Genome size is a fundamental biological characteristic, yet its evolutionary dynamics remain insufficiently understood, partly because few plant groups offer the cytogenetic and phylogenomic data required for genus-level analyses. In this study, we estimated genome size (2C values) for 80 species (c, 75% of the genus), covering all infrageneric categories (three subgenera, ten sections). Genome-size evolution was examined within a newly generated, time-calibrated phylogenetic framework based on the Angiosperms353 target-capture probe set including 89% of the species in the genus, and integrated with updated karyotype descriptors including chromosome numbers, total haploid karyotype length (THL), interchromosomal coefficient of variation in chromosome length (CVCL), and intrachromosomal mean centromeric asymmetry (MCA). Genome size varied 6.5-fold across the genus, ranging from 1.65 to 10.60 pg (i.e., from very small to intermediate genomes). Phylogenetically informed regressions revealed a strong positive relationship between 2C values and THL, indicating that changes in nuclear DNA content are accommodated by proportional modifications in chromosome size. In contrast, genome size showed no significant association with chromosome number or karyotype asymmetry, suggesting that genome-size diversification has occurred largely independently of major chromosomal rearrangements. Chromosome-number reconstructions confirmed a highly conserved karyotype across the genus, with only a single abrupt shift and a small number of minor dysploid changes. Ancestral-state reconstruction and comparative evolutionary modelling revealed that genome-size diversification is strongly shaped by phylogenetic structure and characterised by repeated reductions from an intermediate ancestral genome. Overall, Helianthemum provides a powerful model for understanding how genome size evolves within a conserved chromosomal framework.

The Mediterranean Basin harbours 10

The genus Helianthemum, commonly known as rockroses, encompasses 140 species primarily distributed in the Palearctic region, with notable diversification driven by climatic and geological changes. These plants are valuable for studying speciation processes and ecological divergence. The chemical properties of the leaves have also been investigated for containing valuable bioactive compounds with several therapeutic properties. However, the availability of genomic resources for species in this genus are almost entirely lacking. Here, we assembled and annotated the first reference transcriptome of Helianthemum marifolium, a species with wide morphological variability and infraspecific diversity. Illumina paired-end RNA sequences were generated using leaves from 16 individuals, representing the four recognized subspecies, all cultivated in a greenhouse. RNA reads were assembled with Trinity and Oases, and EvidentialGene produced a transcriptome with 122,002 transcripts. The transcriptome showed 59524 hits on the UniProtBK database through BLASTx. This transcriptome will be an invaluable resource for transcriptome-level population studies, conservation genetics of the many endangered species within the genus, and for deepen into the metabolic pathways of leaf-derived compounds.

The Maunder Minimum was a period with significantly reduced solar activity between 1645 and 1715, approximately. The transition between the low solar activity in the Maunder Minimum and the subsequent “normal” regime of solar activity was gradual. However, there are discrepancies in the solar activity level from sunspot number indices and solar activity proxies in that period. Among the contemporaneous observers, Johann L. Rost and Sebastian Alischer were two key sunspot observers to understand the solar activity in this transition just after the Maunder Minimum. We have revised all their sunspot records, counting the number of groups and individual sunspots to derive reliable data for the solar activity level for the period 1716–1726. We found significant misinterpretations of the sunspot group counting assigned to these astronomers in the existing group number databases. Our new group sunspot counting significantly reduces the number of groups for Rost and Alischer’s observations compared to entries in existing databases. Furthermore, our sunspot number estimates (obtained from the active day fraction methodology) of the maximum amplitude of Solar Cycles −3 and −4 are significantly lower than the amplitudes according to the official sunspot number, but they are compatible with sunspot number values obtained from solar activity proxies such as radioisotopes. Our result would imply that solar activity after the Maunder Minimum recovered more gradually and with a lower intensity than previously considered.

Abstract Past solar activity is of great interest for astrophysical and geophysical studies. Systematic searches over the last four centuries have detailed the evolution of the solar cycle. Brief comments on solar activity for periods with sparse records, such as the year 1791, are crucial. Lorenzo Hervás y Panduro, a Jesuit intellectual, noted in his 1793 book that sunspots were seen almost daily from 1791 January 1 to April 20. This would suggest a solar activity level estimated at a sunspot number of around 70.

