bluuebunny/crossref_metadata_2025 huggingface dataset:
Functional vs. phylogenetic control in the evolution of the vertebral column
Authors: McShea Daniel W.
Published: January 2018

In the evolution of morphology, the importance of both historical constraints and selection for adaptive design has been widely acknowledged, but the relative efficacy of these internal (historical or phylogenetic) and external (selective or functional) factors has been much debated. Innumerable examples can be selected to make a case either way, but disinterested evaluation requires study of instances in which the relative degrees of functional and phylogenetic control are not already known. The vertebral column is an appropriate case: as the central structure for vertebrate locomotion and support, it ought to be subject to strong selection for functional design, yet it is also deeply generatively entrenched in vertebrate development, and therefore, arguably, ought to be less plastic than other structures.

For this analysis, I applied three shape metrics to the vertebral column. The metrics are univariate and measure shape as functions of degree of differentiation within a column. (The metrics were developed in another context as measures of morphological complexity.) Then, a series of tests was conducted: in each, mean shape values for a group of functionally similar mammals (e.g. aquatics) and values for a group of phylogenetically related mammals (e.g. carnivorans) were compared independently with values for a test case, a mammal which belongs to both groups (e.g. aquatic carnivoran, otter). In almost all instances in which differences in resemblance were significant, the test cases more closely resembled their functional kin than their phylogenetic kin, suggesting a predominance of functional control. Results of standard cluster analyses (unweighted-pair-group method) supported this conclusion.
Comparative paleoecology of Paleogene and Neogene mammalian faunas: body-size structure
Authors: Morgan Michele E. , Kappelman John , Badgley Catherine , Gunnell Gregg F. , Gingerich Philip D. , Maas Mary , Legendre Serge
Published: January 2018

In mammalian assemblages, size distributions reflect conditions of vegetation and climate as well as biotic interactions among mammals. Paleogene (Wyoming/Montana) and Neogene (Siwalik) mammalian faunas depict strikingly different size distributions in the cenograms below (rank v. size of herbivorous and omnivorous species), because evolutionary increase to substantial size did not become widespread among lineages until the middle Eocene (after our record).

In the Paleocene to early Eocene, substantial faunal turnover with accompanying change in guild structure occurred with little change in size distributions. While maintaining relatively small sizes, lineages of modern mammalian orders replaced species from archaic groups. However, most mammalian lineages experienced size increase, especially through the Wasatchian (early Eocene).

From the middle to late Miocene, significant size increases occurred upsection within several families of Siwalik carnivores, artiodactyls, and rodents. Families of insectivores, primates, proboscideans, and perissodactyls exhibited little change in species sizes despite changes in species composition and number. The trend toward increasing size preceded the widespread development of C4 grasslands in the Siwaliks, suggesting that biotic rather than abiotic factors influenced the size increase.
Taphonomy and ecology of deep-water Ediacaran organisms from northwestern Canada
Authors: Narbonne Guy M. , Dalrymple Robert W.
Published: January 2018

Although most occurrences of Ediacaran fossils are from shallow-shelf deposits, taxonomically-similar assemblages have recently been described from a 2.5 km-thick succession of dark mudstones and turbiditic sandstones in the Windermere Supergroup of the Mackenzie Mountains, northwestern Canada. The paleogeographic position (20-40 km seaward of the shelf edge), abundant evidence of mass flow, and the complete absence of in situ shallow-water features imply that deposition took place on a slope considerably below storm wave-base. Ediacaran fossils were not observed in axial trough deposits (lower parts of the Twitya and Sheepbed formations), but megafossils occur sporadically in lower to middle slope deposits higher in the same formations. Megafossils and trace fossils are present in upper slope settings (Blueflower Formation) at the top of the Ediacaran succession. The megafossil assemblage varies stratigraphically, but in all formations is dominated by discoid forms (e.g. Cyclomedusa, Ediacaria, Nimbia); frondose forms and vendomiids are very rare.

Megafossils are preserved mainly as positive features on the soles of thin turbidite beds. Most fossiliferous beds begin with the rippled layer of the turbidite (Tc), but a few begin with the graded (Ta) or parallel-laminated (Tb) layer. Consistent orientation and high relief of individuals, evidence of mutual deformation during growth of adjacent organisms, and other taphonomic features imply that virtually all of the taxa represent benthic polypoid and frond-like organisms (not jellyfish). Slump structures occur commonly in the sandstone fill of fossils, suggesting that many of the organisms were buried alive by the turbidite and later decomposed. Other individuals, even on the same bedding plane, exhibit graded to laminated fill identical to that of the overlying turbidite bed, indicating that the depressions on the sea bottom produced by these individuals were empty at the time of turbidite deposition. Escape structures are absent, suggesting that the Ediacaran organisms were not capable of burrowing up through even thin layers of sand.

