Hypothesis Of Expansion Research Articles

Why the behavioural sciences need the concept of the culture-ready brain

From the conceptual gulf dividing social from biological anthropology this paper infers an ideological problem affecting science as a whole. Cultural biases have tended to inhibit or subvert appropriate theorizing and research into unique aspects of the human mind, brain and behaviour. To resolve this problem I suggest that we need a systematic anthropological critique of ‘collective deceptions’ affecting western science, and greater anthropological collaboration with neuroscience and other disciplines. I discuss recent imaging studies which may contribute to a better understanding of the culture-ready brain. Taken in conjunction with fossil and archaeological data, the findings seem more consistent with a ‘play and display’ hypothesis of hominid brain expansion than with current cognocentric hypotheses, suggesting new directions for research. Such research, I argue, could assist integration between behavioural disciplines.

Towards a model of postglacial biogeography in shallow marine species along the Patagonian Province: lessons from the limpet Nacella magellanica (Gmelin, 1791).

BackgroundPatagonia extends for more than 84,000 km of irregular coasts is an area especially apt to evaluate how historic and contemporary processes influence the distribution and connectivity of shallow marine benthic organisms. The true limpet Nacella magellanica has a wide distribution in this province and represents a suitable model to infer the Quaternary glacial legacy on marine benthic organisms. This species inhabits ice-free rocky ecosystems, has a narrow bathymetric range and consequently should have been severely affected by recurrent glacial cycles during the Quaternary. We performed phylogeographic and demographic analyses of N. magellanica from 14 localities along its distribution in Pacific Patagonia, Atlantic Patagonia, and the Falkland/Malvinas Islands.ResultsMitochondrial (COI) DNA analyses of 357 individuals of N. magellanica revealed an absence of genetic differentiation in the species with a single genetic unit along Pacific Patagonia. However, we detected significant genetic differences among three main groups named Pacific Patagonia, Atlantic Patagonia and Falkland/Malvinas Islands. Migration rate estimations indicated asymmetrical gene flow, primarily from Pacific Patagonia to Atlantic Patagonia (Nem=2.21) and the Falkland/Malvinas Islands (Nem=16.6). Demographic reconstruction in Pacific Patagonia suggests a recent recolonization process (< 10 ka) supported by neutrality tests, mismatch distribution and the median-joining haplotype genealogy.ConclusionsAbsence of genetic structure, a single dominant haplotype, lack of correlation between geographic and genetic distance, high estimated migration rates and the signal of recent demographic growth represent a large body of evidence supporting the hypothesis of rapid postglacial expansion in this species in Pacific Patagonia. This expansion could have been sustained by larval dispersal following the main current system in this area. Lower levels of genetic diversity in inland sea areas suggest that fjords and channels represent the areas most recently colonized by the species. Hence recolonization seems to follow a west to east direction to areas that were progressively deglaciated. Significant genetic differences among Pacific, Atlantic and Falkland/Malvinas Islands populations may be also explained through disparities in their respective glaciological and geological histories. The Falkland/Malvinas Islands, more than representing a glacial refugium for the species, seems to constitute a sink area considering the strong asymmetric gene flow detected from Pacific to Atlantic sectors. These results suggest that historical and contemporary processes represent the main factors shaping the modern biogeography of most shallow marine benthic invertebrates inhabiting the Patagonian Province.

Intraspecific variation in Podostemum ceratophyllum (Podostemaceae): evidence of refugia and colonization since the last glacial maximum

Intraspecific variation among 20 populations of Podostemum ceratophyllum Michx. was investigated to test the hypothesis of range expansion from southern refugia since the last glacial maximum. Six noncoding regions of chloroplast DNA were sequenced in 60 individuals. Populations were divided into two groups, north and south of the glacial boundary, in addition to isolated populations in Arkansas and Honduras. Variation in populations north of the boundary was compared with variation in populations to the south and in the isolated populations. Nucleotide diversity was an order of magnitude lower in populations north of the glacial boundary than in those to the south. The Arkansas and Honduras populations showed no variation. The predominant haplotype in northern populations was also found in a Virginia population. Reduced variation north of the glacial boundary suggests a founder event associated with range expansion since the last glacial maximum. Colonization probably occurred from populations in refugia located several hundred kilometers south of the glacial boundary. The results provide insight into the effects of past and current climate change on patterns of geographic distribution and genetic variation in aquatic plants.

