1
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Brocklehurst N. The decline and fall of the mammalian stem. PeerJ 2024; 12:e17004. [PMID: 38436024 PMCID: PMC10906263 DOI: 10.7717/peerj.17004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Accepted: 02/05/2024] [Indexed: 03/05/2024] Open
Abstract
The mammalian crown originated during the Mesozoic and subsequently radiated into the substantial array of forms now extant. However, for about 100 million years before the crown's origin, a diverse array of stem mammalian lineages dominated terrestrial ecosystems. Several of these stem lineages overlapped temporally and geographically with the crown mammals during the Mesozoic, but by the end of the Cretaceous crown mammals make up the overwhelming majority of the fossil record. The progress of this transition between ecosystems dominated by stem mammals and those dominated by crown mammals is not entirely clear, in part due to a distinct separation of analyses and datasets. Analyses of macroevolutionary patterns tend to focus on either the Mammaliaformes or the non-mammalian cynodonts, with little overlap in the datasets, preventing direct comparison of the diversification trends. Here I analyse species richness and biogeography of Synapsida as a whole during the Mesozoic, allowing comparison of the patterns in the mammalian crown and stem within a single framework. The analysis reveals the decline of the stem mammals occurred in two discrete phases. The first phase occurred between the Triassic and Middle Jurassic, during which the stem mammals were more restricted in their geographic range than the crown mammals, although within localities their species richness remained at levels seen previously. The second phase was a decline in species richness, which occurred during the Lower Cretaceous. The results show the decline of stem mammals, including tritylodontids and several mammaliaform groups, was not tied to a specific event, nor a gradual decline, but was instead a multiphase transition.
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Affiliation(s)
- Neil Brocklehurst
- Department of Earth Sciences, University of Cambridge, Cambridge, United Kingdom
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2
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Schnetz L, Butler RJ, Coates MI, Sansom IJ. The skeletal completeness of the Palaeozoic chondrichthyan fossil record. ROYAL SOCIETY OPEN SCIENCE 2024; 11:231451. [PMID: 38298400 PMCID: PMC10827434 DOI: 10.1098/rsos.231451] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Figures] [Subscribe] [Scholar Register] [Received: 09/27/2023] [Accepted: 01/08/2024] [Indexed: 02/02/2024]
Abstract
Chondrichthyes (sharks, rays, ratfish and their extinct relatives) originated and diversified in the Palaeozoic but are rarely preserved as articulated or partly articulated remains because of their predominantly cartilaginous endoskeletons. Consequently, their evolutionary history is perceived to be documented predominantly by isolated teeth, scales and fin spines. Here, we aim to capture and analyse the quality of the Palaeozoic chondrichthyan fossil record by using a variation of the skeletal completeness metric, which calculates how complete the skeletons of individuals are compared to estimates of their original entirety. Notably, chondrichthyan completeness is significantly lower than any published vertebrate group: low throughout the Silurian and Permian but peaking in the Devonian and Carboniferous. Scores increase to a range similar to pelycosaurs and parareptiles only when taxa identified solely from isolated teeth, scales and spines are excluded. We argue that environmental influences probably played an important role in chondrichthyan completeness. Sea level significantly negatively correlates with chondrichthyan completeness records and resembles patterns already evident in records of ichthyosaurs, plesiosaurs and sauropodomorphs. Such observed variations in completeness highlight the impact of different sampling biases on the chondrichthyan fossil record and the need to acknowledge these when inferring patterns of chondrichthyan macroevolution.
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Affiliation(s)
- Lisa Schnetz
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
| | - Richard J. Butler
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
| | - Michael I. Coates
- Department of Organismal Biology and Anatomy, University of Chicago, Chicago, IL 60637-1508, USA
| | - Ivan J. Sansom
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
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3
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Pie MR, Divieso R, Caron FS. Clade density and the evolution of diversity-dependent diversification. Nat Commun 2023; 14:4576. [PMID: 37516766 PMCID: PMC10387094 DOI: 10.1038/s41467-023-39629-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Accepted: 06/16/2023] [Indexed: 07/31/2023] Open
Abstract
The assumption of an ecological limit to the number of species in a given region is frequently invoked in evolutionary studies, yet its empirical basis is remarkably meager. We explore this assumption by integrating data on geographical distributions and phylogenetic relationships of nearly six thousand terrestrial vertebrate species. In particular, we test whether sympatry with closely-related species leads to decreasing speciation rates. We introduce the concept of clade density, which is the sum of the areas of overlap between a given species and other members of its higher taxon, weighted by their phylogenetic distance. Our results showed that, regardless of the chosen taxon and uncertainty in the phylogenetic relationships between the studied species, there is no significant relationship between clade density and speciation rate. We argue that the mechanistic foundation of diversity-dependent diversification is fragile, and that a better understanding of the mechanisms driving regional species pools is sorely needed.
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Affiliation(s)
- Marcio R Pie
- Biology Department, Edge Hill University, Ormskirk, Lancashire, UK.
| | - Raquel Divieso
- Departamento de Zoologia, Universidade Federal do Paraná, Curitiba, Paraná, Brazil
| | - Fernanda S Caron
- Departamento de Zoologia, Universidade Federal do Paraná, Curitiba, Paraná, Brazil
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4
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Henderson S, Dunne EM, Fasey SA, Giles S. The early diversification of ray-finned fishes (Actinopterygii): hypotheses, challenges and future prospects. Biol Rev Camb Philos Soc 2023; 98:284-315. [PMID: 36192821 PMCID: PMC10091770 DOI: 10.1111/brv.12907] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Revised: 09/12/2022] [Accepted: 09/14/2022] [Indexed: 01/12/2023]
Abstract
Actinopterygii makes up half of living vertebrate diversity, and study of fossil members during their Palaeozoic rise to dominance has a long history of descriptive work. Although research interest into Palaeozoic actinopterygians has increased in recent years, broader patterns of diversity and diversity dynamics remain critically understudied. Past studies have investigated macroevolutionary trends in Palaeozoic actinopterygians in a piecemeal fashion, variably using existing compendia of vertebrates or literature-based searches. Here, we present a comprehensive occurrence-based dataset of actinopterygians spanning the whole of the Palaeozoic. We use this to produce the first through-Palaeozoic trends in genus and species counts for Actinopterygii. Diversity through time generally tracks metrics for sampling, while major taxonomic problems pervading the Palaeozoic actinopterygian record obscure diversity trends. Many described species are concentrated in several particularly problematic 'waste-basket' genera, hiding considerable morphological and taxonomic diversity. This taxonomic confusion also feeds into a limited understanding of phylogenetic relationships. A heavy sampling bias towards Europe and North America exists in both occurrence databases and available phylogenetic matrices, with other regions underrepresented despite yielding important data. Scrutiny of the extent to which spatial biases influence the actinopterygian record is lacking, as is research on other forms of bias. Low richness in some time periods may be linked to geological biases, while the effects of taphonomic biases on Palaeozoic actinopterygians have not yet been investigated. Efforts are already underway both to redescribe poorly defined taxa and to describe taxa from underrepresented regions, helping to address taxonomic issues and accuracy of occurrence data. New methods of sampling standardisation utilising up-to-date occurrence databases will be critical in teasing apart biological changes in diversity and those resulting from bias. Lastly, continued phylogenetic work will enable the use of phylogenetic comparative methods to elucidate the origins of actinopterygian biogeography and subsequent patterns of radiation throughout their rise to dominate aquatic faunas.