Ediacaran megafossils are invariably preserved on black, wrinkled surfaces similar to those elsewhere interpreted as microbial mats. Molding of delicate features (including tentacles), preservation of open molds as negative epireliefs, and sedimentological evidence of considerable cohesion of these surfaces relative to the underlying turbiditic muds (Td,e) supports this interpretation, and suggests that microbial mats were as important in the preservation of these deep-water Ediacara faunas as they were in their shallow-water equivalents. The presence of the wrinkled mats and their associated Ediacaran fossils almost exclusively in the pyritic intervals of the succession suggests that both may have lived under exaerobic conditions in this deep-water setting.
Patterns of terrestrial plant carbon: late Mesozoic and Cenozoic
Authors: Olson Jerry , Upchurch Garland R.
Published: January 2018

Variation in terrestrial productivity and biomass impacts evolution through linkages between productivity and biodiversity and through the types of resources available for consumption by herbivores. Geographic variation in terrestrial plant carbon is known on a global scale for extant biomes and is strongly correlated with precipitation, temperature, and the area of wetlands. Although estimates of extant terrestrial plant carbon density are still somewhat uncertain, the highest densities clearly occur in tropical and temperate rainforests, and the lowest occur in deserts, semideserts, and arctic/alpine tundra. Patterns of variation in ancient terrestrial plant carbon can be estimated through the correlation between biome/climate and carbon density, provided individual biomes show little change through time in primary productivity or density of plant carbon.

Density of terrestrial plant carbon has been estimated on a global scale for the latest Cretaceous, late Paleocene/Eocene, middle-late Eocene, early Miocene, and Holocene/Recent using the biomal reconstructions of Wolfe (1984), Upchurch (this symposium), and others. Latest Cretaceous (Maastrichtian) estimates indicate a relatively low value of 700-800 gigatons, which may underestimate carbon due to the presence of extensive latest Cretaceous coastal wetlands. However, much of this figure is readliy explainable by extensive deserts in Asia and little evidence for areally extensive tropical rainforest.

Major increase in terrestrial plant carbon occurred during the Paleocene/earliest Eocene in conjunction with a major areal increase in rainforest. During the early Miocene terrestrial global carbon was approximately 1200-1300 gigatons. This figure decreased by about half between the early Miocene and Holocene/Recent. The decrease in terrestrial carbon density resulted from a decrease in area of tropical and subtropical forests and increase in area of deserts, grasslands, and mediterranean woodlands/chapparal.
What is the significance of supraspecific taxa in macroevolutionary studies
Authors: Rieppel O.
Published: January 2018

For historical reasons, Darwin insisted on continuity of evolutionary transformation, which he believed would result in the “Origin of Species”. By the title of his book, he stigmatized species as the basic unit of evolution. If evolution is a historically unique process, a species originates only once, and if it goes extinct, it is lost forever. As a consequence, no “natural laws”, or general statements can cover the origin or extinction of particular species taxa; only particular statements are possible. For reasons such as these, some authors have proposed to view species as individuals.

Can higher taxa be conceived of as individuals, too? If so, higher taxa would have to perform as units of evolution as species are believed to do. To deny so would introduce a fundamental ontological difference between “species taxa” and “higher taxa” without epistemological justification. I argue that the “discovery procedure” (Nelson, 1989) for species is the same as for higher taxa, and hence that species are taxa. However, the “discovery procedure” for monophyletic taxa results in an inclusive hierarchy of “groups under groups”, which is incompatible with Darwinian causes of evolution, predicting an exclusive hierarchy of ancestors and descendants. If it is agreed that successful scientific explanation must link hypothetical causes to observed effects in a testable manner, the conclusion must be that macroevolutionary scenarios built on species, or higher taxa, are descriptive rather than explanative. The Darwinian unit of evolution is, in fact, the geographically determined population, not the species (as Darwin himself realized). The alternative is to treat the inclusive hierarchy of species and higher taxa, and the pattern it reveals through time and space, as a reflection of history, which means that causes of this historical process are not only non-Darwinian, but remain a “black box” (Nelson, 1989) until today.
A Late Neogene trend in a venerid bivalve chione cancellata, from the Florida peninsula
Authors: Roopnarine Peter D.
Published: January 2018

The objective of this project is to understand the long-term relationships, if any, if within-clade bivalve shell morphology to variations in shell growth rate and possible underlying environmental factors. As a preliminary approach to this problem, a study was undertaken to record the history of shell morphology, on the Florida peninsula, of the venerid bivalve Chione cancellata L. (Lower Pliocene - Recent). Samples were obtained from the following formations: Lower Pinecrest (3.5-3.0 mya), Caloosahatchee Fm. (2.5-1.8 mya), Upper Pinecrest Beds (2.4-1.8 mya), Bermont Fm. (1.6-1.1 mya), Anastasia Fm. (0.05 mya), and Recent. The total data set comprised ten samples.

Eleven morphometric measurements were selected on their predicted sensitivity to growth rate-caused variations in valve convexity. Comparisons of sample data sets were performed using principal components and canonical variates analyses. Only left-handed valves were analyzed. The results of both the principal component and canonical variates analyses indicate that a disproportionately large amount of the variance in the composite data set is accounted for by one morphometric dimension. This dimension is essentially a summary of contrast between anterior hinge morphology and posterior adductor muscle morphology. The samples form three major clusters; (1) Bermont Fm., Anastasia Fm. and Recent samples, (2) Caloosahatchee Fm. and U. Pinecrest samples, and (3) L. Pinecrest samples. There is some overlap of extremes between clusters (2) and (3), but otherwise the clusters are distinct. The result is a gradual but significant change of morphology during a 3.5 m.y. time span.

