523 research outputs found
Kinship dynamics: patterns and consequences of changes in local relatedness
This is the author accepted manuscript. The final version is available from the Royal Society via the DOI in this recordMounting evidence suggests that patterns of local relatedness can change over time in
predictable ways, a process termed kinship dynamics. Kinship dynamics may occur at the level
of the population or social group, where the mean relatedness across all members of the
population or group changes over time, or at the level of the individual where an individualâs
relatedness to its local group changes with age. Kinship dynamics are likely to have
fundamental consequences for the evolution of social behaviour and life history because they
alter the inclusive fitness payoffs to actions taken at different points in time. For instance,
growing evidence suggests that individual kinship dynamics have shaped the evolution of
menopause and age-specific patterns of helping and harming. To date, however, the
consequences of kinship dynamics for social evolution have not been widely explored. Here
we review the patterns of kinship dynamics that can occur in natural populations and highlight
how taking a kinship dynamics approach has yielded new insights into behaviour and life
history evolution. We discuss areas where analysing kinship dynamics could provide new
insight into social evolution and we outline some of the challenges in predicting and
quantifying kinship dynamics in natural populations.Natural Environment Research Council (NERC)Leverhulme Trus
Cavitation of Electrons Bubbles in Liquid Helium Below saturation Pressure
We have used a Hartree-type electron-helium potential together with a density
functional description of liquid He and He to study the explosion of
electron bubbles submitted to a negative pressure. The critical pressure at
which bubbles explode has been determined as a function of temperature. It has
been found that this critical pressure is very close to the pressure at which
liquid helium becomes globally unstable in the presence of electrons. It is
shown that at high temperatures the capillary model overestimates the critical
pressures. We have checked that a commonly used and rather simple
electron-helium interaction yields results very similar to those obtained using
the more accurate Hartree-type interaction. We have estimated that the
crossover temperature for thermal to quantum nucleation of electron bubbles is
very low, of the order of 6 mK for He.Comment: 22 pages, 9 figure
Midday measurements of leaf water potential and stomatal conductance are highly correlated with daily water use of Thompson Seedless grapevines
A study was conducted to determine the relationship between midday measurements of vine water status and daily water use of grapevines measured with a weighing lysimeter. Water applications to the vines were terminated on August 24th for 9 days and again on September 14th for 22 days. Daily water use of the vines in the lysimeter (ETLYS) was approximately 40 L vineâ1 (5.3 mm) prior to turning the pump off, and it decreased to 22.3 L vineâ1 by September 2nd. Pre-dawn leaf water potential (ΨPD) and midday Ψl on August 24th were â0.075 and â0.76 MPa, respectively, with midday Ψl decreasing to â1.28 MPa on September 2nd. Leaf g s decreased from ~500 to ~200 mmol mâ2 sâ1 during the two dry-down periods. Midday measurements of g s and Ψl were significantly correlated with one another (r = 0.96) and both with ETLYS/ETo (r = ~0.9). The decreases in Ψl, g s, and ETLYS/ETo in this study were also a linear function of the decrease in volumetric soil water content. The results indicate that even modest water stress can greatly reduce grapevine water use and that short-term measures of vine water status taken at midday are a reflection of daily grapevine water us
The effects of applied water at various fractions of measured evapotranspiration on reproductive growth and water productivity of Thompson Seedless grapevines
The reproductive growth and water productivity (WPb) of Thompson Seedless grapevines were measured as a function of applied water amounts at various fractions of measured grapevine ETc for a total of eight irrigation treatments. Shoots were harvested numerous times during the growing season to calculate water productivity. Berry weight was maximized at the 0.6â0.8 applied water treatments across years. As applied water amounts increased soluble solids decreased. Berry weight measured at veraison and harvest was a linear function of the mean midday leaf water potential measured between anthesis and veraison and anthesis and harvest, respectively. As applied water amounts increased up to the 0.6â0.8 irrigation treatments there was a significant linear increase in yield. Yields at greater applied water amounts either leveled off or decreased. The reduction in yield on either side of the yearly maximum was due to fewer numbers of clusters per vine. Maximum yield occurred at an ETc ranging from 550 to 700Â mm. Yield per unit applied water and WPb increased as applied water decreased. The results from this study demonstrated that Thompson Seedless grapevines can be deficit irrigated, increasing water use efficiency while maximizing yields
