
Mass Extinction ◽  
New World ◽  
Spatial Organization ◽  
Species Introductions ◽  
The Earth ◽  
Extinction Events ◽  
Mass Extinction Events

AbstractHuman activity leading to both species introductions and extinctions is widely known to influence diversity patterns on local and regional scales. Yet, it is largely unknown whether the intensity of this activity is enough to affect the configuration of biodiversity at broader levels of spatial organization. Zoogeographical regions, or zooregions, are surfaces of the Earth defined by characteristic pools of species, which reflect ecological, historical, and evolutionary processes acting over millions of years. Consequently, it is widely assumed that zooregions are robust and unlikely to change on a human timescale. Here, however, we show that human-mediated introductions and extinctions can indeed reconfigure the currently recognized zooregions of amphibians, mammals, and birds. In particular, introductions homogenize the African and Eurasian zooregions in mammals; reshape boundaries with the reallocation of Oceania to the New World zooregion in amphibians; and divide bird zooregions by increasing biotic heterogeneity. Furthermore, the combined effect of amphibian introductions and extinctions has the potential to divide two zooregions largely representing the Old and the New World. Interestingly, the robustness of zooregions against changes in species composition may largely explain such zoogeographical changes. Altogether, our results demonstrate that human activities can erode the higher-level organization of biodiversity formed over millions of years. Comparable reconfigurations have previously been detectable in Earth’s history only after glaciations and mass extinction events, highlighting the profound and far-reaching impact of ongoing human activity and the need to protect the uniqueness of biotic assemblages from the effects of future species introductions and extinctions.

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