On reproductive strategies in adjacent lagoonal and intertidal-marine populations of the gastropod Hydrobia ulvae

1988 ◽  
Vol 68 (3) ◽  
pp. 365-375 ◽  
Author(s):  
R. S. K. Barnes
Keyword(s):  
Intertidal Zone ◽  
Reproductive Strategies ◽  
Character Displacement ◽  
Height Ratio ◽  
Free Swimming ◽  
Shell Size ◽  
Hydrobia Ulvae ◽  
Wide Range ◽  
Two Populations ◽  
Capsule Size

The coastal prosobranch Hydrobia ulvae is known to occur in a wide range of marine and brackish habitats and to display great variation in its breeding and life-history characteristics. Several hypotheses have been advanced to account for the latter, including that the variation is environmentally induced and that the species can be divided into ecotypes. Comparison of two adjacent populations in Norfolk, U.K., one from the marine intertidal zone and the other from a non-tidal, landlocked, brackish coastal lagoon, however, disclosed that although shell form differed markedly (including a mean height ratio of 1:1.2), there was no difference in such otherwise variable features as numbers of eggs per capsule, size at hatching and larval type. In both, each capsule contained an average of 21-22 eggs, which hatched at a shell length of 152-154 μn to liberate relatyyively long-lived, free-swimming veligers. The two populations were also interfertile. In no respect had the isolated lagoonal population diverged away from the parent marine one towards the contrasting reproductive strategies characterizing the specifically lagoonal species of Hydrobia that occur nearby. The ‘displacement’ of shell size observed in the lagoon in the absence of sympatric hydrobiids is considered to cast further doubt on competitive character displacement in this genus.

scholarly journals Building clone-consistent ecosystem models

2021 ◽  
Vol 17 (2) ◽  
pp. e1008635
Author(s):  
Gerrit Ansmann ◽  
Tobias Bollenbach
Keyword(s):  
Functional Analysis ◽  
Building Blocks ◽  
Data Driven ◽  
Ecological Studies ◽  
Ecosystem Models ◽  
Linear Combinations ◽  
Model Consistency ◽  
Wide Range ◽  
Critical Requirement ◽  
Two Populations

Many ecological studies employ general models that can feature an arbitrary number of populations. A critical requirement imposed on such models is clone consistency: If the individuals from two populations are indistinguishable, joining these populations into one shall not affect the outcome of the model. Otherwise a model produces different outcomes for the same scenario. Using functional analysis, we comprehensively characterize all clone-consistent models: We prove that they are necessarily composed from basic building blocks, namely linear combinations of parameters and abundances. These strong constraints enable a straightforward validation of model consistency. Although clone consistency can always be achieved with sufficient assumptions, we argue that it is important to explicitly name and consider the assumptions made: They may not be justified or limit the applicability of models and the generality of the results obtained with them. Moreover, our insights facilitate building new clone-consistent models, which we illustrate for a data-driven model of microbial communities. Finally, our insights point to new relevant forms of general models for theoretical ecology. Our framework thus provides a systematic way of comprehending ecological models, which can guide a wide range of studies.

scholarly journals Which facial features are central in impression formation?

2020 ◽  
Author(s):  
Bastian Jaeger ◽  
Alex Lee Jones
Keyword(s):  
Machine Learning ◽  
Social Perception ◽  
Impression Formation ◽  
Emotional Expressions ◽  
Facial Features ◽  
Relative Importance ◽  
Height Ratio ◽  
Wide Range

Which facial characteristics do people rely on when forming personality impressions from faces? Previous research has uncovered an array of facial features that influence people’s impressions. Even though some (classes of) features, such as facial width-to-height ratio or resemblances to emotional expressions, play a central role in theories of social perception, their relative importance in impression formation remains unclear. Here, we model faces along a wide range of theoretically important dimensions. We use machine learning to test how well 31 features predict impressions of trustworthiness and dominance in a diverse set of 597 faces. In line with overgeneralization theory, emotion resemblances were most predictive of both traits. Other features that have received a lot of attention in the literature, such as facial width-to-height ratio, were relatively uninformative. Our results highlight the importance of modeling faces along a wide range of dimensions to elucidate their relative importance in impression formation.