Abstract Solar activity in recent centuries is crucial for astrophysics and geophysics, with historical sunspot records providing key insights, particularly for the 17th and 18th centuries. However, certain periods, such as around 1744, are still poorly understood. This note explores a qualitative commentary on solar activity from that time by Diego de Torres Villarroel, a notable Spanish writer. In his pamphlet on the great comet of 1744, Villarroel observed that the Sun appeared unusually clear, with fewer sunspots and faculae than usual, indicating low solar activity. These observations are consistent with the known solar minimum between cycles −1 and 0 around 1744. While Villarroel’s remarks only offer qualitative confirmation of existing knowledge, they are important for filling in gaps in historical records of solar activity and should be preserved for future research.

Abstract This note aims to analyze the evolution of the sunspot number for Solar Cycle 25, updating our previous findings on this topic. We compare daily, monthly and 13 months smoothed sunspot numbers for Solar Cycle 25 with those from previous cycles since mid-18th century (Solar Cycles 1–25). The highest daily, monthly and 13 months smoothed values for Solar Cycle 25 are significantly lower than the mean and median values considering all cycles. In particular, Solar Cycle 25 ranks 17th in terms of the highest 13 months smoothed sunspot number at this point in the cycle. Based on current data and the progression toward its maximum, we conclude that Solar Cycle 25 is likely to be a weak to moderate cycle, consistent with our earlier analyses. In addition, we find that Solar Cycles 13, 14, and 16 have the most similar behavior to that of Solar Cycle 25. Assuming a cycle length for Solar Cycle 25 similar to those of the above cycles, we estimate that the minimum of Solar Cycle 26 will be in 2030–2031.

Abstract The Leonid meteor shower is renowned for its scientific and public interest. In a search for meteorological data from Portuguese stations, records on an observation of the Leonids in 1869 from the Lisbon Geophysical Observatory “Infante Dom Luiz” were found. Given their potential value, a digital version with metadata is provided in the present note (the recovered data are available on doi:10.5281/zenodo.11221019). The observation took place from 9 PM on 1869 November 13 to 6 AM on November 14, local time in Lisbon, with mostly clear skies and 4–5 observers covering completely the sky. They recorded 1980 meteors, noting Zodiacal Light visibility and detailing meteor counts every five minutes.

PREMISE:Divergence of floral morphology and breeding systems are often expected to be linked to angiosperm diversification and environmental niche divergence. However, available evidence for such relationships is not generalizable due to different taxonomic, geographical and time scales. The Palearctic genus Helianthemum shows the highest diversity of the family Cistaceae in terms of breeding systems, floral traits, and environmental conditions as a result of three recent evolutionary radiations since the Late Miocene. Here, we investigated the tempo and mode of evolution of floral morphology in the genus and its link with species diversification and environmental niche divergence.METHODS:We quantified 18 floral traits from 83 taxa and applied phylogenetic comparative methods using a robust phylogenetic framework based on genotyping-by-sequencing data.RESULTS:We found three different floral morphologies, putatively related to three different breeding systems: type I, characterized by small flowers without herkogamy and low pollen to ovule ratio; type II, represented by large flowers with approach herkogamy and intermediate pollen to ovule ratio; and type III, featured by small flowers with reverse herkogamy and the highest pollen to ovule ratio. Each morphology has been highly conserved across each radiation and has evolved independently of species diversification and ecological niche divergence.CONCLUSIONS:The combined results of trait, niche, and species diversification ultimately recovered a pattern of potentially non-adaptive radiations in Helianthemum and highlight the idea that evolutionary radiations can be decoupled from floral morphology evolution even in lineages that diversified in heterogeneous environments as the Mediterranean Basin.

Sunshine duration (SD) represents a valuable parameter for early years when few or none measurements of surface solar radiation (SSR) are available. In the present work, daily and monthly SD records registered in Lisbon (Portugal) for the period 1890–1940 have been digitized to expand the data series available in electronic format, which starts in 1941. The resulting series for the period 1890–2018 can be considered as the earliest one in Portugal and the second one in the Iberian Peninsula. Cloud cover (CC) data for the same period have also been digitized. The SD series exhibits a weak negative trend (without statistical significance) from the 1890s to the 1910s, which is in line with the early dimming period in SSR reported in some regions. Subsequently, no trends are obtained for the period 1910s–1950s, which indicates that the early brightening is not observed in Lisbon unlike other locations in the Iberian Peninsula. After that, two strong statistically significant trends are found for the periods 1950s–1980s and 1980s–2010s in line with the well-known global dimming and brightening periods in SSR, respectively. On the other hand, the CC series presents an increase from 1890 to the 1980s, followed by a decrease up to 2018 (both being statistically significant), which may partially explain the reported SD trends. An analysis of SD under cloudless conditions proved the utility of this quantity to track long-term changes in atmospheric aerosol load. In addition, this analysis and a seasonal one pointed out that aerosols seem to play a relevant role in SD long-term variability.

