scholarly journals Drivers of diversification in individual life courses

2017 ◽  
Author(s):  
Raisa Hernández-Pacheco ◽  
Ulrich K. Steiner
Keyword(s):  
Individual Variability ◽  
Individual Heterogeneity ◽  
Fitness Components ◽  
Evolutionary Mechanisms ◽  
Individual Life ◽  
Structured Population ◽  
Selective Forces ◽  
Life Courses ◽  
Population Entropy ◽  
Stage Composition

ABSTRACTHeterogeneity in life courses among individuals of a population influences the speed of adaptive evolutionary processes, but it is less clear how biotic and abiotic environmental fluctuations influence such heterogeneity. We investigate principal drivers of variability in sequence of stages during an individual’s life in a stage-structured population. We quantify heterogeneity by measuring population entropy, which computes the rate of diversification of individual life courses of a Markov chain. Using individual data of a primate population, we show that density regulates the stage composition of the population, but its entropy and the generating moments of heterogeneity are independent of density. This lack of influence of density on heterogeneity is neither due to low year-to-year variation in entropy nor due to differences in survival among stages, but due to differences in stage transitions. Our analysis thus shows that well-known classical ecological selective forces, such as density regulation, are not linked to potential selective forces governing heterogeneity through underlying stage dynamics. Despite evolution acting heavily on individual variability in fitness components, our understanding is poor whether observed heterogeneity is adaptive and how it evolves and is maintained. Our analysis illustrates how entropy represents a more integrated measure of diversity compared to the population structural composition, giving us new insights about the underlying drivers of individual heterogeneity within populations and potential evolutionary mechanisms.

scholarly journals Drivers of diversity in individual life courses: Sensitivity of the population entropy of a Markov chain

2017 ◽  
Author(s):  
Ulrich K. Steiner ◽  
Shripad Tuljapurkar
Keyword(s):  
Markov Chain ◽  
Population Growth ◽  
Evolutionary Dynamics ◽  
Early Stage ◽  
Structured Populations ◽  
Individual Life ◽  
Individual Level ◽  
Selective Forces ◽  
Life Courses ◽  
Population Entropy

AbstractIndividuals differ in their life courses, but how this diversity is generated, how it has evolved and how maintained is less understood. However, this understanding is crucial to comprehend evolutionary and ecological population dynamics. In structured populations, individual life courses represent sequences of stages that end in death. These sequences can be described by a Markov chain and individuals diversify over the course of their lives by transitioning through diverse discrete stages. The rate at which stage sequences diversify with age can be quantified by the population entropy of a Markov chain. Here, we derive sensitivities of the population entropy of a Markov chain to identify which stage transitions generate—or contribute—most to diversification in stage sequences, i.e. life courses. We then use these sensitivities to reveal potential selective forces on the dynamics of life courses. To do so we correlated the sensitivity of each matrix element (stage transition) with respect to the population entropy, to its sensitivity with respect to fitness λ, the population growth rate. Positive correlation between the two sensitivities would suggest that the stage transitions that selection has acted most strongly on (sensitivities with respect to λ) are also those that contributed most to the diversification of life courses. Using an illustrative example on a seabird population, the Thick-billed Murres on Coats Island, that is structured by reproductive stages, we show that the most influential stage transitions for diversification of life courses are not correlated with the most influential transitions for population growth. Our finding suggests that observed diversification in life courses is neutral rather than adaptive. We are at an early stage of understanding how individual level dynamics shape ecological and evolutionary dynamics, and many discoveries await.

scholarly journals Drivers of diversity in individual life courses: Sensitivity of the population entropy of a Markov chain

2020 ◽  
Vol 133 ◽  
pp. 159-167 ◽  
Author(s):  
Ulrich K. Steiner ◽  
Shripad Tuljapurkar
Keyword(s):  
Markov Chain ◽  
Individual Life ◽  
Life Courses ◽  
Population Entropy

scholarly journals Cold Fusion: Massive Karyotype Evolution in the Antarctic Bullhead Notothen Notothenia coriiceps

2017 ◽  
Vol 7 (7) ◽  
pp. 2195-2207 ◽  
Author(s):  
Angel Amores ◽  
Catherine A Wilson ◽  
Corey A H Allard ◽  
H William Detrich ◽  
John H Postlethwait
Keyword(s):  
Large Scale ◽  
Cold Fusion ◽  
Evolutionary Mechanisms ◽  
Telocentric Chromosome ◽  
Ancestral Chromosome ◽  
Notothenia Coriiceps ◽  
History Of ◽  
Selective Forces ◽  
Chromosome Fusions ◽  
The Antarctic

