Shifts in sexual dimorphism across a mass extinction in ostracods: implications for sexual selection as a factor in extinction risk

Sexual selection often favours investment in expensive sexual traits that help individuals compete for mates. In a rapidly changing environment, however, allocation of resources to traits related to reproduction at the expense of those related to survival may elevate extinction risk. Empirical testing of this hypothesis in the fossil record, where extinction can be directly documented, is largely lacking. The rich fossil record of cytheroid ostracods offers a unique study system in this context: the male shell is systematically more elongate than that of females, and thus the sexes can be distinguished, even in fossils. Using mixture models to identify sex clusters from size and shape variables derived from the digitized valve outlines of adult ostracods, we estimated sexual dimorphism in ostracod species before and after the Cretaceous/Palaeogene mass extinction in the United States Coastal Plain. Across this boundary, we document a substantial shift in sexual dimorphism, driven largely by a pronounced decline in the taxa with dimorphism indicating both very high and very low male investment. The shift away from high male investment, which arises largely from evolutionary changes within genera that persist through the extinction, parallels extinction selectivity previously documented during the Late Cretaceous under a background extinction regime. Our results suggest that sexual selection and the allocation of resources towards survival versus reproduction may be an important factor for species extinction during both background and mass extinctions.

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Diversification events and the effects of mass extinctions on Crocodyliformes evolutionary history

Royal Society Open Science ◽

10.1098/rsos.140385 ◽

2015 ◽

Vol 2 (5) ◽

pp. 140385 ◽

Cited By ~ 43

Author(s):

Mario Bronzati ◽

Felipe C. Montefeltro ◽

Max C. Langer

Keyword(s):

Mass Extinction ◽

Fossil Record ◽

Evolutionary History ◽

Continuous Process ◽

Mass Extinctions ◽

Terrestrial Habitats ◽

History Of ◽

The Rich ◽

A Minor ◽

Diversification Event

The rich fossil record of Crocodyliformes shows a much greater diversity in the past than today in terms of morphological disparity and occupation of niches. We conducted topology-based analyses seeking diversification shifts along the evolutionary history of the group. Our results support previous studies, indicating an initial radiation of the group following the Triassic/Jurassic mass extinction, here assumed to be related to the diversification of terrestrial protosuchians, marine thalattosuchians and semi-aquatic lineages within Neosuchia. During the Cretaceous, notosuchians embodied a second diversification event in terrestrial habitats and eusuchian lineages started diversifying before the end of the Mesozoic. Our results also support previous arguments for a minor impact of the Cretaceous/Palaeogene mass extinction on the evolutionary history of the group. This argument is not only based on the information from the fossil record, which shows basal groups surviving the mass extinction and the decline of other Mesozoic lineages before the event, but also by the diversification event encompassing only the alligatoroids in the earliest period after the extinction. Our results also indicate that, instead of a continuous process through time, Crocodyliformes diversification was patchy, with events restricted to specific subgroups in particular environments and time intervals.

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Within- and among-genus components of size evolution during mass extinction, recovery, and background intervals: a case study of Late Permian through Late Triassic foraminifera

Paleobiology ◽

10.1666/11040.1 ◽

2012 ◽

Vol 38 (4) ◽

pp. 627-643 ◽

Cited By ~ 26

Author(s):

Brianna L. Rego ◽

Steve C. Wang ◽

Demir Altiner ◽

Jonathan L. Payne

Keyword(s):