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Affiliation(s)
- Struan Henderson
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Emma M Dunne
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.,GeoZentrum Nordbayern, Friedrich-Alexander Universität Erlangen-Nürnberg (FAU), Loewenichstraße 28, Erlangen, 91054, Germany
| | - Sophie A Fasey
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Sam Giles
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.,Department of Earth Sciences, Natural History Museum, Cromwell Road, London, SW7 5BD, UK
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5
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Rabosky DL. Evolutionary time and species diversity in aquatic ecosystems worldwide. Biol Rev Camb Philos Soc 2022; 97:2090-2105. [PMID: 35899476 PMCID: PMC9796449 DOI: 10.1111/brv.12884] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Revised: 06/24/2022] [Accepted: 06/27/2022] [Indexed: 01/01/2023]
Abstract
The latitudinal diversity gradient (LDG) is frequently described as the most dramatic biodiversity pattern on Earth, yet ecologists and biogeographers have failed to reach consensus on its primary cause. A key problem in explaining the LDG involves collinearity between multiple factors that are predicted to affect species richness in the same direction. In terrestrial systems, energy input, geographic area, and evolutionary time for species accumulation tend to covary positively with species richness at the largest spatial scales, such that their individual contributions to the LDG are confounded in global analyses. I review three diversity patterns from marine and freshwater systems that break this collinearity and which may thus provide stronger tests of the influence of time on global richness gradients. Specifically, I contrast biodiversity patterns along oceanic depth gradients, in geologically young versus ancient lakes, and in the north versus south polar marine biomes. I focus primarily on fishes due to greater data availability but synthesize patterns for invertebrates where possible. I find that regional-to-global species richness generally declines with depth in the oceans, despite the great age and stability of the deep-sea biome. Geologically ancient lakes generally do not contain more species than young lakes, and the Antarctic marine biome is not appreciably more species rich than the much younger Arctic marine biome. However, endemism is consistently higher in older systems. Patterns for invertebrate groups are less clear than for fishes and reflect a critical need for primary biodiversity data. In summary, the available data suggest that species richness is either decoupled from or only weakly related to the amount of time for diversification. These results suggest that energy, productivity, or geographic area are the primary drivers of large-scale diversity gradients. To the extent that marine and terrestrial diversity gradients result from similar processes, these examples provide evidence against a primary role for evolutionary time as the cause of the LDG.
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Affiliation(s)
- Daniel L. Rabosky
- Museum of Zoology & Department of Ecology and Evolutionary BiologyUniversity of Michigan2032 Biological Sciences BuildingAnn ArborMI48109USA
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6
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Henderson S, Dunne EM, Giles S. Sampling biases obscure the early diversification of the largest living vertebrate group. Proc Biol Sci 2022; 289:20220916. [PMID: 36259213 PMCID: PMC9579763 DOI: 10.1098/rspb.2022.0916] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Extant ray-finned fishes (Actinopterygii) dominate marine and freshwater environments, yet spatio-temporal diversity dynamics following their origin in the Palaeozoic are poorly understood. Previous studies investigate face-value patterns of richness, with only qualitative assessment of biases acting on the Palaeozoic actinopterygian fossil record. Here, we investigate palaeogeographic trends, reconstruct local richness and apply richness estimation techniques to a recently assembled occurrence database for Palaeozoic ray-finned fishes. We identify substantial fossil record biases, such as geographical bias in sampling centred around Europe and North America. Similarly, estimates of diversity are skewed by extreme unevenness in the occurrence distributions, reflecting historical biases in sampling and taxonomic practices, to the extent that evenness has an overriding effect on diversity estimates. Other than a genuine rise in diversity in the Tournaisian following the end-Devonian mass extinction, diversity estimates for Palaeozoic actinopterygians appear to lack biological signal, are heavily biased and are highly dependent on sampling. Increased sampling of poorly represented regions and expanding sampling beyond the literature to include museum collection data will be critical in obtaining accurate estimates of Palaeozoic actinopterygian diversity. In conjunction, applying diversity estimation techniques to well-sampled regional subsets of the 'global' dataset may identify accurate local diversity trends.
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Affiliation(s)
- Struan Henderson
- School of Geography Earth and Environmental Sciences, University of Birmingham, Birmingham B15 2TT, UK
| | - Emma M Dunne
- School of Geography Earth and Environmental Sciences, University of Birmingham, Birmingham B15 2TT, UK.,GeoZentrum Nordbayern, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Sam Giles
- School of Geography Earth and Environmental Sciences, University of Birmingham, Birmingham B15 2TT, UK.,Department of Earth Sciences, Natural History Museum, Cromwell Road, London SW7 5BD, UK
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7
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Benson RBJ, Butler R, Close RA, Saupe E, Rabosky DL. Biodiversity across space and time in the fossil record. Curr Biol 2021; 31:R1225-R1236. [PMID: 34637736 DOI: 10.1016/j.cub.2021.07.071] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The fossil record is the primary source of information on how biodiversity has varied in deep time, providing unique insight on the long-term dynamics of diversification and their drivers. However, interpretations of fossil record diversity patterns have been much debated, with a traditional focus on global diversity through time. Problems arise because the fossil record is spatially and temporally patchy, so 'global' diversity estimates actually represent the summed diversity across a set of geographically and environmentally distinct regions that vary substantially in number and identity through time. Furthermore, a focus on global diversity lumps the signal of ecological drivers at local and regional scales with the signal of global-scale processes, including variation in the distribution of environments and in provincialism (the extent of subdivision into distinct biogeographic regions). These signals cannot be untangled by studying global diversity measures alone. These conceptual and empirical concerns necessitate a shift away from the study of 'biodiversity through time' and towards the study of 'biodiversity across time and space'. Spatially explicit investigations, including analyses of local- and regional-scale datasets, are central to achieving this and allow analysis of geographic scale, location and the environmental parameters directly experienced by organisms. So far, research in this area has revealed the stability of species richness variation among environments through time, and the potential climatic and Earth-system drivers of changing biodiversity. Ultimately, this research program promises to address key questions regarding the assembly of biodiversity, and the contributions of local-, regional- and global-scale processes to the diversification of life on Earth.
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Affiliation(s)
- Roger B J Benson
- Department of Earth Sciences, University of Oxford, South Parks Road, Oxford OX1 3AN, UK.
| | - Richard Butler
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
| | - Roger A Close
- Department of Earth Sciences, University of Oxford, South Parks Road, Oxford OX1 3AN, UK
| | - Erin Saupe
- Department of Earth Sciences, University of Oxford, South Parks Road, Oxford OX1 3AN, UK
| | - Daniel L Rabosky
- Museum of Zoology and Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI 48109, USA
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8
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Furness EN, Garwood RJ, Mannion PD, Sutton MD. Productivity, niche availability, species richness, and extinction risk: Untangling relationships using individual-based simulations. Ecol Evol 2021; 11:8923-8940. [PMID: 34257936 PMCID: PMC8258231 DOI: 10.1002/ece3.7730] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Accepted: 05/11/2021] [Indexed: 11/18/2022] Open
Abstract
It has often been suggested that the productivity of an ecosystem affects the number of species that it can support. Despite decades of study, the nature, extent, and underlying mechanisms of this relationship are unclear. One suggested mechanism is the "more individuals" hypothesis (MIH). This proposes that productivity controls the number of individuals in the ecosystem, and that more individuals can be divided into a greater number of species before their population size is sufficiently small for each to be at substantial risk of extinction. Here, we test this hypothesis using REvoSim: an individual-based eco-evolutionary system that simulates the evolution and speciation of populations over geological time, allowing phenomena occurring over timescales that cannot be easily observed in the real world to be evaluated. The individual-based nature of this system allows us to remove assumptions about the nature of speciation and extinction that previous models have had to make. Many of the predictions of the MIH are supported in our simulations: Rare species are more likely to undergo extinction than common species, and species richness scales with productivity. However, we also find support for relationships that contradict the predictions of the strict MIH: species population size scales with productivity, and species extinction risk is better predicted by relative than absolute species population size, apparently due to increased competition when total community abundance is higher. Furthermore, we show that the scaling of species richness with productivity depends upon the ability of species to partition niche space. Consequently, we suggest that the MIH is applicable only to ecosystems in which niche partitioning has not been halted by species saturation. Some hypotheses regarding patterns of biodiversity implicitly or explicitly overlook niche theory in favor of neutral explanations, as has historically been the case with the MIH. Our simulations demonstrate that niche theory exerts a control on the applicability of the MIH and thus needs to be accounted for in macroecology.
