Latitude Ones Research Articles

History cooling events caused migrations of endangered Cathaya argyrophylla into low latitude refuges

Cathaya argyrophylla, referred as “the giant panda of plants”, is an endangered relict conifer species endemic to subtropical mountainous in China. The remanent populations of C. argyrophylla only survive in four refuges, while how the species migrated into these refuges remains unknown. To investigate the genetic structure and history of C. argyrophylla, here we genotyped four natural populations of C. argyrophylla using restriction site-related DNA sequencing (RAD-Seq). The four populations exhibited a relatively high level of nucleotide diversity (π = 0.29–0.33) and low differentiation (Fst = 0.04–0.12), with relatively high gene flow frequency (Nm = 1.86–6.00). We identified two historical migration events from high latitude populations to low latitude ones. The divergence times were corresponded to the starting time of population decline, which coincided with Naynayxungla Glaciation (∼0.8–0.5 Mya), the last glacial period (LGP, ∼115–11.7 kya) and the Holocene (∼10 kya). These results indicate that historical cooling events drove the endemic status of C. argyrphylla and its migration into low latitude refuges. Our findings provide insights into the evolutionary history and genetic diversity of this endangered species.

Transitions to new climates (TNCs) in the 21st century

We introduce the concept of transition to a new climate (TNC) based on ensembles of model projections. We consider a variable whose distribution due to interannual variability and inter-model spread of responses within a given time slice is measured by a certain compounded standard deviation, a TNC then occurs when the mean change signal of the variable between a future and a reference period exceeds the sum of the standard deviations for the two periods multiplied by a factor, taken here as 1.6 (see text). We calculate TNCs of regional mean annual surface air temperature from the CMIP6 ensemble of 21st century projections for 31 regions of the globe and four SSP scenarios. For the high-end scenarios, SSP5-8.5 and SSP3-7.0, we find the occurrence of at least one TNC in all regions and a second TNC in 15 and 10 regions, respectively, primarily located in tropical and mid-latitude regions and separated by about 40–45 years. For 30 out of 31 regions there is occurrence of a single TNC in the mid-level SSP2-4.5 scenario, while only 20 out of 31 regions experience a TNC in the low end SSP1-2.6. High latitude and polar regions tend to experience fewer and later occurring TNCs than low latitude ones, due to their larger interannual variability and inter-model response. On the one hand, the occurrence of at least one TNC, and in some scenarios and regions two TNCs, imply severe stress for adaptation of natural ecosystems and different socioeconomic sectors. On the other, the pronounced reduction of TNC occurrence in the low end scenarios point to the urgency of implementing effective mitigation policies to curb global warming.

Core surface sub-centennial magnetic flux patches: characteristics and evolution

Short-term constituents of the secular variation, at inter-decadal (20–30 years) and sub-centennial (60–90 years) time scales, present in observatory data and main field models, are also found in the radial field evolution at core surface. The paper is focused on the sub-centennial constituent in the gufm1 model. Time–Longitude (t–λ) plots, covering the 400 years time span of the model, at various latitudes between 70°N and 70°S, show a clear westward movement of the sub-centennial constituent field features in the 20°N–20°S latitude band. The sub-centennial constituent at latitudes larger than 50°N/S stands in fact for the fine structure of high-latitude flux lobes. Since 1900 this fine structure shows a westward displacement. Time–Latitude (t–φ) plots indicate also northward and southward components of the movement. The traveling speeds of the sub-centennial constituent field are derived, on one hand, empirically based on Time–Longitude and Time–Latitude plots, and on the other, mathematically by means of the Radon transform method. Important results of this paper are related to characterization of the evolution of the radial field at core surface at sub-centennial time scales, namely (1) evidencing two types of azimuthal flow, equatorial and high latitude ones, responsible for the observed westward drift of the surface field, and (2) quantitative information on meridional displacements of the core surface magnetic flux patches.

