Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 132
Filtrar
Más filtros











Intervalo de año de publicación
1.
PeerJ ; 12: e17765, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-39148680

RESUMEN

Therocephalia are an important clade of non-mammalian therapsids that evolved a diverse array of morphotypes and body sizes throughout their evolutionary history. The postcranial anatomy of therocephalians has largely been overlooked, but remains important towards understanding aspects of their palaeobiology and phylogenetic relationships. Here, we provide the first postcranial description of the large akidnognathid eutherocephalian Moschorhinus kitchingi by examining multiple specimens from fossil collections in South Africa. We also compare the postcranial anatomy with previously described therocephalian postcranial material and provide an updated literature review to ensure a reliable foundation of comparison for future descriptive work. Moschorhinus shares all the postcranial features of eutherocephalians that differentiate them from early-diverging therocephalians, but is differentiated from other eutherocephalian taxa by aspects concerning the scapula, interclavicle, sternum, manus, and femur. The novel anatomical data from this contribution shows that Moschorhinus possessed a stocky bauplan with a particularly robust scapula, humerus, and femur. These attributes, coupled with the short and robust skull bearing enlarged conical canines imply that Moschorhinus was well equipped to grapple with and subdue prey items. Additionally, the combination of these attributes differ from those of similarly sized coeval gorgonopsians, which would have occupied a similar niche in late Permian ecosystems. Moreover, Moschorhinus was the only large carnivore known to have survived the Permo-Triassic mass extinction. Thus, the subtle but important postcranial differences may suggest a type of niche partitioning in the predator guild during the Permo-Triassic mass extinction interval.


Asunto(s)
Evolución Biológica , Fósiles , Animales , Sudáfrica , Filogenia , Cráneo/anatomía & histología , Dinosaurios/anatomía & histología , Dinosaurios/fisiología , Huesos/anatomía & histología
2.
Biol Lett ; 20(8): 20240265, 2024 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-39192833

RESUMEN

Last year, we published research using phylogenetic comparative methods (PCMs) to reveal no phylogenetic evidence for elevated lineage-level extinction rates in angiosperms across K-Pg (Thompson JB, Ramírez-Barahona S. 2023 No phylogenetic evidence for angiosperm mass extinction at the Cretaceous-Palaeogene (K-Pg) boundary. Biol. Lett. 19, 20230314. (doi:10.1098/rsbl.2023.0314)), results that are in step with the global angiosperm fossil record. In a critique of our paper (Hagen ER. 2024 A critique of Thompson and Ramírez-Barahona (2023) or: how I learned to stop worrying and love the fossil record. EcoEvoRxiv. (doi:10.32942/X2631W)), simulation work is presented to argue we erred in our methodological choices and interpretations, and that we should have deferred to fossil evidence. In our opinion, underlying this critique are poor methodological choices on simulations and philosophical problems surrounding the definition of a mass extinction event, which leads to incorrect interpretations of both the fossil record and PCMs. We further argue that deferring to one source of evidence in favour of the other shuts the door to important evolutionary and philosophical questions.


Asunto(s)
Extinción Biológica , Fósiles , Magnoliopsida , Filogenia , Evolución Biológica
3.
Biol Lett ; 20(8): 20240039, 2024 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-39192834

RESUMEN

A recent study published in Biology Letters by Thompson and Ramírez-Barahona (2023) argued that, according to analyses of diversification on two massive molecular phylogenies comprising thousands of species, there is no evidence that angiosperms (i.e. flowering plants) were affected by the Cretaceous-Paleogene mass extinction. Here, I critique these conclusions from both methodological and philosophical perspectives. I demonstrate that the methods used in their study possess statistical limitations that strongly reduce the power to detect a true mass extinction event using data similar to those analysed by Thompson and Ramírez-Barahona (2023). Additionally, I use their study as a springboard to examine the relationship between phylogenetic and fossil evidence in diversification studies.


