Ammonite evolution and its bearing on the Cenomanian — Turonian boundary problem

Recent records ofVascoceras andNigericeras from the Cenomanian are reviewed and considered to be based upon mis-identification and/or questionable stratigraphic evidence. Phylogenetic relationships suggest that both these genera are wholly Turonian. The new genusProvascoceras is erected for the uppermost CenomanianVascoceras diartianus (d’Oreigny) whilst the Upper CenomanianPseudotissotia inopinata Kennedy & Bayliss is shown to be an homoeomorphous offshoot ofAcompsoceras, unrelated to the Turonian genus, for which the new genusKennediella is proposed. A refined zonal subdivision of the Turonian Stage is proposed.     

Nonflowers near the base of extant angiosperms? Spatiotemporal arrangement of organs in reproductive units of Hydatellaceae and its bearing on the origin of the flower

Reproductive units (RUs) of Trithuria, the sole genus of the early-divergent angiosperm family Hydatellaceae, are compared with flowers of their close relatives in Cabombaceae (Nymphaeales). Trithuria RUs combine features of flowers and inflorescences. They differ from typical flowers in possessing an "inside-out" morphology, with carpels surrounding stamens; furthermore, carpels develop centrifugally, in contrast to centripetal or simultaneous development in typical flowers. Trithuria RUs could be interpreted as pseudanthia of two or more cymose partial inflorescences enclosed within an involucre, but the bractlike involucral phyllomes do not subtend partial inflorescences and hence collectively resemble a typical perianth. Teratological forms of T. submersa indicate a tendency to fasciation and demonstrate that the inside-out structure-the primary feature that separates RUs of Hydatellaceae from more orthodox angiosperm flowers-can be at least partially modified, thus producing a morphology that is closer to an orthodox flower. The Trithuria RU could be described as a "nonflower", i.e., a structure that contains typical angiosperm carpels and stamens but does not allow recognition of a typical angiosperm flower. The term nonflower could combine cases of secondary loss of flower identity and cases of a prefloral condition, similar to those that gave rise to the angiosperm flower. Nonhomology among some angiosperm flowers could be due to iterative shifts between nonfloral construction and flower/inflorescence organization of reproductive organs. Potential testing of these hypotheses using evolutionary-developmental genetics is explored using preliminary data from immunolocalization of the floral meristem identity gene LEAFY in T. submersa, which indicated protein expression at different hierarchical levels.     

Permian and early Triassic isotopic records of carbon and strontium in Australia and a scenario of events about the Permian‐Triassic boundary

The negative shift in δ¹³C values of carbonate carbon at the Permian/Triassic boundary is one of the better documented geochemical signatures of a mass extinction event. The similar negative shift in δ¹³C values in organic carbon from Permian/Triassic boundary marine sediments in Austria and Canada is shown to occur also in marine and non‐marine sediments from Australian sedimentary basins. This negative shift in δ¹³C values is used to calibrate Australian sections lacking diagnostic faunal elements identifying the Permian/Triassic boundary. The minimum in the carbonate ⁸⁷Sr/⁸⁶Sr seawater curve from carbonates across the Guadalupian/Ochoan Stage boundary, mainly from North America, is shown to occur also in brachiopod calcite mainly from the Bowen Basin of eastern Australia, hence providing a second calibration point in the Australian sedimentary record. These two geochemical events support a model of a runaway greenhouse developing about the Permian/Triassic boundary; this is inferred to have contributed to the end‐Permian mass extinction.     

Facies and geochemical evidence bearing on the end‐triassic disappearance of the alpine reef ecosystem

A carbon and oxygen isotope profile is presented across the Triassic‐Jurassic boundary at the classic locality of Kendelbach, Austria. In conjunction with faciès data it lends no support to the claim that the spectacular disappearance of the reef ecosystem at the end of the Triassic was due to a sharp fall of seawater temperature. A model relating mass extinction to sea‐level change is preferred.     

