Organism activity levels predict marine invertebrate survival during ancient global change extinctions

Multistressor global change, the combined influence of ocean warming, acidification, and deoxygenation, poses a serious threat to marine organisms. Experimental studies imply that organisms with higher levels of activity should be more resilient, but testing this prediction and understanding organism vulnerability at a global scale, over evolutionary timescales, and in natural ecosystems remain challenging. The fossil record, which contains multiple extinctions triggered by multistressor global change, is ideally suited for testing hypotheses at broad geographic, taxonomic, and temporal scales. Here, I assess the importance of activity level for survival of well‐skeletonized benthic marine invertebrates over a 100‐million‐year‐long interval (Permian to Jurassic periods) containing four global change extinctions, including the end‐Permian and end‐Triassic mass extinctions. More active organisms, based on a semiquantitative score incorporating feeding and motility, were significantly more likely to survive during three of the four extinction events (Guadalupian, end‐Permian, and end‐Triassic). In contrast, activity was not an important control on survival during nonextinction intervals. Both the end‐Permian and end‐Triassic mass extinctions also triggered abrupt shifts to increased dominance by more active organisms. Although mean activity gradually returned toward pre‐extinction values, the net result was a permanent ratcheting of ecosystem‐wide activity to higher levels. Selectivity patterns during ancient global change extinctions confirm the hypothesis that higher activity, a proxy for respiratory physiology, is a fundamental control on survival, although the roles of specific physiological traits (such as extracellular pCO₂ or aerobic scope) cannot be distinguished. Modern marine ecosystems are dominated by more active organisms, in part because of selectivity ratcheting during these ancient extinctions, so on average may be less vulnerable to global change stressors than ancient counterparts. However, ancient extinctions demonstrate that even active organisms can suffer major extinction when the intensity of environmental disruption is intense.     

Mid-Cretaceous/Albian (Cretaceous) ostracod assemblages from NW Hungary reflecting deep marine,nearshore and non-marine environments

The Albian sediments of the Transdanubian Range in Hungary were deposited in non-marine to fully-marine environments. The studied sections revealed diverse benthic ostracod faunas with moderately-preserved specimens. Forty-six taxa are identified and Cypridea zalanyii n. sp. is newly described. The detailed palaeoecological study of these ostracod faunas provided an opportunity to distinguish eight assemblages. The assemblages include limnic, brackish lagoon, shallow marine, reef and low oxygenated semi-enclosed basin environments in the Northern Tethys region we investigated. This work contributes to the knowledge about Albian non-marine faunas from Europe and explores ecological requirements of brackish faunas.     

Marine influence and incursion in the Gondwana basins of Orissa, India: A review

The Permian–Triassic succession of the Indian Gondwana Sequence was previously considered to have been deposited in a fluviatile-lacustrine environment. Similarly, earlier Lower Gondwanas of Orissa State (a major part of the Mahanadi Master basin) were considered entirely fresh water deposits. Faunal evidence is still scanty in this master basin. Ichnology and palynology along with a few sedimentary records are reviewed and analysed for inferring marine signature. The marine nature of the Talchir, Karharbari, Barakar, Barren Measures and Kamthi sediments of three major basins (Talcher, Ib River and Athgarh) in Orissa State was predicted on the basis of typical marine ichnofossils. Most of these sediments also contain acritarchs reflecting marine marginal environment throughout the Permian. Moreover, evidence of wave activity, salinity raise and discovery of phosphorite in Permian sediments also strengthen this view.Hence, the previous model of continental facies for the Lower Gondwanas is found to be incorrect. The ichnofossils (Skolithos and Cruziana ichno-facies), acritarchs (Foveofusa, Leiosphaeridia, Greinervillites, etc.) and other palynofossils of marine origin can be utilized as a tool for palaeoenvironmental reconstruction. In the Gondwana basins of Orissa (Mahanadi Master basin), consistent occurrence of marine acritarchs and trace fossils with some typical sedimentary structures such as wave ripples has been studied and reviewed from the Talchir (Early Permian) to Upper Kamthi (Triassic) formations at various time intervals. Here marine incursion could have occurred due to the well known global transgressions during Permian and Triassic.     