Asunto(s)
Fósiles , Humanos , Evolución Biológica
4.
Proc Natl Acad Sci U S A ; 121(32): e2318860121, 2024 Aug 06.
Artículo en Inglés | MEDLINE | ID: mdl-39074280

RESUMEN

Elevated temperatures persisted for an anomalously protracted interval following pulsed volcanic carbon release associated with the end-Permian mass extinction, deviating from the expected timescale of climate recovery following a carbon injection event. Here, we present evidence for enhanced reverse weathering-a CO2 source-following the end-Permian mass extinction based on the lithium isotopic composition of marine shales and cherts. We find that the average lithium isotopic composition of Lower Triassic marine shales is significantly elevated relative to that of all other previously measured Phanerozoic marine shales. Notably, the record generated here conflicts with carbonate-based interpretations of the lithium isotopic composition of Early Triassic seawater, forcing a re-evaluation of the existing framework used to interpret lithium isotopes in sedimentary archives. Using a stochastic forward lithium cycle model, we demonstrate that elevated reverse weathering is required to reproduce the lithium isotopic values and trends observed in Lower Triassic marine shales and cherts. Collectively, this work provides direct geochemical evidence for enhanced reverse weathering in the aftermath of Earth's most severe mass extinction.

5.
Heliyon ; 10(10): e31226, 2024 May 30.
Artículo en Inglés | MEDLINE | ID: mdl-38799747

RESUMEN

Sea level fall is considered one of the significant factors leading to the end-Permian mass extinction (EPME). We studied the relative sea level changes in the Beifengjing and Shangsi sections, and the results indicate that a sea level fall occurred in the Upper Yangtze region during the Permian-Triassic transition. Considering that there is no significant change in fossil abundance in the strata following the two sea level falls observed in the Beifengjing section, we conclude that the reduction in shallow marine habitat for sea level fall solely was insufficient to cause the mass extinction. However, sea level fall did exacerbate the input of terrestrial debris into the ocean, leading to the deterioration of the marine environment. We propose that the combined adverse effects of volcanic eruptions, sea level falls, and other events exceeded the threshold for biological survival, ultimately resulting in the catastrophic EPME.

6.
Am Nat ; 203(6): 644-654, 2024 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-38781523

RESUMEN

AbstractWe live in a time of accelerated biological extinctions that has the potential to mirror past mass extinction events. However, the rarity of mass extinctions and the restructuring of diversity they cause complicate direct comparisons between the current extinction crisis and earlier events. Among animals, turtles (Testudinata) are one of few groups that have both a rich fossil record and sufficiently stable ecological and functional roles to enable meaningful comparisons between the end-Cretaceous mass extinction (∼66 Ma) and the ongoing wave of extinctions. Here we analyze the fossil record of the entire turtle clade and identify two peaks in extinction rates over their evolutionary history. The first coincides with the Cretaceous-Paleogene transition, reflecting patterns previously reported for other taxa. The second major extinction event started in the Pliocene and continues until now. This peak is detectable only for terrestrial turtles and started much earlier in Africa and Eurasia than elsewhere. On the basis of the timing, geography, and functional group of this extinction event, we postulate a link to co-occurring hominins rather than climate change as the cause. These results lend further support to the view that negative biodiversity impacts were already incurred by our ancestors and related lineages and demonstrate the severity of this continued impact through human activities.


Asunto(s)
Evolución Biológica , Extinción Biológica , Fósiles , Hominidae , Tortugas , Animales , Fósiles/anatomía & histología , Hominidae/anatomía & histología
7.
Sci Rep ; 14(1): 9946, 2024 Apr 30.
Artículo en Inglés | MEDLINE | ID: mdl-38688982