A Comparison of Two Theories of Perceived Distance on the Ground Plane: The Angular Expansion Hypothesis and the Intrinsic Bias Hypothesis

Two theories of distance perception—ie, the angular expansion hypothesis (Durgin and Li, 2011 Attention, Perception, & Psychophysics 73 1856–1870) and the intrinsic bias hypothesis (Ooi et al, 2006, Perception 35 605–624)—are compared. Both theories attribute exocentric distance foreshortening to an exaggeration in perceived slant, but their fundamental geometrical assumptions are very different. The intrinsic bias hypothesis assumes a constant bias in perceived geographical slant of the ground plane and predicts both perceived egocentric and exocentric distances are increasingly compressed. In contrast, the angular expansion hypothesis assumes exaggerations in perceived gaze angle and perceived optical slant. Because the bias functions of the two angular variables are different, it allows the angular expansion hypothesis to distinguish two types of distance foreshortening—the linear compression in perceived egocentric distance and the nonlinear compression in perceived exocentric distance. While the intrinsic bias is proposed only for explaining distance biases, the angular expansion hypothesis provides accounts for a broader range of spatial biases.

CON: Patients at High Risk for Ovarian Cancer Should Not Undergo Routine Screening

Vesicular pores are observed in many different soil-forming environments. They can also be re-created in the lab through exposure to cyclic wetting and drying. However, little is known about the physical, chemical, and biological mechanisms involved in vesicular pore formation. This study was conducted to test the hypotheses that 1) microbial activity and 2) thermal expansion are important drivers of vesicular pore growth. These hypotheses were tested through laboratory experiments employing treatments to manipulate the biota (i.e., sterile, non-sterile, and glucose-amended treatments) and temperature change (i.e., wetting at 7 °C, 23 °C, and 40 °C before drying at 40 °C). The growth of vesicular pores, as well as vughs and planar voids, was compared among the treatments using bulk densities measured by three-dimensional laser scanning and pore analysis by computed tomography. Pore growth was found to be significantly greater in sterile soils compared to non-sterile and glucose-amended soils. Comparison among the temperature treatments showed the greatest pore growth in the samples that experienced the greatest temperature change between wetting and drying (7 °C to 40 °C). These results support the thermal expansion hypothesis of vesicular pore development, but contradict the microbial activity hypothesis.

Reply to Attia and Bapat

Dear Editor We thank Drs Attia and Bapat for their comments and for sharing their experience. The analogy the authors make with stentless valve implantation is quite logical and supports the hypothesis of non-circular expansion of the deployed valve. [1] This complication is uncommon but illustrates how poorly tolerated acute aortic regurgitation (AR) is after transcatheter aortic valve implantation (TAVI). Indeed unless rapid deployment of an immobile leaflet is possible, all measures should be ready for an immediate insertion of a valve in a valve. The fatal issue in our case was due to severe ventricular dilatation from AR together with the delay incurred by the different attempts to mobilize the frozen leaflet before preparing and implanting the second prosthesis. [2] We fully agree that safe execution of TAVI procedures is dependent on careful monitoring during the procedure which should be performed with anaesthetic, echocardiographic and surgical team coordination.

Phylogeographic patterns of Calophyllum Braziliense Camb. (Calophyllaceae)based on the psbA-trnH cpDNA locus