First Middle–Late Jurassic gladius vestiges provide new evidence on the detailed origin of incirrate and cirrate octopuses (Coleoidea)

Limpet-like and non-mineralized fossils from the upper Kimmeridgian Nusplingen Plattenkalk are identified as internal shells of coleoid cephalopods, more specifically as octobrachian gladii. The significantly reduced median field provokes us to consider this new gladius type to be shorter than the mantle length. It is consequently seen as a vestigial gladius. The first recognition of an unpaired gladius vestige in the fossil record sheds new light on the evolutionary history of the gladius vestiges of incirrate and cirrate Octopoda. Patelloctopus ilgi sp. nov. is most similar to Callovian Pearceiteuthis buyi in having a rudimentary median field with an extraordinary large opening angle and radiating ribs on the lateral fields. Both P. ilgi sp. nov. and P. buyi are therefore combined in the new family Patelloctopodidae. The patella-shaped lateral fields of the gladius vestige exposes Patelloctopus and Pearceiteuthis as members of the superfamily Muensterelloidea, which includes, apart from Patelloctopodidae, the Muensterellidae and Enchoteuthidae. The unpaired patelloctopodid gladius vestige is morphologically intermediate between the muensterelloid gladius type and the paired (bipartite) gladius vestige of Late Cretaceous Palaeoctopodidae (Palaeoctopus, Keuppia). The gladius vestige morphology suggests that the mode of locomotion and the life style of these shallow water inhabitants were similar to those of extant deep-sea octopods (Cirrata) and that the Patelloctopodidae represents the stem group of the Octopoda (Cirrata and Incirrata), although Patelloctopus ilgi sp. nov. might alternatively be a stem incirrate.     

Does rapid evolution matter? Measuring the rate of contemporary evolution and its impacts on ecological dynamics

Rapid contemporary evolution due to natural selection is common in the wild, but it remains uncertain whether its effects are an essential component of community and ecosystem structure and function. Previously we showed how to partition change in a population, community or ecosystem property into contributions from environmental and trait change, when trait change is entirely caused by evolution (Hairston et al. 2005). However, when substantial non-heritable trait change occurs (e.g. due to phenotypic plasticity or change in population structure) that approach can mis-estimate both contributions. Here, we demonstrate how to disentangle ecological impacts of evolution vs. non-heritable trait change by combining our previous approach with the Price Equation. This yields a three-way partitioning into effects of evolution, non-heritable phenotypic change and environment. We extend the approach to cases where ecological consequences of trait change are mediated through interspecific interactions. We analyse empirical examples involving fish, birds and zooplankton, finding that the proportional contribution of rapid evolution varies widely (even among different ecological properties affected by the same trait), and that rapid evolution can be important when it acts to oppose and mitigate phenotypic effects of environmental change. Paradoxically, rapid evolution may be most important when it is least evident.     

From proto-mitosis to mitosis — An alternative hypothesis on the origin and evolution of the mitotic spindle

Based on the assumption that the ancestral proto-eukaryote evolved from an ameboid prokarybte I propose the hypothesis that nuclear division of the proto-eukaryote was effected by the same system of contractile filaments it used for ameboid movement and cytosis. When the nuclear membranes evolved from the cell membrane, contractile filaments remained associated with them. The attachment site of the genome in the nuclear envelope was linked to the cell membrane by specialized contractile filaments. During protomitosis, i.e., nuclear and cell division of the proto-eukaryote, these filaments performed segregation of the chromosomes, whereas others constricted and cleaved the nucleus and the mother cell. When microtubules (MTs) had evolved in the cytoplasm, they also became engaged in nuclear division. Initially, an extranuolear bundle of MTs assisted chromosome segregation by establishing a defined axis. The evolutionary tendency then was towards an increasingly important role for MTs. Spindle pole bodies (SPBs) developed from the chromosomal attachment sites in the nuclear envelope and organized an extranuclear central spindle. The chromosomes remained attached to the SPBs during nuclear division. In a subsequent step the spindle became permanently lodged inside the nucleus. Chromosomes detached from the SPBs and acquired kinetochores and kinetochore-MTs. At first, this spindle segregated chromosomes by elongation, the kinetochore-MTs playing the role of static anchors. Later, spindle elongation was supplemented by poleward movement of the chromosomes. When dissolution of the nuclear envelope at the beginning of mitosis became a permanent feature, the open spindle of higher eukaryotes was born.     

Rediscovery of the lost little dogwood Cornus wardiana (Cornaceae)—Its phylogenetic and morphological distinction and implication in the origin of the Arctic‐Sino‐Himalayan disjunction