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Affiliation(s)
- Euan N. Furness
- Department of Earth Sciences and EngineeringImperial College LondonLondonUK
- Grantham InstituteImperial College LondonLondonUK
| | - Russell J. Garwood
- Department of Earth and Environmental SciencesUniversity of ManchesterManchesterUK
- Earth Sciences DepartmentNatural History MuseumLondonUK
| | | | - Mark D. Sutton
- Department of Earth Sciences and EngineeringImperial College LondonLondonUK
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9
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Jones LA, Dean CD, Mannion PD, Farnsworth A, Allison PA. Spatial sampling heterogeneity limits the detectability of deep time latitudinal biodiversity gradients. Proc Biol Sci 2021; 288:20202762. [PMID: 33622126 PMCID: PMC7934898 DOI: 10.1098/rspb.2020.2762] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
Abstract
The latitudinal biodiversity gradient (LBG), in which species richness decreases from tropical to polar regions, is a pervasive pattern of the modern biosphere. Although the distribution of fossil occurrences suggests this pattern has varied through deep time, the recognition of palaeobiogeographic patterns is hampered by geological and anthropogenic biases. In particular, spatial sampling heterogeneity has the capacity to impact upon the reconstruction of deep time LBGs. Here we use a simulation framework to test the detectability of three different types of LBG (flat, unimodal and bimodal) over the last 300 Myr. We show that heterogeneity in spatial sampling significantly impacts upon the detectability of genuine LBGs, with known biodiversity patterns regularly obscured after applying the spatial sampling window of fossil collections. Sampling-standardization aids the reconstruction of relative biodiversity gradients, but cannot account for artefactual absences introduced by geological and anthropogenic biases. Therefore, we argue that some previous studies might have failed to recover the ‘true’ LBG type owing to incomplete and heterogeneous sampling, particularly between 200 and 20 Ma. Furthermore, these issues also have the potential to bias global estimates of past biodiversity, as well as inhibit the recognition of extinction and radiation events.
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Affiliation(s)
- Lewis A Jones
- Department of Earth Science and Engineering, Imperial College London, South Kensington, London SW7 2AZ, UK
| | - Christopher D Dean
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
| | - Philip D Mannion
- Department of Earth Sciences, University College London, London WC1E 6BT, UK
| | | | - Peter A Allison
- Department of Earth Science and Engineering, Imperial College London, South Kensington, London SW7 2AZ, UK
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10
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Fraser D, Soul LC, Tóth AB, Balk MA, Eronen JT, Pineda-Munoz S, Shupinski AB, Villaseñor A, Barr WA, Behrensmeyer AK, Du A, Faith JT, Gotelli NJ, Graves GR, Jukar AM, Looy CV, Miller JH, Potts R, Lyons SK. Investigating Biotic Interactions in Deep Time. Trends Ecol Evol 2020; 36:61-75. [PMID: 33067015 DOI: 10.1016/j.tree.2020.09.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Revised: 08/31/2020] [Accepted: 09/02/2020] [Indexed: 11/16/2022]
Abstract
Recent renewed interest in using fossil data to understand how biotic interactions have shaped the evolution of life is challenging the widely held assumption that long-term climate changes are the primary drivers of biodiversity change. New approaches go beyond traditional richness and co-occurrence studies to explicitly model biotic interactions using data on fossil and modern biodiversity. Important developments in three primary areas of research include analysis of (i) macroevolutionary rates, (ii) the impacts of and recovery from extinction events, and (iii) how humans (Homo sapiens) affected interactions among non-human species. We present multiple lines of evidence for an important and measurable role of biotic interactions in shaping the evolution of communities and lineages on long timescales.
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Affiliation(s)
- Danielle Fraser
- Palaeobiology, Canadian Museum of Nature, Ottawa, ON, Canada; Biology and Earth Sciences, Carleton University, Ottawa, ON, Canada; Department of Paleobiology and Evolution of Terrestrial Ecosystems Program, Smithsonian Institution, National Museum of Natural History, Washington, DC , USA.
| | - Laura C Soul
- Department of Paleobiology and Evolution of Terrestrial Ecosystems Program, Smithsonian Institution, National Museum of Natural History, Washington, DC , USA
| | - Anikó B Tóth
- Centre for Ecosystem Science, School of Biological, Earth and Environmental Sciences, UNSW, Sydney, NSW, Australia
| | - Meghan A Balk
- Department of Paleobiology and Evolution of Terrestrial Ecosystems Program, Smithsonian Institution, National Museum of Natural History, Washington, DC , USA; BIO5 Institute, University of Arizona, Tucson, AZ, USA
| | - Jussi T Eronen
- Ecosystems and Environment Research Programme, Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland; Helsinki Institute of Sustainability Science, Faculty of Biological and Environmental Sciences, Ecosystems and Environment Research Programme, University of Helsinki, Helsinki, Finland; BIOS research Unit, Helsinki, Finland
| | - Silvia Pineda-Munoz
- Department of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA, USA
| | | | - Amelia Villaseñor
- Department of Anthropology, University of Arkansas, Fayetteville, AR, USA
| | - W Andrew Barr
- Department of Paleobiology and Evolution of Terrestrial Ecosystems Program, Smithsonian Institution, National Museum of Natural History, Washington, DC , USA; Center for the Advanced Study of Human Paleobiology, Department of Anthropology, The George Washington University, Washington, DC, USA
| | - Anna K Behrensmeyer
- Department of Paleobiology and Evolution of Terrestrial Ecosystems Program, Smithsonian Institution, National Museum of Natural History, Washington, DC , USA
| | - Andrew Du
- Department of Anthropology and Geography, Colorado State University, Fort Collins, CO, USA
| | - J Tyler Faith
- Natural History Museum of Utah, University of Utah, Salt Lake City, UT,USA; Department of Anthropology, University of Utah, Salt Lake City, UT, USA
| | | | - Gary R Graves
- Department of Vertebrate Zoology, National Museum of Natural History, Smithsonian Institution, Washington, DC, USA; Center for Macroecology, Evolution and Climate, GLOBE Institute, University of Copenhagen, Copenhagen, Denmark
| | - Advait M Jukar
- Department of Paleobiology and Evolution of Terrestrial Ecosystems Program, Smithsonian Institution, National Museum of Natural History, Washington, DC , USA
| | - Cindy V Looy
- Department of Integrative Biology, Museum of Paleontology, University and Jepson Herbaria, University of California-Berkeley, Berkeley, CA , USA
| | - Joshua H Miller
- Department of Geology, University of Cincinnati, Cincinnati, OH, USA
| | - Richard Potts
- Human Origins Program, National Museum of Natural History, Smithsonian Institution, Washington, DC , USA
| | - S Kathleen Lyons
- School of Biological Sciences, University of Nebraska-Lincoln, Lincoln, NE, USA
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11
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Abstract
AbstractHuman-mediated species invasion and climate change are leading to global extinctions and are predicted to result in the loss of important axes of phylogenetic and functional diversity. However, the long-term robustness of modern communities to invasion is unknown, given the limited timescales over which they can be studied. Using the fossil record of the Paleocene-Eocene thermal maximum (PETM; ∼56 Ma) in North America, we evaluate mammalian community-level response to a rapid global warming event (5°-8°C) and invasion by three Eurasian mammalian orders and by species undergoing northward range shifts. We assembled a database of 144 species body sizes and created a time-scaled composite phylogeny. We calculated the phylogenetic and functional diversity of all communities before, during, and after the PETM. Despite increases in the phylogenetic diversity of the regional species pool, phylogenetic diversity of mammalian communities remained relatively unchanged, a pattern that is invariant to the tree dating method, uncertainty in tree topology, and resolution. Similarly, body size dispersion and the degree of spatial taxonomic turnover of communities remained similar across the PETM. We suggest that invasion by new taxa had little impact on Paleocene-Eocene mammal communities because niches were not saturated. Our findings are consistent with the numerous studies of modern communities that record little change in community-scale richness despite turnover in taxonomic composition during invasion. What remains unknown is whether long-term robustness to biotic and abiotic perturbation are retained by modern communities given global anthropogenic landscape modification.