Background Past climate changes have severely influenced the current distribution of species and their genetic diversity. Phylogeography is the study of the principles and processes governing the geographic distributions of genealogical lineages [1]. South America has the world’s largest area of swamps, floodplains and wetlands in general [2]. Brazil’s major wetlands cover 2% of the country’s huge territory [3]. However, from a plant ecology standpoint, Brazilian freshwater wetlands are largely unknown and the scarce data available refer mostly to flooded forests of the Amazon [4]. Calophyllum Braziliense Camb. (Calophyllaceae), also know as guanandi, jacareuba or landim, is a canopy tree species typical of waterlogged areas from South and Central America. This species occurs in the humid tropical forests of Central America, Amazon Forests, Atlantic Forest (including restingas); and in the riverines forests of the Cerrado biome (brazilian savannah) [5,6]. However, unlike other species typical of flooded areas, C. Braziliense shows none of the morphological features common to flood-adapted plants. Calophyllum Braziliense is a hermaphroditic tree pollinated by bees. Its seeds are animal (mainly by bats) or water dispersed. The timber has excellent characteristics and is widely used. Calophyllum. Braziliense is also used in vegetation restoration programs and its leaves extract presents antiinflammatory activity [7]. This study examines the phylogeographic patterns of C. Braziliense based on the cpDNA intergenic region psbA-trnH. Methods Twenty four populations of C. Braziliense were sampled from Costa Rica (10° 12’N, 83° 47’W) to the Parana State in Brazil (25° 34’S, 48° 27’W). Samples were collected from about 5-10 adult trees in each population, totaling 192 individuals. Total DNA was extracted from leaves or cambium using the CTAB procedure described by Doyle & Doyle [8]. After a screening for cpDNA amplification and polymorphism in C. Braziliense, the psbA-trnH intergenic regions was selected [9]. Sequences were aligned using CLUSTAL-W implemented in the MEGA 4 software. The cpDNA haplotypes were defined by analyzing the sequences with DNASP 4.01. The genetic diversity indexes were estimated in ARLEQUIN 3.01. The phylogenetic relationships among the haplotypes were estimated using the median-joining algorithm implemented in NETWORK 4.1. An analysis of molecular variance (AMOVA) was performed in ARLEQUIN. A spatial analysis of molecular variance (SAMOVA) was conduced using the SAMOVA 1.0 software. To evaluate the hypothesis of population expansion, neutrality tests were computed in DNASP and ARLEQUIN.

Egg-Dumping Behavior is Not Correlated with Wider Host Acceptance in the Seed Beetle Callosobruchus maculatus (Coleoptera: Chrysomelidae: Bruchinae)

Abstract If typical host plants are absent, some herbivorous insects “dump” eggs on unsuitable substrates, even though this can cause complete larval mortality and reduced maternal life span. In the seed beetle Callosobruchus maculatus (F.) (Coleoptera: Chrysomelidae: Bruchinae), the tendency to dump eggs varies genetically both within and between populations. A previous study hypothesized that egg-dumping behavior facilitates host-range expansions, and suggested that such expansions have served to maintain “dumper” genotypes in beetle populations. We tested this hypothesis in two experiments. For both African and Asian beetle populations, full-sib females from &amp;gt;60 families were split among three treatments: no seeds, a less-preferred novel host, and a preferred host. Within each population, we found no correlation among families between the tendency to dump eggs and the tendency to accept the novel host. We also compared egg dumping between selection lines that had adapted to a novel host and a line that had remained on the ancestral host. Females from lines that had evolved greater acceptance of the novel host did not dump more eggs if hosts were absent. Thus, neither experiment supported the host-range expansion hypothesis. Egg distributions on the preferred host in the first experiment provided weak support for a more proximate explanation: family-level variation in the tendency to dump eggs is inversely related to the tendency to avoid superparasitism of seeds. Such a relationship is also evident in comparisons between populations. Given the considerable short-term costs of egg dumping, we suggest that the host-range expansion hypothesis requires unrealistically high frequencies of host deprivation and subsequent host shifts in C. maculatus.

The Pennsylvanian–Permian transition in the low-latitude carbonate record and the onset of major Gondwanan glaciation

Recent studies suggest a marked expansion of glacial ice across much of Gondwana beginning in the earliest Permian. Because expansion of glacial ice results in a lowering of sea level, the imprint of ice expansion should be evident worldwide as significant exposure event, hiatuses, or other evidence for sea level drop at or near the Pennsylvanian–Permian boundary. This literature review investigates the signature of an Early Permian expansion of Gondwanan ice through examination of stratigraphic records from eight carbonate-dominated, palaeotropical regions across Pangaea. Tropical carbonate environments are used because most form in tectonically quiescent regions and are sensitive indicators of eustatic change. Correlation between stratigraphic sections is achieved using the most current biostratigraphic and absolute time constraints available. All studied sections show a sequence boundary or basinward shift in facies at or near the Pennsylvanian–Permian boundary, supporting the hypothesis of a significant expansion of glacial ice and global eustatic lowstand beginning in the Early Permian. By contrast, a series of mid-Sakmarian–Kungurian transgression events in the palaeotropics are interpreted to reflect the asynchronous deglaciation of Gondwana. The stratigraphic framework developed herein will allow for better correlations among stratigraphic records from Gondwana and northern Pangaea, which will ultimately improve the understanding of how carbonate systems respond to global icehouse conditions, such as during the late Palaeozoic.