The next step in the project is to seek an explanation for the above observations. The provinciality of the phenomenon will be tested more extensively with the inclusion of Neogene and Recent samples from the Southern Caribbean and the Atlantic Coastal Plain. Also, considering the dynamism of Florida's oceanographic conditions (temperature, productivity and circulation) during the last 3.5 m.y., correlation of oceanographic conditions with C. cancellata's growth rate and morphology will be examined. The proposed method is a systematic sampling of stable oxygen and carbon isotopes from valves within the samples analyzed.
China and the lost worlds of the dinosaurian era
Authors: Russell Dale A.
Published: January 2018

What is known of dinosaurian biogeography suggests a centre of evolution first on a fragmenting Pangea-Gondwana and then on a consolidating Laurasia. By Cretaceous time members of Gondwanan low-latitude abelisaur-titanosaur assemblages often bore “back-fans,” while those in polar latitudes were relictual and/or highly derived. The time of last contact between South America and Africa is not well constrained, but links to Antarctica continued beyond the end of the Cretaceous. Many Gondwanan tetrapods appear to have waif-dispersed to Laurasia across southern Europe; few crossed in the opposite direction until the end of the period. Laurasian assemblages were then typically dominated by tyrannosaurids and hadrosaurids.

Land masses (“lost worlds”) periodically became isolated from Gondwana-Laurasia. (1) Eastern Asia was isolated between middle Jurassic through Neocomian time, although related temnospondyls and carnosaurs may have co-existed in Austral regions. Mamenchisaurs were the dominant giant terrestrial herbivores, while whip-tailed diplodocids filled the same role in Pangea. Groups of European-North American affinity then replaced many Asian endemics in a manner reminiscent of the Neogene mammalian turnover in South America. (2) In North America. Late Jurassic dinosaur assemblages exhibited Gondwana affinities, but by Late Cretaceous time they were dominated by forms of Asian ancestry. The apparent low diversity of Aptian-Albian dinosaur assemblages and absence of well-marked endemism may have been the result of a brief period of isolation. (3) European archipelagos were a filter bridge between northern lands and Gondwana analogous to the East Indies, which separate comparably different modern biotas in southeast Asia and Australia. (4) During Barremian time India probably hosted an polar dinosaurian assemblage, but low-latitude Gondwana forms (abelisaurids, titanosaurids) were present during at least part of this interval. Isolation ended with the immigration of northern taxa in Maestrichtian time.

Underexplored Mesozoic horizons of great biogeographic interest include (1) the Middle Jurassic-Neocomian of China for microvertebrate materials, (2) the pre-Maestrichtian Cretaceous of India, and (3) the post-Cenomanian of Africa, Australia and Antarctica. Paradoxically, the two recently discovered dinosaurian specimens of the latter age in Antarctica, which represent about as much biogeographic information as all described materials of similar age from Africa combined (none are known from Australia), are presently referred to families with Laurasian distributions.
The Upper Devonian fish locality of Miguasha, Quebec, Canada
Authors: Schultze Hans-Peter
Published: January 2018

At Miguasha, Québec (earlier referred to as Scaumenac Bay), the Escuminac Formation, lowermost Upper Devonian, yields an abundant and diverse fish fauna and flora. Both vertebrates and plant fossils from the locality are reknowned throughout the world. The excellent preservation, including that of endocranial anatomy, enabled Jarvik to describe and illustrate fine anatomical details of the osteolepiform Eusthenopteron. That gives the wrong impression that Miguasha is throughout the Escuminac Formation an outstanding Conservat Fossil-Lagerstätte.

The cliffs at Miguasha bear fishes throughout the approximately 120 m thick Escuminac Formation. The lithology of the sediments changes throughout the sequence. Close to the base of the formation, acanthodians and anaspid-like agnathans occur in laminites, sometimes hundreds on one horizon. In these laminites, soft tissue preservation may occur (anapsid-like agnathans), and diagenetic transformations of acanthodians into organic substance led to misinterprations and recognition of the “larval chordate Scaumenella.” Most common within the sequence are limy concretions with different fish fossils, most commonly Bothriolepis. Three-dimensionally preserved fishes occur within the sandstone-siltstones and sometimes within the concretions. In all these cases, dermal bone is preserved, and in few cases chondral bone too, as in Eusthenopteron. One can characterize these fossiliferous sections of the Escuminac Formation as Concentration Fossil-Lagerstätte, whereas the laminites are Conservat Fossil-Lagerstätten.

The depositional environment was previously interpreted as an intermontaneous basin, based on tectonic and paleogeographic position. More recent paleogeographic reconstructions show a connection with Scottish deposits and to marine deposits in the present day North Sea. The lack of invertebrates and of marine plant remains, and the occurrence of vertebrates in other localities were used as additional indicators for freshwater deposition.

The sedimentological features are ambiguous, the turbidites, such as those found at Miguasha, can occur in marine or large freshwater bodies. Conchostracans occur, sometimes in the thousands on a single plane, in the basal part of the Escuminac Formation. They occur today in freshwater or brackish environments; the same species as the one in the Escuminac Formation is reported from lower Upper Devonian marine deposits in the Baltic (Koknese, Latvia). A detailed comparison of the fish fauna with other lower Upper Devonian fish faunas indicates a coastal marine environment. That is supported by rare trace fossils and by different chemical analyses of the sediments and 87S/86S analysis of Bothriolepis bones.

In conclusion, earlier interpretations of the paleogeographic position of the Escuminac Formation at Miguasha and chemical and faunal indicators contradict each other in the interpretation of the paleoenvironment of the formation.
Escalating energy budgets and oligotrophic refugia: winners and drop-outs in the Red Queen's race
Authors: Thayer Charles W.
Published: January 2018

Preliminary evidence supports a series of predictions and speculations that derive from the hypothesis of evolutionary escalation (Red Queen). If biotic interactions have intensified over geologic time, then:

(1) Energy budgets of individuals have increased. This involves both sides of the equation Consumption = Growth + Reproduction + Respiration (includes locomotion & feeding) + Feces + Excreta. Thus living representatives of formerly successful taxa have lower energy budgets than ecologically similar taxa that were successful later, e.g., reptiles vs. mammals, Sphenodon vs. other reptiles, brachiopods vs. bivalves, Nautilus vs. coeleoids, gymnosperms vs. angiosperms.

