Cenozoic latitudinal response curves: individualistic changes in the latitudinal distributions of marine bivalves and gastropods

Paleobiology ◽  
2015 ◽  
Vol 41 (1) ◽  
pp. 33-44 ◽  
Author(s):  
Andrew A. Zaffos ◽  
Arnold I. Miller
Keyword(s):  
Latitudinal Gradient ◽  
General Trend ◽  
Marine Bivalve ◽  
Latitudinal Distribution ◽  
Response Curves ◽  
Time Period ◽  
Marine Bivalves ◽  
The Many ◽  
The Tropics

AbstractWe use a Gaussian logistic regression model to characterize epoch-to-epoch and stage-tostage changes in the latitudinal response curves of Cenozoic marine bivalve and gastropod genera along the global latitudinal gradient, and analyze these changes to understand the mode and tempo of changes in latitudinal distribution. A ubiquitous ‘‘hollow curve’’ pattern is apparent, wherein smaller changes in response-curve parameters are much more common than larger changes. Curves are strikingly consistent in terms of the average level of change exhibited, despite the many unique environmental and biological changes documented between each of these intervals. This implies that the pace and magnitude of changes in the latitudinal distribution of marine mollusks are not controlled, in aggregate, by time-period-specific conditions. Additionally, we find no evidence for long-term migration from tropical to extratropical latitudes. Our results instead favor a model of either equatorward migration or no general trend. This likely reflects the tendency of genera to maintain their highest concentrations in the tropics even if their ranges become extended out of the tropics over time.

scholarly journals New Records of Two Non-native Clam Species (Bivalvia: Cardiidae) from the Coastal Waters of Bangladesh

2019 ◽  
pp. 1-8
Author(s):  
Md. Royhanur Islam ◽  
Sadman Sakin Nirob ◽  
Md. Habibur Rahman Molla ◽  
Kauser Rahman ◽  
Md. Mozammal Haque ◽  
...  
Keyword(s):  
Marine Invertebrates ◽  
Marine Bivalve ◽  
Bivalve Molluscs ◽  
Potential Biomarker ◽  
Marine Bivalves ◽  
The Family ◽  
The Tropics ◽  
Increasing Trends ◽  
Brackish Water Species ◽  
Water Species

Benthic suspension feeders, such as many marine bivalve molluscs, influence the nutrient and organic cycles of benthic and pelagic systems through their ability to filter a wide size range of particles and deposit organic matters that sink to the bottom. They also play important roles in coastal and marine ecosystems by filtering the water and serving as habitat and prey for a variety of sea life. Due to the increasing trends of environmental contaminations in recent years, many bivalves have been using as a potential biomarker for assessing the worse environment. Moreover, the shell of a bivalve is comprised of calcium carbonate, which may support thousands of calciferous organisms into the water body. Mostly, bivalves inhabit the tropics, as well as temperate and boreal waters, and they can survive and even flourish in extreme environmental conditions like Bangladesh. Nowadays, many bivalve molluscs have been identified as a superior source of bioactive compounds and are using for pharmaceutical and nutraceutical purposes as well as other applications. However, until now, few systematic studies on marine bivalve molluscs have been conducted through which a total of 437 marine and brackish water species were identified and recorded in Bangladesh. But still, our knowledge of taxonomy and systematic on marine molluscs are primitive in the context of the country. Here we report two new species of bivalve molluscs, Parvicardium exiguum and Trachycardium procerum belonging to the family Cardiidae, from the Kutubdia Island of Bangladesh. The study added these two bivalve species, which has not been recorded from the coastal zone of Kutubdia Island during the previous studies. To sum up, studies and survey on taxonomy and systematics in marine bivalves will provide new dimensions for further research about these important marine invertebrates.

scholarly journals Substantial gene flow caused by long-term translocation between wild populations of the Peruvian scallop (Argopecten purpuratus) is supported by RAD-Seq analyses

2020 ◽  
Author(s):  
Ximena Velez-Zuazo ◽  
Sergio P. Barahona ◽  
Omar G. Melo ◽  
Eric Hanschke ◽  
Ian Hanschke ◽  
...  
Keyword(s):  
Gene Flow ◽  
Marine Bivalve ◽  
Wild Populations ◽  
Outlier Loci ◽  
Argopecten Purpuratus ◽  
Marine Bivalves ◽  
Genetic Diversity And Structure ◽  
Aquaculture Industry ◽  
Northern Peru

AbstractThe Peruvian scallop (Argopecten purpuratus, Lamarck 1989) is a marine bivalve of high commercial value in the aquaculture industry, with wild populations distributing from northern Peru to Chile. Its growing demand in the world aquaculture markets and limited availability of hatchery-based seeds, caused long-term seed translocations among wild populations to recover depleted local populations and for production needs. We investigated long-term translocations effects on the genetic diversity and structure of wild populations using next-generation RAD sequencing. We sampled individuals from Sechura, Lobos de Tierra, Samanco and Bahia Independencia in Peru, and La Rinconada in Northern Chile. We identified 6275 polymorphic RAD tags and 8345 SNPs for the five populations. We estimated high observed heterozygosity for all populations and high SNP frequency compared to similar studies on marine bivalves. We detected no spatial divergence among populations in Peru (pairwise FST ranged from 0 to 0.003), but strong differentiation with the population in Chile. Migration rate estimates suggested asymmetric directionality of seed translocation. Overall, our results support a remnant effect of an intense historic translocation and on-going gene flow among wild populations in Peru, challenging the identification of outlier loci and certification of sustainable origin of cultured scallops using genetic markers.