The dwarf dogwoods (subgenus Arctocrania) have been widely known to consist of three circumboreal species Cornus suecica, Cornus canadensis, and Cornus unalaschkensis. A fourth putative species was discovered from the northern Myanmar in 1937, but it had never been formally reported on. Here, we formally report the species on the basis of phylogenetic and morphological evidence and name it Cornus wardiana Rushforth & Wahlsteen (sp. nov.). We conducted phylogenetic and morphometric analyses to determine its evolutionary relationship and differentiation from the existing relatives. We dated the phylogeny using molecular data and conducted a biogeographic analysis to gain insights into the evolution and biogeography of the Arctic‐Sino‐Himalayan disjunction. The phylogenetic analysis used sequences of the nrITS and plastid matK and rbcL genes and included all four dwarf dogwoods and 20 other species representing the three other major lineages of Cornus and the outgroup. The morphometric analyses included 60 populations and 102 specimens of dwarf dogwood, representing the entire range of the subgenus. The results showed that C. wardiana diverged first within subgenus Arctocrania in the Miocene, from a wide‐spread ancestor. Results from principal component analysis and discriminant analysis also showed that the Myanmar samples are well separated from the others. Taken together, these results suggest that the dwarf dogwood lineage split from the big‐bracted dogwoods in Asia or Asia‐western North America during the late Paleocene and spread widely to form a Eurasia‐North America distribution; the Arctic‐Sino‐Himalayan disjunction was the result of southward migration in the Miocene followed by extinction in the intervening highland areas.     

On the origin and domestication of Olea europaea L. (olive) in Andalucía, Spain, based on the biogeographical distribution of its finds

The remains of Olea europaea in archaeological contexts in the southern Iberian Peninsula have been found in the Epipalaeolithic levels of Cueva de Nerja (10860±160 b.p.). The abundant appearance of charcoal and some seed remains from the Copper Age (3rd millennium b.c.) in the coastal zones of the southeast indicate that this species formed part of the vegetation of the Thermo-mediterranean zone and that its fruits were collected during these periods. However, Olea did not appear in the Meso-mediterranean zone until the Roman period, when olive cultivation was introduced there. The presence of charcoal and olive stones from the 1st century a.d. onwards is abundant, together with remains of structures for oil pressing.     

Sudden infant death syndrome and the age‐cause proxy relationship in infancy

Abstract

Evidence from a longitudinal study of the relationship between socioeconomic status and infant mortality in metropolitan Ohio is presented in an effort to throw additional light on the continuing debate over the validity of the age‐cause proxy relationship in infancy. The results indicate that while there is a fairly strong and consistent association between neonatal mortality and endogenous causes of death that is little affected by the classification of Sudden Infant Death Syndrome, the nature of the association between postneonatal mortality and exogenous causes of death varies from weak to moderate depending upon where this cause is included. Additional evidence pertaining to the role of SIDS in contributing to the long‐standing inverse association between infant mortality and socioeconomic status is presented, thus further emphasizing the need for continued research to clarify the etiologic mechanisms of this poorly understood condition.     

Triassic/Jurassic carbonates from the Hochfelln Mountain (Northern Calcareous Alps)—its facies, silicified fauna and implications for the end-Triassic biotic crisis

A suite of Early Mesozoic (Late Triassic, Norian to Early Jurassic) calcareous beds was studied from the Hochfelln Mountain in the Northern Calcareous Alps (NCA, South Germany). The Hauptdolomit Group consists of thick peritidal deposits and is overlain by basin deposits of the Rhaetian Kössen Formation and Rhaetian reefoidal limestone with corals. Unlike many other sections in the Tethys realm, coral growth seems to continue into the Jurassic or starts again relatively early within the Early Jurassic. Silicified corals and other marine invertebrates are present in the calcareous, micritic Hochfelln Beds. A re-examination of previously collected ammonite material indicates the presence of Coroniceras sp. which suggests an Early Sinemurian age for the Hochfelln Beds. Abundant sponge spicules (spiculites) suggest that sponges were the source for the silicification. The site produced one of the most diverse Early Jurassic (Sinemurian) gastropod faunas of the NCA (25–30 species, some undescribed). The relatively diverse Early Sinemurian gastropod fauna and coral growth indicate rapid recovery from the end-Triassic biotic crisis.     

Palynofacies analysis for interpreting paleoenvironment and hydrocarbon potential of Triassic–Jurassic strata in the Sichuan Basin,China

