Drought impact on water use efficiency and intra‐annual density fluctuations in Erica arborea on Elba (Italy)

Erica arborea (L) is a widespread Mediterranean species, able to cope with water stress and colonize semiarid environments. The eco‐physiological plasticity of this species was evaluated by studying plants growing at two sites with different soil moistures on the island of Elba (Italy), through dendrochronological, wood‐anatomical analyses and stable isotopes measurements. Intra‐annual density fluctuations (IADFs) were abundant in tree rings, and were identified as the key parameter to understand site‐specific plant responses to water stress. Our findings showed that the formation of IADFs is mainly related to the high temperature, precipitation patterns and probably to soil water availability, which differs at the selected study sites. The recorded increase in the ¹³C‐derived intrinsic water use efficiency at the IADFs level was linked to reduced water loss rather than to increasing C assimilation. The variation in vessel size and the different absolute values of δ¹⁸O among trees growing at the two study sites underlined possible differences in stomatal control of water loss and possible differences in sources of water uptake. This approach not only helped monitor seasonal environmental differences through tree‐ring width, but also added valuable information on E. arborea responses to drought and their ecological implications for Mediterranean vegetation dynamics.     

Crocus imperati and Crocus suaveolens (Iridaceae), two controversial endemic crocuses from Central and Southern Italy – morphometrics,lectotypification and chorology

Crocus imperati Ten. and Crocus suaveolens Bertol. are the most controversial endemic crocuses in Italy; they have been interpreted by various authors as different species or infraspecific entities and their chorologies are afflicted by numerous misidentifications. This work, by means of an extensive in vivo study across the whole ranges of the two taxa, and using biometrical investigations, aims at clarifying their status. The names C. imperati and C. suaveolens are typified, several taxonomical complications are discussed and an accurate chorology is outlined. The results show that a single qualitative character is constant (the presence or absence of a bracteole) and two other characters allow discrimination in most cases; their combined use, therefore, ensures certain identification of any single individual. No hybrid individual or intermediate populations were detected and the distributional ranges of the two species were confirmed to be contiguous but not overlapping. As a consequence, treatment of the two taxa at specific level appears to be the most appropriate. © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society, 2008, 158 , 194–214.     

The niche variation hypothesis and the evolution of colour polymorphism in birds: a comparative study of owls, nightjars and raptors

We studied the evolution of colour polymorphism in diurnal raptors, owls and nightjars, the avian taxa in which this trait is most widespread, in relation to species ecological niche width and diet. Two main mechanisms have been put forward to explain the maintenance of polymorphism, namely apostatic selection and disruptive selection. The niche variation hypothesis states that species with broader ecological niches should be more variable compared with those with narrow niches because of the action of disruptive selection; the apostatic selection hypothesis conversely suggests that intraspecific colour variation should be promoted in predators by prey forming an avoidance image for the more common colour morph. Our aim was to determine if colour polymorphism occurrence was associated with broad ecological niches as predicted by the niche variation hypothesis, or with predation on intelligent and sharp‐sighted prey as predicted by the avoidance image hypothesis. Pairwise comparisons were made between pairs of closely related species differing in variables expected to influence the occurrence of polymorphism. We found that polymorphic species of all three groups showed wider and more continuous distribution ranges, frequented many different habitats, both open and closed, and lived in seasonally alternating dry/wet climates. Polymorphic species were more migratory compared with monomorphic ones, and they showed an activity pattern covering both day and night. Conversely, colour polymorphism was not higher in species preying on birds and mammals. All these findings support the hypothesis that colour polymorphism evolved in bird species with wider niche breadth and not in species preying on intelligent prey. Therefore, we propose that disruptive selection may be the main mechanism maintaining colour polymorphism in these bird groups by favouring different morphs in different environmental conditions. © 2004 The Linnean Society of London, Biological Journal of the Linnean Society, 2004, 82 , 237–248.     

Differential responses of territorial Tawny Owls Strix aluco to the hooting of neighbours and strangers

Male Tawny Owls Strix aluco have individually distinct hooting calls. A classic play-back experimental design was used to examine the differences in behavioural responses of a known owl to the hooting of a neighbour (familiar) compared with a stranger (unfamiliar) in order to test the hypothesis that such hooting variations are used in calibrating interactions between conspecifics. We tested 12 male Tawny Owls and their mates; the overall intensity of agonistic response was significantly higher when we stimulated birds using playbacks of strangers than when we did so with those of neighbours. The behaviour displayed and the type of voice used by Tawny Owls were stronger toward strange males. Moreover, on the occasions we broadcast a strange male hooting, the singing rate was higher while the latency was lower.     