RESUMEN

This study investigates the mechanisms underlying the varied climate changes witnessed during mass extinctions in the Phanerozoic Eon. Climate shifts during mass extinctions have manifested as either predominant global cooling or predominant warming, yet the causes behind these occurrences remain unclear. We emphasize the significance of sedimentary rock temperature in comprehending these climate shifts. Our research reveals that low-temperature heating of sulfide leads to global cooling through the release of sulfur dioxide (SO2), while intermediate-temperature heating of hydrocarbons and carbonates releases substantial carbon dioxide (CO2), contributing to global warming. High-temperature heating additionally generates SO2 from sulfate, further contributing to global cooling. Different degrees of contact heating of the host rock can lead to different dominant volatile gas emissions, crucially driving either warming or cooling. Moreover, medium to high-temperature shock-heating resulting from asteroid impacts produces soot from hydrocarbons, also contributing to global cooling. Large-scale volcanic activity and asteroid impacts are both events that heat rocks, emitting the same gases and particles, causing climate changes. The findings elucidate the critical role of heating temperature and heating time in understanding major climate changes during mass extinctions.

8.
Biosystems ; 236: 105123, 2024 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-38244715

RESUMEN

In this paper we explore the relevance and integration of system theory and thermodynamics in terms of the Earth system. It is proposed that together, these fields explain the evolution, organization, functionality and directionality of life on Earth. We begin by summarizing historical and current thinking on the definition of life itself. We then investigate the evidence for a single unit of life. Given that any definition of life and its levels of organization are intertwined, we explore how the Earth system is structured and functions from an energetic perspective, by outlining relevant thermodynamic theory relating to molecular, metabolic, cellular, individual, population, species, ecosystem and biome organization. We next investigate the fundamental relationships between systems theory and thermodynamics in terms of the Earth system, examining the key characteristics of self-assembly, self-organization (including autonomy), emergence, non-linearity, feedback and sub-optimality. Finally, we examine the relevance of systems theory and thermodynamics with reference to two specific aspects: the tempo and directionality of evolution and the directional and predictable process of ecological succession. We discuss the importance of the entropic drive in understanding altruism, multicellularity, mutualistic and antagonistic relationships and how maximum entropy production theory may explain patterns thought to evidence the intermediate disturbance hypothesis.


Asunto(s)
Ecosistema , Teoría de Sistemas , Termodinámica , Entropía , Evolución Biológica , Ecología
9.
Biol Rev Camb Philos Soc ; 99(1): 110-130, 2024 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-37667585

RESUMEN

The end-Neoproterozoic transition marked a gradual but permanent shift between distinct configurations of Earth's biosphere. This interval witnessed the demise of the enigmatic Ediacaran Biota, ushering in the structured trophic webs and disparate animal body plans of Phanerozoic ecosystems. However, little consensus exists on the reality, drivers, and macroevolutionary implications of end-Neoproterozoic extinctions. Here we evaluate potential drivers of late-Neoproterozoic turnover by addressing recent findings on Ediacaran geochronology, the persistence of classical Ediacaran macrobionts into the Cambrian, and the existence of Ediacaran crown-group eumetazoans. Despite renewed interest in the possibility of Phanerozoic-style 'mass extinctions' in the latest Neoproterozoic, our synthesis of the available evidence does not support extinction models based on episodic geochemical triggers, nor does it validate simple ecological interpretations centred on direct competitive displacement. Instead, we argue that the protracted and indirect effects of early bilaterian innovations, including escalations in sediment engineering, predation, and the largely understudied impacts of reef-building, may best account for the temporal structure and possible selectivity of late-Neoproterozoic extinctions. We integrate these processes into a generalised model of early eumetazoan-dominated ecologies, charting the disruption of spatial and temporal isotropy on the Ediacaran benthos as a consequence of diversifying macrofaunal interactions. Given the nature of resource distribution in Ediacaran ecologies, the continuities among Ediacaran and Cambrian faunas, and the convergent origins of ecologically disruptive innovations among bilaterians we suggest that the rise of Phanerozoic-type biotas may have been unstoppable.


