Search for Evolutionary Changes in the Periods of the Double-Mode Cepheid TU Cas

The light curves of luminous stars often show spectacular secular changes which can be connected to stellar evolution. Such events are, e.g. the outbursts of P Cygni in the 17th century and 77 Carinae in the last century. Both stars belong to the Luminous Blue Variables, but these changes are not restricted to blue stars. The light curve of HR 8752 (V509 Cassiopeiae) shows a certain similarity to that of the former two stars. When it was first catalogued in the middle of the 19th century, it had been a 6m star. During 100 years the star showed a secular brightening of lm. A similar yellow hypergiant, p Cassiopeiae produced at least two outbursts this century, though both have smaller amplitudes than it is in the case of the LBVs. Moreover, these yellow variables also have an apparently secular colour change: the B − V colour of HR 8752 is decreasing while that of ρ Cassiopeiae is increasing. In both cases evolutionary changes are possible but one cannot exclude other causes. Besides these well studied stars there are several other yellow hypergiants with promising light curves. One of the most interesting cases seems to be R Puppis, which was discovered to be variable in the last century, but then did not show any appreciable change in the following 70-80 years. In the late 1970s, however, it began to vary once more.

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The Remarkable Evolution of the Post-Agb Star FG SGE

Highlights of Astronomy ◽

10.1017/s1539299600021134 ◽

1998 ◽

Vol 11 (1) ◽

pp. 363-363

Author(s):

Johanna Jurcsik ◽

Benjamin Montesinos

Keyword(s):

Time Scales ◽

Effective Temperature ◽

Planetary Nebula ◽

Planetary Nebulae ◽

Central Star ◽

Evolutionary Models ◽

Single Star ◽

Line Intensities ◽

Evolutionary Changes ◽

Evolutionary Studies

FG Sagittae is one of the most important key objects of post-AGB stellar evolutionary studies. As a consequence of a final helium shell flash, this unique variable has shown real evolutionary changes on human time scales during this century. The observational history was reviewed in comparison with predictions from evolutionary models. The central star of the old planetary nebula (Hel-5) evolved from left to right in the HR diagram, going in just hundred years from the hot region of exciting sources of planetary nebulae to the cool red supergiant domain just before our eyes becoming a newly-born post-AGB star. The effective temperature of the star was around 50,000 K at the beginning of this century, and the last estimates in the late 1980s give 5,000-6,500 K. Recent spectroscopic observations obtained by Ingemar Lundström show definite changes in the nebular line intensities. This fact undoubtedly rules out the possibility that, instead of FG Sge, a hidden hot object would be the true central star of the nebula. Consequently, the observed evolutionary changes are connected with the evolution of a single star.

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Variation in regrowth ability in relation to land-use intensity in three common grassland herbs

Journal of Plant Ecology ◽

10.1093/jpe/rtab001 ◽

2021 ◽

Author(s):

Anna Kirschbaum ◽

Oliver Bossdorf ◽

J F Scheepens

Keyword(s):

Land Use ◽

Phenotypic Plasticity ◽

Temporal Variation ◽

Temporal Stability ◽

Common Garden ◽

Grassland Management ◽

Land Use Intensity ◽

Evolutionary Changes ◽

Biomass Removal ◽

Reproductive Biomass

Abstract Aims Plant populations in managed grasslands are subject to strong selection exerted by grazing, mowing and fertilization. Many previous studies showed that this can cause evolutionary changes in mean trait values, but little is known about the evolution of phenotypic plasticity in response to land use. In this study, we aimed to elucidate the relationships between phenotypic plasticity – specifically, regrowth ability after biomass removal – and the intensity of grassland management and levels of temporal variation therein. Methods We conducted an outdoor common garden experiment to test if plants from more intensively mown and grazed sites showed an increased ability to regrow after biomass removal. We used three common plant species from temperate European grasslands, with seed material from 58 – 68 populations along gradients of land-use intensity, ranging from extensive (only light grazing) to very intensive management (up to four cuts per year). Important findings In two out of three species, we found significant population differentiation in regrowth ability after clipping. While variation in regrowth ability was unrelated to the mean land-use intensity of populations of origin, we found a relationship with its temporal variation in P. lanceolata, where plants experiencing less variable environmental conditions over the last 11 years showed stronger regrowth in reproductive biomass after clipping. Therefore, while mean grazing and mowing intensity may not select for regrowth ability, the temporal stability of the environmental heterogeneity created by land use may have caused its evolution in some species.