In this work, we predict the maximum amplitude (using the 13-month smoothed Solar Influences Data Analysis Center (SILSO) Sunspot Number, version 2) of Solar Cycle 25 using as a predictor the slope of the inflection point during the ascending part of the cycle. After a description of the data and methodology employed in this work, we obtain a value of 131 ± 32 for the maximum amplitude of Solar Cycle 25. Finally, we discuss this result in the context of the current debate on the prediction of solar activity and compare it with other predictions of Solar Cycle 25 obtained by other methods.

In this study we assessed karyotype size and symmetry for a comprehensive taxonomic and geographic representation of Helianthemum and reconstructed chromosome number evolution in the genus. Using root tips, we photographed mitotic metaphase spreads to obtain chromosome number, total haploid (monoploid) length of the chromosome set (THL), karyotype formula, Stebbins’ classification of karyotype asymmetry, interchromosomal coefficient of variation of chromosome length (CVCL) and intrachromosomal mean centromeric asymmetry (MCA) using MATO (Measurement and Analysis Tools). We found that shifts in chromosome number are not a major driver in the evolution of Helianthemum, whose chromosome number evolved at a constant rate of single chromosome gain or loss. Karyotype asymmetry is very low and little variable in all taxonomic categories studied, with a predominance of metacentric and submetacentric small to medium-sized chromosomes about 3 μm at the genus level. However, total karyotype length varies from 16.91 μm to 47.84 μm at the species level, with a cytogenetic signature that is not conserved within subgenera and most sections. Overall, H. subg. Plectolobum shows both the longest and the most symmetrical karyotypes. We hypothesize that the variation in karyotype size in Helianthemum is likely a consequence of chromosome rearrangements that have occurred under selective pressures.

Angelo Secchi, an Italian Jesuit and prominent scientist of the 19th century, and one of the founders of modern astrophysics, observed the Sun regularly at the Collegio Romano in Rome, Italy, for more than 25 yr. Results from his observations are reported in articles published in the scientific journals of the time, as well as in drawings and personal notebooks that are stored in the historical archive of the Istituto Nazionale di Astrofisica Osservatorio Astronomico di Roma. The latter material, which reports solar observations performed from 1853–1878, includes original documents from Secchi and from a few of his close collaborators. The above unique material has recently been digitized for preservation purposes and for allowing the scientific exploitation of data not easily accessible so far. A total of more than 5400 digital images have been produced. Here we present the archival material and the new digital data derived from it. We also present results obtained from our primary analysis of the new digital data. In particular, we produced new measurements of the group number from 1853–1878, which will be available for future recalibration of the group number series.

In this work, we present hemispheric sunspot number counts made in the Astronomical Observatory of the University of Valencia for the period 1940 – 1956. We found these data in a secondary source (the bulletins of the Madrid Astronomical Observatory). We digitized the hemispheric sunspot number and group number recorded by the observers. Unfortunately, the sunspot positions or areas were not published in this secondary source. A machine-readable version of the dataset is available as supplementary material. We compare the Valencia hemispheric series with others from other observatories, such as the Madrid Astronomical Observatory, finding similar hemispheric behaviors. We also computed the asymmetry index from the hemispheric data. We found that the northern hemisphere was predominant in our study period (declining phase of Solar Cycle 17, Solar Cycle 18, and rising phase of Solar Cycle 19), and the southern hemisphere was leading. These results agree with those obtained in previous studies. Therefore, the Valencia hemispheric records are one more piece of information to know the behavior of the northern and southern hemispheres during the 20th century.

The recovery of records of past solar observations is crucial to understand the evolution of solar activity. In this context, three records of sunspot observations made at the Royal Observatory of the Spanish Navy in 1789 January and July, and 1790 June are shown in the present work. The aim of the observers who performed these sunspot observations was the discovery of intramercurial planets crossing the solar disk. For that reason, the observers only recorded round and dark spots and they may not have recorded all the sunspots that they observed. However, these records provide us with previously unknown information such as dates of active days (days with sunspots on the Sun) and position of sunspots.