Asunto(s)
Evolución Biológica , Ecosistema , Animales , Fósiles , Biota , Extinción Biológica
10.
Proc Biol Sci ; 290(2012): 20232232, 2023 Dec 06.
Artículo en Inglés | MEDLINE | ID: mdl-38052241

RESUMEN

Mass extinctions have fundamentally altered the structure of the biosphere throughout Earth's history. The ecological severity of mass extinctions is well studied in marine ecosystems by categorizing marine taxa into functional groups based on 'ecospace' approaches, but the ecological response of terrestrial ecosystems to mass extinctions is less well understood due to the lack of a comparable methodology. Here, we present a new terrestrial ecospace framework that categorizes fauna into functional groups as defined by tiering, motility and feeding traits. We applied the new terrestrial and traditional marine ecospace analyses to data from the Paleobiology Database across the end-Triassic mass extinction-a time of catastrophic global warming-to compare changes between the marine and terrestrial biospheres. We found that terrestrial functional groups experienced higher extinction severity, that taxonomic and functional richness are more tightly coupled in the terrestrial, and that the terrestrial realm continued to experience high ecological dissimilarity in the wake of the extinction. Although signals of extinction severity and ecological turnover are sensitive to the quality of the terrestrial fossil record, our findings suggest greater ecological pressure from the end-Triassic mass extinction on terrestrial ecosystems than marine ecosystems, contributing to more prolonged terrestrial ecological flux.


Asunto(s)
Ecosistema , Extinción Biológica , Fósiles , Bases de Datos Factuales , Biodiversidad
11.
Biol Lett ; 19(9): 20230314, 2023 09.
Artículo en Inglés | MEDLINE | ID: mdl-37700701

RESUMEN

The Cretaceous-Palaeogene mass extinction event (K-Pg) witnessed upwards of 75% of animal species going extinct, most notably among these are the non-avian dinosaurs. A major question in macroevolution is whether this extinction event influenced the rise of flowering plants (angiosperms). The fossil record suggests that the K-Pg event had a strong regional impact on angiosperms with up to 75% species extinctions, but only had a minor impact on the extinction rates of major lineages (families and orders). Phylogenetic evidence for angiosperm extinction dynamics through time remains unexplored. By analysing two angiosperm mega-phylogenies containing approximately 32 000-73 000 extant species, here we show relatively constant extinction rates throughout geological time and no evidence for a mass extinction at the K-Pg boundary. Despite high species-level extinction observed in the fossil record, our results support the macroevolutionary resilience of angiosperms to the K-Pg mass extinction event via survival of higher lineages.


Asunto(s)
Dinosaurios , Magnoliopsida , Animales , Extinción Biológica , Filogenia , Fósiles
12.
Proc Natl Acad Sci U S A ; 120(39): e2306987120, 2023 09 26.
Artículo en Inglés | MEDLINE | ID: mdl-37722053

RESUMEN

Mass extinctions during the past 500 million y rapidly removed branches from the phylogenetic tree of life and required millions of years for evolution to generate functional replacements for the extinct (EX) organisms. Here we show, by examining 5,400 vertebrate genera (excluding fishes) comprising 34,600 species, that 73 genera became EX since 1500 AD. Beyond any doubt, the human-driven sixth mass extinction is more severe than previously assessed and is rapidly accelerating. The current generic extinction rates are 35 times higher than expected background rates prevailing in the last million years under the absence of human impacts. The genera lost in the last five centuries would have taken some 18,000 y to vanish in the absence of human beings. Current generic extinction rates will likely greatly accelerate in the next few decades due to drivers accompanying the growth and consumption of the human enterprise such as habitat destruction, illegal trade, and climate disruption. If all now-endangered genera were to vanish by 2,100, extinction rates would be 354 (average) or 511 (for mammals) times higher than background rates, meaning that genera lost in three centuries would have taken 106,000 and 153,000 y to become EX in the absence of humans. Such mutilation of the tree of life and the resulting loss of ecosystem services provided by biodiversity to humanity is a serious threat to the stability of civilization. Immediate political, economic, and social efforts of an unprecedented scale are essential if we are to prevent these extinctions and their societal impacts.


