A Comparative study of germination strategies of two species of genus Allium sect. Allium

Germination experiments were performed with seeds of two species of genus Allium section Allium, a rare and endangered species A. pyrenaicum and a common A. sphaerocephalon. Different pre-treatments and a photoperiod of 24 h darkness were applied in order to simulate different germination conditions. Both species showed a high percentage of viable seeds a part of which were dormant. An elevate percentage of dormant seeds could be caused by a later collection time. Low altitude populations had more mortality than the others, possibly caused by the hard summer conditions during flowering and fruiting time. Comparisons between dates of species coexistence localities only show inter-population variability and it could be caused by the detected dormancy. Darkness accelerates germination, possibly for elongation radicle stimulation. Heat-shock pre-treatments decreased germination time in seeds from localities where fire is a probable event. The rarity of A. Pyrenaicum not seems to be caused by restricted germination requirements but is attributable to distinct habitat preferences, related to his altitudinal range of distribution

Auto- and allopolyploidy in Centaurea sect. Acrocentron s.l. (Asteraceae, Cardueae): karyotype and chromosome banding pattern analyses

Dysploidy and polyploidy are well documented in the large genus Centaurea, especially in sect. Acrocentron and in a small group of species from the Iberian Peninsula described as sect. Chamaecyanus, closely related to Acrocentron. We have explored two interesting cases of polyploid series in both sections: the polyploid series of Centaurea toletana in sect. Chamaecyanus and the series of C. ornata group in sect. Acrocentron. We have carried out a karyological study using both classic karyotype analyses and chromosome banding with fluorochromes.

Cytotaxonomy of North African species of Delphinium L. sect. Delphinium (Ranunculaceae).

S'han estudiat els nombres cromosómics i l'estructura dels cariotipus de 15 poblacions nordafricanes de Delphinium L. sect. Delphinium. Delphinium balansae Boiss. & Reuter, amb cariotipus mes simétric, apareix com a possible ancestre perenne de la resta d'espécies annuals amb cariotipus mes asimétric i mes curt. Es proposa una reorganització taxonómica de la secció, d'on es descriuen dues series noves (ser. Macropeiala ser. nova i ser. Balansae ser. nova.) i es proposen dues combinacions noves (D. nanum subsp. alboliliaceum i D. nanum subsp. elongatum).

Cambium dynamics of Pinus sylvestris and Betula spp. in the northern boreal forest in Finland

Abstract

Effects of competing vegetation and post-planting weed control on the mortality, growth and vole damages to Betula pendula planted on former agricultural land

Abstract

Divergent and narrower climatic niches characterize polyploid species of European primroses in Primula sect. Aleuritia

Aim It is hypothesized that the ecological niches of polyploids should be both distinct and broader than those of diploids - characteristics that might have allowed the successful colonization of open habitats by polyploids during the Pleistocene glacial cycles. Here, we test these hypotheses by quantifying and comparing the ecological niches and niche breadths of a group of European primroses. Location Europe. Methods We gathered georeferenced data of four related species in Primula sect. Aleuritia at different ploidy levels (diploid, tetraploid, hexaploid and octoploid) and used seven bioclimatic variables to quantify niche overlap between species by applying a series of univariate and multivariate analyses combined with modelling techniques. We also employed permutation-based tests to evaluate niche similarity between the four species. Niche breadth for each species was evaluated both in the multivariate environmental space and in geographical space. Results The four species differed significantly from each other in mono-dimensional comparisons of climatological variables and occupied distinct habitats in the multi-dimensional environmental space. The majority of the permutation-based tests either indicated that the four species differed significantly in their habitat preferences and ecological niches or did not support significant niche similarity. Furthermore, our results revealed narrower niche breadths and geographical ranges in species of P. sect. Aleuritia at higher ploidy levels. Main conclusions The detected ecological differentiation between the four species of P. sect. Aleuritia at different ploidy levels is consistent with the hypothesis that polyploids occupy distinct ecological niches that differ from those of their diploid relative. Contrary to expectations, we find that polyploid species of P. sect. Aleuritia occupy narrower environmental and geographical spaces than their diploid relative. These results on the ecological niches of closely related polyploid and diploid species highlight factors that potentially contribute to the evolution and distribution of polyploid species.

Euphorbia pedroi Molero and Rovira, sp. nov. (Sect. Balsamis, Euphorbiaceae).

Se describe la nueva especie Euphorbia pedroi Molero and Rovira

Phylogeny and biogeography of Primula sect. Armerina: implications for plant evolution under climate change and the uplift of the Qinghai-Tibet Plateau.

BACKGROUND: The historical orogenesis and associated climatic changes of mountain areas have been suggested to partly account for the occurrence of high levels of biodiversity and endemism. However, their effects on dispersal, differentiation and evolution of many groups of plants are still unknown. In this study, we examined the detailed diversification history of Primula sect. Armerina, and used biogeographic analysis and macro-evolutionary modeling to investigate a series of different questions concerning the evolution of the geographical and ecological distribution of the species in this section. RESULTS: We sequenced five chloroplast and one nuclear genes for species of Primula sect. Armerina. Neither chloroplast nor nuclear trees support the monophyly of the section. The major incongruences between the two trees occur among closely related species and may be explained by hybridization. Our dating analyses based on the chloroplast dataset suggest that this section began to diverge from its relatives around 3.55 million years ago, largely coinciding with the last major uplift of the Qinghai-Tibet Plateau (QTP). Biogeographic analysis supports the origin of the section in the Himalayan Mountains and dispersal from the Himalayas to Northeastern QTP, Western QTP and Hengduan Mountains. Furthermore, evolutionary models of ecological niches show that the two P. fasciculata clades have significantly different climatic niche optima and rates of niche evolution, indicating niche evolution under climatic changes and further providing evidence for explaining their biogeographic patterns. CONCLUSION: Our results support the hypothesis that geologic and climatic events play important roles in driving biological diversification of organisms in the QTP area. The Pliocene uplift of the QTP and following climatic changes most likely promoted both the inter- and intraspecific divergence of Primula sect. Armerina. This study also illustrates how niche evolution under climatic changes influences biogeographic patterns.

Euphorbia L. sect. Cymatospermum (Prokh.) Prokh. (Euphorbiaceae) en la Peninsula Iberica. Morfologia de las semillas. Precisiones taxonomicas y corologicas sobre algunos taxones criticos

La revisión de las especies ibéricas de Euphorbia sect. Cymatospermum ha precisado de un estudio previo de los caracteres seminales. Se ha examinado la variabilidad morfológica intra e interespecíflca de las semillas y se han definido los caracteres diferenciales para cada taxon. La forma, tamaño y ornamentación epispérmica proporcionan suficientes caracteres para distinguir los táxones reconocidos en este artículo. El estudio de los mucílagos y de los microcaracteres epispérmicos al MEB ha esclarecido las afinidades de las semillas de esta sección respecto a las otras del género, y ha supuesto indagación acerca de su significado funcional y evolutivo.