Abstract Half of all vertebrate species share a series of chromosome fusions that preceded the teleost genome duplication (TGD), but we do not understand the causative evolutionary mechanisms. The “Robertsonian-translocation hypothesis” suggests a regular fusion of each ancestral acro- or telocentric chromosome to just one other by centromere fusions, thus halving the karyotype. An alternative “genome-stirring hypothesis” posits haphazard and repeated fusions, inversions, and reciprocal and nonreciprocal translocations. To study large-scale karyotype reduction, we investigated the decrease of chromosome numbers in Antarctic notothenioid fish. Most notothenioids have 24 haploid chromosomes, but bullhead notothen (Notothenia coriiceps) has 11. To understand mechanisms, we made a RAD-tag meiotic map with ∼10,000 polymorphic markers. Comparative genomics aligned about a thousand orthologs of platyfish and stickleback genes along bullhead chromosomes. Results revealed that 9 of 11 bullhead chromosomes arose by fusion of just two ancestral chromosomes and two others by fusion of three ancestral chromosomes. All markers from each ancestral chromosome remained contiguous, implying no inversions across fusion borders. Karyotype comparisons support a history of: (1) Robertsonian fusions of 22 ancestral chromosomes in pairs to yield 11 fused plus two small unfused chromosomes, like N. angustata; (2) fusion of one of the remaining two ancestral chromosomes to a preexisting fused pair, giving 12 chromosomes like N. rossii; and (3) fusion of the remaining ancestral chromosome to another fused pair, giving 11 chromosomes in N. coriiceps. These results raise the question of what selective forces promoted the systematic fusion of chromosomes in pairs and the suppression of pericentric inversions in this lineage, and provide a model for chromosome fusions in stem teleosts.

scholarly journals Drivers of Diversification in Individual Life Courses

2017 ◽  
Vol 190 (6) ◽  
pp. E132-E144 ◽  
Author(s):  
Raisa Hernández-Pacheco ◽  
Ulrich K. Steiner
Keyword(s):  
Individual Life ◽  
Life Courses

scholarly journals How dependent were the ‘dependent poor’? Poor relief and the life-course in Terling, Essex, 1762–1834

2015 ◽  
Vol 30 (2) ◽  
pp. 193-222 ◽  
Author(s):  
HENRY FRENCH
Keyword(s):  
Life Course ◽  
Life Histories ◽  
Poor Relief ◽  
Poor Law ◽  
Men And Women ◽  
Individual Life ◽  
Southern England ◽  
Life Courses ◽  
The Life Course ◽  
The Impact

ABSTRACTDespite the volume of research on the Old Poor Law, only in the last two decades have detailed local studies begun to assess the impact of relief payments across the life-courses of individuals. Their conclusions have been mixed. While many have found that the rural labouring poor of southern England were increasingly frequent recipients of poor relief after the 1780s, recent studies have indicated that ‘dependence’ on relief was generally intermittent, not permanent. Based on a new dataset for the Essex village of Terling, this study sets individual life-histories within the broader chronology of change to show how young, able-bodied men and women became relief recipients much more often after 1795 than they had before.

scholarly journals Individual variability in cardiac biomarker release after 30 min of high-intensity rowing in elite and amateur athletes

2015 ◽  
Vol 40 (9) ◽  
pp. 951-958 ◽  
Author(s):  
Alejandro Legaz-Arrese ◽  
Isaac López-Laval ◽  
Keith George ◽  
Juan José Puente-Lanzarote ◽  
Diego Moliner-Urdiales ◽  
...  
Keyword(s):  
High Intensity ◽  
Time Course ◽  
Troponin I ◽  
Individual Variability ◽  
Cardiac Biomarkers ◽  
Individual Heterogeneity ◽  
Reference Limit ◽  
Athletic Status ◽  
Elite Rowers ◽  
Upper Reference Limit

This study had two objectives: (i) to examine individual variation in the pattern of cardiac troponin I (cTnI) and N-terminal pro-brain natriuretic peptide (NT-proBNP) release in response to high-intensity rowing exercise, and (ii) to establish whether individual heterogeneity in biomarker appearance was influenced by athletic status (elite vs. amateur). We examined cTnI and NT-proBNP in 18 elite and 14 amateur rowers before and 5 min, 1, 3, 6, 12, and 24 h after a 30-min maximal rowing test. Compared with pre-exercise levels, peak postexercise cTnI (pre: 0.014 ± 0.030 μg·L–1; peak post: 0.058 ± 0.091 μg·L–1; p = 0.000) and NT-proBNP (pre: 15 ± 11 ng·L–1; peak post: 31 ± 19 ng·L–1; p = 0.000) were elevated. Substantial individual heterogeneity in peak and time-course data was noted for cTnI. Peak cTnI exceeded the upper reference limit (URL) in 9 elite and 3 amateur rowers. No rower exceeded the URL for NT-proBNP. Elite rowers had higher baseline (0.019 ± 0.038 vs. 0.008 ± 0.015 μg·L–1; p = 0.003) and peak postexercise cTnI (0.080 ± 0.115 vs. 0.030 ± 0.029 μg·L–1; p = 0.022) than amateur rowers, but the change with exercise was similar between groups. There were no significant differences in baseline and peak postexercise NT-proBNP between groups. In summary, marked individuality in the cTnI response to a short but high-intensity rowing bout was observed. Athletic status did not seem to affect the change in cardiac biomarkers in response to high-intensity exercise.