Asunto(s)
Ecosistema , Extinción Biológica , Animales , Humanos , Filogenia , Efectos Antropogénicos , Biodiversidad , Mamíferos
13.
Glob Chang Biol ; 29(20): 5775-5787, 2023 10.
Artículo en Inglés | MEDLINE | ID: mdl-37578114

RESUMEN

The world's primates have been severely impacted in diverse and profound ways by anthropogenic pressures. Here, we evaluate the impact of various infrastructures and human-modified landscapes on spatial patterns of primate species richness, at both global and regional scales. We overlaid the International Union for the Conservation of Nature (IUCN) range maps of 520 primate species and applied a global 100 km2 grid. We used structural equation modeling and simultaneous autoregressive models to evaluate direct and indirect effects of six human-altered landscapes variables (i.e., human footprint [HFP], croplands [CROP], road density [ROAD], pasture lands [PAST], protected areas [PAs], and Indigenous Peoples' lands [IPLs]) on global primate species richness, threatened and non-threatened species, as well as on species with decreasing and non-decreasing populations. Two-thirds of all primate species are classified as threatened (i.e., Critically Endangered, Endangered, and Vulnerable), with ~86% experiencing population declines, and ~84% impacted by domestic or international trade. We found that the expansion of PAST, HFP, CROP, and road infrastructure had the most direct negative effects on primate richness. In contrast, forested habitat within IPLs and PAs was positively associated in safeguarding primate species diversity globally, with an even stronger effect at the regional level. Our results show that IPLs and PAs play a critical role in primate species conservation, helping to prevent their extinction; in contrast, HFP growth and expansion has a dramatically negative effect on primate species worldwide. Our findings support predictions that the continued negative impact of anthropogenic pressures on natural habitats may lead to a significant decline in global primate species richness, and likely, species extirpations. We advocate for stronger national and international policy frameworks promoting alternative/sustainable livelihoods and reducing persistent anthropogenic pressures to help mitigate the extinction risk of the world's primate species.


Asunto(s)
Comercio , Conservación de los Recursos Naturales , Humanos , Animales , Internacionalidad , Primates , Ecosistema , Especies en Peligro de Extinción , Extinción Biológica , Biodiversidad
14.
Sci Total Environ ; 901: 166461, 2023 Nov 25.
Artículo en Inglés | MEDLINE | ID: mdl-37607630

RESUMEN

Aerosol-bound water, a ubiquitous and abundant component of atmospheric aerosols, has an impact on regional climate, visibility, human health, the hydrological cycle, and atmospheric chemistry. Yet, the intricate relationship between aerosol liquid water (ALWC) and chemical composition and relative humidity (RH) was not well understood. The present study explores ALWC derived from the ISORROPIA II model using real-time, high-resolution data of non-refractory submicron chemical species and meteorological parameters (temperature and RH) collected over the Indian Ocean as part of the ICARB (Integrated Campaign for Aerosols, Gases, and Radiation Budget)-2018 experiment. Results show that ALWC values over the South Eastern Arabian Sea (SEAS) were found to be higher by 4-6 times than those observed over the Equatorial Indian Ocean (EIO) due to a large decrease in aerosol loading from SEAS to EIO. ALWC peaked in the early morning hours (4:00-7:00), with greater values during the nighttime and lower values during the daytime across SEAS, which is comparable with RH variation. While the ratio of organics-to-SO42- mass fraction linearly decreased with increasing mass-based growth factors (MGFs) over EIO, such a scenario was not observed over SEAS. The latitudinal gradient of mass fraction of ALWC had shown a decrease towards EIO, consistent with organic fraction. The extinction coefficient of the dry mass of submicron particles is noticeably increased by 40 % by ALWC over SEAS and EIO. Moreover, ALWC could enhance the aerosol negative forcing by an average of 66 % (64 %) over SEAS (EIO) at the top of the atmosphere during the cruise period. These inferences imply that ALWC is the key factor in assessing the role of aerosols on atmospheric radiative forcing. Overall, the present study highlights the serious need to consider the ALWC in climate forcing simulations, particularly in moist tropical environments where their effect can be significant.