Mass Extinction ◽

Extinction Risk ◽

Maximum Size ◽

Size Reduction ◽

Late Triassic ◽

Mass Extinctions ◽

Late Permian ◽

Biotic Recovery ◽

Size Evolution ◽

Selective Extinction

One of the best-recognized patterns in the evolution of organismal size is the tendency for mean and maximum size within a clade to decrease following a major extinction event and to increase during the subsequent recovery interval. Because larger organisms are typically thought to be at higher extinction risk than their smaller relatives, it has commonly been assumed that size reduction mostly reflects the selective extinction of larger species. However, to our knowledge the relative importance of within- and among-lineage processes in driving overall trends in body size has never been compared quantitatively. In this study, we use a global, specimen-level database of foraminifera to study size evolution from the Late Permian through Late Triassic. We explicitly decompose size evolution into within- and among-genus components. We find that size reduction following the end-Permian mass extinction was driven more by size reduction within surviving species and genera than by the selective extinction of larger taxa. Similarly, we find that increase in mean size across taxa during Early Triassic biotic recovery was a product primarily of size increase within survivors and the extinction of unusually small taxa, rather than the origination of new, larger taxa. During background intervals we find no strong or consistent tendency for extinction, origination, or within-lineage change to move the overall size distribution toward larger or smaller sizes. Thus, size stasis during background intervals appears to result from small and inconsistent effects of within- and among-lineage processes rather than from large but offsetting effects of within- and among-taxon components. These observations are compatible with existing data for other taxa and extinction events, implying that mass extinctions do not influence size evolution by simply selecting against larger organisms. Instead, they appear to create conditions favorable to smaller organisms.

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Extinction from a paleontological perspective

European Review ◽

10.1017/s1062798700000582 ◽

1993 ◽

Vol 1 (3) ◽

pp. 207-216 ◽

Cited By ~ 5

Author(s):

David M. Raup

Keyword(s):

Mass Extinction ◽

Fossil Record ◽

Mass Extinctions ◽

Evolutionary Time ◽

Widespread Species ◽

Chance Coincidence ◽

Independent Events

Extinction of widespread species is common in evolutionary time (millions of years) but rare in ecological time (hundreds or thousands of years). In the fossil record, there appears to be a smooth continuum between background and mass extinction; and the clustering of extinctions at mass extinctions cannot be explained by the chance coincidence of independent events. Although some extinction is selective, much is apparently random in that survivors have no recognizable superiority over victims. Extinction certainly plays an important role in evolution, but whether it is constructive or destructive has not yet been determined.

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Climate Change and Mass Extinction Risk in an Endemic-Rich Late Devonian Fauna

10.21203/rs.3.rs-622347/v1 ◽

2021 ◽

Author(s):

Jaleigh Q. Pier ◽

Sarah K. Brisson ◽

J. Andrew Beard ◽

Michael T Hren ◽

Andrew M Bush

Keyword(s):

Climate Change ◽

Environmental Stress ◽

Mass Extinction ◽

Extinction Risk ◽

Foreland Basin ◽

Late Devonian ◽

Mass Extinctions ◽

Brachiopod Fauna ◽

The Many ◽

Geographically Isolated

Abstract The fossil record can illuminate factors that contribute to extinction risk during times of global environmental disturbance; for example, inferred thermal tolerance is an important predictor of extinction during several mass extinctions that corresponded with climate change1,2. Additionally, members of geographically isolated biotas may face higher risk because they have less opportunity to migrate to suitable climate refugia during environmental disturbances. Here, we investigate how these two types of risk intersect in the well-preserved brachiopod fauna of the Appalachian Foreland Basin during the two pulses of the Frasnian-Famennian mass extinction (Late Devonian, ~372 Ma3,4). The selectivity of extinction supports climate change (cooling) as the primary kill mechanism in this fauna, with warm-adapted taxa going extinct preferentially. Overall, the extinction was mild relative to other regions, despite the many endemic species. However, taxa that were vulnerable to climate change went extinct more rapidly, during the first extinction pulse, such that the second pulse was insignificant. These results suggest that vulnerable taxa in geographically isolated biotas face heightened extinction risk at the initiation of environmental stress, but that other regions may “catch up” if environmental stress repeats or intensifies.

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Synchronology, taxonomy and reality

Philosophical Transactions of the Royal Society of London Series B Biological Sciences ◽

10.1098/rstb.1989.0088 ◽

1989 ◽

Vol 325 (1228) ◽

pp. 263-277 ◽

Cited By ~ 5

Keyword(s):

Mass Extinction ◽

Fossil Record ◽

Secondary Data ◽

Primary Data ◽

Mass Extinctions

Geochronometry is only of limited help in establishing the timing of evolutionary events. Biostratigraphy and the establishment of a global standard stratigraphic scale are essential. These must be handled sensibly. Suggested periodicity of extinctions is dismissed. So called ‘mass extinctions’ are assessed by reference to the Ordovician-Silurian, Frasnian-Famennian and Cretaceous-Tertiary examples. Too ready use of the term ‘mass extinction’ tends to over-dramatize the patterns truly obtainable from the fossil record. It is easier to play with secondary data than to collect primary data.

