1,721,032 research outputs found
Guida Botanica al Parco Alto Garda Bresciano
No full textUn invito a scoprire le splendide attrattive botaniche del Parco Alto Garda Bresciano, dal lago alle cime più alte.
Dopo una colloquiale introduzione sulle peculiarità della vita vegetale, si prosegue osservando l’affascinante interazione tra le piante, l’uomo e le caratteristiche fisiche e climatiche del territorio, fino a delineare una sintesi paesaggistica che pone in relazione la varietà di habitat con l’eccezionale ricchezza floro-vegetazionale del Parco Alto Garda Bresciano.
Più di 900 illustrazioni aiuteranno a riconoscere le piante e le comunità vegetali delle diverse unità di paesaggio. Le note escursionistiche consentiranno, inoltre, di osservare direttamente tutte le tipologie vegetazionali descritte, nonché tutte le piante più rappresentative dell’Alto Garda Bresciano
Distribution of genetic variability in southern populations of Scots pine (Pinus sylvestris L.) from the Alps to the Apennines
No full textWas Charles Darwin right in his explanation of the ‘abominable mystery’?
Full text linkThe site and time of origin of angiosperms are still debated. The co-occurrence of many of the early
branching lineages of flowering plants in a region somewhere between Australia and the SW Pacific islands
suggests a possible Gondwanan origin of angiosperms. The recent recognition of Zealandia, a 94%
submerged continent in the east of Australia, could explain the discrepancy between molecular clocks and
fossil records about the age of angiosperms, supporting the old Darwinian hypothesis of a “lost continent”
to explain the “abominable mystery” regarding the origin and rapid radiation of flowering plants
Distribution of genetic variability in southern populations of Scots pine (Pinus sylvestris L.) from the Alps to the Apennines.
No full textAlpine and Northern Apennine populations of Pinus sylvestris L. collected from 8 different Italian sites were analysed by mitochondrial nadI intron and InterSimple Sequence Repeat (ISSR) markers, in order to describe the natural level of genetic variability and to clarify their genetic relationships. The small Northern Apennine populations are the southernmost populations of this conifer in Italy. All the analysed populations were spontaneous and reforested areas were excluded. The analysis of the polymorphisms in the nad 1 intron sequence confirmed that the Italian P. sylvestris populations have the same mitotype (mitotype a) as the Central European ones. In the genomic ISSR analysis the proportion of shared alleles between the individuals showed the highest degree of differentiation between French and Italian populations and a divergence between the Alpine and Apennine populations. Alpine populations showed a higher genetic variability (GD 0,310 ± 0,0252) than Apennine samples (GD 0,217 ± 0,019). In addition, the individuals from the Apennines did not show a clear population structure, suggesting a common genetic constitution of the Apennine P. sylvestris. It is likely that this constitution is the result of a progressively genetic isolation between the Alpine and the Northern Apennine populations from the early Holocene. The genetic constitution of the Northern Apennine populations suggests the opportunity of a management where in situ conservation of such small populations could be coupled to their use as sources of suitable local reforesting materials
Geomorphological disturbance affects ecological driving forces and plant turnover along an altitudinal stress gradient on alpine slopes
No full textThe altitudinal gradient is considered as a stress gradient for plant species because the development and fitness of plant communities tend to decrease as a result of the extreme environmental conditions present at high elevations. Abiotic factors are predicted to be the primary filter for species assemblage in high alpine areas, influencing biotic interactions through both competition for resources and positive interactions among species. We hypothesised that the relative importance of the ecological driving forces that affect the biotic interactions within plant communities changes along an elevation gradient on alpine debris slopes. We used multiple gradient analyses of 180 vegetation plots along an altitudinal range from 1,600 to 2,600 m and single 100 m-bands in the Adamello-Presanella Group (Central Alps) to investigate our hypothesis; we measured multiple environmental variables related to different ecological driving forces. Our results illustrate that resource limitations at higher elevations affect not only the shift from competition to facilitation among species. A geomorphological disturbance regime along alpine slopes favours the resilience of the high-altitude species within topographic/geomorphological traps. An understanding of the ecological driving forces and positive interactions as a function of altitude may clarify the mechanisms underlying plant responses to present and future environmental changes
A reappraisal of the evolutionary and developmental pathway of apomixis and its genetic control in angiosperms
Full text linkApomixis sensu stricto (agamospermy) is asexual reproduction by seed. In angiosperms it represents an easy byway of life cycle renewal through gamete-like cells that give rise to maternal embryos without ploidy reduction (meiosis) and ploidy restitution (syngamy). The origin of apomixis still represents an unsolved problem, as it may be either evolved from sex or the other way around. This review deals with a reappraisal of the origin of apomixis in order to deepen knowledge on such asexual mode of reproduction which seems mainly lacking in the most basal angiosperm orders (i.e., Amborellales, Nymphaeales and Austrobaileyales, also known as ANA-grade), while it clearly occurs in different forms and variants in many unrelated families of monocots and eudicots. Overall findings strengthen the hypothesis that apomixis as a whole may have evolved multiple times in angiosperm evolution following different developmental pathways deviating to different extents from sexuality. Recent developments on the genetic control of apomixis in model species are also presented and adequately discussed in order to shed additional light on the antagonist theories of gain-and loss-of-function over sexuality
Unexpected impacts of climate change on Alpine vegetation
No full textThe vegetation in a high alpine site of the European Alps experienced changes in area between 1953 and 2003 as a result of climate change. Shrubs showed rapid expansion rates of 5.6% per decade at altitudes between 2400 m and 2500 m. Above 2500 m, vegetation coverage exhibited unexpected patterns of regression associated with increased precipitation and permafrost degradation. As these changes follow a sharp increase in both summer and annual temperatures after 1980, we suggest that vegetation of the alpine (2400-2800 m) and nival (above 2800 m) belts respond in a fast and flexible way, contradicting previous hypotheses that alpine and nival species appear to have a natural inertia and are able to tolerate an increase of 1-2 degrees C in mean air temperature
Preliminary assessment of the genetic diversity in Lamyropsis microcephala (Asteraceae)
No full textEndangered species with small and isolated populations has been a key topic of conservation biology studies in the last decade. Lamyropsis microcephala is among the most significant narrow endemic plants in the Mediterranean region, laying on the Gennargentu massif of the Sardinia island (Italy). Due to heavy threat factors, this species has rapidly become threatened with extinction. The ISSR technique was used to assess the genetic variation and structure of the individuals growing in the four remnant localities known to date, with the aim to implement further conservation strategies. Results indicated a degree of differentiation among the four subpopulations, in particular for the Fonni one. The estimates of Nei’s genetic diversity (H) ranged from 0.0563 (Fonni) and 0.1104 (Bau ‘e Laccos). AMOVA values showed that 53% of the total variation may be attributed to the individuals within subpopulations, while 47% is due to differences among subpopulations (P < 0.001). Results also highlighted a scarce gene flow (Nm = 0.503)
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