15.
Ecol Evol ; 13(8): e10403, 2023 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-37560179

RESUMEN

Biologists have long sought to quantify the number of species on Earth. Often missing from these efforts is the contribution of microorganisms, the smallest but most abundant form of life on the planet. Despite recent large-scale sampling efforts, estimates of global microbial diversity span many orders of magnitude. It is important to consider how speciation and extinction over the last 4 billion years constrain inventories of biodiversity. We parameterized macroevolutionary models based on birth-death processes that assume constant and universal speciation and extinction rates. The models reveal that richness beyond 1012 species is feasible and in agreement with empirical predictions. Additional simulations suggest that mass extinction events do not place hard limits on modern-day microbial diversity. Together, our study provides independent support for a massive global-scale microbiome while shedding light on the upper limits of life on Earth.

16.
Elife ; 122023 08 08.
Artículo en Inglés | MEDLINE | ID: mdl-37551884

RESUMEN

Sauropterygia was a taxonomically and ecomorphologically diverse clade of Mesozoic marine reptiles spanning the Early Triassic to the Late Cretaceous. Sauropterygians are traditionally divided into two groups representing two markedly different body plans - the short-necked, durophagous Placodontia and the long-necked Eosauropterygia - whereas Saurosphargidae, a small clade of armoured marine reptiles, is generally considered as the sauropterygian sister-group. However, the early evolutionary history of sauropterygians and their phylogenetic relationships with other groups within Diapsida are still incompletely understood. Here, we report a new saurosphargid from the Early Triassic (Olenekian) of South China - Prosaurosphargis yingzishanensis gen. et sp. nov. - representing the earliest known occurrence of the clade. An updated phylogenetic analysis focussing on the interrelationships among diapsid reptiles recovers saurosphargids as nested within sauropterygians, forming a clade with eosauropterygians to the exclusion of placodonts. Furthermore, a clade comprising Eusaurosphargis and Palatodonta is recovered as the sauropterygian sister-group within Sauropterygomorpha tax. nov. The phylogenetic position of several Early and Middle Triassic sauropterygians of previously uncertain phylogenetic affinity, such as Atopodentatus, Hanosaurus, Majiashanosaurus, and Corosaurus, is also clarified, elucidating the early evolutionary assembly of the sauropterygian body plan. Finally, our phylogenetic analysis supports the placement of Testudines and Archosauromorpha within Archelosauria, a result strongly corroborated by molecular data, but only recently recovered in a phylogenetic analysis using a morphology-only dataset. Our study provides evidence for the rapid diversification of sauropterygians in the aftermath of the Permo-Triassic mass extinction event and emphasises the importance of broad taxonomic sampling in reconstructing phylogenetic relationships among extinct taxa.