Diversity of planktonic microorganisms in the Arctic Ocean

The present paper begins by reviewing recent developments in our understanding of the diversity of planktonic microorganisms in the Arctic Ocean, taking into account recent data from high throughput sequencing techniques. This data has enabled deeper analysis of the many thousands of different microorganisms present in natural samples. The Arctic Ocean is similar to the other oceans in terms of the abundance and general composition of microbial communities. However, some traits are unique. For example, there are essentially no cyanobacteria in the Arctic and their ecological role seems to be taken up by picoeukaryotic algae. Recent comparisons of the bacterial communities from the two Polar oceans with those from temperate waters showed that Polar communities were closer to each other than to the lower latitude ones. However, they only shared about 15% of the taxa. Newer data considerably increases the coverage of Arctic sites sampled and indicates that bacterial communities in the Arctic vary significantly across regions and seasons. In particular several recent cruises have provided access to the Arctic Ocean during the winter, the least known season and we review two instances of active microbes during the winter. First a bloom of Thaumarchaeota that may have been based on the use of urea as a source of carbon and reducing power, and second the increase in picoeukaryotic algae as soon as light reaches the ocean in February. Both examples show that there is considerable microbial activity during the Polar winter.

Genetic diversity within vertebrate species is greater at lower latitudes

The latitudinal gradient of species diversity is one of the oldest recognized patterns in biology. While the cause of the pattern remains debated, the global signal of greater diversity toward the tropics is widely established. Whether the pattern holds for genetic diversity within species, however, has received much less attention. We examine latitudinal variation of intraspecific genetic diversity by contrasting nucleotide distance within low- and high-latitude animal groups. Using mitochondrial DNA markers across 72 vertebrate species that together span six continents, two oceans, and 129 degrees of latitude, we found significantly greater genetic diversity at low latitudes within mammalian species, and trends consistent with this pattern in reptiles, amphibians, fish, and birds. The signal held even after removing species whose current geographic ranges include areas recently covered by glaciers during the late Pleistocene and which presumably have experienced colonization bottlenecks in high latitudes. Higher genetic diversity within species was found at low latitudes also for genera that do not possess higher species richness toward the tropics. Moreover, examination of a subset of species with sufficient sampling across a broad geographic range revealed that genetic variation demonstrates a typical gradient, with mid-latitude populations intermediate in genetic diversity between high and low latitude ones. These results broaden the pattern of the global latitudinal diversity gradient, to now include variation within species. These results are also concordant with other studies indicating that low latitude populations and species are on different evolutionary trajectories than high latitude ones, and we speculate that higher rates of evolution toward the equator are driving the pattern for genetic diversity within species.

Cephalopod and brachiopod fossils from the Pacific: Evidence from the Upper Cretaceous of the Magellan Seamounts

Maastrichtian cephalopods and a brachiopod were dredged from the Butakov, Fedorov, Kotsebu, Il’ichev, Govorov, Gelendzhik, and Ita-Mai-Tai guyots in the Magellan Seamounts. The ammonoids Hypophylloceras sp., Phyllopachiceras sp., Anagaudryceras? sp. A, Anagaudryceras? sp. B, Gaudryceras aff. propemite Marshall, Gaudryceras sp., and Pseudophyllites cf. indra (Forbes), and the single brachiopod Basiliolidae gen. and sp. indet. are a first discovery in this oceanic region, following earlier finds of belemnites (Dimitobelus? sp., Dimitobelidae gen. and sp. nov., and Belemnitella? sp.), and two ammonoid species (Zelandites aff. japonicus Matsumoto and Tetragonitidae gen. and sp. indet.). The Late Cretaceous Magellan Seamounts dimitobelid belemnite fauna shows affinities with southern high latitude forms (New Zealand) and the ammonoid fauna with northern, middle and high latitude ones (Hokkaido-Sakhalin and/or Kamchatka). This suggests by the end of the Cretaceous major surface palaeo-currents from S and N sides in direction of the central Palaeo-Pacific, a position coinciding with the plate tectonic reconstruction of the Magellan Seamounts.

Comparisons between ground-based FTIR and MIPAS N<sub>2</sub>O and HNO<sub>3</sub> profiles before and after assimilation in BASCOE

