Pattern of movements of adult Barbus haasi in a small Mediterranean stream

Most adult Barbus haasi , at a 1950 m-long site in Vallvidrera creek, were highly sedentary and resided within a home range <20 m (32 m²), while a small group were more mobile. On successive sampling occasions, between 52·3 and 64·9% of fish were recaptured in the same 10-m-long section in which they had previously been captured. Movements over long distances were infrequent, and only 5·6% of the fish moved >100 m. The movement pattern of the population was seasonally stable, although the mean distances were slightly greater in summer because of the medium-range movements of a few individuals. Overall, upstream and downstream movements were equally common but a significant downstream movement occurred in spring. The size of the fish did not influence the movement rate. Fish inhabiting those sections of the stream with greater depth, slower current and more cover had a lower movement rate than fish occupying shallower, exposed sections. The restricted movement of B. haasi could increase the survival of fish by increasing the probability of staying in the remaining pools during summer dry-out, and may therefore be of adaptive significance.     

Twilight activity patterns and angling vulnerability of yellowmouth barracuda (Sphyraena viridensis Cuvier, 1829), a range-expanding thermophilic fish

Among the thermophilic fishes that have become established in the north-western Mediterranean as a consequence of sea warming, the yellowmouth barracuda (Sphyraena viridensis Cuvier, 1829) appears to be one of the most successful and abundant in the coastal rocky environment, having increasingly become the object of recreational and commercial exploitation in the study area. Lure-fishing sessions were carried out from May 2016 to November 2018 in the Catalan Sea (NE Spain) at dawn and dusk, with the aim of providing new insight into the behavioural, spatial and feeding ecology and vulnerability to angling of this poorly known species. Generalized mixed-effects linear models showed that S. viridensis is a crepuscular inshore dweller, whose vulnerability to angling is significantly influenced by solar and lunar light intensities, being highest in the pre-spawn and spawning periods. Asymmetries between dawn and dusk activity patterns were detected, evidently related to a drop in aggressiveness at dusk following the spawning period. The simple study design adopted may be applied to other contexts, aiming to the recognition of several levels of fish vulnerability to angling.     

Phylogeny, speciation and species turnover. The case of the Mediterranean gastropods of genus Cyclope Risso, 1826

The genus Cyclope Risso, 1826 (family Nassariidae) has appeared in the fossil record since the Pliocene. Although it is still found today, the teleoconch morphology has never undergone modification, despite the fact that the protoconch morphologies of fossils (multispiral) and living forms (paucispiral) are different. They vary in their embryological and larval development and, hence, are two different species: C. migliorinii (Bevilacqua, 1928), the fossil species, and C. neritea (Linnaeus, 1758), the living species. We discuss the morphologic modifications in the evolution of this genus: the speciation that leads to its appearance and the speciation driving the Pliocene species to the living one. The order and the direction of these changes are based on phylogenetic analysis. No intermediate forms have been found showing a gradual morphological change that could have been worked by natural selection. Our analysis takes as the origin of the morphological novelties the genetic modifications in the ontogenetic processes which resulted in rapid and important phenotypic changes. Both speciation processes are sympatric cladogenetic. The changes that determine the appearance of the genus affect only the teleoconch, not the larval development. The modifications that lead from one species to the other, within the genus Cycope, affect the larval development exclusively. This points to a certain disconnection between the development of the embryo-larval phase and the young-adult formation, such that evolutionary processes could have occurred independently in different ontogenetic stages. The influence of larval ecology in relation to extinction of the ancestor and persistence of the derived species is also analysed. We hypothesize that climatic fluctuations may have affected the planktonic larvae of the fossil species, driving it to extinction. The living species, developing without the planktonic phase, would have resisted these climatic changes. We consider that the mechanisms described as drivers of the evolution of this genus can be of more general validity in prosobranch gastropods.     

Body size increase in insular rodent populations: a role for predators?

Insular mammalian populations living in areas of small size are often characterized by a drastic change in body mass compared to related continental populations or species. Generally, small mammals (less than 100 g) evolve into giant forms while large mammals (up to 100 g) evolve into dwarf forms. These changes, coupled with changes in other life, behavioural, physiological or demographic traits are referred to generally as the insular syndrome. We tested in this study the relative contribution of three factors — area of island, numbers of competitor species and number of predator species — to changes in body size of the woodmouse (Apodemus sylvaticus) in the Western Mediterranean Sea. Our results, based on a comparative analysis using the phylogenetic independent contrasts method, indicate that the increase in body size is related both to the decrease of island size and to the lower number of predator species. A decrease of competitor species does not seem to have an important effect.     