(2) The price of success (cals. per reproducing offspring) has increased. Thus Red Queen evolution leads to energetic inefficiency.

(3) Energetic escalation is fueled by increasing plant biomass and turnover, especially on land (angiosperms, including N-fixers such as legumes). The enlarged trophic base pemits diversification without reduction of niche size. Evolution of marine benthos (our primary record of evolution) may be fueled directly by fixed C or indirectly by fixed N (shelf waters are normally N-limited), both increasingly supplied from land as a result of steady state mortality (deciduousness, self-thinning, short life-cycles) or disturbance mortality (fire, wind) of bigger standing crops. The Mesozoic origin of new phytoplankton such as diatoms may be a consequence of terrestrial angiosperms. In turn, diatoms produce lipid, a more energy-dense food than the carbohydrate produced by other phytoplankton. Increased skeletonization of Mesozoic phytoplankton may have diluted the food of Paleozoic-style suspension-feeders, especially brachiopods. Brachiopods have blind guts, which they readily stuff with non-nutritive particles and tight (efficient) energy budgets that might not sustain increased feeding costs.

4) Archaic organisms survive in oligotrophic refugia that exclude more recent, high-energy enemies. Marine animals move to deeper water (explaining offshore migration over the Phanerozoic, e.g., Latimeria, Nautilus, Zoophycos.). Other refugia are high latitudes, caves, or dark fiords. Living articulate brachiopods flourish in all of these except the fluvial-influenced Arctic Ocean. Refugia for archaic flora restrict light, water, or N (high latitudes and elevations, forest floor, poor soil).

5) Survival in oligotrophic refugia selects for lower energy budgets, including reduction of respiring tissue, so Cope's Rule is reversed (thecideid brachiopods, lycopods, sphenopsids).
Cryptic variation and its manifestation in the Lower Trentonian

Rafinesquina

lineage (Ordovician, New York State)
Authors: Titus Robert
Published: January 2018

Species populations commonly carry a great deal of genetic variation which is not expressed in individual phenotypes. Cryptic variation can be carried in recessive alleles, in cases of heterosis, or where modifier genes inhibit expression of the hidden trait. Other genetic and ecological factors also allow cryptic variation. Stabilizing selection prevents the expression of hidden traits; normalizing selection weeds out the deviants and canalizing selection suppresses their traits. Together the two keep the species near the top of the adaptive peak. Cryptic variation balances a species' need to be well-adapted to its environment and also for it to maintain a reserve of variation for potential environmental change. Expression of cryptic traits is rare and is usually associated with times of greatly reduced natural selection and rapid population growth, when the lower slopes of the adaptive peak are exposed.

A possible example of the manifestation of cryptic traits occurs within the lower Trentonian Rafinesquina lineage of New York State. The two most commonly reported species of the genus have been reappraised in terms of cryptic variation. Extensive collections of Rafinesquina “lennoxensis” reveal far more intergrading morphotypes than had hitherto been recognized. The form which Salmon (1942) described is broadly U-shaped with sulcate margins. It grades into very convex forms as well as sharply-defined or convexly geniculate types. Of great importance, all forms grade into the flat, U-shaped, alate R. trentonensis, which is, by far, the most common and widespread lower Trentonian member of the genus. The R. “lennoxensis” assemblage has a very narrow biostratigraphy, being confined to a few locations in the upper Napanee Limestone. This places it in a quiet, protected, low stress, lagoonal setting behind the barrier shoal facies of the Kings Falls Limestone.

The R. “lennoxensis” assemblage does not constitute a natural biologic species; it is reinterpreted as an assemblage of phenodeviants occupying a low stress, low natural selection lagoon facies. All such forms should be included within R. trentonensis. Given the evolutionary plasticity of this genus, extensive cryptic variation is not surprising.
Nuculid bivalves from Surma Group, Mizoram, India
Authors: Tiwari R.P.
Published: January 2018

The records of nuculid bivalves from the Surma Group sediments of Mizoram, India, are very rare. This paper describes 3 known and 4 new forms of bivalves of the family nuculidae which were collected in the course of field study from Upper Bhuban Formation of Bhuban Subgroup (Surma Group), Mizoram. They are : Nucula alcocki Noetling, Nucula warsarensis Eames, Nucula cf. pulchara Hinds, Nucula agrawali n.sp., Nucula sahnii n.sp., Nucula tewarii n.sp., and Acila (Truncacila) kachharai n.sp. The first three forms, though, known from the other areas of the Indian subcontinent, are reported for the first time from the study area and their synonymy is updated.

These forms, together with the other associated vivalves, gastropods and decapod crustacea, indicate a Lower Miocene (Aquitanian-Burdigalian) age and shallow marine enviroment of deposition for the Upper Bhuban Formation.
Economics and evolution
Authors: Vermeij Geerat J.
Published: January 2018

Individual organisms compete for resources. Among competitive dominants, per-capita energy use has generally increased through time. This increase has had a ripple effect on all other species by increasing the number of competitive and predatory encounters among individuals. Species unable to cope with such biological rigors have become restricted to environments where resource supply is low and where encounters with enemies are few. Among species that hold their own in biologically rigorous habitats, construction materials that are cheap to produce and that enable individuals to grow and respond quickly have generally been favored over those that exact a high cost in energy and time. Extinction interrupts but does not reverse or fundamentally alter these long-term between-clade evolutionary trends. The availability of resources to organisms, as well as the opportunity for evolutionary change, depends on extrinsic events and factors as well as on the competitive abilities of organisms.