Abstract. Within the framework of the Network for Detection of Atmospheric Composition Change (NDACC), regular ground-based Fourier transform infrared (FTIR) measurements of many species are performed at several locations. Inversion schemes provide vertical profile information and characterization of the retrieved products which are therefore relevant for contributing to the validation of MIPAS profiles in the stratosphere and upper troposphere. We have focused on the species HNO3 and N2O at 5 NDACC-sites distributed in both hemispheres, i.e., Jungfraujoch (46.5° N) and Kiruna (68° N) for the northern hemisphere, and Wollongong (34° S), Lauder (45° S) and Arrival Heights (78° S) for the southern hemisphere. These ground-based data have been compared with MIPAS offline profiles (v4.61) for the year 2003, collocated within 1000 km around the stations, in the lower to middle stratosphere. To get around the spatial collocation problem, comparisons have also been made between the same ground-based FTIR data and the corresponding profiles resulting from the stratospheric 4D-VAR data assimilation system BASCOE constrained by MIPAS data. This paper discusses the results of the comparisons and the usefullness of using BASCOE profiles as proxies for MIPAS data. It shows good agreement between MIPAS and FTIR N2O partial columns: the biases are below 5% for all the stations and the standard deviations are below 7% for the three mid-latitude stations, and below 10% for the high latitude ones. The comparisons with BASCOE partial columns give standard deviations below 4% for the mid-latitude stations to less than 8% for the high latitude ones. After making some corrections to take into account the known bias due to the use of different spectroscopic parameters, the comparisons of HNO3 partial columns show biases below 3% and standard deviations below 15% for all the stations except Arrival Heights (bias of 5%, standard deviation of 21%). The results for this species, which has a larger spatial variability, highlight the necessity of defining appropriate collocation criteria and of accounting for the spread of the observed airmasses. BASCOE appears to have more deficiencies in producing proxies of MIPAS HNO3 profiles compared to N2O, but the obtained standard deviation of less than 10% between BASCOE and FTIR is reasonable. Similar results on profiles comparisons are also shown in the paper, in addition to partial column ones.

Distribution, behavior and fate of PCBs in the marine environment

I am extremely grateful and honored for being awarded the Okada Prize (1985) for my study. The present article reviews my research on the distribution, behavior and fate of PCBs in the marine environment. The outline of this study is summarized as follows: 1. Polychlorinated biphenyls (PCBs) were detectable in the wide range of environmental media and biota of the Seto-Inland Sea, Japan, in which much high concentrations were found in sediment and biological samples due to their hydrophobic, lipophilic and less biodegradable properties as well as their extensive production and use in estuarine and coastal regions. 2. PCBs extend the boundaries of their distribution all over the global environment, being evidenced by their occurrence in open ocean atmosphere, hydrosphere and biosphere, even in Antarctica. The global contamination of PCBs is much more prominent in northern hemisphere than in southern hemisphere. 3. The sinking rate of PCBs from surface to deeper layers in open ocean water column is relatively slower in tropical waters than in high latitude ones. This implies the possible prolonged contamination of persistent synthetic organic chemicals in the tropical marine environment. 4. The bioaccumulation processes in marine ecosystems can be explained by the physicochemical and biochemical properties of PCBs and the metabolic capacity of organisms. In higher animals, additional factors such as parturition and lactation are also related to this process. 5. Total PCB load in global environment was estimated to be about 370 thousand tons. Of this, most amounts were in coastal sediment and open ocean water. Presently, about 780 thousand tons of PCBs are still in use mainly in electrical equipments. In order to reduce the PCB levels in marine environment, pertinent measures to prevent the further discharge and safe disposal of PCBs are required.

Environmental Behavior and Fate of Persistent Organochlorines (Recent Evidences on Dynamics in Environment and Toxicity of Organochlorine Compounds) (Proceedings of the 11 th Symposium on Environmental Pollutants and Toxicology)

The persistent organochlorines such as PCBs, DDT compounds and HCH (BHC) isomers were detectable all over the environmental media and biota, in which much higher levels were found in agricultural soil, coastal sediment and biological samples due to their hydrophobic, lipophilic and less biodegradable properties. These pollutants extend the boundaries of distribution over the global environment, being evidenced by their occurrence in Antarctic atmosphere, hydrosphere and biosphere. In open ocean environment, organochlorine contamination is much more prominent in northern hemisphere than in southern hemisphere. The open ocean water serves as a vast reservoir and final sink of these persistent organochlorines. The clearance rate of these chemicals from surface to deeper layer in open ocean water columns is relatively slower in tropical waters than in high latitude ones. This implies the possible prolonged contamination of persistent organochlorines in the tropical marine environment, even if their uses would be stopped in the future. The bioaccumulation processes in marine organisms depend primarily on the physicochemical and biochemical properties of organochlorines and the metabolic capacity and life-span of organisms. The species-specific drug metabolizing enzymes might be related to the differencial ecotoxicity of xenobiotics in wild animals. Of these organochlorines, PCBs are most noticeable chemicals in view of the future trend of environmental contamination. About two thirds of cummulative production of PCBs are still in use mainly for electrical equipments. The pertinent measures to prevent the further discharge of PCBs are required to reduce the present status of contamination in abiotic and biotic environment.