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Confidence intervals for the duration of a mass extinction

Paleobiology ◽

10.1666/11016.1 ◽

2012 ◽

Vol 38 (2) ◽

pp. 265-277 ◽

Cited By ~ 11

Author(s):

Steve C. Wang ◽

Aaron E. Zimmerman ◽

Brendan S. McVeigh ◽

Philip J. Everson ◽

Heidi Wong

Keyword(s):

Confidence Interval ◽

Confidence Intervals ◽

Late Cretaceous ◽

Mass Extinction ◽

Fossil Record ◽

Mass Extinctions ◽

Late Permian ◽

Stratigraphic Section ◽

Stratigraphic Thickness ◽

Seymour Island

A key question in studies of mass extinctions is whether the extinction was a sudden or gradual event. This question may be addressed by examining the locations of fossil occurrences in a stratigraphic section. However, the fossil record can be consistent with both sudden and gradual extinctions. Rather than being limited to rejecting or not rejecting a particular scenario, ideally we should estimate therangeof extinction scenarios that is consistent with the fossil record. In other words, rather than testing the simplified distinction of “sudden versus gradual,” we should be asking, “How gradual?”In this paper we answer the question “How gradual could the extinction have been?” by developing a confidence interval for the duration of a mass extinction. We define the duration of the extinction as the time or stratigraphic thickness between the first and last taxon to go extinct, which we denote by Δ. For example, we would like to be able to say with 90% confidence that the extinction took place over a duration of 0.3 to 1.1 million years, or 24 to 57 meters of stratigraphic thickness. Our method does not deny the possibility of a truly simultaneous extinction; rather, in this framework, a simultaneous extinction is one whose value of Δ is equal to zero years or meters.We present an algorithm to derive such estimates and show that it produces valid confidence intervals. We illustrate its use with data from Late Permian ostracodes from Meishan, China, and Late Cretaceous ammonites from Seymour Island, Antarctica.

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Accelerated mass extinction in an isolated biota during Late Devonian climate changes

Scientific Reports ◽

10.1038/s41598-021-03510-6 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Jaleigh Q. Pier ◽

Sarah K. Brisson ◽

J. Andrew Beard ◽

Michael T. Hren ◽

Andrew M. Bush

Keyword(s):

Climate Change ◽

Environmental Stress ◽

Mass Extinction ◽

Extinction Risk ◽

Foreland Basin ◽

Late Devonian ◽

Mass Extinctions ◽

Brachiopod Fauna ◽

The Many ◽

Geographically Isolated

AbstractThe fossil record can illuminate factors that contribute to extinction risk during times of global environmental disturbance; for example, inferred thermal tolerance was an important predictor of extinction during several mass extinctions that corresponded with climate change. Additionally, members of geographically isolated biotas may face higher risk because they have less opportunity to migrate to suitable climate refugia during environmental disturbances. Here, we investigate how different types of risk intersect in the well-preserved brachiopod fauna of the Appalachian Foreland Basin during the two pulses of the Frasnian–Famennian mass extinction (Late Devonian, ~ 372 Ma). The selectivity of extinction is consistent with climate change (cooling) as a primary kill mechanism in this fauna. Overall, the extinction was mild relative to other regions, despite the many endemic species. However, vulnerable taxa went extinct more rapidly, during the first extinction pulse, such that the second pulse was insignificant. These results suggest that vulnerable taxa in geographically isolated biotas face heightened extinction risk at the initiation of environmental stress, but that taxa in other regions may eventually see elevated extinction risk if environmental stress repeats or intensifies.

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Are Insects Heading Toward Their First Mass Extinction? Distinguishing Turnover From Crises in Their Fossil Record

Annals of the Entomological Society of America ◽

10.1093/aesa/saaa042 ◽

2020 ◽

Author(s):

Sandra R Schachat ◽

Conrad C Labandeira

Keyword(s):

