Ma(th)ssX Webinars

Abstract:

Theory regarding the causation of mass extinctions is in need of systematization. Every mass extinction has both an ultimate cause, i.e., the trigger that leads to various climato-environmental changes, and one or more proximate cause(s), i.e., the specific climato-environmental changes that result in elevated biotic mortality. With regard to ultimate causation, strong cases can be made that bolide (i.e., meteor) impacts, large igneous province (LIP) eruptions, and bioevolutionary events have each triggered one or more of the Phanerozoic Big Five mass extinctions, and that tectono-oceanic changes have triggered some second-order extinction events. With regard to proximate mechanisms, most extinctions are related to either carbon-release or carbon-burial processes, the former being associated with climatic warming, ocean acidification, reduced marine productivity, and lower carbonate d13C values, and the latter with climatic cooling, increased marine productivity, and higher carbonate d13C values. In this context, mass extinction causation can be usefully classified using a matrix of ultimate and proximate factors. 

Short bio of the speaker:

Thomas Algeo (Professor, University of Cincinnati; Visiting Professor, China University of Geosciences-Wuhan) completed his Ph.D. at the University of Michigan in 1989 and worked at an oil company before joining the faculty of the University of Cincinnati in 1991. He has specialized in the development of elemental proxies for paleoenvironmental analysis, laying the foundation for the modern approach to reconstruction of redox, salinity, and productivity conditions, as well as other environmental parameters such as watermass restriction, in paleoenvironmental systems. He has studied all of the Big Five mass extinctions and is the author of a leading theory for the Late Devonian extinctions, linking them to the evolution of vascular land plants. His research has included many aspects of paleoclimatology.

For more details about the speaker, please visit Thomas Algeo’s webpage.

The recorded webinar is here.

Abstract:

Mass extinctions are natural experiments on the short- and long-term consequences of pushing biotas past breaking points, often with lasting effects on the structure and function of biodiversity. General properties of mass extinctions—exceptionally severe, taxonomically broad, global losses of taxa – are starting to come into focus through comparisons among different currencies of biodiversity, including morphological, functional, and phylogenetic diversity. Ongoing improvements in the taxonomic and stratigraphic resolution of these events for multiple clades will sharpen tests for selectivity and help to isolate hitchhiking effects, where organismal traits are carried by differential survival or extinction of taxa owing to other organismal or higher-level attributes, such as geographic range size. It is not just the extinction filter that deserves attention, as the longer-term impact of extinctions derives in part from their ensuing rebounds. (The term “recovery” is a misnomer, as the biota does not return to its pre-extinction state in any of the currencies mentioned above.) In a macroevolutionary model system, we find that despite losing ~60% of genera and ~20% of family-level diversity, marine bivalves lost only ~5% of their functional diversity in the end-Cretaceous extinction, a result inconsistent with stochastic loss, and in striking contrast to the parallel drop in today’s oceans of taxonomic and functional diversity with latitude. The mass extinction evened out the distribution of genera among functional groups; diversification through the Cenozoic restored the unevenness of that distribution, but it shuffled the richnesses of functional groups relative to the pre-extinction fauna, albeit without shifting low-diversity or novel groups into higher ranks, implying long-term diversity limitations to certain functional groups, despite opportunities presented by a disrupted ecosystem. New clades and functions can arise during rebounds, but the ecological landscape is dominated by surviving clades, even 66 Myr after the extinction, emphasizing the importance of preserving existing functional diversity and their constituent clades today.

Short bio of the speaker:

David Jablonski (Professor, University of Chicago) is a paleontologist who studies macroevolution, which takes place above the species level and encompasses large-scale patterns of evolution, mass extinction, diversification and the origin of evolutionary breakthroughs. His research emphasizes the integration of data from living and fossil organisms to study the origins and the fates of lineages and adaptations. He is a research associate of the Field Museum in Chicago and a former honorary research fellow of the Natural History Museum in London. A member of the National Academy of Sciences, Prof. Jablonski also is a fellow of the American Academy of Arts and Sciences and of the Paleontological Society and a was the recipient of 2017 Paleontological Society Medal.

For more details about the speaker, please visit David Jablonski’s webpage.

The recorded webinar is here.

