Genital and allozyme similarity between Arion urbiae and A. anguloi (Mollusca: Pulmonata)

A comparison of the genital features of Arion urbiae and A. anguloi suggests that the species are extremely similar, if not identical. This hypothesis is supported by an electrophoretic analysis of 13 putative enzynme loci, which shows that the two species are also genetically yery similar (I = 0.947), while the related A. subfuscus consists of two distinct genetic types (I = 0.421). These results are further confirmed by a study of esterase profiles obtained with isoelectric focusing. It is therefore concluded that A. urbiae and A. anguloi are most probably conspecifie, whereas the genetic types of A. subfuscus may represent two different species.     

Cytoplasmic and Apoplastic Location of Phenolic Compounds in the Covering Tissue of the Brassica napus Radicle Between Embryogenesis and Germination

The localization and intensity of cytoplasmic and apoplasticdeposits of phenolic compounds in Brassica napus L. change betweenembryogenesis and 36 h after seed germination. In the late stageof embryogenesis there were no phenolic compounds that wouldbe precipitated with caffeine, located either in the cytoplasmor outside the plasmalemma. Seeds collected at this stage rotduring germination. During seed maturation phenolic compoundswere localized in small vesicles which correspond to vesicular-shapedendoplasmic reticulum (ER) characteristic of this stage. Thiswas followed by slightly larger deposits in vacuoles, and inmature seed dark deposits accumulated outside the plasmalemma.In these dormant seeds the deposits were thus mostly betweenthe plasmalemma and the cell wall. After 3 h in water such darkdeposits appeared outside the cell wall on the embryo surface.After 6 h the cytoplasmic deposits were very few, and after24 h deposits reappeared in the round vesicles and long ER cisternae.After 36 h, when the emerging radicle and hypocotyl were 3 mmlong, there were large deposits of phenolic compounds in thevacuoles of various sizes. The occurrence of these depositsparalleled the previously demonstrated waves of embryo activityat the same stages of development, such as mitoses, synthesisof DNA, RNA, and protein, and mobilization of storage material. Embryogenesis, phenolic compounds, germination, seedling     

Phylogeography and genetic structure of the edible sea urchin Paracentrotus lividus (Echinodermata: Echinoidea) inferred from the mitochondrial cytochrome b gene

Phylogeographical analysis of Paracentrotus lividus was carried out by means of sequencing the mitochondrial cytochrome b gene (1143 bp) of 260 individuals collected at 22 Mediterranean and four Atlantic localities. Against a background of high haplotype diversity and shallow genetic structuring, we observed significant genetic divergence between the Adriatic Sea and the rest of the Mediterranean, as well as between the Mediterranean and the Atlantic sample groups. Furthermore, on the largest spatial scale, isolation by distance was detected. Three main haplogroups were identified by network and Bayesian assignment analyses. The relative proportions of haplogroups were different in the four regions considered, with the exception of Western and Eastern Mediterranean that showed a similar pattern. This result together with the outcome of S_nn statistics, analysis of molecular variance and network analyses allowed to identify three weakly differentiated populations corresponding to the Atlantic, Western + Eastern Mediterranean, and Adriatic seas. Analyses of mismatch distribution and neutrality tests were consistent with the presence of genetic structuring and past demographic expansion(s). From a fisheries perspective, the results obtained in the present study are consistent with genetic sustainability of current exploitation; local depleted stocks are recurrently replenished by recruits that may have originated from nonharvested areas. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 100 , 910–923.     

Cytogenetics of species of Chamaecrista (Leguminosae – Caesalpinioideae) native to southern Brazil

Chromosome numbers, karyotypes, meiotic behaviour and pollen analysis are presented for species of Chamaecrista Moench (Leguminosae, Caesalpinioideae, Cassieae ) native to southern Brazil: C. nictitans ssp. patellaria , C. nictitans ssp. disadena , C. repens , C. rotundifolia , C. flexuosa , C. vestita and C. desvauxii . Meiotic behaviour is reported for the first time for all the taxa and was very regular; only bivalents were formed at diakinesis and metaphase I, chromosome disjunction and segregation were regular at anaphases I and II, meiotic indexes were over 99% and pollen fertility was over 92%. Pollen grains were subprolate in C. flexuosa and C. vestita and prolate–spheroidal in the other taxa. Karyotypes were symmetrical in all six species and the data are original, except for C. nictitans ssp. p atellaria. Chromosome number is presented for the first time for C. repens (2 n  = 16) and has been confirmed for the other taxa: 2 n  = 14 for C. desvauxii , 2 n  = 32 for the tetraploid C. nictitans ssp. patellaria and C. nictitans ssp. disadena , and 2 n  = 16 for the other species. These two basic numbers found in the genus, x  = 7 and x  = 8, point to chromosome evolution by dysploidy, which has also been accompanied by polyploidy.  © 2006 The Linnean Society of London, Botanical Journal of the Linnean Society , 2006, 150 , 429–439.     