Middle Paleolithic occupation on a Marine Isotope Stage 5 lakeshore in the Nefud Desert, Saudi Arabia

Major hydrological variations associated with glacial and interglacial climates in North Africa and the Levant have been related to Middle Paleolithic occupations and dispersals, but suitable archaeological sites to explore such relationships are rare on the Arabian Peninsula. Here we report the discovery of Middle Paleolithic assemblages in the Nefud Desert of northern Arabia associated with stratified deposits dated to 75,000 years ago. The site is located in close proximity to a substantial relict lake and indicates that Middle Paleolithic hominins penetrated deeply into the Arabian Peninsula to inhabit landscapes vegetated by grasses and some trees. Our discovery supports the hypothesis of range expansion by Middle Paleolithic populations into Arabia during the final humid phase of Marine Isotope Stage 5, when environmental conditions were still favorable.

The mechanism of lens placode formation: A case of matrix-mediated morphogenesis

Although placodes are ubiquitous precursors of tissue invagination, the mechanism of placode formation has not been established and the requirement of placode formation for subsequent invagination has not been tested. Earlier measurements in chicken embryos supported the view that lens placode formation occurs because the extracellular matrix (ECM) between the optic vesicle and the surface ectoderm prevents the prospective lens cells from spreading. Continued cell proliferation within this restricted area was proposed to cause cell crowding, leading to cell elongation (placode formation). This view suggested that continued cell proliferation and adhesion to the ECM between the optic vesicle and the surface ectoderm was sufficient to explain lens placode formation. To test the predictions of this “restricted expansion hypothesis,” we first confirmed that the cellular events that accompany lens placode formation in chicken embryos also occur in mouse embryos. We then showed that the failure of lens placode formation when the transcription factor, Pax6 was conditionally deleted in the surface ectoderm was associated with greatly diminished accumulation of ECM between the optic vesicle and ectoderm and reduced levels of transcripts encoding components of the ECM. In accord with the “restricted expansion hypothesis,” the Pax6-deleted ectoderm expanded, rather than being constrained to a constant area. As a further test, we disrupted the ECM by deleting Fn1, which is required for matrix assembly and cell–matrix adhesion. As in Pax6 CKO embryos, the Fn1 CKO lens ectoderm expanded, rather than being constrained to a fixed area and the lens placode did not form. Ectoderm cells in Fn1 CKO embryos expressed markers of lens induction and reorganized their cytoskeleton as in wild type ectoderm, but did not invaginate, suggesting that placode formation establishes the minimal mechanical requirements for invagination.

Financial Innovations, Credit Default Swaps, and Syndicated Loans

Loan syndication suffers from two types of agency problems – an adverse selection problem (lead arrangers pass on bad loans to the participants) and a moral hazard problem (lead arrangers shirk on their costly monitoring duties). Therefore, a lead arranger has to take a big share of the loan to certify the quality of borrower and to credibly commit to its monitoring duty. I argue that the invention of the CDS provides an instrument to reduce these agency problems when participant lenders purchase CDS protections from lead arrangers, which then allows lead arrangers to take smaller shares of loans. The interest rate on loan and the premium on CDS can serve as a reconciliation mechanism to reduce adverse selection problem because if a lead arranger bluffs the quality of a borrower and under-charge loan interest rate and CDS premium, the lead arranger will suffer two immediate losses – lower interest and CDS incomes, which will not be a feasible long term strategy for institutions willing to maintain their reputations. In the event of borrower default and physical settlement is used, lead arrangers have to take the loans back and pay the face values of loans to participants. The monetary interest can provide lead arrangers enough incentives to monitor borrowers. Therefore, besides explicitly managing risk, participant lenders can use CDSs to “trade” the monitoring duty back to lead arrangers. Using the credit derivatives data from Y-9C and more than 10,000 loan facilities, I found strong evidence supporting the syndicate expansion hypothesis that CDS plays a significant role in expanding loan syndicates, reducing lead arrangers’ capital contributions in the syndicates resulting in large loans for borrowers. The paper thus provides empirical evidence to show how financial innovations can profoundly impact banking practices.