The Sichuan Basin is one of the largest petroliferous basins in China. The continental fluvial?lacustrine sediments of the Upper Triassic Xujiahe Formation and the Lower Jurassic Zhenzhuchong Formation yield diverse fossil organisms and host one of the most important gas reservoirs in the basin. However, paleontological implication for the paleoenvironment and hydrocarbon source is less documented. Here, we report, for the first time for this basin, results from palynofacies analyses combined with thermal alteration data in the Early Mesozoic deposit of the Qilixia section, northeastern Sichuan Basin. The results show that, organic matters in sediments are dominated by phytoclasts, with less abundant palynomorphs and a few amorphous organic matters (AOMs). Four palynofacies assemblages were identified, reflecting depositional settings in a general proximal and oxic fluvial?deltaic environment, with two distal–proximal sedimentary cycles. The prominent dominance of opaque phytoclasts within the lower Zhenzhuchong Formation may be related to frequent wildfires across the Triassic–Jurassic transition. Palynofacies data (especially the relative abundance of opaque phytoclasts) may reflect 405 kyr eccentricity cyclicity pattern. The palynofacies and thermal alteration index (TAI), combined with geochemical data indicate the presence of type III kerogen in mature to post-mature phases, suggesting gas potential of the Xujiahe and Zhenzhuchong formations in the northeastern Sichuan Basin. This study provides significant implications for better understanding the paleoenvironment variations during the Triassic–Jurassic transition and the future gas exploration in this area.     

Age‐Related Effects on the Biological Clock and its Behavioral Output in a Primate

In humans, activity rhythms become fragmented and attenuated in the elderly. This suggests an alteration of the circadian system per se that could in turn affect the expression of biological rhythms. In primates, very few studies have analyzed the effect of aging on the circadian system. The mouse lemur provides a unique model of aging in non‐human primates. To assess the effect of aging on the circadian system of this primate, we recorded the circadian and daily rhythms of locomotor activity of mouse lemurs of various ages. We also examined age‐related changes in the daily rhythm of immunoreactivities for vasoactive intestinal polypeptide (VIP) and arginine‐vasopressin (AVP) in suprachiasmatic nucleus neurons (SCN), two major peptides of the biological clock. Compared to adult animals, aged mouse lemurs showed a significant increase in daytime activity and an advanced activity onset. Moreover, when maintained in constant dim red light, aged animals exhibited a shortening of the free‐running period compared to adult animals. In adults, AVP immunoreactivity (ir) peaked during the second part of the day, and VIP ir peaked during the night. In aged mouse lemurs, the peaks of AVP ir and VIP ir were significantly shifted with no change in amplitude. AVP ir was most intense at the beginning of the night; whereas, VIP ir peaked at the beginning of the daytime. A weakened oscillator could account for the rhythmic disorders often observed in the elderly. Changes in the daily rhythms of AVP ir and VIP ir may affect the ability of the SCN to transmit rhythmic information to other neural target sites, and thereby modify the expression of some biological rhythms.     

Minorities policy in the post‐Soviet republics: The case of the Gagauzi

This article explores the obstacles to crafting comprehensive policies for ethnic minorities within the Soviet successor states. It focuses on a case that has been viewed as a model for the peaceful resolution of ethnic conflict in the region: Moldova's devolution of power to its small Gagauz (Christian Turkic) minority. The relationship between the Moldovan government and the Gagauzi reached its nadir in 1990, when Moldovan volunteer forces and Gagauz irregulars stood at the brink of all‐out civil war over the issue of a separate Gagauz political entity. Since then, however, Moldova has created a special administrative unit known as Gagauz Yeri ('the Gagauz land'). In contrast to other ethno‐territorial disputes in the former Soviet Union, the Gagauz case has illustrated that a range of policy options exists between the extremes of maintaining a highly centralized, unitary state structure and the devolution of authority to loosely related confederative units.     

On the origin and evolution of new genes——a genomic and experimental perspective

The inherent interest on the origin of genetic novelties can be traced back to Darwin, But it was not until recently that we were allowed to investigate the fundamental process of origin of new genes by the studies on newly evolved young genes. Two indispensible steps are involved in this process: origin of new gene copies through various mutational mechanisms and evolution of novel functions, which fur-ther more leads to fixation of the new copies within populations. The theoretical framework for the former step formed in 1970s. Ohno proposed gene duplication as the most important mechanism producing new gene copies. He also believed that the most common fate for new gene copies is to become pseudogenes. This classical view was validated and was also challenged by the characterization of the first functional young gene jingwei in Drosophila. Recent genome-wide comparison on young genes of Drosophila has elucidated a compre-hensive picture addressing remarkable roles of various mechanisms besides gene duplication during origin of new genes. Case surveys revealed it is not rare that new genes would evolve novel structures and functions to contribute to the adaptive evolution of organisms.Here, we review recent advances in understanding how new genes originated and evolved on the basis of genome-wide results and ex-perimental efforts on cases, We would finally discuss the future directions of this fast-growing research field in the context of functional genomics era.