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12
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Close RA, Benson RBJ, Saupe EE, Clapham ME, Butler RJ. The spatial structure of Phanerozoic marine animal diversity. Science 2020; 368:420-424. [PMID: 32327597 DOI: 10.1126/science.aay8309] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Accepted: 03/09/2020] [Indexed: 11/02/2022]
Abstract
The global fossil record of marine animals has fueled long-standing debates about diversity change through time and the drivers of this change. However, the fossil record is not truly global. It varies considerably in geographic scope and in the sampling of environments among intervals of geological time. We account for this variability using a spatially explicit approach to quantify regional-scale diversity through the Phanerozoic. Among-region variation in diversity is comparable to variation through time, and much of this is explained by environmental factors, particularly the extent of reefs. By contrast, influential hypotheses of diversity change through time, including sustained long-term increases, have little explanatory power. Modeling the spatial structure of the fossil record transforms interpretations of Phanerozoic diversity patterns and their macroevolutionary explanations. This necessitates a refocus of deep-time diversification studies.
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Affiliation(s)
- R A Close
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK.
| | - R B J Benson
- Department of Earth Sciences, University of Oxford, Oxford OX1 3AN, UK
| | - E E Saupe
- Department of Earth Sciences, University of Oxford, Oxford OX1 3AN, UK
| | - M E Clapham
- Department of Earth and Planetary Sciences, UC Santa Cruz, Santa Cruz, CA 95064, USA
| | - R J Butler
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
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13
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Benevento GL, Benson RBJ, Friedman M. Patterns of mammalian jaw ecomorphological disparity during the Mesozoic/Cenozoic transition. Proc Biol Sci 2020; 286:20190347. [PMID: 31039714 PMCID: PMC6532522 DOI: 10.1098/rspb.2019.0347] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The radiation of mammals after the Cretaceous/Palaeogene (K/Pg) boundary was a major event in the evolution of terrestrial ecosystems. Multiple studies point to increases in maximum body size and body size disparity, but patterns of disparity for other traits are less clear owing to a focus on different indices and subclades. We conducted an inclusive comparison of jaw functional disparity from the Early Jurassic-latest Eocene, using six mechanically relevant mandibular ratios for 256 species representing all major groups. Jaw functional disparity across all mammals was low throughout much of the Mesozoic and remained low across the K/Pg boundary. Nevertheless, the K/Pg boundary was characterized by a pronounced pattern of turnover and replacement, entailing a substantial reduction of non-therian and stem-therian disparity, alongside a marked increase in that of therians. Total mammal disparity exceeded its Mesozoic maximum for the first time during the Eocene, when therian mammals began exploring previously unoccupied regions of function space. This delay in the rise of jaw functional disparity until the Eocene probably reflects the duration of evolutionary recovery after the K/Pg mass extinction event. This contrasts with the more rapid expansion of maximum body size, which occurred in the Palaeocene.
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Affiliation(s)
- Gemma Louise Benevento
- 1 Department of Earth Sciences, University of Oxford , Oxford OX1 3AN , UK.,2 School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston , Birmingham B15 2TT , UK
| | - Roger B J Benson
- 1 Department of Earth Sciences, University of Oxford , Oxford OX1 3AN , UK
| | - Matt Friedman
- 1 Department of Earth Sciences, University of Oxford , Oxford OX1 3AN , UK.,3 Museum of Paleontology and Department of Earth and Environmental Sciences, University of Michigan , 1105 N University Avenue, Ann Arbor, MI 48109 , USA
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14
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Close RA, Benson RBJ, Alroy J, Carrano MT, Cleary TJ, Dunne EM, Mannion PD, Uhen MD, Butler RJ. The apparent exponential radiation of Phanerozoic land vertebrates is an artefact of spatial sampling biases. Proc Biol Sci 2020; 287:20200372. [PMID: 32259471 PMCID: PMC7209054 DOI: 10.1098/rspb.2020.0372] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
There is no consensus about how terrestrial biodiversity was assembled through deep time, and in particular whether it has risen exponentially over the Phanerozoic. Using a database of 60 859 fossil occurrences, we show that the spatial extent of the worldwide terrestrial tetrapod fossil record itself expands exponentially through the Phanerozoic. Changes in spatial sampling explain up to 67% of the change in known fossil species counts, and these changes are decoupled from variation in habitable land area that existed through time. Spatial sampling therefore represents a real and profound sampling bias that cannot be explained as redundancy. To address this bias, we estimate terrestrial tetrapod diversity for palaeogeographical regions of approximately equal size. We find that regional-scale diversity was constrained over timespans of tens to hundreds of millions of years, and similar patterns are recovered for major subgroups, such as dinosaurs, mammals and squamates. Although the Cretaceous/Palaeogene mass extinction catalysed an abrupt two- to three-fold increase in regional diversity 66 million years ago, no further increases occurred, and recent levels of regional diversity do not exceed those of the Palaeogene. These results parallel those recovered in analyses of local community-level richness. Taken together, our findings strongly contradict past studies that suggested unbounded diversity increases at local and regional scales over the last 100 million years.