scholarly journals Neutral theory for life histories and individual variability in fitness components

2012 ◽  
Vol 109 (12) ◽  
pp. 4684-4689 ◽  
Author(s):  
U. K. Steiner ◽  
S. Tuljapurkar
Keyword(s):  
Life Histories ◽  
Neutral Theory ◽  
Individual Variability ◽  
Fitness Components

scholarly journals Putting the spiritual into practice

2018 ◽  
Vol 8 (1) ◽  
Author(s):  
Julia Von Boguslawski ◽  
Jasmine Westerlund
Keyword(s):  
Twentieth Century ◽  
Religious Culture ◽  
Individual Life ◽  
Guiding Principle ◽  
Surrounding World ◽  
Early Twentieth Century ◽  
Life Courses ◽  
Shed Light

The aim of this article is to examine how Rudolf Steiner’s anthroposophical ideas were reflected and put into practice in the lives of the Finnish couple Olly (Olga) Donner (1881–1956, neé Sinebrychoff) and Uno Donner (1872–1958). They encountered anthroposophy in 1913 and subsequently embraced it as the guiding principle of their lives. Through a close examination of these two people we aim to shed light on how a new worldview like anthroposophy, which was gaining followers in early twentieth-century Finland, was also a manifestation of wider changes in religious culture in Europe. Our perspective could be described as biographical in the sense that it has been characterised by Simone Lässig (2008: 11) who writes that ‘the reconstruction of individual life courses helps to discover more about the context – for example, about daily rituals, pious practices, or kinship relationship’. Thus, the biographical perspective serves as a tool for grasping how something as deeply personal as an anthroposophical worldview was understood and practised, not only by Olly and Uno Donner, but also by a larger group of people who in the early twentieth century were looking for new ways to make sense of the surrounding world.

scholarly journals Medawar and Hamilton on the selective forces in the evolution of ageing

2021 ◽  
Vol 43 (4) ◽  
Author(s):  
Stefano Giaimo
Keyword(s):  
Evolutionary Theory ◽  
Overlapping Generations ◽  
Mathematical Expression ◽  
Fitness Components ◽  
Selective Force ◽  
Full Spectrum ◽  
Selective Forces ◽  
The Relationship ◽  
Modern Evolutionary Theory ◽  
Biological Literature

AbstractBoth Medawar and Hamilton contributed key ideas to the modern evolutionary theory of ageing. In particular, they both suggested that, in populations with overlapping generations, the force with which selection acts on traits declines with the age at which traits are expressed. This decline would eventually cause ageing to evolve. However, the biological literature diverges on the relationship between Medawar’s analysis of the force of selection and Hamilton’s. Some authors appear to believe that Hamilton perfected Medawar’s insightful, yet ultimately erroneous analysis of this force, while others see Hamilton’s analysis as a coherent development of, or the obvious complement to Medawar’s. Here, the relationship between the two analyses is revisited. Two things are argued for. First, most of Medawar’s alleged errors that Hamilton would had rectified seem not to be there. The origin of these perceived errors appears to be in a misinterpretation of Medawar’s writings. Second, the mathematics of Medawar and that of Hamilton show a significant overlap. However, different meanings are attached to the same mathematical expression. Medawar put forth an expression for the selective force on age-specific fitness. Hamilton proposed a full spectrum of selective forces each operating on age-specific fitness components, i.e. mortality and fertility. One of Hamilton’s expressions, possibly his most important, is of the same form as Medawar’s expression. But Hamilton’s selective forces on age-specific fitness components do not add up to yield Medawar’s selective force on age-specific fitness. It is concluded that Hamilton’s analysis should be considered neither as a correction to Medawar’s analysis nor as its obvious complement.

Guilty Pleasures? Feminism and Everyday Life in the 1980s

2019 ◽  
pp. 121-158
Author(s):  
Margaretta Jolly
Keyword(s):  
Life Course ◽  
Everyday Life ◽  
The State ◽  
Individual Life ◽  
Life Courses ◽  
Domestic Lives ◽  
Life Course Analysis

The chapter interweaves individual life course analysis with the development of feminism, exploring the homes, food, clothes and leisure enjoyed by midlife activists. Exploring municipal feminism and Women Against Pit Closures mobilisation during the miners’ strike through the stories of Valerie Wise and Betty Cook, the chapter skirts simple narratives of movement success or decline to explore the domestic lives of feminists. These could fuel activism and enable alternative life courses and families, but also show the need for rest, pleasure and privacy. Shopping too is revealed as an area of shame as well as where feminists pioneered ethical forms of consumption, particularly in sexual goods or clubs, whilst acknowledging the divisive context of Thatcher’s Britain. The chapter closes with a portrait of Barbara Jones, radical lesbian feminist, woman builder and ecological designer, whose vivid S&A interview captures feminism’s transformative effects alongside its troubled relationship to capitalism, money and the state. 150 words

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