Age and sex influence social interactions, but not associations, within a killer whale pod
This is the author accepted manuscript. The final version is available from the Royal Society via the DOI in this record.Data accessibility:
The processed contact, surfacing, and association networks, measures of dyadic
sampling effort, estimated maternal kinship, individual attributes, and functions to
conduct GLMQAP and general double-semi-partialling are included in the âaninetâ R
package on GitHub (https://github.com/MNWeiss/aninet). The raw time-series of
detections and interactions, and R code necessary to reproduce all analyses, are
available in the online supplementary material.Social structure is a fundamental aspect of animal populations. In order to understand
the function and evolution of animal societies, it is important to quantify how individual
attributes, such as age and sex, shape social relationships. Detecting these influences
in wild populations under natural conditions can be challenging, especially when social
interactions are difficult to observe and broad-scale measures of association are used
as a proxy. In this study, we use unoccupied aerial systems to observe association,
synchronous surfacing, and physical contact within a pod of southern resident killer
whales (Orcinus orca). We show that interactions do not occur randomly between
associated individuals, and that interaction types are not interchangeable. While age
and sex did not detectably influence association network structure, both interaction networks showed significant social homophily by age and sex, and centrality within the
contact network was higher among females and young individuals. These results
suggest killer whales exhibit interesting parallels in social bond formation and social
life histories with primates and other terrestrial social mammals, and demonstrate how
important patterns can be missed when using associations as a proxy for interactions
in animal social network studies.Natural Environment Research Council (NERC)National Fish and Wildlife FoundationPaul G Allen Family FoundationUW Center for Conservation BiologyCenter for Whale Researc
The extraordinary evolutionary history of the reticuloendotheliosis viruses
The reticuloendotheliosis viruses (REVs) comprise several closely related amphotropic retroviruses isolated from birds. These viruses exhibit several highly unusual characteristics that have not so far been adequately explained, including their extremely close relationship to mammalian retroviruses, and their presence as endogenous sequences within the genomes of certain large DNA viruses. We present evidence for an iatrogenic origin of REVs that accounts for these phenomena. Firstly, we identify endogenous retroviral fossils in mammalian genomes that share a unique recombinant structure with REVsâunequivocally demonstrating that REVs derive directly from mammalian retroviruses. Secondly, through sequencing of archived REV isolates, we confirm that contaminated Plasmodium lophurae stocks have been the source of multiple REV outbreaks in experimentally infected birds. Finally, we show that both phylogenetic and historical evidence support a scenario wherein REVs originated as mammalian retroviruses that were accidentally introduced into avian hosts in the late 1930s, during experimental studies of P. lophurae, and subsequently integrated into the fowlpox virus (FWPV) and gallid herpesvirus type 2 (GHV-2) genomes, generating recombinant DNA viruses that now circulate in wild birds and poultry. Our findings provide a novel perspective on the origin and evolution of REV, and indicate that horizontal gene transfer between virus families can expand the impact of iatrogenic transmission events
Developmental Transcriptional Networks Are Required to Maintain Neuronal Subtype Identity in the Mature Nervous System
During neurogenesis, transcription factors combinatorially specify neuronal fates and then differentiate subtype identities by inducing subtype-specific gene expression profiles. But how is neuronal subtype identity maintained in mature neurons? Modeling this question in two Drosophila neuronal subtypes (Tv1 and Tv4), we test whether the subtype transcription factor networks that direct differentiation during development are required persistently for long-term maintenance of subtype identity. By conditional transcription factor knockdown in adult Tv neurons after normal development, we find that most transcription factors within the Tv1/Tv4 subtype transcription networks are indeed required to maintain Tv1/Tv4 subtype-specific gene expression in adults. Thus, gene expression profiles are not simply âlocked-in,â but must be actively maintained by persistent developmental transcription factor networks. We also examined the cross-regulatory relationships between all transcription factors that persisted in adult Tv1/Tv4 neurons. We show that certain critical cross-regulatory relationships that had existed between these transcription factors during development were no longer present in the mature adult neuron. This points to key differences between developmental and maintenance transcriptional regulatory networks in individual neurons. Together, our results provide novel insight showing that the maintenance of subtype identity is an active process underpinned by persistently active, combinatorially-acting, developmental transcription factors. These findings have implications for understanding the maintenance of all long-lived cell types and the functional degeneration of neurons in the aging brain