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Affiliation(s)
- Roger A Close
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
| | - Roger B J Benson
- Department of Earth Sciences, University of Oxford, Oxford OX1 3AN, UK
| | - John Alroy
- Department of Biological Sciences, Macquarie University, NSW 2109, Australia
| | - Matthew T Carrano
- Department of Paleobiology, National Museum of Natural History, Smithsonian Institution, Washington, DC 20013, USA
| | - Terri J Cleary
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
| | - Emma M Dunne
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
| | - Philip D Mannion
- Department of Earth Sciences, University College London, London WC1E 6BT, UK
| | - Mark D Uhen
- Department of Atmospheric, Oceanic, and Earth Sciences, George Mason University, Fairfax, VA 22030, USA
| | - Richard J Butler
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
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15
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De Celis A, Narváez I, Ortega F. Spatiotemporal palaeodiversity patterns of modern crocodiles (Crocodyliformes: Eusuchia). Zool J Linn Soc 2019. [DOI: 10.1093/zoolinnean/zlz038] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Abstract
Eusuchia is a crocodyliform clade with a rich and diverse fossil record dating back to the Mesozoic. There are several recent studies that analyse crocodyliform palaeodiversity over time, but none of them focuses exclusively on eusuchians. Thus, we estimated subsampled eusuchian palaeodiversity species dynamics over time not only at a global scale, but also by continents and main crocodylian lineages (Alligatoroidea, Crocodyloidea and Gavialoidea). These estimates reveal complex spatiotemporal palaeodiversity patterns, in which two maxima can be detected: the first during the Palaeocene and the second, which is also the biggest, in the middle-late Miocene. The Palaeocene shift is related to a North American alligatoroid diversification, whereas the middle–late Miocene maximum is related to a diversification of the three main Crocodylia lineages in Gondwanan land masses, but especially in South America. Additionally, a model-based study using generalized least squares was carried out to analyse the relationships between different abiotic and sampling proxies and eusuchian palaeodiversity. The results show that palaeotemperature is the most important factor amongst the analysed proxies, in accordance with previous studies. However, the results suggest that, along with palaeotemperature, other abiotic and/or biotic factors might also be driving eusuchian palaeodiversity dynamics.
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Affiliation(s)
- Ane De Celis
- Grupo de Biología Evolutiva, Departamento de Física Matemática y de Fluidos, Universidad Nacional de Educación a Distancia, Madrid, Spain
| | - Iván Narváez
- Grupo de Biología Evolutiva, Departamento de Física Matemática y de Fluidos, Universidad Nacional de Educación a Distancia, Madrid, Spain
| | - Francisco Ortega
- Grupo de Biología Evolutiva, Departamento de Física Matemática y de Fluidos, Universidad Nacional de Educación a Distancia, Madrid, Spain
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16
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O’Sullivan JD, Knell RJ, Rossberg AG. Metacommunity‐scale biodiversity regulation and the self‐organised emergence of macroecological patterns. Ecol Lett 2019; 22:1428-1438. [DOI: 10.1111/ele.13294] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Revised: 01/21/2019] [Accepted: 05/05/2019] [Indexed: 01/07/2023]
Affiliation(s)
- Jacob D. O’Sullivan
- School of Biological and Chemical Sciences Queen Mary University of London Mile End Road LondonE1 4NS UK
| | - Robert J. Knell
- School of Biological and Chemical Sciences Queen Mary University of London Mile End Road LondonE1 4NS UK
| | - Axel G. Rossberg
- School of Biological and Chemical Sciences Queen Mary University of London Mile End Road LondonE1 4NS UK
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17
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Grossnickle DM, Smith SM, Wilson GP. Untangling the Multiple Ecological Radiations of Early Mammals. Trends Ecol Evol 2019; 34:936-949. [PMID: 31229335 DOI: 10.1016/j.tree.2019.05.008] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Revised: 05/14/2019] [Accepted: 05/21/2019] [Indexed: 11/16/2022]
Abstract
The ecological diversification of early mammals is one of the most globally transformative events in Earth's history and the Cretaceous Terrestrial Revolution (KTR) and end-Cretaceous mass extinction are commonly hailed as catalysts. However, a confounding issue when examining this diversification is that it comprised nested radiations of mammalian subclades within the broader scope of mammalian evolution. In the past 200 million years, various independent groups experienced large-scale radiations, each involving ecological diversification from ancestral lineages of small insectivores; examples include Jurassic mammaliaforms, Late Cretaceous metatherians, and Cenozoic placentals. Here, we review these ecological radiations, highlighting the nuanced complexity of early mammal evolution, the value of ecomorphological fossil data, and the importance of phylogenetic context in macroevolutionary studies.
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Affiliation(s)
| | - Stephanie M Smith
- Integrative Research Center, Field Museum of Natural History, Chicago, IL, USA
| | - Gregory P Wilson
- Department of Biology, University of Washington, Seattle, WA, USA
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18
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Ivany LC, Czekanski-Moir J. Reined-in richness. Nat Ecol Evol 2019; 3:520-521. [PMID: 30911149 DOI: 10.1038/s41559-019-0863-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Linda C Ivany
- Department of Earth Sciences, Syracuse University, Syracuse, NY, USA.
| | - Jesse Czekanski-Moir
- Department of Environmental and Forest Biology, State University of New York College of Environmental Science and Forestry, Syracuse, NY, USA.
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19
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Diversity dynamics of Phanerozoic terrestrial tetrapods at the local-community scale. Nat Ecol Evol 2019; 3:590-597. [PMID: 30778186 DOI: 10.1038/s41559-019-0811-8] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Accepted: 01/14/2019] [Indexed: 11/09/2022]
Abstract
The fossil record provides one of the strongest tests of the hypothesis that diversity within local communities is constrained over geological timescales. Constraints to diversity are particularly controversial in modern terrestrial ecosystems, yet long-term patterns are poorly understood. Here we document patterns of local richness in Phanerozoic terrestrial tetrapods using a global data set comprising 145,332 taxon occurrences from 27,531 collections. We show that the local richness of non-flying terrestrial tetrapods has risen asymptotically since their initial colonization of land, increasing at most threefold over the last 300 million years. Statistical comparisons support phase-shift models, with most increases in local richness occurring: (1) during the colonization of land by vertebrates, concluding by the late Carboniferous; and (2) across the Cretaceous/Paleogene boundary. Individual groups, such as mammals, lepidosaurs and dinosaurs also experienced early increases followed by periods of stasis often lasting tens of millions of years. Mammal local richness abruptly tripled across the Cretaceous/Paleogene boundary, but did not increase over the next 66 million years. These patterns are consistent with the hypothesis that diversity is constrained at the local-community scale.
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20
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Dunne EM, Close RA, Button DJ, Brocklehurst N, Cashmore DD, Lloyd GT, Butler RJ. Diversity change during the rise of tetrapods and the impact of the 'Carboniferous rainforest collapse'. Proc Biol Sci 2019; 285:rspb.2017.2730. [PMID: 29436503 PMCID: PMC5829207 DOI: 10.1098/rspb.2017.2730] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2017] [Accepted: 01/18/2018] [Indexed: 11/12/2022] Open
Abstract
The Carboniferous and early Permian were critical intervals in the diversification of early four-limbed vertebrates (tetrapods), yet the major patterns of diversity and biogeography during this time remain unresolved. Previous estimates suggest that global tetrapod diversity rose continuously across this interval and that habitat fragmentation following the 'Carboniferous rainforest collapse' (CRC) drove increased endemism among communities. However, previous work failed to adequately account for spatial and temporal biases in sampling. Here, we reassess early tetrapod diversity and biogeography with a new global species-level dataset using sampling standardization and network biogeography methods. Our results support a tight relationship between observed richness and sampling, particularly during the Carboniferous. We found that subsampled species richness initially increased into the late Carboniferous, then decreased substantially across the Carboniferous/Permian boundary before slowly recovering in the early Permian. Our analysis of biogeography does not support the hypothesis that the CRC drove endemism; instead, we found evidence for increased cosmopolitanism in the early Permian. While a changing environment may have played a role in reducing diversity in the earliest Permian, our results suggest that the CRC was followed by increased global connectivity between communities, possibly reflecting both reduced barriers to dispersal and the diversification of amniotes.