Those who have raised methodological and theoretical objections against this economic interpretation of the history of life deny the overriding importance of organisms as agents of natural selection, emphasize the random nature of extinction, deny the existence of long-term trends, favor a larger role for mutualistic as opposed to antagonistic interactions, or accord a larger role to species-level attributes in evolution that are not reducible to the properties of individual organisms. These arguments are either unpersuasive or incorrect. The long-term economics of life may have important lessons for our own use of resources.
Fossil mammals from the central Chilean Andes: a new interval in the South American land mammal succession, and implications for Eocene-Oligocene boundary events and Andean tectonics
Authors: Wyss A.R. , Flynn J.J. , Swisher C.C. , Charrier R. , Norell M.A.
Published: January 2018

Biostratigraphically significant samples have been collected from six localities in post-Neocomian terrestrial deposits of the central Andean Main Range (34° 50 S latitude), Chile. Localities are distributed over an area of 13 km by 5 km, and span more than 2500 m of section.

Two eastern localities occurring lowest in the sequence yield a diverse suite of more than 20 taxa indicative of a new biochronologic interval between the Mustersan (?middle Eocene) and Deseadan (?late Oligocene-early Miocene) South American Land Mammal Ages (LMA); speculatively it also is older than the enigmatic Divisideran “LMA”. Noteworthy occurrences include the first South American appearance of rodents, argyrolagoid marsupials, and interatheriine interathere and advanced notohippid Notoungulata, as well as the last appearance of polydolopid marsupials, and notopithicine and notostylopid Notoungulata. Four K-Ar and Ar40-Ar39 analyses on a flow and tuff which directly underlie one locality yield ages between 35.6 ± 0.9 and 37.56 ± 0.14 Ma; the fossiliferous unit itself has produced four Ar40-Ar39 dates between 31.7 ± 0.3 and 31.37 ± 0.08 Ma in one locality. Therefore, the new biochronologic interval appears to be earliest Oligocene in age, and is the oldest sequence representing Simpson's “Second Faunal Stratum”. The “Tinguiririca” assemblage is the oldest South American mammalian fauna dominated by herbivores (in a diversity of taxa) with high-crowned or evergrowing teeth, documenting major changes caused by interaction between a major phase of tectonic uplift in the central Andes and global climatic changes near the Eocene-Oligocene boundary.

We recently recovered about one dozen skulls and jaws from several sites some 10 km west of, and 2500 m stratigraphically above, these lowest localities. The fauna from these new western sites appears advanced over the localities to the east, and probably is younger than about 20 Ma, based on stratigraphy and Ar40-Ar39 dates from units overlying the eastern localities. The new faunas should help resolve controversy concerning the younger limit of the Deseadan LMA.

Discovery of the mammal faunas has profoundly altered understanding of central Andean geology: 1) we identified an unconformity between Jurassic marine/late Cretaceous clastic units and volcaniclastic mid-Tertiary deposits, indicating that a dramatic episode of volcanism previously attributed to the late Mesozoic is in fact 30 m.y. younger; 2) consequently, the late Cretaceous/early Tertiary is characterized by non-deposition or erosion, rather than by volcanic deposition as had been hypothesized earlier; and 3) our paleomagnetic results also indicate previously unrecognized, but significant post-Miocene clockwise tectonic rotation (up to 20°) of units in this part of the Andes.
Global Jurassic floras and climate
Authors: Yao Jiping
Published: January 2018

The present day vegetation types on the earth are to a large extent controlled by climatic conditions that are mainly reflected in variations in moisture availability and temperature through the annual cycle. Therefore, fossil plants can be used as a tool to elucidate both spatial and temporal climatic changes. The global climates of the Jurassic can be interpreted with fossil floras because many parts of world have yielded abundant floral localities. Those records not only provide a strong basis for the qualitative depiction of vegetation patterns, but also provide quantitative data for the reconstruction of paleophytogeographic provinces and climatic changes. The computer program known as “Detrended Correspondence Analysis” written by Hill (1979) was used in this study. The floral data for this quantitative approach was assembled at the generic level mainly from the published literature. By definition, it is a method based on ordination scores, that is, the species ordination scores are averages of the sample ordination scores, and vice versa.

The scatter diagrams of the first two axes of genera and sample sites derived by detrended correspondence analysis were obtained for the intervals of Early, Middle, and Late Jurassic. The gradient variations of both genera and sample sites are reflected by the scores along axis 1 and 2 because axis 1 and axis 2 maximize the correlation of species and sample sites according to this technique. In the ordination score diagrams, the genera in similar climatic environments and the sample sites in similar paleogeographic regions are relatively close to each other along axis1 and axis2.

One of characteristics of the Jurassic vegetation is the taxonomic stability through the period compared with other periods of time. Therefore, the generic scores of axis1 for the Early and Middle, Middle and Late, and Early and Late Jurassic can be plotted against each other. The regression line can be used to assign the scores to the ordered genera. This is the technique used to complement the ordered genera from the gradient score diagrams and to eliminate the effect of some local genera. The genera adjacent to the regression line can be reliably used to reflect climatic gradients. The gradient changes were used to define biomes and to determine phytogeographic patterns on a global scale.