Magmatic-vapor expansion and the formation of high-sulfidation gold deposits: Chemical controls on alteration and mineralization

Large bulk-tonnage high-sulfidation gold deposits, such as Yanacocha, Peru, are the surface expression of structurally-controlled lode gold deposits, such as El Indio, Chile. Both formed in active andesite–dacite volcanic terranes. Fluid inclusion, stable isotope and geologic data show that lode deposits formed within 1500 m of the paleo-surface as a consequence of the expansion of low-salinity, low-density magmatic vapor with very limited, if any, groundwater mixing. They are characterized by an initial ‘Sulfate’ Stage of advanced argillic wallrock alteration ± alunite commonly with intense silicification followed by a ‘Sulfide’ Stage — a succession of discrete sulfide–sulfosalt veins that may be ore grade in gold and silver. Fluid inclusions in quartz formed during wallrock alteration have homogenization temperatures between 100 and over 500 °C and preserve a record of a vapor-rich environment. Recent data for El Indio and similar deposits show that at the commencement of the Sulfide Stage, ‘condensation’ of Cu–As–S sulfosalt melts with trace concentrations of Sb, Te, Bi, Ag and Au occurred at > 600 °C following pyrite deposition. Euhedral quartz crystals were simultaneously deposited from the vapor phase during crystallization of the vapor-saturated melt occurs to Fe-tennantite with progressive non-equilibrium fractionation of heavy metals between melt-vapor and solid. Vugs containing a range of sulfides, sulfosalts and gold record the changing composition of the vapor. Published fluid inclusion and mineralogical data are reviewed in the context of geological relationships to establish boundary conditions through which to trace the expansion of magmatic vapor from source to surface and consequent alteration and mineralization. Initially heat loss from the vapor is high resulting in the formation of acid condensate permeating through the wallrock. This Sulfate Stage alteration effectively isolates the expansion of magmatic vapor in subsurface fracture arrays from any external contemporary hydrothermal activity. Subsequent fracturing is localized by the embrittled wallrock to provide high-permeability fracture arrays that constrain vapor expansion with minimization of heat loss. The Sulfide Stage vein sequence is then a consequence of destabilization of metal-vapor species in response to depressurization and decrease in vapor density. The geology, mineralogy, fluid inclusion and stable isotope data and geothermometry for high-sulfidation, bulk-tonnage and lode deposits are quite different from those for epithermal gold–silver deposits such as McLaughlin, California that formed near-surface in groundwater-dominated hydrothermal systems where magmatic fluid has been diluted to less than about 30%. High sulfidation gold deposits are better termed ‘Solfataric Gold Deposits’ to emphasize this distinction. The magmatic-vapor expansion hypothesis also applies to the phenomenology of acidic geothermal systems in active volcanic systems and equivalent magmatic-vapor discharges on the flanks of submarine volcanoes.

Genetic diversity in India and the inference of Eurasian population expansion

BackgroundGenetic studies of populations from the Indian subcontinent are of great interest because of India's large population size, complex demographic history, and unique social structure. Despite recent large-scale efforts in discovering human genetic variation, India's vast reservoir of genetic diversity remains largely unexplored.ResultsTo analyze an unbiased sample of genetic diversity in India and to investigate human migration history in Eurasia, we resequenced one 100-kb ENCODE region in 92 samples collected from three castes and one tribal group from the state of Andhra Pradesh in south India. Analyses of the four Indian populations, along with eight HapMap populations (692 samples), showed that 30% of all SNPs in the south Indian populations are not seen in HapMap populations. Several Indian populations, such as the Yadava, Mala/Madiga, and Irula, have nucleotide diversity levels as high as those of HapMap African populations. Using unbiased allele-frequency spectra, we investigated the expansion of human populations into Eurasia. The divergence time estimates among the major population groups suggest that Eurasian populations in this study diverged from Africans during the same time frame (approximately 90 to 110 thousand years ago). The divergence among different Eurasian populations occurred more than 40,000 years after their divergence with Africans.ConclusionsOur results show that Indian populations harbor large amounts of genetic variation that have not been surveyed adequately by public SNP discovery efforts. Our data also support a delayed expansion hypothesis in which an ancestral Eurasian founding population remained isolated long after the out-of-Africa diaspora, before expanding throughout Eurasia.