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Affiliation(s)
- Emma M Dunne
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham B15 2TT, UK
| | - Roger A Close
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham B15 2TT, UK
| | - David J Button
- Paleontology Research Lab, North Carolina Museum of Natural Sciences, 11 W Jones St, Raleigh, NC 27607, USA.,Department of Biological Sciences, North Carolina State University, 3510 Thomas Hall, Campus Box 7614, Raleigh, NC 27695, USA
| | - Neil Brocklehurst
- Museum für Naturkunde, Leibniz-Institut für Evolutions- und Biodiversitätsforschung, Invalidenstraße 43, 10115 Berlin, Germany
| | - Daniel D Cashmore
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham B15 2TT, UK
| | - Graeme T Lloyd
- School of Earth and Environment, University of Leeds, Leeds LS2 9JT, UK
| | - Richard J Butler
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham B15 2TT, UK
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21
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Abstract
Dinosaurs were large-bodied land animals of the Mesozoic that gave rise to birds. They played a fundamental role in structuring Jurassic–Cretaceous ecosystems and had physiology, growth, and reproductive biology unlike those of extant animals. These features have made them targets of theoretical macroecology. Dinosaurs achieved substantial structural diversity, and their fossil record documents the evolutionary assembly of the avian body plan. Phylogeny-based research has allowed new insights into dinosaur macroevolution, including the adaptive landscape of their body size evolution, patterns of species diversification, and the origins of birds and bird-like traits. Nevertheless, much remains unknown due to incompleteness of the fossil record at both local and global scales. This presents major challenges at the frontier of paleobiological research regarding tests of macroecological hypotheses and the effects of dinosaur biology, ecology, and life history on their macroevolution.
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Affiliation(s)
- Roger B.J. Benson
- Department of Earth Sciences, University of Oxford, Oxford OX1 3AN, United Kingdom
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22
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Multi-scale interplays of biotic and abiotic drivers shape mammalian sub-continental diversity over millions of years. Sci Rep 2018; 8:13413. [PMID: 30194335 PMCID: PMC6128930 DOI: 10.1038/s41598-018-31699-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Accepted: 08/23/2018] [Indexed: 11/20/2022] Open
Abstract
The reconstruction of deep-time diversity trends is key to understanding current and future species richness. Studies that statistically evaluate potential factors affecting paleodiversity have focused on continental and global, clade-wide datasets, and thus we ignore how community species richness build-up to generate large-scale patterns over geological timescales. If community diversity is shaped by biotic interactions and continental and global diversities are governed by abiotic events, which are the modulators of diversity in subcontinental regions? To address this question, we model Iberian mammalian species richness over 13 million years (15 to 2 Ma) using exhaustive fossil evidence for subcontinental species’ ecomorphology, environmental context, and biogeographic affinities, and quantitatively evaluate their impact on species richness. We find that the diversity of large Iberian mammals has been limited over time, with species richness showing marked fluctuations, undergoing substantial depletions as diversity surpasses a critical limit where a significant part of the niches is unviable. The strength of such diversity-dependence has also shifted. Large faunal dispersals and environmental heterogeneity increased the system’s critical diversity limit. Diversity growth rate (net migration and diversification) also oscillated, mainly modulated by functional saturation, patchiness of canopy cover, and local temperature and aridity. Our study provides quantitative support for subcontinental species pools being complex and dynamic systems where diversity is perpetually imbalanced over geological timescales. Subcontinental diversity-dependence dynamics are mainly modulated by a multi-scale interplay of biotic and abiotic factors, with abiotic factors playing a more relevant role.
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23
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Close RA, Evers SW, Alroy J, Butler RJ. How should we estimate diversity in the fossil record? Testing richness estimators using sampling‐standardised discovery curves. Methods Ecol Evol 2018. [DOI: 10.1111/2041-210x.12987] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Roger A. Close
- School of Geography, Earth and Environmental SciencesUniversity of Birmingham Edgbaston Birmingham UK
| | | | - John Alroy
- Department of Biological SciencesFaculty of Science and EngineeringMacquarie University Sydney NSW Australia
| | - Richard J. Butler
- School of Geography, Earth and Environmental SciencesUniversity of Birmingham Edgbaston Birmingham UK
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24
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Cleary TJ, Benson RBJ, Evans SE, Barrett PM. Lepidosaurian diversity in the Mesozoic-Palaeogene: the potential roles of sampling biases and environmental drivers. ROYAL SOCIETY OPEN SCIENCE 2018; 5:171830. [PMID: 29657788 PMCID: PMC5882712 DOI: 10.1098/rsos.171830] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Accepted: 02/13/2018] [Indexed: 05/27/2023]
Abstract
Lepidosauria is a speciose clade with a long evolutionary history, but there have been few attempts to explore its taxon richness through time. Here we estimate patterns of terrestrial lepidosaur genus diversity for the Triassic-Palaeogene (252-23 Ma), and compare observed and sampling-corrected richness curves generated using Shareholder Quorum Subsampling and classical rarefaction. Generalized least-squares regression (GLS) is used to investigate the relationships between richness, sampling and environmental proxies. We found low levels of richness from the Triassic until the Late Cretaceous (except in the Kimmeridgian-Tithonian of Europe). High richness is recovered for the Late Cretaceous of North America, which declined across the K-Pg boundary but remained relatively high throughout the Palaeogene. Richness decreased following the Eocene-Oligocene Grande Coupure in North America and Europe, but remained high in North America and very high in Europe compared to the Late Cretaceous; elsewhere data are lacking. GLS analyses indicate that sampling biases (particularly, the number of fossil collections per interval) are the best explanation for long-term face-value genus richness trends. The lepidosaur fossil record presents many problems when attempting to reconstruct past diversity, with geographical sampling biases being of particular concern, especially in the Southern Hemisphere.
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Affiliation(s)
- Terri J. Cleary
- Department of Earth Sciences, Natural History Museum, Cromwell Road, London SW7 5BD, UK
- Department of Cell and Developmental Biology, University College London, Gower Street, London WC1E 6BT, UK
| | - Roger B. J. Benson
- Department of Earth Sciences, University of Oxford, South Parks Road, Oxford OX1 3AN, UK
| | - Susan E. Evans
- Department of Cell and Developmental Biology, University College London, Gower Street, London WC1E 6BT, UK
| | - Paul M. Barrett
- Department of Earth Sciences, Natural History Museum, Cromwell Road, London SW7 5BD, UK
- Department of Cell and Developmental Biology, University College London, Gower Street, London WC1E 6BT, UK
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25
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Tennant JP, Chiarenza AA, Baron M. How has our knowledge of dinosaur diversity through geologic time changed through research history? PeerJ 2018; 6:e4417. [PMID: 29479504 PMCID: PMC5822849 DOI: 10.7717/peerj.4417] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Accepted: 02/06/2018] [Indexed: 11/20/2022] Open
Abstract
Assessments of dinosaur macroevolution at any given time can be biased by the historical publication record. Recent studies have analysed patterns in dinosaur diversity that are based on secular variations in the numbers of published taxa. Many of these have employed a range of approaches that account for changes in the shape of the taxonomic abundance curve, which are largely dependent on databases compiled from the primary published literature. However, how these ‘corrected’ diversity patterns are influenced by the history of publication remains largely unknown. Here, we investigate the influence of publication history between 1991 and 2015 on our understanding of dinosaur evolution using raw diversity estimates and shareholder quorum subsampling for the three major subgroups: Ornithischia, Sauropodomorpha, and Theropoda. We find that, while sampling generally improves through time, there remain periods and regions in dinosaur evolutionary history where diversity estimates are highly volatile (e.g. the latest Jurassic of Europe, the mid-Cretaceous of North America, and the Late Cretaceous of South America). Our results show that historical changes in database compilation can often substantially influence our interpretations of dinosaur diversity. ‘Global’ estimates of diversity based on the fossil record are often also based on incomplete, and distinct regional signals, each subject to their own sampling history. Changes in the record of taxon abundance distribution, either through discovery of new taxa or addition of existing taxa to improve sampling evenness, are important in improving the reliability of our interpretations of dinosaur diversity. Furthermore, the number of occurrences and newly identified dinosaurs is still rapidly increasing through time, suggesting that it is entirely possible for much of what we know about dinosaurs at the present to change within the next 20 years.