Abstract:

Most of the geophysical and geodynamical processes are scaling – therefore they are scale free, and exhibit qualitatively the same kind of variability across many orders of magnitude. Temperature (climate, the geomorphology, volume of volcanic eruptions, as well as the magnitude of earthquakes all of them are scaling. Therefore, based on the first principles, since principal external drivers of evolution are scaling we should expect similar symmetry of dynamics to be inherited in diversity dynamics, which if true can give significant insights on the expected evolutionary change at all time scales. The empirical Haar fluctuation analysis of the Phanerozoic marine animal biodiversity based on Paleobiology Database and the Sepkoski datasets shows the presence of negative scaling in the temporal distribution of origination and extinction rates. This pattern suggests increasing biotic regulation of extinction and origination rates with increasing time scales. On the other hand the diversity shows a crossover of power laws. At short time scales up to tens of Ma biodiversity shows positive scaling (increasing divergence), and at the longest time scales greater than 40 Ma, it shows the negative scaling or convergence of diversity to some long-term values. This mixed power law pattern of biodiversity change in the marine biosphere is explained as a result of competition of destabilizing external forcing (e.g. climate) and the self-stabilizing biotic interactions.

Short bio of the speaker:

Andrej Spiridonov is a Professor of paleontology and geology at Vilnius University, Lithuania. His work is dedicated to the understanding of evolutionary patterns and the ontology of evolutionary processes as a function of space and time scales in all kinds of systems. Most of his empirical works were concentrated on the empirical studies of the early to middle Paleozoic oceanic extinction events. His works lead to discovery and recognition of scaling and crossover phenomena in Phanerozoic extinction, origination and biodiversity phenomena, which lead to the quantitatively explicit delimitation of dominions of the Court Jester (random geological/geophysical/astrophysical forces) and the Red Queen (biotic self-regulating interactions) in controlling diversity at the global level. He develops, and applies quantitative techniques (e.g. recurrence quantification analysis) in dynamical characterization of paleoecological and macroevolutionary dynamics.

For more details about the speaker, please visit Andrej Spiridonov's webpage.

The recorded webinar is here.

Abstract:

Much research on the current biodiversity crisis has focused on the rate of modern extinctions compared to that known from the fossil record. Here we compare modern extinctions and Phanerozoic extinctions with respect to their age selectivity. We evaluate age selectivity using logistic regression to quantify the relationship between extinction risk and genus age. For modern groups, we estimate extinction risk using assessments of threatened species from the International Union for Conservation of Nature (IUCN) Red List. We limit our analysis to genera with both a fossil record as well as substantial evaluation by the IUCN. For fossil groups, we compiled data from the Paleobiology Database supplemented with the Sepkoski Compendium. We confirm earlier findings that for fossil groups, older genera (i.e., those having older origination times) are more likely to survive during background extinctions, but this relationship largely disappears during mass extinction events. For modern groups, we find little relationship between extinction risk and genus age for multiple taxa at the class and phylum levels. Thus, modern extinctions differ from what has been observed in Phanerozoic background intervals, but are instead consistent with dynamics observed in the Big Five mass extinctions. 

Short bio of the speaker:

Steve Wang is a Professor of Statistics at Swarthmore College. His research centers on developing statistical methods to study paleobiology, evolution, and extinction, with a particular focus on mass extinctions, macroevolution, and the Signor-Lipps effect, which addresses the incompleteness of the fossil record. He creates methods to test for sudden extinctions and estimates their timing and duration, while also placing confidence intervals on the stratigraphic ranges of taxa. He also explores large-scale questions in the history of life using statistical analysis and paleontological databases. His research includes investigating whether modern extinctions resemble historical background or mass extinctions and studying the reliability of observed extinction rates as indicators of their causes. 

For more details about the speaker, please visit Steve Wang's webpage.

The recorded webinar is here.

Abstract:

Mass extinctions mark the major turning points in life’s history and vary in intensity from near complete catastrophes, such as that at the end of the Permian 252 million years ago, to more minor crises that begin to blur into background levels of extinction. Although the end-Cretaceous event is the most famous example, it is probably unique in being associated with a giant meteorite impact. For all the other crises (particularly those of the past 300 million years) the common factor is the contemporaneous eruption of giant fields of basalt lava that accumulate to form large igneous provinces (LIPs). Even the end-Cretaceous extinction coincides with the Deccan LIP of western India thus providing an alternative cause for the dinosaur’s extinction, and fostering one of the greatest scientific debates of the past 40 years. Despite the clear link between LIPs and mass extinction there is a major problem in that there are many more LIPs than there are extinction events. This raises a lot of questions: do the eruptions have to be a certain volume? Or does the eruption rate have to exceed a certain threshold? Or do the eruptions have to be in a specific location? Maybe LIPs aren’t the key and it’s something else? We don’t know. We are still a long way from understanding such questions which lie at the heart of how our Earth’s system works.