Factors affecting individual body weight in field populations of the mudsnail Hydrobia ulvae

1990 ◽  
Vol 70 (1) ◽  
pp. 99-106 ◽  
Author(s):  
Donald J. Morrisey
Keyword(s):  
Body Weight ◽  
Body Size ◽  
Character Displacement ◽  
Sediment Type ◽  
Sympatric Populations ◽  
Factors Affecting ◽  
Hydrobia Ulvae ◽  
Native Sediment ◽  
Individual Body ◽  
Average Body

Differences in average body size among allopatric and sympatric populations of hydrobiid mudsnails have been interpreted as the consequence of interspecific competitive interactions. Recently, however, doubts have been expressed concerning the certainty with which size differences can be ascribed simply to character displacement. Other environmental factors are known to influence body size in hydrobiids. In the present study one of these, sediment type, was investigated.Average body weight of Hydrobia ulvae (Pennant) living on fine mud was consistently higher than that of members of the same species living on adjacent muddy sand. Snails were transplanted from one sediment type to the other, confined within cages, and their growth rates compared with those of control animals caged on their native sediment. The results of this experiment suggested that substrate type is one factor controlling body size, but the inconclusive nature of the results indicate that others are also involved.

Influence of temperature on the hatch of Heterodera avenae Woll. populations from Algeria

Nematology ◽  
2001 ◽  
Vol 3 (2) ◽  
pp. 171-178 ◽  
Author(s):  
Aïssa Mokabli ◽  
Jean-Pierre Gauthier ◽  
Roger Rivoal ◽  
Sylvie Valette
Keyword(s):  
Coastal Plain ◽  
Climatic Conditions ◽  
Heterodera Avenae ◽  
Seasonal Temperature ◽  
Wide Range ◽  
Influence Of Temperature On ◽  
Higher Temperature ◽  
The Times ◽  
Response To Temperature ◽  
Two Populations

AbstractTwo Algerian populations of Heterodera avenae originating from Oued Smar in a sub-humid coastal plain and from Tiaret in an inland semi-arid plain were subjected to different temperature treatments and juvenile emergence evaluated. These populations were compared with two populations, Fr1 and Fr4 from southern and northen France, respectively, which represent two ecotypes with respect to hatching cycles in response to temperature. The two Algerian populations hatched over a wide range of constant temperatures (3 to 25°C) but differed in the times at which juveniles emerged from the cysts. Simulation of seasonal temperature variations (from summer to autumn or winter and, conversely, from winter to spring or summer) demonstrated diapause in these two populations, induced by higher temperature (20 and 25°C) treatments and broken subsequently by lower temperatures (3 and 7°C). Both Algerian populations of H. avenae represent the Mediterranean ecotype, with biological variations that may represent regional adaptations to more or less severe climatic conditions.

scholarly journals Analyzing the effects of altitudes on the metabolic diversity and forskolin content in Coleus forskohlii roots by HPTLC and HPLC

2020 ◽  
Author(s):  
Pawan Singh Rana ◽  
Pooja Saklani ◽  
Chandresh Chandel
Keyword(s):  
Soxhlet Extraction ◽  
Plant Roots ◽  
Coleus Forskohlii ◽  
Metabolic Diversity ◽  
Phytochemical Composition ◽  
Commercial Use ◽  
Wide Range ◽  
Medicinal Properties ◽  
Two Populations ◽  
Important Medicinal Plant

AbstractIntroductionColeus forskohlii is an important medicinal plant native to India. It grows wild in a wide range of altitude in the Indian Himalayan region and contains some important phytochcemicals which possess remarkable medicinal properties. The plant contains terpenoid like Forskolin in its roots.ObjectiveConsidering the medicinal importance of C. forskohlii, being the only source of Forskolinand its availability over a wide altitude range, the effect of altitude on the metabolic diversity and forskolin content was assessed using the HPTLC and HPLC.MethodsFive populations of Coleus forskohlii collected from five locations of varying altitude from Uttarakhand, India. The plant roots were extracted with methanol by soxhlet extraction. The metabolic diversity was analyzed by employing HPTLC fingerprinting while forskolin was extracted and quantified by HPLC.ResultsSignificant differences were observed in the phytochemical composition through the HPTLC chromatograms among the studied population across the altitudes. The Gopeshwar population (1488m) showed highest number of bands on HPTLC chromatogram each of which corresponds to acompound. Results of HPLC shows differences in forskolin quantity in studied populations and the Piaplkoti population(1339m) showed highest forskolin accumulation.ConclusionThe present study confirms that altitude and changing environment affects the nature and quantity of secondary metabolites in C. forskohlii and the environmental conditions might be instrumental factor for intraspecific metabolic diversity. The Pipalkoti (1339m) and Gopeshwar (1488m) populations were found suitable for the forskolin production as well as other metabolites and these two populations can be propagated for commercial use.

scholarly journals INITIAL GENETIC LINKAGE MAP AND EXPERIMENTS TOWARD TAGGING GENES WHICH CONTROL CHILLING REQUIREMENT IN BLUEBERRY (VACCINIUM SPP.)