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Affiliation(s)
- Jonathan P Tennant
- Department of Earth Science and Engineering, Imperial College London, London, UK
| | | | - Matthew Baron
- Department of Earth Science, University of Cambridge, Cambridge, UK.,Earth Sciences Department, Natural History Museum, London, UK
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26
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Vavrek MJ. The fragmentation of Pangaea and Mesozoic terrestrial vertebrate biodiversity. Biol Lett 2017; 12:rsbl.2016.0528. [PMID: 27651536 DOI: 10.1098/rsbl.2016.0528] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Accepted: 09/01/2016] [Indexed: 11/12/2022] Open
Abstract
During the Mesozoic (242-66 million years ago), terrestrial regions underwent a massive shift in their size, position and connectivity. At the beginning of the era, the land masses were joined into a single supercontinent called Pangaea. However, by the end of the Mesozoic, terrestrial regions had become highly fragmented, both owing to the drifting apart of the continental plates and the extremely high sea levels that flooded and divided many regions. How terrestrial biodiversity was affected by this fragmentation and large-scale flooding of the Earth's landmasses is uncertain. Based on a model using the species-area relationship (SAR), terrestrial vertebrate biodiversity would be expected to nearly double through the Mesozoic owing to continental fragmentation, despite a decrease of 24% in total terrestrial area. Previous studies of Mesozoic vertebrates have generally found increases in terrestrial diversity towards the end of the era, although these increases are often attributed to intrinsic or climatic factors. Instead, continental fragmentation over this time may largely explain any observed increase in terrestrial biodiversity. This study demonstrates the importance that non-intrinsic effects can have on the taxonomic success of a group, and the importance of geography to understanding past biodiversity.
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Affiliation(s)
- Matthew J Vavrek
- Department of Natural History, Royal Ontario Museum, 100 Queen's Park, Toronto, Ontario, Canada M5S 2C6
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27
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Herrera JP. Primate diversification inferred from phylogenies and fossils. Evolution 2017; 71:2845-2857. [PMID: 28913907 DOI: 10.1111/evo.13366] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Revised: 09/07/2017] [Accepted: 09/10/2017] [Indexed: 02/06/2023]
Abstract
Biodiversity arises from the balance between speciation and extinction. Fossils record the origins and disappearance of organisms, and the branching patterns of molecular phylogenies allow estimation of speciation and extinction rates, but the patterns of diversification are frequently incongruent between these two data sources. I tested two hypotheses about the diversification of primates based on ∼600 fossil species and 90% complete phylogenies of living species: (1) diversification rates increased through time; (2) a significant extinction event occurred in the Oligocene. Consistent with the first hypothesis, analyses of phylogenies supported increasing speciation rates and negligible extinction rates. In contrast, fossils showed that while speciation rates increased, speciation and extinction rates tended to be nearly equal, resulting in zero net diversification. Partially supporting the second hypothesis, the fossil data recorded a clear pattern of diversity decline in the Oligocene, although diversification rates were near zero. The phylogeny supported increased extinction ∼34 Ma, but also elevated extinction ∼10 Ma, coinciding with diversity declines in some fossil clades. The results demonstrated that estimates of speciation and extinction ignoring fossils are insufficient to infer diversification and information on extinct lineages should be incorporated into phylogenetic analyses.
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Affiliation(s)
- James P Herrera
- Richard Gilder Graduate School, Department of Mammalogy and Division of Vertebrate Paleontology, American Museum of Natural History, New York, New York 10024.,Department of Mammalogy, American Museum of Natural History, New York, New York 10024
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28
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Close RA, Benson RBJ, Upchurch P, Butler RJ. Controlling for the species-area effect supports constrained long-term Mesozoic terrestrial vertebrate diversification. Nat Commun 2017; 8:15381. [PMID: 28530240 PMCID: PMC5458146 DOI: 10.1038/ncomms15381] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Accepted: 03/23/2017] [Indexed: 11/13/2022] Open
Abstract
Variation in the geographic spread of fossil localities strongly biases inferences about the evolution of biodiversity, due to the ubiquitous scaling of species richness with area. This obscures answers to key questions, such as how tetrapods attained their tremendous extant diversity. Here, we address this problem by applying sampling standardization methods to spatial regions of equal size, within a global Mesozoic-early Palaeogene data set of non-flying terrestrial tetrapods. We recover no significant increase in species richness between the Late Triassic and the Cretaceous/Palaeogene (K/Pg) boundary, strongly supporting bounded diversification in Mesozoic tetrapods. An abrupt tripling of richness in the earliest Palaeogene suggests that this diversity equilibrium was reset following the K/Pg extinction. Spatial heterogeneity in sampling is among the most important biases of fossil data, but has often been overlooked. Our results indicate that controlling for variance in geographic spread in the fossil record significantly impacts inferred patterns of diversity through time. Species richness increases with area sampled, potentially confounding biodiversity patterns from the fossil record. Here, the authors standardize spatial sampling to control for this bias and show that terrestrial vertebrate diversification was bounded during the Mesozoic but that equilibria were reset following the K/Pg extinction.
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Affiliation(s)
- Roger A Close
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
| | - Roger B J Benson
- Department of Earth Sciences, University of Oxford, Oxford OX1 3AN, UK
| | - Paul Upchurch
- Department of Earth Sciences, University College London, London WC1E 6BT, UK
| | - Richard J Butler
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
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29
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Nicholson DB, Holroyd PA, Valdes P, Barrett PM. Latitudinal diversity gradients in Mesozoic non-marine turtles. ROYAL SOCIETY OPEN SCIENCE 2016; 3:160581. [PMID: 28018649 PMCID: PMC5180147 DOI: 10.1098/rsos.160581] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Accepted: 10/24/2016] [Indexed: 05/26/2023]
Abstract
The latitudinal biodiversity gradient (LBG)-the pattern of increasing taxonomic richness with decreasing latitude-is prevalent in the structure of the modern biota. However, some freshwater taxa show peak richness at mid-latitudes; for example, extant Testudines (turtles, terrapins and tortoises) exhibit their greatest diversity at 25° N, a pattern sometimes attributed to recent bursts of climatically mediated species diversification. Here, we test whether this pattern also characterizes the Mesozoic distribution of turtles, to determine whether it was established during either their initial diversification or as a more modern phenomenon. Using global occurrence data for non-marine testudinate genera, we find that subsampled richness peaks at palaeolatitudes of 15-30° N in the Jurassic, 30-45° N through the Cretaceous to the Campanian, and from 30° to 60° N in the Maastrichtian. The absence of a significant diversity peak in southern latitudes is consistent with results from climatic models and turtle niche modelling that demonstrate a dearth of suitable turtle habitat in Gondwana during the Jurassic and Late Cretaceous. Our analyses confirm that the modern testudinate LBG has a deep-time origin and further demonstrate that LBGs are not always expressed as a smooth, equator-to-pole distribution.