The quantitative analysis clearly shows that the use of floral data can achieve fast and satisfactory results in paleoclimatic studies of the Jurassic. For example, the cool-wet temperate climate is reflected by a ginkgophyte dominated deciduous flora, such as Ginkgo, Czekanowskia, Phoenicopsis, and Baiera, whereas the subtropical warm and drier climate is represented by cycad dominated floras, such as Anomozamites, Nilssonia, Pterophylum, Ptilophyllwn, Ctenis, and Otozamites. The general conclusion of earlier workers that Jurassic floras were especially uniform through the earth is true in the relative sense only, and the ordination study allows for the subdivision of the rather shallow gradients that do exist.
Zlichovian–Givetian bivalve fauna from the planktonic facies (Nandan Facies) of Nandan, Guangxi, South China
Authors: Renjie Zhang
Published: January 2018

A large amount of pteriomorphs of bivalve have been found in the Zlichovian–Givetian black mudstone-siltpelite in the trough in basin facies-zone of Luofu, Nandan, northwest Guangxi, South China. This fauna consists of 20 species, placed in 11 genera and 6 families, of which 1 family, 2 genera and 8 species are new. It has a very low diversity while compared with the contemperaneous fauna of Xiangzhou facies. This fauna is characterized by: a. Only 2 subclasses, the Pteriomorphia and Cryptodonta of 6 subclasses of Bivalvia were presented in the Nandan facies fauna; b. Among the occurred 6 families: Praecardiidae, Antipleuridae, Lunulacardiidae, Pterineidae, Posidoniidae, and Guangxiconchiidae, the Guangxiconchiidae (fam. nov.) is the most falourishing one. About 80% of individuals of bivalves belong to it. In contrast, the Pterineidae which was very flourish in the Xiangzhou facies, is represented by a small amount of specimens. In the generic level, the Guangxiconcha is mostly developed and distributed from Zlichovian to Givetian; c. This is a basically cosmopolitan fauna, and may compare with the contemperaneous bivalve fauna of the same facies of western Europe and North America. Among 11 genera of this fauna, 7 genera: Ptychopteria(Actinopteria), Cheiopteria, Pterochaenia, Posidonia, Lunulacardium and Buchiola are the cosmopolitan or basically cosmopolitan taxa, while Guangxiconcha, Nandannia and Opisthonia are the endemics to South China. 62% of the species are the endemics; d. This fauna is dominated by the small-sized, thin-shalled and fragile taxa. Except for Buchiola and Ptychopteria, most taxa are ornamented by fine concentrical line, or acrossed by very weakly radial line; e. About 54% of taxa and 90% of total individuals of this fauna may be the byssal attached epifauna, most of them may be the pseudoplanktonic bivalves.

Seven bivalve zones of Zlichovian–Givetian of Nandan, Guangxi have been recognized, and compared with the associated tentaculitid zones.
Richard Monastersky Receives 2017 Robert C. Cowen Award for Sustained Achievement in Science Journalism
Authors:   AGU
Published: January 2018

Richard Monastersky received the 2017 Cowen Award for Sustained Achievement in Science Journalism at the American Geophysical Union Fall Meeting Honors Ceremony, held on 13 December 2017 in New Orleans, La. The award honors “a journalist or team of journalists who have made significant, lasting, and consistent contributions to accurate reporting on the Earth and space sciences for the general public."
Caloric restriction lowers endocannabinoid tonus and improves cardiac function in type 2 diabetes
Authors: van Eyk Huub J. , van Schinkel Linda D. , Kantae Vasudev , Dronkers Charlotte E. A. , Westenberg Jos J. M. , de Roos Albert , Lamb Hildo J. , Jukema J. Wouter , Harms Amy C. , Hankemeier Thomas , van der Stelt Mario , Jazet Ingrid M. , Rensen Patrick C. N. , Smit Johannes W. A.
Published: January 2018

Background/Objectives

Endocannabinoids (ECs) are associated with obesity and ectopic fat accumulation, both of which play a role in the development of cardiovascular disease (CVD) in type 2 diabetes (T2D). The effect of prolonged caloric restriction on ECs in relation to fat distribution and cardiac function is still unknown. Therefore, our aim was to investigate this relationship in obese T2D patients with coronary artery disease (CAD).

Subjects/Methods

In a prospective intervention study, obese T2D patients with CAD (n = 27) followed a 16 week very low calorie diet (VLCD; 450–1000 kcal/day). Cardiac function and fat accumulation were assessed with MRI and spectroscopy. Plasma levels of lipid species, including ECs, were measured using liquid chromatography-mass spectrometry.

Results

VLCD decreased plasma levels of virtually all measured lipid species of the class of N-acylethanolamines including the EC anandamide (AEA; −15%, p = 0.016), without decreasing monoacylglycerols including the EC 2-arachidonoylglycerol (2-AG). Baseline plasma AEA levels strongly correlated with the volume of subcutaneous white adipose tissue (SAT; R2 = 0.44, p < 0.001). VLCD decreased the volume of SAT (−53%, p < 0.001), visceral white adipose tissue (VAT) (−52%, p < 0.001), epicardial white adipose tissue (−15%, p < 0.001) and paracardial white adipose tissue (−28%, p < 0.001). VLCD also decreased hepatic (−86%, p < 0.001) and myocardial (−33%, p < 0.001) fat content. These effects were accompanied by an increased left ventricular ejection fraction (54.8 ± 8.7–56.2 ± 7.9%, p = 0.016).