Does interference competition explain why White Terns of Aride Island,Seychelles, breed predominantly when marine productivity is lower?

White Terns Gygis alba breed throughout the year on Aride Island but show a marked preference to nest during the northwest monsoon (November–March), when interspecific competition and also marine productivity are considered to be lower. In this study we investigated and compared breeding and foraging parameters of White Terns between the northwest and southeast (May–September) monsoons to assess whether interspecific competition affected foraging activity and explained the timing of breeding of White Terns. Goatfish (Mullidae) dominated the diet of White Terns and no significant differences were found in diet composition between the northwest and southeast monsoons. Similar diets and patterns of food provisioning of White Terns between the two monsoons do not support the hypothesis of strong exploitation competition during the southeast monsoon. On the other hand, foraging behaviour and frequency of capture attempts of White Terns differed between the two monsoons. The percentages of multi‐species flocks with White Terns and of large flocks with more than 25 noddies Anous and terns Onychoprion were significantly higher during the southeast monsoon. Moreover, capture attempt frequencies of White Terns foraging in multi‐species flocks were lower than those of solitary individuals, and both solitary and flocking White Terns had significantly lower capture attempt frequencies during the southeast monsoon in comparison with the northwest monsoon. These results suggest that interference competition depresses foraging activity of flock‐foraging White Terns, particularly during the southeast monsoon, which could potentially explain why White Terns breed preferentially during the northwest monsoon. However, and despite avoiding interference competition, White Terns nesting during the northwest monsoon did not show higher breeding success than those nesting during the southeast monsoon. Other hypotheses that might explain the preference of White Terns for breeding during the northwest monsoon, such as avoidance of agonistic interactions with Lesser Noddies Anous tenuirostris at nest sites, should also be investigated.     

Influence of contrasting availabilities of water and nutrients on the radiation use efficiency in C3 and C4 grasses

The radiation use efficiency (RUE) model is one of the most used tools to generate large spatial and temporal scale net primary productivity (NPP) estimations by remote sensing. It involves two key issues to make accurate estimations of NPP: the estimation of the fraction of photosynthetically active radiation (PAR) intercepted by vegetation (fPAR) and the estimation of the plant RUE. The objectives of this work were to quantify the above‐ground RUE under optimal water and nutrient conditions in two C₃ and one C₄ grass species and to analyse the effect of restrictions in these factors upon RUE by comparing both metabolic pathways. Grasses were cultivated from seeds and four treatments combining contrasting availabilities of water and nutrients were applied. RUE values were calculated from measurements of the incoming PAR, fPAR and productivity. In each of the species, plants with sufficient water and nutrients showed the highest RUE (2.61–3.52 g MJ^?1), whereas those with deficiencies in both resources presented the lowest RUE (1.15–2.39 g MJ^?1). Cynodon dactylon (C₄) was the species with higher value of RUE and no significant differences were detected between treatments. However, no significant differences were detected between C. dactylon and D. glomerata under no stress treatment (N1W1) and between C. dactylon and L. perenne under water stress treatment (N1W0). RUE values of Dactylis glomerata (C₃) diminished if only one of the two stress factors was presented, while Lolium perenne (C₃) only when both stress factors were present. The decreases under stress treatments were between 35% and 60% compared with the no stress treatment. When regional NPP is estimated it is therefore important to take into account the decrease in the RUE, especially in areas under severe stress.     

Silica bodies and hooked papillae in lemmas of Melica species (Gramineae: Pooideae)

Melica (sensu lato ) is a genus with approximately 80 species distributed in the temperate regions of both hemispheres. The genus has been better studied morphologically than anatomically, but morphological patterns have led to conflicting subdivisions either into sections, or by segregation of the genus Bromelica . The lemma epidermis is examined here under scanning electron microscopy (SEM) for 40 species of Melica to see if it exhibits characters of systematic significance. Silica bodies and hooked papillae are reported in the lemma for the first time in the genus. Patterns of variation are evident within four structures that terminate in points: prickles, hooks, hooked papillae and macro-hairs. Fourteen qualitative characters for lemma epidermis are used in phenetic analyses. The presence or absence of macro-hairs conflicts with some other patterns, but gives some support to the classification of Papp. Characters associated with the split of the clusters were micro-hairs (straight and geniculate) and the distribution and frequency of prickles in both costal and intercostal zones. As a conclusion, Melica is not a coherent taxonomic grouping and a simple segregation of Bromelica from Melica genus is rejected.  © 2003 The Linnean Society of London , Botanical Journal of the Linnean Society , 2003, 141, 447 – 463.