The Contribution of Ciliated Protozoa to Plankton and Benthos Biomass in a European Ricefield

The densities and biomass of ciliates inhabiting the water-sediment interface and the water column of an experimental ricefield were investigated throughout four annual cycles. Ciliate abundance and biomass were higher at the water-sediment interface than in the water column. In both sites, large ciliates (> 10⁵μm³) contributed the higher biomass values, but the highest densities were found in the intermediate size class (10⁴-10⁵μm³). The prorodontid Coleps hirtus dominated the ciliate assemblage and usually comprised > 50% of total ciliate density. Blooms of C. hirtus , occurred in June in the water column and in July at the sediment surface. During the four cycles of rice cultivation, the average daily values for production of the entire ciliate community was 69.6 mgC/m²/d, and the net production efficiency (K₂) was 72.0%. The estimated production values in the present study are high if compared to production measured for ciliates in other freshwater ecosystems.     

European and Mediterranean oaks (Quercus L.; Fagaceae): SEM characterization of the micromorphology of the abaxial leaf surface

This paper examines micromorphological characteristics (trichomes, waxes, stomata) of the abaxial leaf surface of European and Mediterranean oaks. Observations were performed In-scanning electron microscopy, and the purpose of the investigation was to ascertain whether it is possible to distinguish the different species taxonomically using these features. Several species, as well as some subspecific entities and taxa considered doubtful, were taken into consideration. Subgenera appear to be well-defined: e.g. the subgenus Quercus is characterized by waxes arranged in vertical scales, the subgenera Cenis and Sclerophyllodris by smooth waxes. They differ because the former has markedly elliptical stomata, while the latter two have roundish stomata. The different species are also fairly easy to distinguish, and this fact confirms the taxonomical validity of the parameters we have taken into consideration. In some cases subspecific entities and doublful species do not diflcr at all from the related species, but in others they present such marked variations that it is difficult even to classify them with certainty. The most critical taxonomic groups (i.e. those which include a number of specific and subspecific entities often too difficult to distinguish from each other) are the series Quercus robur – Quercus petraea,– Quercus pubescens and the Quercus faginea,– Quercus Insitanica Quercus canariensis group.     

CONSUMER ACCEPTABILITY OF VEGETABLE SOUPS

The aim of this study was to investigate whether product label information “produced with organic ingredients” and “stabilization technology” affects consumer acceptability of vegetable soups. Three focus group interviews were preliminarily conducted in order to gain information about the appropriate terminology to use in the next consumer test. In all, 109 subjects were recruited by means of a background questionnaire. They were then divided into three groups according to age, gender and soup preference. Each group evaluated three different types of soup in two phases, first blind and then with information. At the end of the second phase, the participants filled in a conjoint analysis questionnaire. The results demonstrated that if consumers were informed that soup is prepared with organic ingredients, they would improve their acceptability scores, whatever the soup type. Stabilization technology information had no effect. Conjoint results revealed that consumers appreciate soups made with organic legumes and cereals and without seasoning. However, differences among subgroups were found.     

IMPROVISATION OF NEW NOTES DURING SINGING BY MALE SARDINIAN WARBLERS SYLVIA MELANOCEPHALA

ABSTRACT

The songs of Sardinian warblers Sylvia melanocephala are extremely complex and variable, and even consecutive songs uttered by the same male usually differ. To provide a better understanding of the nature of the variation recorded, an attempt has been made to determine size and composition of the note repertoire of three selected individuals. The analysis was carried out on samples each consisting of several dozen songs, and the various notes were sorted on the basis of the visual similarity of their spectrographs patterns. Each male turned out to have a very large note repertoire which does not show any overlap with those of other males, with the only exception a particular note found in the songs of all the males. In two birds out of three, however, the graphs of the occurrence of new notes in consecutive songs show no tendency to become asymptotic. This suggests that the assessment of note repertoire size in these birds is not accurate, as they continue inserting new notes in their songs even after they ha ve uttered several dozen songs. A table recording the presence or absence of the various notes in consecutive songs revealed that at least two of the three birds used different sets of notes in different bouts of songs, switching from one to another after short pauses made between two consecutive bouts. All this makes the attempt to assess the actual size of the note repertoire in these birds very difficult, and makes it probable that Sardinian warblers do not possess a finite repertoire of notes. The pattern of note selection observed for the three males in this study is best explained by assuming that these birds improvise new notes as they sing.