Short bio of the speaker:

Paul Wignall is a Professor of Palaeoenvironments at the University of Leeds.  Prof. Wignall obtained an undergraduate degree in Geology from the University of Oxford and then completed a PhD in Palaeoecology at the University of Birmingham.  Prof. Wignall is well known for his research on extinction in the fossil record, particularly the Permian-Triassic mass extinction. He has published extensively on the importance of oceanic anoxia and high temperatures as kill mechanisms during this event. 

For more details about the speaker, please visit Paul Wignall’s webpage.

The recorded webinar is here.

Abstract:

Tipping points occur when change in a system becomes self-sustaining once forced beyond a threshold, leading to long-lasting shifts in system state. Many potential tipping points have been identified in the Earth’s climate system that could be at risk with ongoing warming, with data from past climate change forming key evidence. In this talk I will discuss recent assessments of future climate tipping points and evidence for their involvement in past climate change and extinction events, such as during the Eocene–Oligocene Transition, the Palaeocene-Eocene Thermal Maximum, Ocean Anoxic Events, and Snowball Earth episodes.

Short bio of the speaker:

Dr David Armstrong McKay is a Research Impact Fellow at the University of Exeter’s Global Systems Institute and an Associated Researcher at Stockholm Resilience Centre, working on understanding and enhancing Earth system and socio-ecological resilience. He completed his PhD on Earth system modelling of palaeoclimate disruptions at the National Oceanography Centre Southampton, followed by postdocs at the University of Southampton and Stockholm Resilience Centre. His research topics cover climate feedbacks and tipping points, dynamics and indicators of ecological resilience, and the sustainability of local to global food systems. Recent projects include leading the assessment of Earth system tipping points for the Global Tipping Points Report and helping to estimate safe and just Earth system boundaries for climate change and nutrient pollution for the Earth Commission.

For more details about the speaker, please visit David McKay’s webpage.

The recorded webinar is here.

Abstract:

Palaeontology shows us that many billions of species that once existed are now extinct, and their natural extinctions enabled new species to inherit the Earth. We identify mass extinctions during which 50–95% of species were killed off, and yet life always recovered. In fact, some of the great diversifications in the history of life were triggered by the opportunities afforded by mass extinctions. So, extinction in the context of modern life, especially the needless slaughter of species by human action or carelessness, is inexcusable. Who does not mourn the loss of the Polynesian tree snail or the dodo? Palaeontologists of course work on longer time scales and can see how extinction events have released the potential of new groups to show their evolutionary mettle. This is one of the wonders of exploring the geological record but should not allow us to think we can hasten the extinction of any modern species.

Short bio of the speaker:

Michael James Benton OBE FRS FRSE  is a British palaeontologist, and professor of vertebrate palaeontology in the School of Earth Sciences at the University of Bristol. He obtained his PhD degree in 1981 from Newcastle University. Benton's research investigates palaeobiology, palaeontology, and macroevolution. His research interests include (but not limited to) diversification of life, quality of the fossil record, mass extinctions, Triassic ecosystem evolution, and the origin of the dinosaurs. He has made fundamental contributions to understanding the history of life, particularly concerning how biodiversity changes through time. Benton has published more than 400 research papers, several research monographs and several palaeontology textbooks. 

For more details about the speaker, please visit Michael Benton’s webpage.

The recorded webinar is here.

Abstract:

During the last 500 million years, the evolution of complex life on Earth has been frequently punctuated by geologically brief episodes of severe biodiversity loss. In my lecture, I will give a broad overview of these mass extinction events in Earth’s history, in particular focussing on the relevance of the research topic, potential causes of past extinctions, open questions, and potential directions of future research. I will argue that mathematical modelling is important for improving our understanding of extinction events – and particularly to link past extinctions to the current biodiversity crisis.

Short bio of the speaker:

Georg Feulner is Deputy Head of the Department Earth System Analysis at the Potsdam Institute for Climate Impact Research (PIK, Germany) where he leads working groups on climate model development and Earth’s climate history. Georg studied physics at the University of Cambridge (UK) and University of Munich (LMU, Germany) where he also obtained his PhD, and teaches at the University of Potsdam (Germany). Georg's research focuses on climate modelling, deep-time paleoclimatology (in particular the climate on early Earth, Snowball Earth episodes, past greenhouse climates and climate changes during mass-extinction events) as well as present and future climate change.

For more details about the speaker, please visit Georg Feulner’s webpage.

The recorded webinar is here.