scholarly journals Factors affecting litter size in Western Gartersnake (Thamnophis elegans) in British Columbia: place, time, and size of mother

2018 ◽  
Vol 132 (1) ◽  
pp. 36-42
Author(s):  
Patrick T. Gregory ◽  
Daniel R. Farr
Keyword(s):  
British Columbia ◽  
Body Size ◽  
Litter Size ◽  
Life History Traits ◽  
Geographic Location ◽  
Foraging Success ◽  
Factors Affecting ◽  
Residual Variation ◽  
Genetic And Environmental Factors ◽  
Thamnophis Elegans

Life-history traits of organisms are influenced by both genetic and environmental factors. We used counts of offspring in captive-born litters to determine how geographic location, year-to-year variation, and body size of mother affected litter size of Western Gartersnake (Thamnophis elegans) in four widely separated populations in British Columbia. Litter size varied significantly among populations, but that variation was largely explained by differences in maternal body size among populations; that is, larger females had larger litters. With maternal size treated as a covariate, there was no further significant effect of location or of different years within sites on litter size. The overall regression, pooled over sites and years, between litter size and size of mother accounted for 55% of the total variation in litter size. Nonetheless, the significant variation in body size among locations calls for explanation and the consequent differences in litter size could be important demographically. Presumably, the large amount of unexplained residual variation reflects other differences, beyond body size, between individual mothers. Such differences among individuals might be determined by genetics or by environmental effects such as foraging success, but our data cannot address this question.

Decrease in litter size in the shrew Crocidura suaveolens (Mammalia, Insectivora) from Corsica (France): Evolutionary response to insularity?

1997 ◽  
Vol 75 (6) ◽  
pp. 954-958 ◽  
Author(s):  
Roger Fons ◽  
Françoise Poitevin ◽  
Josette Catalan ◽  
Henri Croset
Keyword(s):  
Life History ◽  
Body Size ◽  
Litter Size ◽  
Life History Traits ◽  
Breeding Experiment ◽  
Adult Body Size ◽  
Three Generations ◽  
Evolutionary Response ◽  
Adult Body ◽  
Genetically Determined

Populations of the lesser white-toothed shrew, Crocidura suaveolens (Pallas, 1811), from Corsica show an increase in adult body size associated with a decrease in litter size. The average number of embryos in wild Corsican females is smaller (mean 2.6, n = 62) than in mainland females (mean 4.6, n = 173). A breeding experiment was run for 4 years, yielding three generations. Under standard breeding conditions, the differences between island and mainland populations were maintained and were significant (median litter size was 2 for Corsica and 5 for the mainland). These differences in life-history traits were therefore proved experimentally to be genetically determined. Hypotheses concerning the mechanisms responsible for these differences are discussed.

Fast and slow life histories of carnivores

2011 ◽  
Vol 89 (8) ◽  
pp. 692-704 ◽  
Author(s):  
Evi Paemelaere ◽  
F. Stephen Dobson
Keyword(s):  
Life History ◽  
Body Size ◽  
Litter Size ◽  
Life Histories ◽  
Life History Traits ◽  
Life Cycles ◽  
Age At Maturity ◽  
Negatively Associated ◽  
Trade Offs ◽  
Body Sizes

The fast–slow continuum hypothesis explains life-history traits as reflecting the causal influence of mortality patterns in interaction with trade-offs among traits, particularly more reproductive effort at a cost of shorter lives. Variation among species of different body sizes produce more or less rapid life cycles (respectively, from small to large species), but the fast–slow continuum remains for birds and mammals when body-size effects are statistically removed. We tested for a fast–slow continuum in mammalian carnivores. We found the above trade-offs initially supported in a sample of 85 species. Body size, however, was strongly associated with phylogeny (ρ = 0.79), and thus we used regression techniques and independent contrasts to make statistical adjustments for both. After adjustments, the life-history trade-offs were not apparent, and few associations of life-history traits were significant. Litter size was negatively associated with age at maturity, but slightly positively associated with offspring mass. Litter size and mass were negatively associated with the length of the developmental period. Gestation length showed weak but significant negative associations with age at maturity and longevity. We conclude that carnivores, despite their wide range of body sizes and variable life histories, at best poorly exhibited a fast–slow continuum.