Around 252 million years ago, just before the start of a period of time known as the Triassic, over 90% of animals, plants and other species on Earth went extinct in what was the worst mass extinction event in the planet's history. It is thought to have happened because of an increase in volcanic eruptions that led to global warming, acid rain and other catastrophic changes in the environment. The loss of so many species caused ecosystems to restructure as the surviving species evolved to fill niches left by those that had gone extinct. On land, reptiles diversified to give rise to dinosaurs, the flying pterosaurs, and the ancestors of modern crocodiles, lizards, snakes and turtles. Some of these land-based animals evolved to live in water, resulting in many species of marine reptiles emerging during the Triassic period. This included the saurosphargids, a group of marine reptiles that lived in the Middle Triassic around 247­237 million years ago. They were 'armoured' with a shield made of broadened ribs superficially similar to that of turtles, and a covering of bony plates. However, it is unclear how the saurosphargids evolved and how closely they are related to other marine reptiles. Here, Wolniewicz et al. studied a new species of saurosphargid named Prosaurosphargis yingzishanensis that was found fossilized in a quarry in South China. The animal was around 1.5 metres long and had a chest shield and armoured plates like other saurosphargids. The characteristics of the rock surrounding the fossil suggest that this individual lived in the Early Triassic, several million years before other saurosphargid species. The team used a phylogenetic approach to infer the evolutionary relationships between P. yingzishanensis and numerous other land-based and marine reptiles based on over 220 anatomical characteristics of the animals. The resulting evolutionary tree indicated that the saurosphargids represented an early stage in the evolution of a larger group of marine reptiles known as the sauropterygians. The analysis also identified the closest land-based relatives of sauropterygians. These findings provide evidence that marine reptiles rapidly diversified in the aftermath of the mass extinction event 252 million years ago. Furthermore, they contribute to our understanding of how ecosystems recover after a major environmental crisis.


Asunto(s)
Evolución Biológica , Reptiles , Animales , Filogenia , Reptiles/anatomía & histología , Vertebrados , China , Fósiles
17.
Biol Rev Camb Philos Soc ; 98(5): 1732-1748, 2023 10.
Artículo en Inglés | MEDLINE | ID: mdl-37189305

RESUMEN

The global-scale decline of animal biodiversity ('defaunation') represents one of the most alarming consequences of human impacts on the planet. The quantification of this extinction crisis has traditionally relied on the use of IUCN Red List conservation categories assigned to each assessed species. This approach reveals that a quarter of the world's animal species are currently threatened with extinction, and ~1% have been declared extinct. However, extinctions are preceded by progressive population declines through time that leave demographic 'footprints' that can alert us about the trajectories of species towards extinction. Therefore, an exclusive focus on IUCN conservation categories, without consideration of dynamic population trends, may underestimate the true extent of the processes of ongoing extinctions across nature. In fact, emerging evidence (e.g. the Living Planet Report), reveals a widespread tendency for sustained demographic declines (an average 69% decline in population abundances) of species globally. Yet, animal species are not only declining. Many species worldwide exhibit stable populations, while others are even thriving. Here, using population trend data for >71,000 animal species spanning all five groups of vertebrates (mammals, birds, reptiles, amphibians and fishes) and insects, we provide a comprehensive global-scale assessment of the diversity of population trends across species undergoing not only declines, but also population stability and increases. We show a widespread global erosion of species, with 48% undergoing declines, while 49% and 3% of species currently remain stable or are increasing, respectively. Geographically, we reveal an intriguing pattern similar to that of threatened species, whereby declines tend to concentrate around tropical regions, whereas stability and increases show a tendency to expand towards temperate climates. Importantly, we find that for species currently classed by the IUCN Red List as 'non-threatened', 33% are declining. Critically, in contrast with previous mass extinction events, our assessment shows that the Anthropocene extinction crisis is undergoing a rapid biodiversity imbalance, with levels of declines (a symptom of extinction) greatly exceeding levels of increases (a symptom of ecological expansion and potentially of evolution) for all groups. Our study contributes a further signal indicating that global biodiversity is entering a mass extinction, with ecosystem heterogeneity and functioning, biodiversity persistence, and human well-being under increasing threat.