Conclusions

Caloric restriction in T2D patients with CAD decreases AEA levels, but not 2-AG levels, which is paralleled by decreased lipid accumulation in adipose tissue, liver and heart, and improved cardiovascular function. Interestingly, baseline AEA levels strongly correlated with SAT volume. We anticipate that dietary interventions are worthwhile strategies in advanced T2D, and that reduction in AEA may contribute to the improved cardiometabolic phenotype induced by weight loss.
MiR-770 suppresses the chemo-resistance and metastasis of triple negative breast cancer via direct targeting of STMN1
Authors: Li Yaming , Liang Yiran , Sang Yuting , Song Xiaojin , Zhang Hanwen , Liu Ying , Jiang Liyu , Yang Qifeng
Published: January 2018

Chemo-resistance and metastasis of triple negative breast cancer (TNBC) contributed the most of treatment failure in the clinic. MicroRNAs (miRNAs) have been proved to be involved in many biological processes and diseases. In this study, we aimed to determine the role of miR-770 in the regulation of chemo-resistance and metastasis of TNBC. Clinically, miR-770 was highly expressed in chemo-sensitive tissues and predicted a better prognosis of TNBC. Functionally, ectopic expression of miR-770 suppressed the doxorubicin-resistance of TNBC cell lines via regulation of apoptosis and tumor microenvironment, which was mediated by exosomes. Moreover, miR-770 overexpression inhibited the migration and invasion. Rescue of STMN1 could partly reverse the effect of miR-770 in TNBC behaviors. Furthermore, we also demonstrated that overexpression of miR-770 inhibited DOX resistance and metastasis in vivo. Taken together, our results proved that miR-770 could suppress the doxorubicin-resistance and metastasis of TNBC cells, which broaden our insights into the underlying mechanisms in chemo-resistance and metastasis, and provided a new prognostic marker for TNBC cells.
∆133p53 isoform promotes tumour invasion and metastasis via interleukin-6 activation of JAK-STAT and RhoA-ROCK signalling
Authors: Campbell Hamish , Fleming Nicholas , Roth Imogen , Mehta Sunali , Wiles Anna , Williams Gail , Vennin Claire , Arsic Nikola , Parkin Ashleigh , Pajic Marina , Munro Fran , McNoe Les , Black Michael , McCall John , Slatter Tania L. , Timpson Paul , Reddel Roger , Roux Pierre , Print Cristin , Baird Margaret A. , Braithwaite Antony W.
Published: January 2018

∆122p53 mice (a model of ∆133p53 isoform) are tumour-prone, have extensive inflammation and elevated serum IL-6. To investigate the role of IL-6 we crossed ∆122p53 mice with IL-6 null mice. Here we show that loss of IL-6 reduced JAK-STAT signalling, tumour incidence and metastasis. We also show that ∆122p53 activates RhoA-ROCK signalling leading to tumour cell invasion, which is IL-6-dependent and can be reduced by inhibition of JAK-STAT and RhoA-ROCK pathways. Similarly, we show that Δ133p53 activates these pathways, resulting in invasive and migratory phenotypes in colorectal cancer cells. Gene expression analysis of colorectal tumours showed enrichment of GPCR signalling associated with ∆133TP53 mRNA. Patients with elevated ∆133TP53 mRNA levels had a shorter disease-free survival. Our results suggest that ∆133p53 promotes tumour invasion by activation of the JAK-STAT and RhoA-ROCK pathways, and that patients whose tumours have high ∆133TP53 may benefit from therapies targeting these pathways.
Protein phosphatase 5 regulates titin phosphorylation and function at a sarcomere-associated mechanosensor complex in cardiomyocytes
Authors: Krysiak Judith , Unger Andreas , Beckendorf Lisa , Hamdani Nazha , von Frieling-Salewsky Marion , Redfield Margaret M. , dos Remedios Cris G. , Sheikh Farah , Gergs Ulrich , Boknik Peter , Linke Wolfgang A.
Published: January 2018

Serine/threonine protein phosphatase 5 (PP5) is ubiquitously expressed in eukaryotic cells; however, its function in cardiomyocytes is unknown. Under basal conditions, PP5 is autoinhibited, but enzymatic activity rises upon binding of specific factors, such as the chaperone Hsp90. Here we show that PP5 binds and dephosphorylates the elastic N2B-unique sequence (N2Bus) of titin in cardiomyocytes. Using various binding and phosphorylation tests, cell-culture manipulation, and transgenic mouse hearts, we demonstrate that PP5 associates with N2Bus in vitro and in sarcomeres and is antagonistic to several protein kinases, which phosphorylate N2Bus and lower titin-based passive tension. PP5 is pathologically elevated and likely contributes to hypo-phosphorylation of N2Bus in failing human hearts. Furthermore, Hsp90-activated PP5 interacts with components of a sarcomeric, N2Bus-associated, mechanosensor complex, and blocks mitogen-activated protein-kinase signaling in this complex. Our work establishes PP5 as a compartmentalized, well-controlled phosphatase in cardiomyocytes, which regulates titin properties and kinase signaling at the myofilaments.
Mechanically-sensitive miRNAs bias human mesenchymal stem cell fate via mTOR signalling
Authors: Frith Jessica E. , Kusuma Gina D. , Carthew James , Li Fanyi , Cloonan Nicole , Gomez Guillermo A. , Cooper-White Justin J.
Published: January 2018