Differential effects on life history traits and body size of two anuran species inhabiting an environment related to fluorite mine

2018 ◽  
Vol 93 ◽  
pp. 36-44 ◽  
Author(s):  
Manuel A. Otero ◽  
Favio E. Pollo ◽  
Pablo R. Grenat ◽  
Nancy E. Salas ◽  
Adolfo L. Martino
Keyword(s):  
Life History ◽  
Body Size ◽  
Life History Traits ◽  
Differential Effects ◽  
Anuran Species

scholarly journals Transformation of Criteria for the Efficiency of Economic Activities of Countries in the Context of the Modern Model of Globalization

2019 ◽  
Vol 20 (2) ◽  
pp. 261-293 ◽  
Author(s):  
Galina Makarova ◽  
Vasilii Rudyakov
Keyword(s):  
Geographic Location ◽  
Developed Countries ◽  
Economic Research ◽  
Economic Science ◽  
Main Task ◽  
Economic Activities ◽  
Factors Affecting ◽  
Trade Relations ◽  
Stage Of Development ◽  
National Economies

Although macroeconomics as an independent economic science emerged only in the twen­tieth century, the first steps in developing the macroeconomic aspect of efficiency were taken several centuries earlier — beginning from the 16th — 17th centuries — at the pre-industrial stage of development of society. Due to the underdevelopment of the production sphere, the search for sources of growth in the efficiency of national economies at that time was mainly carried out from the most general economic positions — as an integral part of solving the main task of the economics of those eras — searching for ways and means of increasing the wealth of nations. At the same time, naturally, among the first were the climatic and foreign economic factors of increasing the efficiency of national economies. For example, factors related to identifying the advantages of various countries in a geographic location and the ability to solve their economic problems by using the most advantageous options for organizing and conducting foreign economic and trade relations. The transition of developed countries to new stages of development — industrial and postindustrial, as well as the selection by John M. Keynes of the new direction of economic research — macroeconomics, historically leads both to a deepening of the meaning of the very category of “macroeconomic efficiency” and to more detailed studies of factors affecting it.

scholarly journals Life history and habitat do not mediate temporal changes in body size due to climate warming in rodents

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e9792
Author(s):  
Aluwani Nengovhela ◽  
Christiane Denys ◽  
Peter J. Taylor
Keyword(s):  
Life History ◽  
Body Size ◽  
Climate Warming ◽  
Life History Traits ◽  
Vegetation Type ◽  
Reproductive Rate ◽  
Temporal Changes ◽  
Temporal Response ◽  
Extrinsic Factors ◽  
African Species

Temporal changes in body size have been documented in a number of vertebrate species, with different contested drivers being suggested to explain these changes. Among these are climate warming, resource availability, competition, predation risk, human population density, island effects and others. Both life history traits (intrinsic factors such as lifespan and reproductive rate) and habitat (extrinsic factors such as vegetation type, latitude and elevation) are expected to mediate the existence of a significant temporal response of body size to climate warming but neither have been widely investigated. Using examples of rodents, we predicted that both life history traits and habitat might explain the probability of temporal response using two tests of this hypothesis. Firstly, taking advantage of new data from museum collections spanning the last 106 years, we investigated geographical and temporal variation in cranial size (a proxy for body size) in six African rodent species of two murid subfamilies (Murinae and Gerbillinae) of varying life history, degree of commensality, range size, and habitat. Two species, the commensal Mastomys natalensis, and the non-commensal Otomys unisulcatus showed significant temporal changes in body size, with the former increasing and the latter decreasing, in relation with climate warming. Commensalism could explain the increase in size with time due to steadily increasing food availability through increased agricultural production. Apart from this, we found no general life history or habitat predictors of a temporal response in African rodents. Secondly, in order to further test this hypothesis, we incorporated our data into a meta-analysis based on published literature on temporal responses in rodents, resulting in a combined dataset for 50 species from seven families worldwide; among these, 29 species showed no significant change, eight showed a significant increase in size, and 13 showed a decline in size. Using a binomial logistic regression model for these metadata, we found that none of our chosen life history or habitat predictors could significantly explain the probability of a temporal response to climate warming, reinforcing our conclusion based on the more detailed data from the six African species.