HortScience ◽  
1995 ◽  
Vol 30 (2) ◽  
pp. 193c-193
Author(s):  
Amnon Levi ◽  
Elizabeth Ogden ◽  
Lisa J. Rowland
Keyword(s):  
Genetic Linkage ◽  
Rapd Markers ◽  
Genetic Linkage Map ◽  
Bulked Segregant Analysis ◽  
Breeding Population ◽  
Chilling Requirement ◽  
Chilling Requirements ◽  
Wide Range ◽  
Vaccinium Darrowi ◽  
Two Populations

Efforts are underway to develop genetic linkage maps for two interspecific blueberry populations (Vaccinium darrowi × V. elliottii and V. caesariense-derived populations). To date, 72 RAPD markers have been mapped, and another 200 markers have been identified as suitable for mapping in the V. darrowi × V. elliottii-derived population. Inheritance of 40 RAPD markers has been followed, and additional 40 RAPD markers have been identified as suitable for mapping in the V. darrowi × V. caesariense population. These two populations are comprised of individual plants that should have a wide range of chilling requirements. At a later date, plants will be classified according to their chilling requirements to identify RAPD markers that cosegregate with chilling requirements. Presently, a bulked-segregant analysis is being performed on a tetraploid breeding population (primarily V. corymbosum) to identify RAPD markers linked to chilling requirement genes.

scholarly journals DISCUSSION ON HEIGHT SYSTEMS IN STEREOSCOPIC MAPPING USING THE ZY-3 SATELLITE IMAGES

2018 ◽  
Vol XLII-3 ◽  
pp. 2385-2389
Author(s):  
L. Zhao ◽  
X. Fu ◽  
G. Zhu ◽  
J. Zhang ◽  
C. Han ◽  
...  
Keyword(s):  
Bundle Adjustment ◽  
Liaoning Province ◽  
Height Ratio ◽  
Mapping Accuracy ◽  
Wide Range ◽  
Crossing Time ◽  
Similar Accuracy ◽  
Almost All ◽  
Distinguishing Features ◽  
Continuous Strip

The ZY-3 is the civil high-resolution optical stereoscopic mapping satellite independently developed by China. It is mainly used for 1&amp;thinsp;:&amp;thinsp;50,000 scale topographic mapping. One of the distinguishing features of the ZY-3 is that the panchromatic triplet camera can obtain thousands of kilometers of continuous strip stereo data. The working mode is suitable for wide-range stereoscopic mapping, in particular global DEM extraction. The ZY-3 constellation is operated in a sun-synchronous at an altitude 505&amp;thinsp;km, with a 10:30&amp;thinsp;AM equator crossing time and a 29-day revisiting period. The panchromatic triplet sensors have excellent base-to-height ratio, which is advantageous for obtaining good mapping accuracy.<br> In this paper the China quasi-geoid, EGM2008 and the height conversion method are discussed. It is pointed out that according to the current surveying and mapping specifications, almost all maps and charts use mean sea level for elevation. Experiments on bundle adjustment and DEM extraction with different height systems have been carried out in Liaoning Province of China. The results show that the similar accuracy can be obtained using different elevation system. According to the principle of geodesy and photogrammetry, it is recommended to use ellipsoidal height for satellite photogrammetric calculation and use the orthometric height in mapping production.

scholarly journals Differential inhibition onto developing and mature granule cells generates high-frequency filters with variable gain

eLife ◽  
2015 ◽  
Vol 4 ◽  
Author(s):  
María Belén Pardi ◽  
Mora Belén Ogando ◽  
Alejandro F Schinder ◽  
Antonia Marin-Burgin
Keyword(s):  
Granule Cells ◽  
Hippocampal Neurogenesis ◽  
Adult Hippocampal Neurogenesis ◽  
Information Encoding ◽  
High Frequencies ◽  
Wide Range ◽  
Mature Neurons ◽  
Different Populations ◽  
Immature Cells ◽  
Two Populations