Preconceptional factors associated with very low birthweight delivery in East and West Berlin: a case control study
BACKGROUND: Very low birthweight, i.e. a birthweight < 1500 g, is among the strongest determinants of infant mortality and childhood morbidity. To develop primary prevention approaches to VLBW birth and its sequelae, information is needed on the causes of preterm birth, their personal and social antecedents, and on conditions associated with very low birthweight. Despite the growing body of evidence linking sociodemographic variables with preterm delivery, little is known as to how this may be extrapolated to the risk of very low birthweight. METHODS: In 1992, two years after the German unification, we started to recruit two cohorts of very low birthweight infants and controls in East and West Berlin for a long-term neurodevelopmental study. The present analysis was undertaken to compare potential preconceptional risk factors for very low birthweight delivery in a case-control design including 166 mothers (82 East vs. 84 West Berlin) with very low birthweight delivery and 341 control mothers (166 East vs. 175 West). RESULTS: Multivariate logistic regression analysis was used to assess the effects of various dichotomous parental covariates and their interaction with living in East or West Berlin. After backward variable selection, short maternal school education, maternal unemployment, single-room apartment, smoking, previous preterm delivery, and fetal loss emerged as significant main effect variables, together with living in West Berlin as positive effect modificator for single-mother status. CONCLUSION: Very low birthweight has been differentially associated with obstetrical history and indicators of maternal socioeconomic status in East and West Berlin. The ranking of these risk factors is under the influence of the political framework
Performance of CMS muon reconstruction in pp collision events at sqrt(s) = 7 TeV
The performance of muon reconstruction, identification, and triggering in CMS
has been studied using 40 inverse picobarns of data collected in pp collisions
at sqrt(s) = 7 TeV at the LHC in 2010. A few benchmark sets of selection
criteria covering a wide range of physics analysis needs have been examined.
For all considered selections, the efficiency to reconstruct and identify a
muon with a transverse momentum pT larger than a few GeV is above 95% over the
whole region of pseudorapidity covered by the CMS muon system, abs(eta) < 2.4,
while the probability to misidentify a hadron as a muon is well below 1%. The
efficiency to trigger on single muons with pT above a few GeV is higher than
90% over the full eta range, and typically substantially better. The overall
momentum scale is measured to a precision of 0.2% with muons from Z decays. The
transverse momentum resolution varies from 1% to 6% depending on pseudorapidity
for muons with pT below 100 GeV and, using cosmic rays, it is shown to be
better than 10% in the central region up to pT = 1 TeV. Observed distributions
of all quantities are well reproduced by the Monte Carlo simulation.Comment: Replaced with published version. Added journal reference and DO
Performance of CMS muon reconstruction in pp collision events at sqrt(s) = 7 TeV
The performance of muon reconstruction, identification, and triggering in CMS
has been studied using 40 inverse picobarns of data collected in pp collisions
at sqrt(s) = 7 TeV at the LHC in 2010. A few benchmark sets of selection
criteria covering a wide range of physics analysis needs have been examined.
For all considered selections, the efficiency to reconstruct and identify a
muon with a transverse momentum pT larger than a few GeV is above 95% over the
whole region of pseudorapidity covered by the CMS muon system, abs(eta) < 2.4,
while the probability to misidentify a hadron as a muon is well below 1%. The
efficiency to trigger on single muons with pT above a few GeV is higher than
90% over the full eta range, and typically substantially better. The overall
momentum scale is measured to a precision of 0.2% with muons from Z decays. The
transverse momentum resolution varies from 1% to 6% depending on pseudorapidity
for muons with pT below 100 GeV and, using cosmic rays, it is shown to be
better than 10% in the central region up to pT = 1 TeV. Observed distributions
of all quantities are well reproduced by the Monte Carlo simulation.Comment: Replaced with published version. Added journal reference and DO
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