Vicariance patterns in the Mediterranean Sea: east–west cleavage and low dispersal in the endemic seagrass Posidonia oceanica

Aim The seagrass, Posidonia oceanica is a clonal angiosperm endemic to the Mediterranean Sea. Previous studies have suggested that clonal growth is far greater than sexual recruitment and thus leads to low clonal diversity within meadows. However, recently developed microsatellite markers indicate that there are many different genotypes, and therefore many distinct clones present. The low resolution of markers used in the past limited our ability to estimate clonality and assess the individual level. New high‐resolution dinucleotide microsatellites now allow genetically distinct individuals to be identified, enabling more reliable estimation of population genetic parameters across the Mediterranean Basin. We investigated the biogeography and dispersal of P. oceanica at various spatial scales in order to assess the influence of different evolutionary factors shaping the distribution of genetic diversity in this species. Location The Mediterranean. Methods We used seven hypervariable microsatellite markers, in addition to the five previously existing markers, to describe the spatial distribution of genetic variability in 34 meadows spread throughout the Mediterranean, on the basis of an average of 35.6 (± 6.3) ramets sampled. Results At the scale of the Mediterranean Sea as a whole, a strong east–west cleavage was detected (amova) . These results are in line with those obtained using previous markers. The new results showed the presence of a putative secondary contact zone at the Siculo‐Tunisian Strait, which exhibited high allelic richness and shared alleles absent from the eastern and western basins. F statistics (pairwise θ ranges between 0.09 and 0.71) revealed high genetic structure between meadows, both at a small scale (about 2 to 200 km) and at a medium scale within the eastern and western basins, independent of geographical distance. At the intrameadow scale, significant spatial autocorrelation in six out of 15 locations revealed that dispersal can be restricted to the scale of a few metres. Main conclusions A stochastic pattern of effective migration due to low population size, turnover and seed survival is the most likely explanation for this pattern of highly restricted gene flow, despite the importance of an a priori seed dispersal potential. The east–west cleavage probably represents the outline of vicariance caused by the last Pleistocene ice age and maintained to this day by low gene flow. These results emphasize the diversity of evolutionary processes shaping the genetic structure at different spatial scales.     

Seasonal changes in net photosynthesis rates and photosynthetic capacity in leaves of Cistus salvifolius,a European mediterranean semi-deciduous shrub

Summary During five different periods between Nov. 1982 and Aug. 1983, the diurnal patterns exhibited in photosynthetic CO₂ uptake and stomatal conductance were observed under natural conditions on twigs of Cistus salvifolius, a Mediterranean semi-deciduous shrub which retains a significant proportion of its leaves through the summer drought. During the same periods, net photosynthesis at saturating CO₂ partial pressure was measured on the same twigs as a function of irradiance at different temperatures. From these data, photosynthetic capacity, defined here as the CO₂- and light-saturated net photosynthesis rate, was obtained as a function of leaf temperature. C. salvifolius is a winter growing species, shoot growth being initiated in Nov. and continuing through May. Photosynthetic capacity was quite high in Nov., March and June, exceeding 40 mol m^-2 s^-1 at optimum temperature. In Dec., photosynthetic capacity was somewhat reduced, perhaps due to low night-time temperatures (<5°C) during the measurement period. In Aug., capacity in oversummering shoots at optimum temperature fell to less than 8 mol m^-2 s^-1, due to water trees and perhaps leaf aging. Seasonal changes in maximal photosynthetic rates under ambient conditions were similar, and like those found in co-occurring evergreen sclerophylls. Like the evergreens, Cistus demonstrated considerable stomatal control of transpirational water loss, particularly in oversummering leaves. During each measurement period except Aug. when capacity was quite low, the maximum rates of net photosynthesis measured under ambient conditions were less than half the measured photosynthetic capacities at comparable temperatures, suggesting an apparent excess nitrogen investment in the photosynthetic apparatus.     