scholarly journals Tropical Rainfall Variability on Interannual-to-Interdecadal and Longer Time Scales Derived from the GPCP Monthly Product

2007 ◽  
Vol 20 (15) ◽  
pp. 4033-4046 ◽  
Author(s):  
Guojun Gu ◽  
Robert F. Adler ◽  
George J. Huffman ◽  
Scott Curtis
Keyword(s):  
Rainfall Variability ◽  
Volcanic Eruptions ◽  
Linear Change ◽  
Tropical Ocean ◽  
Tropical Rainfall ◽  
Enso Events ◽  
Time Period ◽  
The Tropics ◽  
The Impact

Abstract Global and large regional rainfall variations and possible long-term changes are examined using the 27-yr (1979–2005) Global Precipitation Climatology Project (GPCP) monthly dataset. Emphasis is placed on discriminating among variations due to ENSO, volcanic events, and possible long-term climate changes in the Tropics. Although the global linear change of precipitation in the dataset is near zero during the time period, an increase in tropical rainfall is noted in the dataset, with a weaker decrease over Northern Hemisphere middle latitudes. Focusing on the Tropics (25°S–25°N), the dataset indicates an upward linear change (0.06 mm day−1 decade−1) and a downward linear change (−0.01 mm day−1 decade−1) over tropical ocean and land, respectively. This corresponds to an about 5.5% increase (ocean) and 1% decrease (land) during the entire 27-yr time period. The year 2005 has the largest annual tropical total precipitation (land plus ocean) for the GPCP record. The five highest years are (in descending order) 2005, 2004, 1998, 2003, and 2002. For tropical ocean the five highest years are 1998, 2004, 2005, 2002, and 2003. Techniques are applied to isolate and quantify variations due to ENSO and two major volcanic eruptions during the time period (El Chichón, March 1982; Mount Pinatubo, June 1991) in order to examine longer-time-scale changes. The ENSO events generally do not impact the tropical total rainfall, but rather induce significant anomalies with opposite signs over tropical land and ocean. The impact of the two volcanic eruptions is estimated to be about a 5% reduction in tropical rainfall over both land and ocean. A modified dataset (with ENSO and volcano effects removed) retains the same approximate linear change slopes, but with reduced variances, thereby increasing the statistical significance levels associated with the long-term rainfall changes in the Tropics. However, although care has been taken to ensure that this dataset is as homogeneous as possible, firm establishment of the existence of the discussed changes as long-term trends may require continued analysis of the input datasets and a lengthening of the observation period.

Stability and Change in Emotional Intelligence: Exploring the Transition to Young Adulthood

2005 ◽  
Vol 26 (2) ◽  
pp. 100-106 ◽  
Author(s):  
James D.A. Parker ◽  
Donald H. Saklofske ◽  
Laura M. Wood ◽  
Jennifer M. Eastabrook ◽  
Robyn N. Taylor
Keyword(s):  
High School ◽  
Emotional Intelligence ◽  
Postsecondary Education ◽  
Life Transition ◽  
Full Time ◽  
Major Life ◽  
Long Term Stability ◽  
Time Period ◽  
Transition From High School

Abstract. The concept of emotional intelligence (EI) has attracted growing interest from researchers working in various fields. The present study examined the long-term stability (32 months) of EI-related abilities over the course of a major life transition (the transition from high school to university). During the first week of full-time study, a large group of undergraduates completed the EQ-i:Short; 32 months later a random subset of these students (N = 238), who had started their postsecondary education within 24 months of graduating from high school, completed the measures for a second time. The study found EI scores to be relatively stable over the 32-month time period. EI scores were also found to be significantly higher at Time 2; the overall pattern of change in EI-levels was more than can be attributed to the increased age of the participants.

The Many Faces of Socioeconomic Change

2017 ◽  
Author(s):  
John Toye
Keyword(s):  
Socioeconomic Development ◽  
Adam Smith ◽  
First Century ◽  
Social Progress ◽  
Long Time ◽  
The Face ◽  
Scientific Expertise ◽  
The Many ◽  
Century Development

This book provides a survey of different ways in which economic sociocultural and political aspects of human progress have been studied since the time of Adam Smith. Inevitably, over such a long time span, it has been necessary to concentrate on highlighting the most significant contributions, rather than attempting an exhaustive treatment. The aim has been to bring into focus an outline of the main long-term changes in the way that socioeconomic development has been envisaged. The argument presented is that the idea of socioeconomic development emerged with the creation of grand evolutionary sequences of social progress that were the products of Enlightenment and mid-Victorian thinkers. By the middle of the twentieth century, when interest in the accelerating development gave the topic a new impetus, its scope narrowed to a set of economically based strategies. After 1960, however, faith in such strategies began to wane, in the face of indifferent results and general faltering of confidence in economists’ boasts of scientific expertise. In the twenty-first century, development research is being pursued using a research method that generates disconnected results. As a result, it seems unlikely that any grand narrative will be created in the future and that neo-liberalism will be the last of this particular kind of socioeconomic theory.