Amniotes through major biological crises: faunal turnover among Parareptiles and the end‐Permian mass extinction

Abstract: The Parareptilia are a small but ecologically and morphologically diverse clade of Permian and Triassic crown amniotes generally considered to be phylogenetically more proximal to eureptiles (diapsids and their kin) than to synapsids (mammals and their kin). A recent supertree provides impetus for an analysis of parareptile diversity through time and for examining the influence of the end‐Permian mass extinction on the clade’s origination and extinction rates. Phylogeny‐corrected measures of diversity have a significant impact on both rates and the distribution of origination and extinction intensities. Time calibration generally results in a closer correspondence between origination and extinction rate values than in the case of no time correction. Near the end‐Permian event, extinction levels are not significantly higher than origination levels, particularly when time calibration is introduced. Finally, regardless of time calibration and/or phylogenetic correction, the distribution of rates does not differ significantly from unimodal. The curves of rate values are discussed in the light of the numbers and distributions of both range extensions and ghost lineages. The disjoint time distributions of major parareptile clades (e.g. procolophonoids and nycteroleterids‐pareiasaurs) are mostly responsible for the occurrence of long‐range extensions throughout the Permian. Available data are not consistent with a model of sudden decline at the end‐Permian but rather suggest a rapid alternation of originations and extinctions in a number of parareptile groups, both before and after the Permian/Triassic boundary.     

Ammonoid age control of the Early Triassic marine reptiles from Chaohu (South China)

Here we described a series of ammonoid specimens from the Early Triassic of Chaohu, South China and recognized the occurrence of Procolumbites for the first time in this area. The Procolumbites layer is about one meter above the first appearance of Chaohusaurus, indicating that the oldest Chaohusaurus is within the Procolumbites Zone of middle Spathian age. This new age constrain is significantly older than the previously suggested Subcolumbites Zone assignment (early late Spathian). To date, Chaohusaurus is the oldest known ichthyopterygian.     

Middle Triassic Xingyi Fauna: Showing turnover of marine reptiles from coastal to oceanic environments

The late Ladinian (Middle Triassic) Xingyi Fauna from the Zhuganpo Member of the Falang Formation yields abundant and well-preserved marine reptiles. Bed-by-bed excavation at Wusha in Xingyi of Guizhou Province reveals two marine vertebrate assemblages in a fossiliferous horizons that span 5.1 m in total thickness. The lower assemblage is marked by the near-shore sauropterygians, including the pachypleurosaur Keichousaurus, the nothosaurians Nothosaurus and Lariosaurus, with a strong paleobiogeographic affinity to western Tethys. The upper assemblage consists of oceanic ichthyosaurs and pistosaurs, including the large shastasaurid ichthyosaur Guizhouichthyosaurus, the euichthyosaur Qianichthyosaurus, pistosaurs Yunguisaurus and Wangosaurus, and the thalattosaur Xinpusaurus, with a closer paleobiogeographic affinity to North America. The coastal pachypleurosaur and nothosaurid sauropterygians disappeared in the upper assemblage, suggesting that they were replaced by an oceanic marine reptile community that emerged. The reptilian composition of the upper assemblage is similar to that of the Guanling Biota, which is of the Early Carnian (Late Triassic) in age and thus somewhat younger than the Xingyi Fauna. The ecological turnover of marine reptiles from near-shore to the open ocean community corresponds to the paleoenvironmental changes indicated by lithofacies analysis, δ¹³C and the global sea level changes.     

Local extinctions and recolonisations of passerine bird populations in small woods

This paper considers, for eight species of woodland bird, the factors that influenced both local extinctions and recolonisations in 145 woods over 3 years. In all species, probability of local extinction was inversely related to population size; most local extinctions occurred in woods containing one to three breeding pairs. However, considerable variation in extinction probabilities occurred between species and between years. In addition, the suitability of habitat within a wood (more extinctions in less suitable woods) was important for wren Troglodytes troglodytes, song thrush Turdus philomelos and blue tit Parus caeruleus; also, the structure of the surrounding landscape was important for blue tit, great tit Parus major, and chaffinch Fringilla coelebs (more extinctions in localities with less woodland). In only two species was the probability of recolonisation related to any of the measured variables. Wrens were more likely to recolonise larger woods, whereas song thrushes were more likely to recolonise woods with a high habitat suitability rating and those which are more isolated from other woodland     

Effect of end-Triassic CO<Subscript>2</Subscript> maximum on carbonate sedimentation and marine mass extinction

Correlation of stratigraphic sections from different continents suggests a worldwide interruption of carbonate sedimentation at the Triassic–Jurassic boundary, which coincided with one of the most catastrophic mass extinctions in the Phanerozoic. Both events are linked by a vulcanogenic maximum of carbon dioxide, which led to a temporary undersaturation of sea water with respect to aragonite and calcite and a corresponding suppression of carbonate sedimentation including non-preservation of calcareous skeletons. Besides the frequently cited climatic effect of enhanced carbon dioxide, lowering the saturation state of sea water with respect to calcium carbonate was an additional driving force of the end-Triassic mass extinction, which chiefly affected organisms with thick aragonitic or high-magnesium calcitic skeletons. Replacement of aragonite by calcite, as found in the shells of epifaunal bivalves, was an evolutionary response to this condition.     

Distribution of South African marine benthic invertebrates applied to the selection of priority conservation areas

Available data on species distributions and endemicity were compiled and examined for 11 groups of South African marine invertebrates (2533 species). For five groups species richness adhered to a well‐documented pattern, increasing from west to east, but for the other groups species richness was highest along the south coast. Endemicity was generally highest along the south coast, and lowest along the east coast. The data base was then analysed using several types of complementarity analyses, each producing a minimum set of potential reserve areas, which cumulatively represent all invertebrate species analysed. Approaches based solely on rarity, species richness and endemicity demonstrated individual biases, suggesting a need to combine all three interests. Combining the three techniques produced similar results to the individual analyses, showing conservation priorities to be highest along the east coast. Specifically, the areas of Port Elizabeth and Durban were ranked high in all analyses. Consistently, a total of 16 sites was necessary to represent all species analysed. Comparisons with similar analyses on fish and seaweeds revealed similar findings. Existing invertebrate records were shown to be biased towards centres of high sampling activity, demonstrating a need of future sampling attention in under‐represented areas.     

Magnetostratigraphy of the Sherwood Sandstone Group (Lower and Middle Triassic), south Devon, UK: detailed correlation of the marine and non-marine Anisian

The Sherwood Sandstone Group in south Devon consists of the Budleigh Salterton Pebble Beds and the Otter Sandstone Formation. The Otter Sandstone Formation comprises four lithostratigraphic sub-units, from the base labelled A-D, and contains tetrapods corresponding to the Perovkan land vertebrate faunachron, and is consequently a key European non-marine Anisian succession. A total of 181 palaeomagnetic specimens from 92 horizons were measured to determine the palaeomagnetic signal. The magnetic properties and characteristic remanence is predominantly carried by haematite, most of which probably formed early in the depositional and diagenetic history. The lower part of the Sherwood Sandstone Group (Budleigh Salterton Pebble Beds and Otter Sandstone Formation, unit A, lower part of unit B) has predominantly normal polarity (magnetozones BS1, BS2 and BS3n) with three thin reversed polarity magnetozones. The lower part of unit B to the lower part of unit C of the Otter Sandstone Formation is predominantly reverse polarity (magnetozones BS3r, BS4 and BS5), but includes three short normal polarity intervals. The upper ca. 50 m of unit C shows a mix of normal and reverse polarity (BS6, BS7) with normal dominating. The ca. 15-m-thick unit D is entirely of normal polarity (BS8n). The magnetostratigraphy allows unambiguous comparison with conodont and ammonite calibrated magnetostratigraphies from elsewhere in Europe. These show that the BS2 and BS3n magnetozones of the Otter Sandstone Formation are lower Aegean to middle Pelsonian (lower to middle Anisian). The BS3r to BS5r magnetozone interval, is middle Pelsonian to lower Illyrian (middle to upper Anisian), and the BS6 to BS8n magnetozone interval is middle Illyrian to lower Fassanian. The top of unit D is correlated to an interval in the middle of the Nevadites Zone (close to the Anisian-Ladinian boundary). Consequently, the Otter Sandstone Formation correlates with the Muschelkalk in the Polish Basin, but is equivalent to only part of the Germanic Basin Muschelkalk. The continuous magnetostratigraphy from the Sherwood Sandstone Group, provides additional details of the polarity pattern through the Pelsonian to Illyrian interval, which appears to be lacking in discontinuous marine sections. A synthesis of adjacent European sedimentary basins in combination with the magnetostratigraphy, suggests that the Budleigh Salterton Pebble Beds are probably Late Spathian to lower Aegean.     

Oldest known non-marine diatoms (Aulacoseira) from the uppermost Cretaceous Deccan Intertrappean beds and Lameta Formation of India

Non-marine diatoms occur in the Deccan Intertrappean beds (Upper Cretaceous) of Mohgaon-Kalan, Chhindwara District, Madhya Pradesh and Pisdura, Lameta Formation (Upper Cretaceous), Maharashtra, India. This represents the oldest record of non-marine diatoms yet reported and the oldest from the Indian subcontinent. The diatoms were recovered from thin sections of chert and dinosaur coprolites by random fracturing. Solitary forms are the most common but colonial filaments up to five cells were also observed. Based on the morphological characters, the diatoms are identified as Aulacoseira Thwaites. The Lower Cretaceous marine diatom genus Archepyrgus Gersonde and Harwood also resembles Aulacoseira in general morphological characters and it seems that Aulacoseira evolved from Archepyrgus and migrated to the non-marine realm.     

The influence of local extinctions on the probability of fixation of chromosomal rearrangements

We investigated the influence of local extinctions in a subdivided population on the probability of fixation of an initially rare allele, for different migration rates. The selective regimes considered were strict underdominance, meiotic drive, and underdominance associated with meiotic drive. We show that local extinctions can increase the probability of fixation of initially rare alleles in underdominant loci for relatively high migration rates, even when both homozygotes have the same fitness. This increase is due to drift during founder events. On the contrary, local extinctions decrease the probability of fixation of alleles favoured by meiotic drive. For a locus where both meiotic drive and underdominance act, the effect of local extinctions depends on the relative strength of the two selective regimes and the initial frequency of the rare allele. For parameter values such that the rare allele is initially selected against, local extinctions decrease the probability of fixation for low migration rates while they cause an increase for moderate migration rates. When the parameter values are such that the rare allele should always be favoured by selection, local extinctions always decrease the probability of fixation. In this latter case, we show the existence of an optimal migration rate which maximizes the probability of fixation.     

Responses of marine organisms to physical and chemical impacts

Studies on the effects of a variety of exogenous and anthropogenic environmental factors, including endocrine disruptors, heavy metals, UV light, high temperature, and others, on marine organisms have been presented at the 2nd Bilateral Seminar Italy–Japan held in November 2006. Reports were discussed in order to reveal the current situation of marine ecosystems, aiming at evaluation and prediction of environmental risks.

中国海洋生态保护制度的转型发展--从海洋保护区走向海洋生态红线区

海洋生态环境的持续恶化与生态学认知的提高使海洋生态红线区管理制度成为必然。总结了中国海洋保护区现状与存在问题;分析了发展海洋生态红线的必要性、区划原则、概念及组成体系;提出海洋保护区与海洋生态红线区可分别籍空间统一性、决策统一性、工作内容与管理要求的一致性相关联,海洋保护区的核心、关键和重要因素与海洋生态红线的范围划定、宏观应对策略制定、微观管理规定一一对应。对海洋保护区管理向海洋生态红线区划与管理的转变给出了若干建议,认为海洋生态红线区划指标体系可以参照海洋保护区绩效评估、保护区选划与评估指标;并从海洋生态红线的尺度,陆海统筹的生态系统格局-结构\过程-机理,复杂生态系统与海洋生态红线的结合,海洋生态红线基点观测等方面对海洋生态红线的研究和工作方向进行了展望。     

Impacts of climate warming and habitat loss on extinctions at species' low-latitude range boundaries

Polewards expansions of species' distributions have been attributed to climate warming, but evidence for climate‐driven local extinctions at warm (low latitude/elevation) boundaries is equivocal. We surveyed the four species of butterflies that reach their southern limits in Britain. We visited 421 sites where the species had been recorded previously to determine whether recent extinctions were primarily due to climate or habitat changes. Coenonympha tullia had become extinct at 52% of study sites and all losses were associated with habitat degradation. Aricia artaxerxes was extinct from 50% of sites, with approximately one‐third to half of extinctions associated with climate‐related factors and the remainder with habitat loss. For Erebia aethiops (extinct from 24% of sites), approximately a quarter of the extinctions were associated with habitat and three‐quarters with climate. For Erebia epiphron, extinctions (37% of sites) were attributed mainly to climate with almost no habitat effects. For the three species affected by climate, range boundaries retracted 70–100 km northwards (A. artaxerxes, E. aethiops) and 130–150 m uphill (E. epiphron) in the sample of sites analysed. These shifts are consistent with estimated latitudinal and elevational temperature shifts of 88 km northwards and 98 m uphill over the 19‐year study period. These results suggest that the southern/warm range margins of some species are as sensitive to climate change as are northern/cool margins. Our data indicate that climate warming has been of comparable importance to habitat loss in driving local extinctions of northern species over the past few decades; future climate warming is likely to jeopardize the long‐term survival of many northern and mountain species.     

The loss of indirect interactions leads to cascading extinctions of carnivores

Species extinctions are biased towards higher trophic levels, and primary extinctions are often followed by unexpected secondary extinctions. Currently, predictions on the vulnerability of ecological communities to extinction cascades are based on models that focus on bottom‐up effects, which cannot capture the effects of extinctions at higher trophic levels. We show, in experimental insect communities, that harvesting of single carnivorous parasitoid species led to a significant increase in extinction rate of other parasitoid species, separated by four trophic links. Harvesting resulted in the release of prey from top‐down control, leading to increased interspecific competition at the herbivore trophic level. This resulted in increased extinction rates of non‐harvested parasitoid species when their host had become rare relative to other herbivores. The results demonstrate a mechanism for horizontal extinction cascades, and illustrate that altering the relationship between a predator and its prey can cause wide‐ranging ripple effects through ecosystems, including unexpected extinctions.     

Deforestation and apparent extinctions of endemic forest beetles in Madagascar

Madagascar has lost about half of its forest cover since 1953 with much regional variation, for instance most of the coastal lowland forests have been cleared. We sampled the endemic forest-dwelling Helictopleurini dung beetles across Madagascar during 2002-2006. Our samples include 29 of the 51 previously known species for which locality information is available. The most significant factor explaining apparent extinctions (species not collected by us) is forest loss within the historical range of the focal species, suggesting that deforestation has already caused the extinction, or effective extinction, of a large number of insect species with small geographical ranges, typical for many endemic taxa in Madagascar. Currently, roughly 10% of the original forest cover remains. Species-area considerations suggest that this will allow roughly half of the species to persist. Our results are consistent with this prediction.     

On Permian and Triassic insect faunas in relation to biogeography and the Permian-Triassic crisis

The taxonomic diversity dynamics of pterygote insects in the Permian and Triassic at the family/age level are considered. Different metrics of taxonomic diversity are compared. Biogeographic and taphonomic aspects of changes in the composition of insect faunas in the Permian and about the P-T transition are discussed. Some changes in the Permian insect faunas are of a biogeographic nature and do not indicate global changes in diversity. Insects with aquatic immatures were rather common in the Permian and Early Triassic, but these immatures are well represented in only few localities.     

Phanerozoic survivors: Actinopterygian evolution through the Permo‐Triassic and Triassic‐Jurassic mass extinction events

Actinopterygians (ray‐finned fishes) successfully passed through four of the big five mass extinction events of the Phanerozoic, but the effects of these crises on the group are poorly understood. Many researchers have assumed that the Permo‐Triassic mass extinction (PTME) and end‐Triassic extinction (ETE) had little impact on actinopterygians, despite devastating many other groups. Here, two morphometric techniques, geometric (body shape) and functional (jaw morphology), are used to assess the effects of these two extinction events on the group. The PTME elicits no significant shifts in functional disparity while body shape disparity increases. An expansion of body shape and functional disparity coincides with the neopterygian radiation and evolution of novel feeding adaptations in the Middle‐Late Triassic. Through the ETE, small decreases are seen in shape and functional disparity, but are unlikely to represent major changes brought about by the extinction event. In the Early Jurassic, further expansions into novel areas of ecospace indicative of durophagy occur, potentially linked to losses in the ETE. As no evidence is found for major perturbations in actinopterygian evolution through either extinction event, the group appears to have been immune to two major environmental crises that were disastrous to most other organisms.     

End-Permian mass extinction of calcareous algae and microproblematica from Liangfengya,South China

A new assemblage of calcareous algae and microproblematica is reported from the Changxing Formation at the Liangfengya section in Chongqing, South China. This assemblage comprises eighteen species of seven genera, including three genera of gymnocodiaceaens (Gymnocodium, Permocalculus, and Tauridium), three genera of dasycladaleans (Epimastopora, Macroporella, and Mizzia), and one genus of microproblematica (Pseudovermiporella). A new algal species, Tauridium elongatum nov. sp., is described. Quantitative analysis indicates that the last occurrences of 22% of the species (4 out of 18) fall into a 52 cm thick interval of the uppermost Changhsingian. No calcareous algae are found in the Permian-Triassic boundary (P-T boundary) beds and the overlying Feixianguan Formation. Four out of 10 species have a stratigraphic abundance greater than 10% and all vanished in the uppermost Changhsingian. An abrupt extinction for calcareous algae occurred in the Clarkina yini conodont Zone.