Mass Extinction ◽

Fossil Record ◽

Taxonomic Diversity ◽

Insect Diversity ◽

Mass Extinctions ◽

Sudden Loss ◽

Faunal Turnover ◽

Sixth Mass Extinction ◽

Extinction Event ◽

Permian Extinction

Abstract Time and again, over hundreds of millions of years, environmental disturbances have caused mass extinctions of animals ranging from reptiles to corals. The anthropogenic loss of species diversity happening now is often discussed as the ‘sixth mass extinction’ in light of the ‘Big Five’ mass extinctions in the fossil record. But insects, whose taxonomic diversity now appears to be threatened by human activity, have a unique extinction history. Prehistoric losses of insect diversity at the levels of order and family appear to have been driven by competition among insect lineages, with biotic replacement ensuring minimal net losses in taxonomic diversity. The end-Permian extinction, the ‘mother of mass extinctions’ in the seas, was more of a faunal turnover than a mass extinction for insects. Insects’ current biotic crisis has been measured in terms of the loss of abundance and biomass (rather than the loss of species, genera, or families) and these are essentially impossible to measure in the fossil record. However, should the ongoing loss of insect abundance and biomass cause the demise of many insect families, the current extinction event may well be the first sudden loss of higher-level insect diversity in our planet’s history. This is not insects’ sixth mass extinction—in fact, it may become their first.

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Numerical experiments with model monophyletic and paraphyletic taxa

Paleobiology ◽

10.1017/s0094837300015852 ◽

1993 ◽

Vol 19 (2) ◽

pp. 168-184 ◽

Cited By ~ 76

Author(s):

J. John Sepkoski ◽

David C. Kendrick

Keyword(s):

Monte Carlo ◽

Monte Carlo Simulations ◽

Mass Extinction ◽

Fossil Record ◽

Numerical Experiments ◽

Mass Extinctions ◽

Diversity Patterns ◽

Extinction Rates ◽

Low Levels

The problem of how accurately paraphyletic taxa versus monophyletic (i.e., holophyletic) groups (clades) capture underlying species patterns of diversity and extinction is explored with Monte Carlo simulations. Phylogenies are modeled as stochastic trees. Paraphyletic taxa are defined in an arbitrary manner by randomly choosing progenitors and clustering all descendants not belonging to other taxa. These taxa are then examined to determine which are clades, and the remaining paraphyletic groups are dissected to discover monophyletic subgroups. Comparisons of diversity patterns and extinction rates between modeled taxa and lineages indicate that paraphyletic groups can adequately capture lineage information under a variety of conditions of diversification and mass extinction. This suggests that these groups constitute more than mere “taxonomic noise” in this context. But, strictly monophyletic groups perform somewhat better, especially with regard to mass extinctions. However, when low levels of paleontologic sampling are simulated, the veracity of clades deteriorates, especially with respect to diversity, and modeled paraphyletic taxa often capture more information about underlying lineages. Thus, for studies of diversity and taxic evolution in the fossil record, traditional paleontologic genera and families need not be rejected in favor of cladistically-defined taxa.

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Machine learning (decision tree analysis) identifies ecological selectivity patterns across the end-Permian mass extinction

10.1101/2020.10.09.332999 ◽

2020 ◽

Author(s):

William J. Foster ◽

Georgy Ayzel ◽

Terry T. Isson ◽

Maria Mutti ◽

Martin Aberhan

Keyword(s):

Machine Learning ◽

Decision Tree ◽

Mass Extinction ◽

Extinction Risk ◽

Machine Learning Algorithms ◽

Stationary Mode ◽

Mass Extinctions ◽

Tree Algorithms ◽

Extinction Selectivity ◽

Permian Mass Extinction

AbstractDecision tree algorithms are rarely utilized in paleontological research, and here we show that machine learning algorithms can be used to identify determinants of extinction as well as predict extinction risk. This application of decision tree algorithms is important because the ecological selectivity of mass extinctions can reveal critical information on organismic traits as key determinants of extinction and hence the causes of extinction. To understand which factors led to the mass extinction of life during an extreme global warming event, we quantified the ecological selectivity of marine extinctions in the well-studied South China region during the end-Permian mass extinction using the categorized gradient boosting algorithm. We find that extinction selectivity varies between different groups of organisms and that a synergy of multiple environmental stressors best explains the overall end-Permian extinction selectivity pattern. Extinction risk was greater for genera that were limited to deep-water habitats, had a stationary mode of life, possessed a siliceous skeleton or, less critically, had calcitic skeletons. These selective losses directly link the extinction to the environmental effects of rapid injections of carbon dioxide into the ocean-atmosphere system, specifically the combined effects of expanded oxygen minimum zones, rapid warming, and ocean acidification.

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