Reduced predator species richness drives the body gigantism of a frog species on the Zhoushan Archipelago in China

1. Shifts in the body size of insular vertebrates have been an interesting theme in ecological and evolutionary studies. Four primary factors, including predation pressures, resource availability, inter-species competition and immigrant selection, have been proposed to explain the trend in insular body size. Life-history theory predicts that body size, average age, the proportion of old-aged members and the density of insular populations are negatively correlated with predator species richness, and that body size and population density are positively related to resource availability. The niche expansion hypothesis argues that a positive relationship is expected to exist between insular body size and prey size, which varies in response to extinction due to small or large competitors. The immigrant hypothesis predicts that insular body size is positively correlated with distance to the mainland. 2. We tested these hypotheses by using populations of rice frogs Rana limnocharis on 20 islands in the Zhoushan Archipelago and two sites of nearby mainland China. 3. The body size (snout-vent length) of rice frogs on half of the islands was larger before and after the variable of age was controlled for; rice frog density and prey availability was higher and prey size was larger on most of the islands as compared to the two mainland sites. On the islands, the body size and other features [e.g. average age, the proportion of old-aged frogs (ages 3 and 4) and density] of the rice frogs were negatively associated with predator species richness; female body size and other features were positively associated with prey availability. The inference of multivariate linear models based on corrected Akaike Information Criterion (AIC(c) ) showed that the relative importance of predator species richness on body size and each of the other features was larger than that of prey availability, prey size and distance to the mainland. In addition, the parameters for predator species richness were all negative. 4. The results provided strong support for the life-history theory of predation pressures, but weak evidence for the life-history theory of prey availability, the niche expansion or the immigrant hypothesis. The reduced predator species richness was a dominant factor contributing to the body gigantism of rice frogs on the islands.

Nucleotide diversity of a ND5 fragment confirms that population expansion is the most suitable explanation for the mtDNA haplotype polymorphism of Drosophila subobscura

Results from mitochondria (mt) DNA restriction site analyses (RSAs) have revealed that wild populations of Drosophila subobscura are formed by two common (I and II) and some rare, often endemic, low-frequency haplotypes. In the study reported here, we analysed nucleotide diversity in a 942-bp fragment of the mtDNA ND5 gene in 48 D. subobscura individuals captured from three populations that showed haplotypes I, II or the less common ones, as well as in one additional individual belonging to D. guanche that was taken as an outgroup. RSAs and sequencing results were compared. The two approaches yielded similar nucleotide variability parameters, suggesting a consistency in the results obtained from mtDNA dynamics in natural populations of D. subobscura. Patterns of polymorphism at ND5 are most consistent with the hypothesis of population expansion after a bottleneck that may have occurred since the last glaciation or which may occur seasonally after the summer and winter. However, we cannot rule out that selection has a role in maintaining the two major haplotypes at intermediate frequencies in worldwide populations of D. subobscura.

Cytotype Distribution and Colonization History of the Steppe PlantIris aphylla

The polyploid origin and colonization history of Iris aphylla in central and southeastern Europe were investigated by means of karyological and AFLP analyses. The study indicated two chromosome races within I. aphylla based on chromosomal numbers 2n = 24 and 2n = 48. The overall chromosome counts and determined ploidy suggest tetraploidy as the most common ploidy level for this species in Europe. Only one diploid I. aphylla population was found, with a restricted distribution area in the Slovak Karst. The analyses showed that tetraploids arose independently at least three or more times in the past. The karyological results were in agreement with the AFLP data and strongly suggested that migration between the two Carpathian Mts. sites occurred recently via the Dukielska Pass. The low number of AFLP fragments unique to each population supports the hypothesis of recent range expansion and colonization of different environments in central Europe by I. aphylla. All populations were genetically depauperated and had 0–3 unique bands, indicating that not enough time elapsed for many unique fragments to form through mutation. We also observed relatively high and significant differentiation between the one diploid and all investigated tetraploid I. aphylla populations (ΦST = 0.470, p < 0.001). The high and significant values of genetic differentiation can be explained by several factors such as anthropopression and natural succession, which have fragmented the open calcareous habitats in central Europe.