Adult hippocampal neurogenesis provides the dentate gyrus with heterogeneous populations of granule cells (GC) originated at different times. The contribution of these cells to information encoding is under current investigation. Here, we show that incoming spike trains activate different populations of GC determined by the stimulation frequency and GC age. Immature GC respond to a wider range of stimulus frequencies, whereas mature GC are less responsive at high frequencies. This difference is dictated by feedforward inhibition, which restricts mature GC activation. Yet, the stronger inhibition of mature GC results in a higher temporal fidelity compared to that of immature GC. Thus, hippocampal inputs activate two populations of neurons with variable frequency filters: immature cells, with wide‐range responses, that are reliable transmitters of the incoming frequency, and mature neurons, with narrow frequency response, that are precise at informing the beginning of the stimulus, but with a sparse activity.

scholarly journals Adaptation to temporally fluctuating environments by the evolution of maternal effects

2015 ◽  
Author(s):  
Snigdhadip Dey ◽  
Steve Proulx ◽  
Henrique Teotonio
Keyword(s):  
Maternal Effects ◽  
Experimental Evolution ◽  
Reproductive Strategies ◽  
Correlated Response ◽  
Bet Hedging ◽  
Offspring Performance ◽  
Trade Offs ◽  
Wide Range ◽  
Fluctuating Environments ◽  
Selection For

Most organisms live in ever-challenging temporally fluctuating environments. Theory suggests that the evolution of anticipatory (or deterministic) maternal effects underlies adaptation to environments that regularly fluctuate every other generation because of selection for increased offspring performance. Evolution of maternal bet-hedging reproductive strategies that randomize offspring phenotypes is in turn expected to underlie adaptation to irregularly fluctuating environments. Although maternal effects are ubiquitous their adaptive significance is unknown since they can easily evolve as a correlated response to selection for increased maternal performance. Using the nematode Caenorhabditis elegans, we show the experimental evolution of maternal provisioning of offspring with glycogen, in populations facing a novel anoxia hatching environment every other generation. As expected with the evolution of deterministic maternal effects, improved embryo hatching survival under anoxia evolved at the expense of fecundity and glycogen provisioning when mothers experienced anoxia early in life. Unexpectedly, populations facing an irregularly fluctuating anoxia hatching environment failed to evolve maternal bet-hedging reproductive strategies. Instead, adaptation in these populations should have occurred through the evolution of balancing trade-offs over multiple generations, since they evolved reduced fitness over successive generations in anoxia but did not go extinct during experimental evolution. Mathematical modelling confirms our conclusion that adaptation to a wide range of patterns of environmental fluctuations hinges on the existence of deterministic maternal effects, and that they are generally much more likely to contribute to adaptation than maternal bet-hedging reproductive strategies.

Development of a resource-saving technology of production of strip-type profiles by drawing in roller dies using dummy passes

2021 ◽  
Vol 77 (9) ◽  
pp. 1054-1062
Author(s):  
K. Yu. Klyuchnikov ◽  
V. G. Razdobreev ◽  
A. I. Leshchenko ◽  
D. G. Palamar’
Keyword(s):  
Steel Strip ◽  
Machine Building ◽  
Capital Investments ◽  
Height Ratio ◽  
Resource Saving ◽  
Instrument Making ◽  
Wide Range ◽  
Technology Of Production ◽  
Periodic Section ◽  
Drawing Method

The rolling-drawing process is used in the production of a large number of shaped profiles of complex configuration, including thin-walled, strip and periodic section profiles. This process, in comparison with drawing in monolithic dies, allows to reduce energy costs by 20–40 %, to increase deformation in one pass to 40–50 %, to reduce the number of preparatory operations (heat treatment, pickling), to exclude the use of expensive lubricants for drawing. Compared to the production of profiles by the method of cold rolling, the rolling-die process has a higher technological flexibility, does not require significant capital investments when organizing the production of precise profiles. At the same time, due to the presence of tensile stresses at the edges of the profile, which can cause their destruction, the assortment of strip-type profiles produced by this method was previously limited to readymade profiles with a ratio of width to height of no more than two. The authors of this work have previously developed a technology for the production of crimped steel strip with a width-to-height ratio of more than 10 by the rolling-drawing method. However, the developed calibration provides for a large number of transitions, complicates the organization of the production of strip profiles of a wide range of sizes, especially in the production of low-tonnage batches. To decrease the number of transitions, the use of dummy paases was proposed. It was shown that this will make it possible to increase the width-to-height ratio of strip-type profiles to 20, and, accordingly, reduce the production cost. The proposed technology for the production of strip-type profiles by the method of drawing in roller dies using dummy passes will allow to comprehensively solve the problem of providing machine-building and instrument-making enterprises by especially precise profiles of a wide range of sizes.

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