Asunto(s)
Conservación de los Recursos Naturales , Ecosistema , Animales , Humanos , Especies en Peligro de Extinción , Biodiversidad , Extinción Biológica , Mamíferos
18.
Curr Biol ; 33(11): 2283-2290.e3, 2023 06 05.
Artículo en Inglés | MEDLINE | ID: mdl-37220743

RESUMEN

Catastrophic ecosystem disruption in the late Permian period resulted in the greatest loss of biodiversity in Earth's history, the Permian-Triassic mass extinction (PTME).1 The dominant terrestrial vertebrates of the Permian (synapsids) suffered major losses at this time, leading to their replacement by reptiles in the Triassic.2 The dominant late Permian predatory synapsids, gorgonopsians, were completely extirpated by the PTME. The largest African gorgonopsians, the Rubidgeinae, have traditionally been assumed to go extinct at the Permo-Triassic boundary (PTB).3,4,5 However, this apparent persistence through the sustained extinction interval characterizing the continental PTME6 is at odds with ecological theory indicating that top predators have high extinction risk.7 Here, we report the youngest known large-bodied gorgonopsians, gigantic specimens from the PTB site of Nooitgedacht 68 in South Africa. These specimens are not rubidgeine, and instead are referable to Inostrancevia, a taxon previously thought to be a Russian endemic.8 Based on comprehensive review of the South African gorgonopsian record, we show that rubidgeines were early victims of ecosystem disruption preceding the PTME and were replaced as top predators by Laurasian immigrant inostranceviines. The reign of this latter group was short-lived, however; by the PTB, gorgonopsians were extinct, and a different group (therocephalians) became the largest synapsid predators, before themselves going extinct. The extinction and replacement of top predators in rapid succession at the clade level underlines the extreme degree of ecosystem instability in the latest Permian and earliest Triassic, a phenomenon that was likely global in extent.


Asunto(s)
Evolución Biológica , Ecosistema , Animales , Fósiles , Extinción Biológica , Vertebrados , Biodiversidad
19.
Heliyon ; 9(4): e15221, 2023 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-37095985

RESUMEN

An environmental-animal crisis is currently ongoing and is becoming increasingly severe due to human activity. However, the magnitude, timing, and processes related to this crisis are unclear. This paper clarifies the likely magnitude and timing of animal extinctions and changes in the contribution rates of select causes (global warming, pollution, deforestation, and two hypothetical nuclear conflicts) of animal extinctions during 2000-2300 CE. This paper demonstrates that an animal crisis marked by a 5-13% terrestrial tetrapod species loss and 2-6% marine animal species loss will occur in the next generation during 2060-2080 CE if humans do not engage in nuclear wars. These variations are due to magnitudes of pollution, deforestation, and global warming. The main causes of this crisis will change from pollution and deforestation to deforestation in 2030 under the low CO2 emission scenarios but will change from pollution and deforestation to deforestation in 2070 and then to deforestation and global warming after 2090 under the medium CO2 emissions. A nuclear conflict will increase animal species loss up to approximately 40-70% for terrestrial tetrapod species and 25-50% for marine animal species, including errors. Therefore, this study shows that the animal species conservation priority is to prevent nuclear war, reduce deforestation rates, decrease pollution, and limit global warming, in this order.

20.
R Soc Open Sci ; 10(3): 221507, 2023 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-36938535

RESUMEN

Many modern extinction drivers are shared with past mass extinction events, such as rapid climate warming, habitat loss, pollution and invasive species. This commonality presents a key question: can the extinction risk of species during past mass extinction events inform our predictions for a modern biodiversity crisis? To investigate if it is possible to establish which species were more likely to go extinct during mass extinctions, we applied a functional trait-based model of extinction risk using a machine learning algorithm to datasets of marine fossils for the end-Permian, end-Triassic and end-Cretaceous mass extinctions. Extinction selectivity was inferred across each individual mass extinction event, before testing whether the selectivity patterns obtained could be used to 'predict' the extinction selectivity exhibited during the other mass extinctions. Our analyses show that, despite some similarities in extinction selectivity patterns between ancient crises, the selectivity of mass extinction events is inconsistent, which leads to a poor predictive performance. This lack of predictability is attributed to evolution in marine ecosystems, particularly during the Mesozoic Marine Revolution, associated with shifts in community structure alongside coincident Earth system changes. Our results suggest that past extinctions are unlikely to be informative for predicting extinction risk during a projected mass extinction.

SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA