Resistance of spiders to Cretaceous-Tertiary extinction events

Throughout Earth history a small number of global catastrophic events leading to biotic crises have caused mass extinctions. Here, using a technique that combines taxonomic and numerical data, we consider the effects of the Cenomanian-Turonian and Cretaceous-Tertiary mass extinctions on the terrestrial spider fauna in the light of new fossil data. We provide the first evidence that spiders suffered no decline at the family level during these mass extinction events. On the contrary, we show that they increased in relative numbers through the Cretaceous and beyond the Cretaceous-Tertiary extinction event.     

Geologic Time Scale 2004 – why, how, and where next!

A Geologic Time Scale (GTS2004) is presented that integrates currently available stratigraphic and geochronologic information. The construction of Geologic Time Scale 2004 (GTS2004) incorporated different techniques depending on the data available within each interval. Construction involved a large number of specialists, including contributions by past and present subcommissions officers of the International Commission on Stratigraphy (ICS), geochemists working with radiogenic and stable isotopes, stratigraphers using diverse tools from traditional fossils to astronomical cycles to database programming, and geomathematicians. Anticipated advances during the next four years include formalization of all Phanerozoic stage boundaries, orbital tuning extended into the Cretaceous, standardization of radiometric dating methods and resolving poorly dated intervals, detailed integrated stratigraphy for all periods, and on-line stratigraphic databases and tools. The geochronological science community and the International Commission on Stratigraphy are focusing on these issues. The next version of the Geologic Time Scale is planned for 2008, concurrent with the planned completion of boundary-stratotype (GSSP) definitions for all international stages.     

Fossil ovipositions of dragonflies: Review and interpretation

The paper deals with the stratigraphic range and morphology of fossil formations on plants interpreted as insect ovipositions. Our analysis of the insect fossil record has shown that the endophytic ovipositions probably belong to the Kennedyina and Triadophlebiina (in the Paleozoic and Lower Mesozoic) and to the Calopterygina (in the Upper Mesozoic and Cenozoic).     

Fossil avian eggshell preserves ancient DNA

Owing to exceptional biomolecule preservation, fossil avian eggshell has been used extensively in geochronology and palaeodietary studies. Here, we show, to our knowledge, for the first time that fossil eggshell is a previously unrecognized source of ancient DNA (aDNA). We describe the successful isolation and amplification of DNA from fossil eggshell up to 19 ka old. aDNA was successfully characterized from eggshell obtained from New Zealand (extinct moa and ducks), Madagascar (extinct elephant birds) and Australia (emu and owl). Our data demonstrate excellent preservation of the nucleic acids, evidenced by retrieval of both mitochondrial and nuclear DNA from many of the samples. Using confocal microscopy and quantitative PCR, this study critically evaluates approaches to maximize DNA recovery from powdered eggshell. Our quantitative PCR experiments also demonstrate that moa eggshell has approximately 125 times lower bacterial load than bone, making it a highly suitable substrate for high-throughput sequencing approaches. Importantly, the preservation of DNA in Pleistocene eggshell from Australia and Holocene deposits from Madagascar indicates that eggshell is an excellent substrate for the long-term preservation of DNA in warmer climates. The successful recovery of DNA from this substrate has implications in a number of scientific disciplines; most notably archaeology and palaeontology, where genotypes and/or DNA-based species identifications can add significantly to our understanding of diets, environments, past biodiversity and evolutionary processes.     

Fossil evidence of insect pathogens

The present report describes fossil evidence of insect pathogens, heretofore, almost non-existent, from six samples of amber ranging in age from 15 to 100 million years. They include a cytoplasmic polyhedrosis virus and trypanosomatid infection in an adult biting midge (Diptera: Ceratopogonidae), and a nuclear polyhedrosis virus in an adult sand fly (Diptera: Phlebotomidae), both from Early Cretaceous Burmese amber, several types of fungal thalli on the cuticle of an adult mosquito (Culicidae: Diptera), as well as a fungal growth on the prothorax of a fungus gnat (Mycetophilidae: Diptera) in Dominican amber and large tumors in the body cavity of a caterpillar (Lepidoptera) in Mexican amber. These discoveries suggest that insect polyhedrosis viruses were present 100 million years ago and present the possibility that vertebrate arboviruses (especially those in the family Reoviridae) could have evolved from cytoplasmic polyhedrosis viruses infecting biting insects. The flagellates in the Early Cretaceous biting midge represent the first fossil record of monogenetic trypanosomatid infections of arthropods.     

Interpreting the origin of mammals: new approaches to the history of palaeontology

New sociological techniques in the history of science are described. Their value is illustrated by reinterpreting the diagnostic disputes which occurred following the first discovery of the Stonesfield mammals. It is concluded that contextual explanations are more sympathetic to early savants and more conducive to the integration of science and social history.     

Conceptualising ‘fossiliferous deposit’ against ‘palaeontological deposit’: some semantic (and epistemological) considerations

This short essay intends to provide insight into the concepts of ‘fossiliferous deposit’ and ‘palaeontological deposit’ by identifying some of their semantic differences. From the moment that fossiliferous deposits are technically accessible to the palaeontologist, they are ‘palaeontological’ ones, but not before. However, not all palaeontological deposits must inevitably be ‘fossiliferous’ deposits in the sense of containing mineralised remains of the anatomical parts of organisms. As a consequence of the existence of fossiliferous deposits, the science of palaeontology exists, with the result that fossiliferous deposits become ‘palaeontological deposits’, together with the non-fossiliferous strata that are able to provide data on the ecological and/or ethological conditions of fossil beings from remains that are not ‘fossils’. From the point of view of philosophy of science, fossiliferous and palaeontological deposits should be considered as two different epistemological (as well as ontological) categories. Consequently, by identifying semantic differences, the concepts of ‘fossiliferous deposit’ and ‘palaeontological deposit’ can be framed better within the philosophical development of the palaeontological sciences. In addition to the central issue addressed in this essay, a brief discussion on the epistemic value of the dichotomy ‘to deposit’ versus ‘to reposit’ applied to palaeontological museology is brought up.     

Molecular phylogeny of araneomorph spiders

The reconstruction of the phylogeny of spiders based on morphological and ethological characters is hampered by frequent homoplasies. Therefore, fragments of the 28S rRNA gene have been sequenced to elucidate some crucial points in the evolution of spiders. The following results were obtained. (1) The 28S rRNA gene data support the monophyly of the Entelegynae. Thus, the number of different subunits and the number of hexamers which form a haemocyanin complex must have been reduced at least twice within the spiders. The character state pattern within the spiders and within the Arachnida suggests that these reductions are due to a decrease in the selection on the oxygen binding properties of the haemocyanins as a result of the evolution of tracheae. (2) The semientelegyne spiders are not a transition stage between the Haplogynae and the Entelegynae. The lack of separate fertilization ducts in these species is probably due to secondary reduction. This reduction has decisive consequences for the flow of the sperm and for sperm competition. (3) Furthermore, the 28S rRNA gene data tentatively support the hypothesis that the orb web is either a plesiomorphy or has evolved at least twice.     

The Hymenoptera associated with spiders in Europe

The Hymenoptera known to be obligatory parasitoids or predators of spiders or their eggs in Europe form a rather diverse assemblage. Their biologies are briefly reviewed; known host associations are summarized for each genus; and a key is given to the genera of Hymenoptera (other than Pompilidae) involved.     

Individual differences in boldness positively correlate with heart rate in orb-weaving spiders of genus Larinioides

Recent years have seen a dramatic increase in the number of studies devoted to consistent individual differences in behavior, termed ＂behavioral syndromes＂ or animal ＂personality＂. In particular, ecologists and evolutionary biologists alike seek to explore the functional consequences of individuals＇ personalities and explanations for their general maintenance. Understand ing the mechanistic underpinnings to personality is arguably key to a deeper understanding of their functional consequences and maintenance. In particular, consistent individual differences in metabolic rate have been proposed as a general explanation for the maintenance of consistent individual differences in boldness, aggressiveness, and activity level. In this paper we explore whether consistent individual differences in boldness are associated with heat rate, a proxy for metabolic rate, in two species of orbweaving spider： Larinioides cornutus and L. patagiatus. We first documented consistent individual differences in boldness in L. cornutus but not L. patagiatus, as estimated by individuals＇ latency to resume movement following an aversive stimulus. We also measured individuals＇ heart rate twice in a separate situation. We then tested for an association between individuals＇ boldness and their heart rate during these two events. We found that increased boldness was associated with increased heart. Thus, indi viduals that resumed movement quickly following an aversive stimulus also exhibited faster heart rates. Our studies provide fur ther evidence that consistent individual differences in key physiological attributes, like metabolic rate, might be a general mecha nism underlying consistent individual differences in behavior .     

The hybodont shark, Priohybodus d'Erasmo, 1960 (Early Cretaceous, northern Africa)

Priohybodus arambourgi d'Erasmo, 1960 is redescribed on the basis of nearly 200 teeth and a dorsal fin spine from the Chicla Sandstone (Aptian to Albian, Early Cretaceous) near Nalut in northwestern Libya. The generic distinction of Priohybodus is confirmed; its geological record is so far confined to the Late Jurassic and Early Cretaceous of Africa.     

FOSSIL OONOPID SPIDERS IN CRETACEOUS AMBERS FROM CANADA AND MYANMAR

Abstract:  The spider family Oonopidae is described from Cretaceous ambers from Myanmar and Canada for the first time. Orchestina albertenis sp. nov. is the first spider to be described from Canadian Grassy Lake amber and only the second spider to be described from Canadian amber. The specimen in amber from Myanmar extends the known range of the extant genus Orchestina back another 10 million years from the previously oldest specimen in Turonian New Jersey amber. Despite being unknown as sedimentary fossils, Oonopidae occur in more fossil deposits than any other spider family and were already widespread by the Cretaceous. The family contains the oldest example of an extant spider genus along with Archaeidae, also from Burmese amber.     

Genome size and endonuclear DNA replication in spiders

Although genome sizes (C-values) are now available for 115 arachnid species (Gregory and Shorthouse [2003] J Hered 94:285-290), the extent of genome amplification (endonuclear DNA replication or polyploidization) accompanying tissue differentiation in this diverse and abundant class of invertebrates remains unknown. To explore this aspect of arachnid development, samples of hemolymph and other tissues were taken from wild-caught specimens as air-dried smears, stained with the Feulgen reaction for DNA, and assayed using both scanning and image analysis densitometry. Cells from midgut diverticula and Malpighian tubules of Argiope and Lycosa (=Pardosa) often showed giant nuclei with 50-100 pg of DNA per nucleus, reflecting at least four cycles of endonuclear DNA replication when compared to the DNA content of hemocytes or sperm from the same specimen. Nuclei with markedly elevated DNA levels also appeared, but far less frequently, in tissue samples from several other arachnid species (Antrodiaetus, Hypochilus, Latrodectus, Liphistus and Loxosceles), but revealed no correlation with differences in somatic cell (2C) genome sizes. Our data show that several DNA classes of polysomatic nuclei regularly arise during tissue differentiation in some species of spiders and may provide an interesting model system for further study of patterns of tissue-specific variation in DNA endoreduplication during development.     

Wolbachia and other endosymbiont infections in spiders

Maternally inherited endosymbiotic bacteria, such as Wolbachia, Rickettsia and Spiroplasma, have been shown to have wide-ranging effects on the reproduction of their hosts. We present data on the presence of each of these sorts of bacteria in spiders, a group for which there are currently few data, but where such infections could explain many observed reproductive characteristics, such as sex ratio skew. The Wolbachia and Spiroplasma variants that we find in spiders belong to the same clades previously found to infect other arthropods, but many of the rickettsias belong to two, novel, hitherto spider-specific bacterial lineages. We find evidence for coexistence of different bacterial types within species, and in some cases, within individuals. We suggest that spiders present a useful opportunity for studying the effect of these sorts of bacteria on the evolution of host traits, such as those that are under sexual selection.     

Barcoding generalist predators by polymerase chain reaction: carabids and spiders

Identification of arthropod predators is challenging when closely related species are found at a given locality. Identification of the immature stages is especially problematic, because distinguishing morphological features are difficult to use or have not been described. We used polymerase chain reaction (PCR) to distinguish closely related carabids and spiders, and to match eggs and larvae (or nymphs) with identified adult parents. Within the Carabidae, we amplified species-specific mitochondrial cytochrome oxidase I (COI) fragments for three species each in the genera Poecilus and Harpalus, and two each in Chlaenius and Bembidion. Within the Araneae, we amplified species-specific COI fragments for two Hibana species (Anyphaenidae), Pardosa milvina and Rabidosa rabida (Lycosidae), Frontinella communis and Grammonota texana (Linyphiidae), and Cheiracanthium inclusum (Miturgidae). We are able to correctly identify all immature stages tested--eggs, larvae (or nymphs) and pupae--by comparison of the amplified fragments with those of the adults. Using COI markers as species identifiers is a tenet of the Barcode of Life initiative, an international consortium to provide a molecular identifier for every animal species.     

Miniaturized orb-weaving spiders: behavioural precision is not limited by small size

The special problems confronted by very small animals in nervous system design that may impose limitations on their behaviour and evolution are reviewed. Previous attempts to test for such behavioural limitations have suffered from lack of detail in behavioural observations of tiny species and unsatisfactory measurements of their behavioural capacities. This study presents partial solutions to both problems. The orb-web construction behaviour of spiders provided data on the comparative behavioural capabilities of tiny animals in heretofore unparalleled detail; species ranged about five orders of magnitude in weight, from approximately 50-100mg down to some of the smallest spiders known (less than 0.005mg), whose small size is a derived trait. Previous attempts to quantify the 'complexity' of behaviour were abandoned in favour of using comparisons of behavioural imprecision in performing the same task. The prediction of the size limitation hypothesis that very small spiders would have a reduced ability to repeat one particular behaviour pattern precisely was not confirmed. The anatomical and physiological mechanisms by which these tiny animals achieve this precision and the possibility that they are more limited in the performance of higher-order behaviour patterns await further investigation.     

A synthesis on cave‐dwelling spiders in Europe

We provide the first overview on spiders living in subterranean habitats in Europe, including the first European subterranean spider checklist. In Europe, there are 486 spider species known to dwell in caves and other subterranean habitats, distributed across 22 families. Despite a few species being able to colonize caves across the whole continent, approximately 90% of the species show a restricted distribution, occurring exclusively in one or two countries. From a biogeographic perspective, southern Europe emerges as the main hot spot of subterranean spider diversity, showing the highest richness of endemic species. Compared to other temperate regions of the world, some families appear to be well represented and other poorly represented (or lacking) in European subterranean habitats. Overall, it appears that the taxonomical knowledge on subterranean spiders in Europe is sufficient, but not evenly distributed. As this checklist represents a useful baseline for advances in this field, we point out specific areas of interest for future research.     

中生代鞘翅目扁甲总科化石的研究进展

扁甲总科隶属于鞘翅目多食亚目扁甲系,目前包含25个现生科和3个化石科,其中10个科仅分布于南半球,特别是澳大利亚、新西兰和南美。当前的分子系统发育学研究显示扁甲总科的起源时间为晚三叠世至早侏罗世,而冈瓦纳古陆与劳亚古陆的分离也发生在早侏罗世约1.8亿年前。因此对中生代扁甲总科化石的研究是解释扁甲总科如今分布格局的重要基础,也有助于研究扁甲总科的演化历史。本文简要回顾了现生扁甲总科的研究历史,并对其中生代的化石研究进行了概述,迄今在中生代地层发现有12科54种扁甲总科化石。