Mechanotransduction is a strong driver of mesenchymal stem cell (MSC) fate. In vitro, variations in matrix mechanics invoke changes in MSC proliferation, migration and differentiation. However, when incorporating MSCs within injectable, inherently soft hydrogels, this dominance over MSC response substantially limits our ability to couple the ease of application of hydrogels with efficiently directed MSC differentiation, especially in the case of bone generation. Here, we identify differential miRNA expression in response to varying hydrogel stiffness and RhoA activity. We show that modulation of miR-100-5p and miR-143-3p can be used to bias MSC fate and provide mechanistic insight by demonstrating convergence on mTOR signalling. By modulating these mechanosensitive miRNAs, we can enhance osteogenesis in a soft 3D hydrogel. The outcomes of this study provide new understanding of the mechanisms regulating MSC mechanotransduction and differentiation, but also a novel strategy with which to drive MSC fate and significantly impact MSC-based tissue-engineering applications.
The protective role of DOT1L in UV-induced melanomagenesis
Authors: Zhu Bo , Chen Shuyang , Wang Hongshen , Yin Chengqian , Han Changpeng , Peng Cong , Liu Zhaoqian , Wan Lixin , Zhang Xiaoyang , Zhang Jie , Lian Christine G. , Ma Peilin , Xu Zhi-xiang , Prince Sharon , Wang Tao , Gao Xiumei , Shi Yujiang , Liu Dali , Liu Min , Wei Wenyi , Wei Zhi , Pan Jingxuan , Wang Yongjun , Xuan Zhenyu , Hess Jay , Hayward Nicholas K. , Goding Colin R. , Chen Xiang , Zhou Jun , Cui Rutao
Published: January 2018

The DOT1L histone H3 lysine 79 (H3K79) methyltransferase plays an oncogenic role in MLL-rearranged leukemogenesis. Here, we demonstrate that, in contrast to MLL-rearranged leukemia, DOT1L plays a protective role in ultraviolet radiation (UVR)-induced melanoma development. Specifically, the DOT1L gene is located in a frequently deleted region and undergoes somatic mutation in human melanoma. Specific mutations functionally compromise DOT1L methyltransferase enzyme activity leading to reduced H3K79 methylation. Importantly, in the absence of DOT1L, UVR-induced DNA damage is inefficiently repaired, so that DOT1L loss promotes melanoma development in mice after exposure to UVR. Mechanistically, DOT1L facilitates DNA damage repair, with DOT1L-methylated H3K79 involvement in binding and recruiting XPC to the DNA damage site for nucleotide excision repair (NER). This study indicates that DOT1L plays a protective role in UVR-induced melanomagenesis.
Qualitative systematic review of barriers and facilitators to self-management of chronic obstructive pulmonary disease: views of patients and healthcare professionals
Authors: Russell Siân , Ogunbayo Oladapo J. , Newham James J. , Heslop-Marshall Karen , Netts Paul , Hanratty Barbara , Beyer Fiona , Kaner Eileen
Published: January 2018

Self-management interventions for chronic obstructive pulmonary disease (COPD) can improve quality of life, reduce hospital admissions, and improve symptoms. However, many factors impede engagement for patients and practitioners. Qualitative research, with its focus on subjective experience, can provide invaluable insights into such factors. Therefore, a systematic review and synthesis of qualitative evidence on COPD self-management from the perspective of patients, carers, and practitioners was conducted. Following a systematic search and screening, 31 studies were appraised and data extracted for analysis. This review found that patients can adapt to COPD; however, learning to self-manage is often a protracted process. Emotional needs are considerable; frustration, depression, and anxiety are common. In addition, patients can face an assortment of losses and limitations on their lifestyle and social interaction. Over time, COPD can consume their existence, reducing motivation. Support from family can prove vital, yet tinged with ambivalence and burden. Practitioners may not have sufficient time, resources, or appropriate skills or confidence to provide effective self-management support, particularly in regard to patients’ psychosocial needs. This can compound patients’ capability to engage in self-management. For COPD self-management to be effective, patients’ psychosocial needs must be prioritised alongside medication and exacerbation management. In addition, patients’ personal beliefs regarding COPD and its management should be reviewed periodically to avoid problematic behaviours and enhance positive adaptions to the disease. Patients with COPD are not a homogenous group and no one intervention will prove effective for all. Finally, practitioners require greater education, training, and support to successfully assist patients.
Expression of the methionine sulfoxide reductase lost during evolution extends Drosophila lifespan in a methionine-dependent manner
Authors: Lee Byung Cheon , Lee Hae Min , Kim Sorah , Avanesov Andrei S. , Lee Aro , Chun Bok-Hwan , Vorbruggen Gerd , Gladyshev Vadim N.
Published: January 2018

Accumulation of oxidized amino acids, including methionine, has been implicated in aging. The ability to reduce one of the products of methionine oxidation, free methionine-R-sulfoxide (Met-R-SO), is widespread in microorganisms, but during evolution this function, conferred by the enzyme fRMsr, was lost in metazoa. We examined whether restoration of the fRMsr function in an animal can alleviate the consequences of methionine oxidation. Ectopic expression of yeast fRMsr supported the ability of Drosophila to catalyze free Met-R-SO reduction without affecting fecundity, food consumption, and response to starvation. fRMsr expression also increased resistance to oxidative stress. Moreover, it extended lifespan of flies in a methionine-dependent manner. Thus, expression of an oxidoreductase lost during evolution can enhance metabolic and redox functions and lead to an increase in lifespan in an animal model. More broadly, our study exposes the potential of a combination of genetic and nutritional strategies in lifespan control.