Elucidating genetic signatures of native and introduced populations of the Cycad Blue, Chilades pandava to Taiwan: a threat both to Sago Palm and to native Cycas populations worldwide

Foreign plants are usually introduced for food or aesthetic reasons. Most of these plants are non-invasive, but can alter the evolutionary trajectory of the associated native insects or inadvertently spread potential pests. A hitherto poorly documented example is the rapid expansion of Chilades pandava, a Cycas-feeding butterfly. Since about 1990, large numbers of the Sago Palm Cycas revoluta were introduced into Taiwan. Invading or introduced with this hostplant, Ch. pandava has rapidly spread to all major parts of Taiwan. To trace the source of outbreaks, we sampled 810 specimens covering 50 Taiwanese localities and other regions using mitochondrial COII sequences. Overall haplotype diversity was high (h = 0.791), but only 29 haplotypes were found. The haplotype C which dominates outbreak populations from western Taiwan was endemic to the island. This is consistent with the hypothesis of a local range expansion of Ch. pandava, rather than an introduction. In addition, the Taiwanese Central Mountain Ridge may constitute a primary biogeographic barrier restricting gene flow between eastern and western populations. Our study not only flags an important new invasive insect that needs to be monitored and controlled within the horticultural trade and for in situ cycad conservation, but also provides a clearly documented case of the transformation of a native tropical butterfly into a pest via introduced horticultural plants.

Modelling suitable areas for Hyla meridionalis under current and future hypothetical expansion scenarios

AbstractNew records of the frog Hyla meridionalis have been reported on the Iberian Central mountain range, although it is not clear if those records correspond to an expansion process or to a lack of sampling. The species' global distribution was modelled to identify possible areas of expansion in the current environment and in a near future environment. To verify the effects of modelling a dynamic situation, the hypothetical expansion process from south to north was simulated in the current scenario. The species records were partitioned in four different datasets and modelled iteratively over a study area enclosing all records: records only from North Africa, from North Africa and South Iberian Peninsula, from North Africa and all the Iberian Peninsula, and from the entire distribution. The complete dataset was also used to extrapolate the model to a current and future global environmental scenarios. The models were compared by subtraction per pairs and by Cohen's Kappa. No spatio-temporal trends were detected in species records; therefore, the hypothesis of a recent expansion is nor supported. The species spread only to the Mediterranean part of the Iberian Peninsula when modelling only with African records, and to Europe when modelling also with Iberian records. The extrapolation models were moderately similar: large suitable areas were predicted in all the continents. Temperature variables contributed more to models. The species can expand to new suitable areas, although it is not possible to know if it would expand outside the biogeographical regions where the species is present.

Temperature enhancements and vertical winds in the lower thermosphere associated with auroral heating during the DELTA campaign

[1] A coordinated observation of the atmospheric response to auroral energy input in the polar lower thermosphere was conducted during the Dynamics and Energetics of the Lower Thermosphere in Aurora (DELTA) campaign. N2 rotational temperature was measured with a rocket-borne instrument launched from the Andoya Rocket Range, neutral winds were measured from auroral emissions at 557.7 nm with a Fabry-Perot Interferometer (FPI) at Skibotn and the KEOPS, and ionospheric parameters were measured with the European Incoherent Scatter (EISCAT) UHF radar at Tromso. Altitude profiles of the passive energy deposition rate and the particle heating rate were estimated using data taken with the EISCAT radar. The local temperature enhancement derived from the difference between the observed N2 rotational temperature and the MSISE-90 model neutral temperature were 70–140 K at 110–140 km altitude. The temperature increase rate derived from the estimated heating rates, however, cannot account for the temperature enhancement below 120 km, even considering the contribution of the neutral density to the estimated heating rate. The observed upward winds up to 40 m s �1 seem to respond nearly instantaneously to changes in the heating rates. Although the wind speeds cannot be explained by the estimated heating rate and the thermal expansion hypothesis, the present study suggests that the generation mechanism of the large vertical winds must be responsible for the fast response of the vertical wind to the heating event.