scholarly journals Sociolinguistic Markers of Friendship Among Persons With Dementia in Long-Term Care

2020 ◽  
Vol 4 (Supplement_1) ◽  
pp. 575-575
Author(s):  
Pamela Saunders
Keyword(s):  
Social Interaction ◽  
Long Term Care ◽  
Ethnographic Study ◽  
Linguistic Features ◽  
Term Care ◽  
Socially Constructed ◽  
Time Period ◽  
Pronominal Reference ◽  
Field Notes

Abstract Sociolinguistics and discourse analysis provide tools through which to examine how friendship is socially constructed through language and communication. Research on social isolation and loneliness reveals the importance of social interaction on the psychological and physical health of older adults. Given that linguistic, communicative, and functional abilities decline as dementia progresses, it is challenging to identify markers of friendship. The Friendship Project is an ethnographic study of social interaction among persons with dementia living in a long-term care setting. The data are from transcripts and field-notes of social interactions among residents with a range of cognitive impairments over a six-month time period. Results reveal that persons with dementia employ specific linguistic features such as narrative, evaluation, evidentials, and pronominal reference to make meaning and create relationships over time. Practical implications will be discussed.

scholarly journals Confronting ethical challenges in long-term research programs in the tropics

2021 ◽  
Vol 255 ◽  
pp. 108933
Author(s):  
Reinmar Seidler ◽  
Richard B. Primack ◽  
Varun R. Goswami ◽  
Sarala Khaling ◽  
M. Soubadra Devy ◽  
...  
Keyword(s):  
Ethical Challenges ◽  
Research Programs ◽  
The Tropics

scholarly journals Global climatology and trends in convective environments from ERA5 and rawinsonde data

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Mateusz Taszarek ◽  
John T. Allen ◽  
Mattia Marchio ◽  
Harold E. Brooks
Keyword(s):  
Large Scale ◽  
Climate Models ◽  
Global Climate ◽  
Convective Available Potential Energy ◽  
Global Climate Models ◽  
Convective Precipitation ◽  
The Past ◽  
The Tropics ◽  
Rawinsonde Data

AbstractGlobally, thunderstorms are responsible for a significant fraction of rainfall, and in the mid-latitudes often produce extreme weather, including large hail, tornadoes and damaging winds. Despite this importance, how the global frequency of thunderstorms and their accompanying hazards has changed over the past 4 decades remains unclear. Large-scale diagnostics applied to global climate models have suggested that the frequency of thunderstorms and their intensity is likely to increase in the future. Here, we show that according to ERA5 convective available potential energy (CAPE) and convective precipitation (CP) have decreased over the tropics and subtropics with simultaneous increases in 0–6 km wind shear (BS06). Conversely, rawinsonde observations paint a different picture across the mid-latitudes with increasing CAPE and significant decreases to BS06. Differing trends and disagreement between ERA5 and rawinsondes observed over some regions suggest that results should be interpreted with caution, especially for CAPE and CP across tropics where uncertainty is the highest and reliable long-term rawinsonde observations are missing.

scholarly journals Long-Term Concrete Shrinkage Influence on the Performance of Reinforced Concrete Structures

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 254
Author(s):  
Alinda Dey ◽  
Akshay Vijay Vastrad ◽  
Mattia Francesco Bado ◽  
Aleksandr Sokolov ◽  
Gintaris Kaklauskas
Keyword(s):  
Reinforced Concrete ◽  
Reinforced Concrete Structures ◽  
Tension Stiffening ◽  
Model Code ◽  
Concrete Shrinkage ◽  
Time Period ◽  
Governing Factor ◽  
Model Code 2010 ◽  
Mathematical Process

The contribution of concrete to the tensile stiffness (tension stiffening) of a reinforced concrete (RC) member is a key governing factor for structural serviceability analyses. However, among the current tension stiffening models, few consider the effect brought forth by concrete shrinkage, and none studies take account of the effect for very long-term shrinkage. The present work intends to tackle this exact issue by testing multiple RC tensile elements (with different bar diameters and reinforcement ratios) after a five-year shrinking time period. The experimental deformative and tension stiffening responses were subjected to a mathematical process of shrinkage removal aimed at assessing its effect on the former. The results showed shrinkage distinctly lowered the cracking load of the RC members and caused an apparent tension stiffening reduction. Furthermore, both of these effects were exacerbated in the members with higher reinforcement ratios. The experimental and shrinkage-free behaviors of the RC elements were finally compared to the values predicted by the CEB-fib Model Code 2010 and the Euro Code 2. Interestingly, as a consequence of the long-term shrinkage, the codes expressed a smaller relative error when compared to the shrinkage-free curves versus the experimental ones.

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