scholarly journals WHATEVER YOU WANT: INCONSISTENT RESULTS IS THE RULE, NOT THE EXCEPTION, IN THE STUDY OF PRIMATE BRAIN EVOLUTION

2018 ◽  
Author(s):  
Andreas Wartel ◽  
Patrik Lindenfors ◽  
Johan Lind
Keyword(s):  
Body Size ◽  
Brain Evolution ◽  
Data Sets ◽  
Data Set ◽  
Scientific Rigor ◽  
Explanatory Variables ◽  
Primate Brain ◽  
Residual Variation ◽  
The Many ◽  
Brain Data

AbstractPrimate brains differ in size and architecture. Hypotheses to explain this variation are numerous and many tests have been carried out. However, after body size has been accounted for there is little left to explain. The proposed explanatory variables for the residual variation are many and covary, both with each other and with body size. Further, the data sets used in analyses have been small, especially in light of the many proposed predictors. Here we report the complete list of models that results from exhaustively combining six commonly used predictors of brain and neocortex size. This provides an overview of how the output from standard statistical analyses changes when the inclusion of different predictors is altered. By using both the most commonly tested brain data set and a new, larger data set, we show that the choice of included variables fundamentally changes the conclusions as to what drives primate brain evolution. Our analyses thus reveal why studies have had troubles replicating earlier results and instead have come to such different conclusions. Although our results are somewhat disheartening, they highlight the importance of scientific rigor when trying to answer difficult questions. It is our position that there is currently no empirical justification to highlight any particular hypotheses, of those adaptive hypotheses we have examined here, as the main determinant of primate brain evolution.

scholarly journals Ida Halpern: A Post-Colonial Portrait of a Canadian Pioneer Ethnomusicologist

2013 ◽  
Vol 16 (1) ◽  
pp. 41-59
Author(s):  
Kenneth Chen
Keyword(s):  
British Columbia ◽  
First Nations ◽  
Coast Salish ◽  
Factors Affecting ◽  
Post Colonial ◽  
Musical Development

The work of Ida Halpern (1910–87), one of Canada's first musicologists and a pioneer ethnomusicologist, has been largely ignored. This essay illuminates her most important contribution to the musical development of this country: the documentation of Native musics. Halpern devoted some four decades to recording and analyzing over five hundred songs of the Kwakwaka'wakw, the Nuuchahnulth, the Haida, the Nuxalk, and the Coast Salish First Nations of British Columbia—a truly remarkable achievement considering that a large part of her fieldwork was conducted during a period when it was illegal for Native cultures to be celebrated, much less preserved. The author discusses the strengths and weaknesses of her methodology as well as some factors affecting the reception of her work by academic peers and by the communities she worked with. While Halpern did not always thoroughly investigate context, she endeavoured to write heteroglossically and to invent a theory that accounted for the music of these songs.

Genetic and environmental factors affecting some measures of yield and fertility in a registered Canadian Holstein dairy herd in Iran

2002 ◽  
Vol 2002 ◽  
pp. 190-190
Author(s):  
Ali Toosi
Keyword(s):  
Environmental Factors ◽  
Genetic Parameters ◽  
Dairy Herd ◽  
Cattle Breeding ◽  
Factors Affecting ◽  
Lactation Curve ◽  
Dairy Cattle Breeding ◽  
Important Trait ◽  
Genetic And Environmental Factors ◽  
Production Characteristics

Milk production is the most important trait in dairy cattle breeding. Measures of additional traits are also important. Traits of lactation curve are important in their relation to production characteristics. The two major reasons for which dairy cows are disposed are fertility problems and low milk yield (Hansen et al.,1983). The objectives of this study were 1) To evaluate effects of some environmental factors on some measures of yield and fertility, and 2) To estimate genetic parameters for these traits applying REML procedures under sire model.

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