Relationships between the responses of spring wheat genotypes to temperature and photoperiodic treatments and their performance in the field

SUMMARYThirty-eight spring wheat genotypes of north temperate or low latitude origin, all reasonably well adapted to the English environment, were grown in controlled environments providing the four combinations of 10 and 14 h photoperiods and temperatures of 8 and 16 °C for 6 weeks. They were then transferred to a glasshouse to assess their responses to these treatments. In separate experiments the responses of the genotypes to vernalization for 2 and 4 weeks at 2 and 8 °C were compared with unvernalized controls. The genotypes were also compared in field experiments from early, intermediate or late sowing over 3 years.Both high temperatures and long days hastened ear emergence. At the higher temperature more leaves and spikelets were produced on the main stem while in long days the plants had fewer leaves and spikelets.Most genotypes of north temperate and low latitude origin were responsive to photoperiod but not to the vernalization treatments. As a group, the low latitude ones were as responsive as the north temperate group. Five genotypes of north temperate origin were responsive to vernalization but not to photoperiod and were designated as ‘winter’ ones. Pitic 62 and Hork, from low latitudes, were responsive to vernalization and Hork was unique in also being responsive to photoperiod. The main difference between the north temperate and low latitude genotypes was in time to ear emergence and it is suggested that these differences were due to the effects of earliness genes as distinct from those determining photoperiodic response.Taking all genotypes individually there were no correlations between yield or its sensitivity to sowing date and any of the attributes measured in controlled environments. However, considering class means, the winter genotypes were the latest to reach ear emergence in the field, and their yields, while greatest from the earliest sowings, were proportionally more depressed by late sowing than the others of the north temperate origin. Thus, it may be unwise for plant breeders to incorporate a vernalization response in spring wheat varieties unless genes for ‘earliness’ are also included. The low latitude class gave only slightly lower yields than the north temperate class.It is concluded that genes other than those controlling responses to photoperiod, temperature and vernalization were more important determinants of the differences in yield among this set of genotypes.

Classification and Investigation of Solar Flare Situations Conformably to Interplanetary and Magnetospheric Disturbances

A new classification of large solar flares is presented. If the time spacings between the flares are over 2.5 days, the flares and the corresponding interplanetary streams are classified as isolated ones. The concepts of the nearest, intermediate and distant flare zones (N, I and D zones) are introduced. The limits of the zones are determined at 30° longitude intervals and at 15° latitude ones. The classification is applied to the flares of 1966-1974 (Ivanov et al., 1979). It allows one to study the interplanetary and the magnetospherical disturbances more systematically.

Comparisons between Results of Polar Coordinates Derived from Time Data and Those from Latitude Ones

Computations of the polar coordinates are carried out by the use of time data and of latitude data separately. The results from time data and those from latitude data are proved to have mutual differences in annual term in particular. That is, polar loci obtained from latitude results give almost circular forms, while those from time results give elliptic forms elongated rather seriously on the X-axis.

Solar Flare and F Layer Critical Frequency

ABSTRACTIn an earlier study of the effect of some Mogel-Dellinger type of fade-outs at several stations, it was found that, after the fade-out, the trend of variation of the deviation Δf of F-2 critical frequency from the mean had a phase reversal at about 14°N geomagnetic latitude1. Three of the selected fade-outs and flares associated with them had started before ground sunrise at the Indian Stations. This paper deals with further investigation of the possible effect of solar flares on F layer critical frequency, f0F during the presunrise period. The analysis carried out for a large number of flares shows consistent results at stations in India and Japan. The flare associated changes in f0F at lower latitude stations are found to be opposite in phase to those at higher latitude ones. At Ahmedabad (14°N representing a lower latitude station) Δf becomes negative after flares corresponding to the period 0100–0400 hrs. local time, whereas for flares corresponding to 0400–0500 hrs. local time it becomes posi...