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The diversity of opsins in Lake Baikal amphipods (Amphipoda: Gammaridae)

BMC Ecology and Evolution ◽

10.1186/s12862-021-01806-9 ◽

2021 ◽

Vol 21 (1) ◽

Author(s):

Polina Drozdova ◽

Alena Kizenko ◽

Alexandra Saranchina ◽

Anton Gurkov ◽

Maria Firulyova ◽

...

Keyword(s):

Lake Baikal ◽

Visual Pigments ◽

Ancient Lake ◽

Climate History ◽

Habitat Depth ◽

Long Wavelength ◽

Evolutionary Scenario ◽

Evolutionary Changes ◽

Evolutionary Success ◽

Multiple Species

Abstract Background Vision is a crucial sense for the evolutionary success of many animal groups. Here we explore the diversity of visual pigments (opsins) in the transcriptomes of amphipods (Crustacea: Amphipoda) and conclude that it is restricted to middle (MWS) and long wavelength-sensitive (LWS) opsins in the overwhelming majority of examined species. Results We evidenced (i) parallel loss of MWS opsin expression in multiple species (including two independently evolved lineages from the deep and ancient Lake Baikal) and (ii) LWS opsin amplification (up to five transcripts) in both Baikal lineages. The number of LWS opsins negatively correlated with habitat depth in Baikal amphipods. Some LWS opsins in Baikal amphipods contained MWS-like substitutions, suggesting that they might have undergone spectral tuning. Conclusions This repeating two-step evolutionary scenario suggests common triggers, possibly the lack of light during the periods when Baikal was permanently covered with thick ice and its subsequent melting. Overall, this observation demonstrates the possibility of revealing climate history by following the evolutionary changes in protein families.

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A population-based analysis in 375,233 cases of heart failure stages A, B and C. Real world epidemiology of prevalence and temporal trends in South-European populations

European Heart Journal ◽

10.1093/ehjci/ehaa946.0960 ◽

2020 ◽

Vol 41 (Supplement_2) ◽

Author(s):

S Jimenez ◽

M Cainzos-Achirica ◽

D Monterde ◽

L Garcia-Eroles ◽

C Enjuanes ◽

...

Keyword(s):

Heart Failure ◽

Chronic Conditions ◽

Temporal Trends ◽

Population Level ◽

Population Based ◽

Relative Increase ◽

Funding Source ◽

Private Company ◽

Healthcare Database ◽

Evolutionary Changes

Abstract Background Prevalence of congestive heart failure (CHF) and predisposing conditions has described previously. Most of these studies evaluated centre-European or north-American populations. However, the prevalence and evolutionary changes of Heart Failure stages A, B and C has not been fully elucidated in Mediterranean cohorts. Purpose To estimate the prevalence of CHF (HF Stage C) and four additional key chronic cardiovascular, metabolic and renal conditions predisposing to the development of CHF (HF Stages A and B) at a population level in a south-European healthcare area. We analysed the evolutionary changes in the prevalence in these five conditions. Methods In a healthcare area of 1,3Millions inhabitants, we extracted health related information of all individuals ≥55 years old. We analysed data of 375,233 individuals included in the population-based healthcare database of a public Institute of Health between 2015 and 2017. The conditions of interest were CHF, chronic kidney disease (CKD), diabetes mellitus (DM), ischemic heart disease (IHD) and hypertension (HTN). Results The prevalence of chronic conditions was high, particularly of HTN (48.2–48.9%) and DM individuals (14.6–14.8%). The other conditions were less frequent, with prevalence around 2–4% for IHD, 5–9% for CKD and 2–4% for CHF (Table). However, the less frequent conditions had a striking upward trend with over 1,500 new prevalent cases per year between 2015 and 2017 for CHF (45% relative increase), more than 2,500 new prevalent cases for IHD (67% relative increase) and more than 4,000 new prevalent cases per year for CKD (44% relative increase). Conclusion In this south European cohort, there were a high prevalence of HTN and DM as risk factors and a significant trend of increasing prevalence in high cost chronic conditions such as CHF, IHD and CKD. Funding Acknowledgement Type of funding source: Private company. Main funding source(s): The present study was funded by an unrestricted research grant from Vifor Pharma.

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