A sunspot catalog was published by the Madrid Astronomical Observatory from sunspot observations made by Rafael Carrasco and his assistants for the period November 1931 – December 1933. We have digitized this catalog and carried out a quality control to detect inconsistencies. We present a machine-readable version of this sunspot catalog together with an erratum list. Moreover, we compared the Madrid sunspot number and area with other reference series. We found that sunspots in the northern hemisphere were predominant during this period, confirming previous studies. We have also analyzed the group morphological typologies registered in the catalog and show a butterfly diagram drawn with this new information. A comparison with the sunspot catalog by the Royal Greenwich Observatory shows that almost all the groups included in the Carrasco’s catalog are also present in the aforementioned catalog.

Long-term studies on hemispheric asymmetry can help to understand better the solar dynamo. We present the hemispheric sunspot number calculated from daily sunspot observations made at the Madrid Astronomical Observatory for the period 1935–1986 (corresponding approximately to Solar Cycles 17–21). From this data set, we also analyzed the asymmetry index and hemispheric phase shifts. We conclude that the northern hemisphere was predominant in Solar Cycles 17–20, whereas the southern hemisphere was predominant in Solar cycle 21. The strongest asymmetries are found in Solar Cycles 20 (with a relative difference between both hemispheres of 44%) and 19 (39%). A normalization of the Madrid hemispheric sunspot number was also made with respect to the sunspot number (Version 2). Our results agree with previous studies on hemispheric asymmetry around the mid-20th century and their secular trends.

Long-term solar activity can be studied using several parameters. Some of the most used are based on the sunspot counting. The active day fraction (ADF) is the simplest index derived from this counting. It is reliable in periods of low solar activity such as the Maunder minimum (MM). In this work, we study the relationship between the ADF and the sunspot number. We have obtained that the optimal fit of that relationship is an exponential function whose exponent is a degree 3 polynomial including all data except those with ADF equal to 100%. Then, we use that fit to estimate the sunspot number during the MM from the ADF calculated from the most recent sunspot group number database. Our estimations of the annual sunspot numbers are below 15, except that for 1656, which is 40.8, whereas our estimations of the triennial sunspot numbers are below 10 from 1648 to 1714. We have found peaks of the solar cycle in the middle of the 1650s, 1670s, 1680s, and 1700s but no clear evidence of solar cycle in the 1660s and 1690s, likely due to the scarcity of the available data. Our results agree with previous works obtaining values significantly higher than those of the group sunspot number derived by Hoyt and Schatten in 1998 but still fully compatible with a grand minimum period.

BACKGROUND AND AIMS:Several biogeographical models have been proposed to explain the colonization and diversification patterns of Macaronesian lineages. In this study, we calculated the diversification rates and explored what model best explains the current distribution of the 15 species endemic to the Canary Islands belonging to Helianthemum sect. Helianthemum (Cistaceae). METHODS:We performed robust phylogenetic reconstructions based on genotyping-by-sequencing data and analysed the timing, biogeographical history and ecological niche conservatism of this endemic Canarian clade. KEY RESULTS:Our phylogenetic analyses provided strong support for the monophyly of this clade, and retrieved five lineages not currently restricted to a single island. The pristine colonization event took place in the Pleistocene (~1.82 Ma) via dispersal to Tenerife by a Mediterranean ancestor. CONCLUSIONS:The rapid and abundant diversification (0.75-1.85 species per million years) undergone by this Canarian clade seems the result of complex inter-island dispersal events followed by allopatric speciation driven mostly by niche conservatism, i.e. inter-island dispersal towards niches featuring similar environmental conditions. Nevertheless, significant instances of ecological niche shifts have also been observed in some lineages, making an important contribution to the overall diversification history of this clade.

Molecular systematics requires the establishment of a robust phylogenetic framework including extensive geographical and taxonomic sampling. In this work, we proposed systematic changes in the genus Helianthemum based on phylogenetic trees obtained by both maximum likelihood and Bayesian analyses of GBS data. The implications of these phylogenetic results for the systematics of Helianthemum entail the establishment of a new subgenus and novel re-ascriptions of sections and species along with some nomenclatural novelties. The following new combinations are proposed: Helianthemum subg. Eriocarpum (Dunal) Martín-Hernanz, Velayos, Albaladejo & Aparicio; H. oelandicum subsp. conquense (Borja & Rivas Goday ex G.López) Martín-Hernanz, Velayos, Albaladejo & Aparicio; H. nummularium subsp. cantabricum (M.Laínz) Martín-Hernanz, Velayos, Albaladejo & Aparicio; H. nummularium subsp. tinetense (M.Mayor & Fern.Benito) Martín-Hernanz, Velayos, Albaladejo & Aparicio.