The fate of15N labeled nitrogen applied to mature citrus trees

Summary The efficiency and balance of nitrogen from one year's application was studied in a long-term fertigation experiment. Enriched nitrogen fertilizer, K¹⁵NO₃, was applied to a 22-year-old Shamouti orange tree with a history of high N applications (N₃) and to an N-starved tree (N₁). The distribution of N in the different parts of the trees and in the soil was determined after the experimental trees were excavated. Similar total recovery of the labeled fertilizer N was found in the trees and soil in both treatments (N₁−61.7% N₃−56%). However, the distribution between tree and soil was different. The amount of recovered residual fertilizer in the soil was much larger in the N₃ treatment than in N₁. The highest percentage of fertilizer N was found in the new organs,i.e. fruits, twigs and leaves. The roots and branches took up only 6–14% from the labeled fertilizer. Only 20.9% of the leaf N and 23.4% of the fruit N in the N₃ tree originated in the labeled fertilizer, indicating translocation of N from older parts of the tree to new growth. Evidence was found of storage of N in the wooded branches, while the roots contained a surprisingly small part of labeled fertilizer. Contribution 1599E.     

Delimitation and classification ofBromus fasciculatus (Poaceae)

The syntypes ofBromus madritensis var.delilei Boiss. comprise two different elements: specimens ofB. haussknechtii Boiss. and ofB. fasciculatus C. Presl s.l. By its lectotypification and on the basis of new morphological characters, the validation ofB. fasciculatus subsp.delilei (Boiss.)H. Scholz 1971 was substantiated. This subspecies represents the eastern marginal segregate of the south-Mediterranean species.B. fasciculatus var.alexandrinus Thell. is a minor variant of the typical subspecies.Dedicated to Prof.K. H. Rechinger on the occasion of his 80th birthday.     

On subspecific taxa ofHypericum empetrifolium (Hypericaceae) from Crete

The morphology, altitudinal distribution and phytocoenology ofHypericum empetrifolium Willd., var.oliganthum Rech. fil. and var.tortuosum Rech. fil. are reassessed and as a result, the taxa are treated at subspecific rank. Essential characters proved to be growth form, number of flowers, foliage and epidermal surface characters, shape of seeds and testa sculpturing.The different growth forms can be interpreted as adaptations to the local habitats.Hypericum empetrifolium Willd. subsp.empetrifolium is a low subshrub of various vegetation types known as phrygana whereasHypericum empetrifolium Willd. subsp.oliganthum (Rech. f.)Hagemann grows as a cushion-like dwarf shrub in chasmophyte associations rich in relic species.Hypericum empetrifolium Willd. subsp.tortuosum (Rech. f.)Hagemann is confined in the high mountain regions and grows as a true dwarf espalier shrub with low spreading shoots.Dedicated to Hofrat Univ.-Prof. DrK. H. Rechinger on the occasion of his 80th birthday.     

Effect of pupation environment on the quality of pupae and adults of the Mediterranean fruit fly

When mature larvae of the Mediterranean fruit fly, Ceratitis capitata (Wiedemann) pupated in bran rather than naked there was an increase in adult eclosion, but no difference in 9 day pupal weight, 9 day lipid content, or flight ability. There was no difference when pupation occurred at 20 or 25°C. Pupation in sand at 20°C caused severe mortality, while pupation in sand at 25°C did not. Data are presented which favour naked pupation over pupation in any medium, and evidence is presented which indicates that collection of mature larvae in a rotary tumbler rather than by the conventional popping method is economically preferable and is without significant biologically adverse effects.

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Résumé Si des larves mûres de Ceratitis capitata se nymphosent dans du son ou à l'air libre, dans le premier cas le taux d'éclosions est plus élevé, mais le poids et la teneur en lipides au neuvième jour de nymphose ainsi que l'aptitude au vol sont identiques dans les deux. Il n'y a pas de différences pour les pupaisons à 20°C et 25°C, mais la pupaison dans le sable à 20°C provoque une forte mortalité, tandis qu'à 25°C le sable n'a aucun effet. Les résultats obtenus sont favorable à une pupaison à nu plutôt que dans un substrat, et des arguments sont apportés montrant que la collecte des larves mûres dans un culbuteur rotatif ne provoque significativement pas plus d'effets nocifs que la méthode classique du saut.