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Affiliation(s)
- David B. Nicholson
- Department of Earth Sciences, The Natural History Museum, Cromwell Road, London SW7 5BD, UK
| | - Patricia A. Holroyd
- Museum of Paleontology, University of California, 1101 Valley Life Sciences Building, Berkeley, CA 94720, USA
| | - Paul Valdes
- School of Geographical Sciences, University of Bristol, University Road, Bristol BS8 1SS, UK
| | - Paul M. Barrett
- Department of Earth Sciences, The Natural History Museum, Cromwell Road, London SW7 5BD, UK
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30
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Dinosaurs in decline tens of millions of years before their final extinction. Proc Natl Acad Sci U S A 2016; 113:5036-40. [PMID: 27092007 DOI: 10.1073/pnas.1521478113] [Citation(s) in RCA: 70] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Whether dinosaurs were in a long-term decline or whether they were reigning strong right up to their final disappearance at the Cretaceous-Paleogene (K-Pg) mass extinction event 66 Mya has been debated for decades with no clear resolution. The dispute has continued unresolved because of a lack of statistical rigor and appropriate evolutionary framework. Here, for the first time to our knowledge, we apply a Bayesian phylogenetic approach to model the evolutionary dynamics of speciation and extinction through time in Mesozoic dinosaurs, properly taking account of previously ignored statistical violations. We find overwhelming support for a long-term decline across all dinosaurs and within all three dinosaurian subclades (Ornithischia, Sauropodomorpha, and Theropoda), where speciation rate slowed down through time and was ultimately exceeded by extinction rate tens of millions of years before the K-Pg boundary. The only exceptions to this general pattern are the morphologically specialized herbivores, the Hadrosauriformes and Ceratopsidae, which show rapid species proliferations throughout the Late Cretaceous instead. Our results highlight that, despite some heterogeneity in speciation dynamics, dinosaurs showed a marked reduction in their ability to replace extinct species with new ones, making them vulnerable to extinction and unable to respond quickly to and recover from the final catastrophic event.
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Starrfelt J, Liow LH. How many dinosaur species were there? Fossil bias and true richness estimated using a Poisson sampling model. Philos Trans R Soc Lond B Biol Sci 2016; 371:20150219. [PMID: 26977060 PMCID: PMC4810813 DOI: 10.1098/rstb.2015.0219] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/09/2015] [Indexed: 11/12/2022] Open
Abstract
The fossil record is a rich source of information about biological diversity in the past. However, the fossil record is not only incomplete but has also inherent biases due to geological, physical, chemical and biological factors. Our knowledge of past life is also biased because of differences in academic and amateur interests and sampling efforts. As a result, not all individuals or species that lived in the past are equally likely to be discovered at any point in time or space. To reconstruct temporal dynamics of diversity using the fossil record, biased sampling must be explicitly taken into account. Here, we introduce an approach that uses the variation in the number of times each species is observed in the fossil record to estimate both sampling bias and true richness. We term our technique TRiPS (True Richness estimated using a Poisson Sampling model) and explore its robustness to violation of its assumptions via simulations. We then venture to estimate sampling bias and absolute species richness of dinosaurs in the geological stages of the Mesozoic. Using TRiPS, we estimate that 1936 (1543-2468) species of dinosaurs roamed the Earth during the Mesozoic. We also present improved estimates of species richness trajectories of the three major dinosaur clades: the sauropodomorphs, ornithischians and theropods, casting doubt on the Jurassic-Cretaceous extinction event and demonstrating that all dinosaur groups are subject to considerable sampling bias throughout the Mesozoic.
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Affiliation(s)
- Jostein Starrfelt
- Centre for Ecological and Evolutionary Synthesis, Department of Biosciences, University of Oslo, PO Box 1066 Blindern, 0316 Oslo, Norway
| | - Lee Hsiang Liow
- Centre for Ecological and Evolutionary Synthesis, Department of Biosciences, University of Oslo, PO Box 1066 Blindern, 0316 Oslo, Norway
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Near-Stasis in the Long-Term Diversification of Mesozoic Tetrapods. PLoS Biol 2016; 14:e1002359. [PMID: 26807777 PMCID: PMC4726655 DOI: 10.1371/journal.pbio.1002359] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Accepted: 12/15/2015] [Indexed: 11/21/2022] Open
Abstract
How did evolution generate the extraordinary diversity of vertebrates on land? Zero species are known prior to ~380 million years ago, and more than 30,000 are present today. An expansionist model suggests this was achieved by large and unbounded increases, leading to substantially greater diversity in the present than at any time in the geological past. This model contrasts starkly with empirical support for constrained diversification in marine animals, suggesting different macroevolutionary processes on land and in the sea. We quantify patterns of vertebrate standing diversity on land during the Mesozoic–early Paleogene interval, applying sample-standardization to a global fossil dataset containing 27,260 occurrences of 4,898 non-marine tetrapod species. Our results show a highly stable pattern of Mesozoic tetrapod diversity at regional and local levels, underpinned by a weakly positive, but near-zero, long-term net diversification rate over 190 million years. Species diversity of non-flying terrestrial tetrapods less than doubled over this interval, despite the origins of exceptionally diverse extant groups within mammals, squamates, amphibians, and dinosaurs. Therefore, although speciose groups of modern tetrapods have Mesozoic origins, rates of Mesozoic diversification inferred from the fossil record are slow compared to those inferred from molecular phylogenies. If high speciation rates did occur in the Mesozoic, then they seem to have been balanced by extinctions among older clades. An apparent 4-fold expansion of species richness after the Cretaceous/Paleogene (K/Pg) boundary deserves further examination in light of potential taxonomic biases, but is consistent with the hypothesis that global environmental disturbances such as mass extinction events can rapidly adjust limits to diversity by restructuring ecosystems, and suggests that the gradualistic evolutionary diversification of tetrapods was punctuated by brief but dramatic episodes of radiation. A large-scale examination of the fossil record reveals slow diversification rates in tetrapods across the 190-million-year Mesozoic era, followed by a possible rapid and abrupt 4-fold increase in species richness after the Cretaceous-Paleogene mass extinction event. Vertebrates invaded the land more than 360 million years ago. Since then, they diversified to more than 30,000 tetrapod species today, including birds, mammals, squamates, and amphibians. The fossil record provides our best window onto diversification across such long spans of time, but is unevenly sampled. Previous studies counted observed families of fossil tetrapods and supported an expansionist model, entailing large and unbounded diversity increases through time. We applied methods that correct for differences in sampling through time and space to a comprehensive species-level database of Mesozoic to early Cenozoic fossil tetrapods. We find strong evidence that tetrapod diversity increased during the Mesozoic, but that the long-term net rate of diversification was low; species richness only doubled or tripled over 190 million years. This is enigmatic because today’s high biodiversity could not have been realised at such a slow rate. Diversification rates must have been much higher during other intervals, or rapid diversification might have been concentrated during brief episodes such as the earliest Cenozoic. Patterns of diversification on geological timescales and their relationships to hypothesised drivers such as ecological opportunity and environmental volatility must receive renewed scrutiny if we are to understand how land vertebrates and other animals attained the high biodiversity seen today.
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