Search results for "Population"
showing 10 items of 9945 documents
Temporal genetic structure in a poecilogonous polychaete: the interplay of developmental mode and environmental stochasticity
2014
Background: Temporal variation in the genetic structure of populations can be caused by multiple factors, including natural selection, stochastic environmental variation, migration, or genetic drift. In benthic marine species, the developmental mode of larvae may indicate a possibility for temporal genetic variation: species with dispersive planktonic larvae are expected to be more likely to show temporal genetic variation than species with benthic or brooded non-dispersive larvae, due to differences in larval mortality and dispersal ability. We examined temporal genetic structure in populations of Pygospio elegans, a poecilogonous polychaete with within-species variation in developmental m…
Karyotype dispersal of the common lizard Zootoca vivipara (Lichtenstein, 1823) in eastern and northeastern Fennoscandia
2015
The wide-ranging Eurasian common lizard Zootoca vivipara (Lichtenstein, 1823) is remarkably uniform morphologically but highly varied in its karyotype. Previous studies have revealed two distinctly different chromosomal forms of Z. v. vivipara in the Baltic basin. Moreover, a zone of secondary contact between these forms has been localized on the southern Baltic Sea seashore. Intraspecific karyotype diversity for Z. vivipara and new zones of secondary contact have recently been suggested for other parts of the Baltic Sea seashore. We studied the karyotype of Z. vivipara in central, western and northern parts of Finland. All the individuals karyotyped represented the Russian form of Z. v. vi…
Estimating finite mixtures of semi-Markov chains: an application to the segmentation of temporal sensory data
2019
Summary In food science, it is of great interest to obtain information about the temporal perception of aliments to create new products, to modify existing products or more generally to understand the mechanisms of perception. Temporal dominance of sensations is a technique to measure temporal perception which consists in choosing sequentially attributes describing a food product over tasting. This work introduces new statistical models based on finite mixtures of semi-Markov chains to describe data collected with the temporal dominance of sensations protocol, allowing different temporal perceptions for a same product within a population. The identifiability of the parameters of such mixtur…
Searching for differences in Swift's intermediate GRBs
2010
Gamma-ray bursts are usually classified through their high-energy emission into short-duration and long-duration bursts, which presumably reflect two different types of progenitors. However, it has been shown on statistical grounds that a third, intermediate population is needed in this classification scheme, although an extensive study of the properties of this class has so far not been done. The large amount of follow-up studies generated during the Swift era allows us to have a suficient sample to attempt a study of this third population through the properties of their prompt emission and their afterglows. Our study is focused on a sample of GRBs observed by Swift during its first four y…
Population genetic structure of aposematic alpine wood tiger moths (Parasemia plantaginis)
2012
Alpine landscape with natural fragmentation restricts gene flow among populations and causes spatio-genetic structuring (high genetic differentiation) in species living there. Consequently, alpine habitat fragmentation and dispersal barriers should make isolated populations such as wood tiger moth (Parasemia plantaginis) populations prone to lose genetic diversity by local adaptation and fixation of fittest phenotype in each local population. This species is also known to be aposematic. Yellow colour on the males’ hind wings in wood tiger moth is presumed to work more efficiently against visual hunting predators due to increased conspicuousness. In addition, in field experiments with wood t…
Sex-specific genetic differences in endurance swimming of Trinidadian guppies.
2015
Abstract Swim performance is considered a main fitness‐determining trait in many aquatic organisms. Swimming is generally the only way most aquatic prey can escape predation, and swimming capacity is directly linked to food capture, habitat shifts, and reproduction. Therefore, evolutionary studies of swim performance are important to understand adaptation to aquatic environments. Most studies, however, concentrate on the importance of burst‐swim responses to predators, and little is known about its effect on endurance. Even fewer studies associate differences in organism swim capabilities to key gender‐specific responses. In this experiment, we assess the gender‐specific genetic basis of sw…
Underdiagnosis Of Asthma And Associated Risk Factors In Italian General Population Samples
2017
Background: asthma underdiagnosis was reported in many recent studies, in particular in older subjects. Aim: to assess the risk factors associated with asthma underdiagnosis in two Italian general population samples. Methods: two general population samples living in Pisa (Central Italy, urban/suburban area) and Po Delta (North Italy, rural area) participated in some cross-sectional studies between 1980 and 2011. Through a questionnaire on health status and risk factors, Pisa sample was investigated in 1985-1988, 1991-1993 and 2009-2011; Po Delta sample was investigated in 1980-1982 and 1988-1991. Individuals reporting asthma symptoms or diagnosis in the previous studies were recently enroll…
¿Cabe hablar de una «generación de la crisis»? Discusión en torno a una noción sobreexplotada
2018
This article states that nowadays there is an overuse (or a misuse) of the «Generation» idea. The discussion among many authors over the «Generation of crisis» concept suggests that it is useful to outline the characteristics of the target of population of the collective of youth who are mainly affected by the economic and social crisis over the past years. Nevertheless, through analyzing the meanings of the «Generation of Crisis» made by Mannheim, Ortega and other classic authors, it is clear that the social class approach together with the generational one are needed to define this concrete concept. The conclusion of the articleis that both approaches are seen as underpinning their utilit…
The Social Life of Viruses
2021
Despite their simplicity, viruses exhibit certain types of social interactions. Situations in which a given virus achieves higher fitness in combination with other members of the viral population have been described at the level of transmission, replication, suppression of host immune responses, and host killing, enabling the evolution of viral cooperation. Although cellular coinfection with multiple viral particles is the typical playground for these interactions, cooperation between viruses infecting different cells is also established through cellular and viral-encoded communication systems. In general, the stability of cooperation is compromised by cheater genotypes, as best exemplified…
Body size at birth and age-related macular degeneration in old age
2019
Purpose To study associations between body size at birth and age-related macular degeneration (AMD) in old age. Methods The study sample consists of 1497 community-dwelling individuals (56.1% women) aged 67-89 years with birth data and retinal data collected twice in old age 5 years apart. Birth data (weight, length, birth order) were extracted from original birth records. Digital retinal photographs were graded to determine AMD status. Data on covariates were collected at the baseline physical examination in old age. Multivariable regression analyses were used to study the association between birth data and AMD adjusting for known confounding factors, including birth year cohort effects. R…