Production and morphology of fruit and seeds in Genisteae (Fabaceae) of south-west Spain

The productivity and morphology of fruit and seeds were studied in 30 species (and subspecies) of the tribe Genisteae (Fabaceae) in south-west Spain. The morphological characters of greatest taxonomic value both for the segregation of the two subtribes (Genistinae and Lupininae) recognized in Genisteae and for the delimitation of the lower taxonomic levels (genus and species) are the size of the pod and characters of the pericarp, the colour and weight of the seeds, whether or not an ad exists, and the shape, size, and position of the hilum. In contrast, characters of little taxonomic interest are pod colour, shape and number of seeds, and characters of the lens. There were also found to be major relationships between fruit and seed, and between these and other floral (e.g. corolla size) or reproductive (e.g. polledovule [P/O] and seed/ovule [S/O] ratios) attributes. Thus in this tribe, pod size was positively correlated with corolla size, seed size, the number of viable seeddfruit, and the S/O and P/O ratios. Corolla size was positively correlated with the number of viable seeds/ fruit and with the seed weight. Similarly, the number of seeddfruit was positively correlated with the fruit's weight and with the number of ovules/ovary. Also, the weight of the seeds was positively correlated with the pollen/ovule ratio. There was also positive correlation between the S/O and P/O ratios.     

Ionic Requirements for Catecholamine Aggregating Actions on the Teleost Poecilia reticulata Melanophores

Norepinephrine (NE) and phenylephrine (Phe) were employed to study the ionic requirements for alpha adrenoceptor activation in the teleost Poecilia reticulata melanophores. As expected the beta adrenoceptor blocker, propranolol, increased the sensitivity of the preparation to NE (5.8 times), and was therefore employed in all the experimental procedures. Neither cocaine (a neuronal uptake blocker) nor dexamethasone (an extraneuronal uptake blocker) enhanced the sensitivity of the preparation to NE, suggesting that these inactivating mechanisms would not play a role in P. reticulata pigmentary system. However, in the absence of calcium, the dose-response curve (DRC) to NE was displaced to the left about 3.5 times, whereas the DRC to Phe was not affected. These results indicate that a neuronal uptake is active, but was not demonstrated by the classical pharmacological tools, probably due to an assymmetric display of the nervous endings. The DRC to NE was rightward displaced (14.1 times) in the presence of the calcium channel blocker Verapamil, whereas the DRC to Phe was not affected. These data suggest that P. reticulata melanophores possess a mixed population of alpha₁ and alpha₂ adrenoceptors, the activation of the latter eliciting an extracellular calcium influx. In sodium-free saline, the DRC to NE was rightward shifted (6.6 times) and the response to Phe was impaired in such a way that the maximal response was not achieved. The DRC to both NE and Phe were rightward displaced (7.9 and 2.7 times respectively) in the presence of the sodium channel blocker tetrodotoxin (TTX) 10^?7M. In potassium-free saline, the melanophore sensitivity to Phe was increased, whereas the responses to NE were not affected, suggesting a differential sensitivity of the two alpha adrenoceptor subtypes to the resulting membrane hyperpolarization. Based on the literature and on our data we propose that P. reticulata melanophores possess a mixed population of alpha₁ and alpha₂ receptors. The activation of both subtypes of alpha adrenoceptors elicits a Na⁺ ion influx through TTX-sensitive sodium channels. The stimulation of alpha₂ adrenoceptors also requires an extracellular calcium influx, through the opening of slow calcium channels.     

Linking plant functional traits with post‐fire sprouting vigour in woody species in central Argentina

Abstract Sprouting vigour is determined by the plant amount of reserves and intrinsic growth rate of plants. While the first factor has been well studied, the second is far less understood. Although a higher growth rate would imply a higher sprouting vigour, fast‐growing species may have less below‐ground reserves, and thus, a lower sprouting potential. The relative importance of both opposite effects was little explored in the literature. To analyse the influence of growth rate on sprouting vigour, one growth season after a fire we measured plant height of the old (pre‐fire) and new (post‐fire) tissue in 194 individuals of 14 woody species from a woodland in central Argentina. We calculated a mean value of pre‐ and post‐fire height for each species, and obtained from a data‐base potential height at maturity, wood density (WD) and specific leaf area (SLA), as surrogates of intrinsic growth rate. We performed a forward stepwise multiple regression using WD and SLA, together with mean pre‐fire height or potential height as independent variables, and mean post‐fire height (as an indicator of resprout vigour) as the dependent variable. Interactions were also tested. Pre‐fire height, WD and their interaction term were the variables that best explained post‐fire height. We also analysed the relationship between pre‐ and post‐fire size for each species independently by fitting hyperbolic functions. Then we correlated both parameters of the functions to species characteristics (WD, SLA, potential height and mean pre‐fire height). Both parameters of the hyperbolic functions were significantly correlated only with WD, but not with the other species characteristics. All results together indicate that species with low WD (i.e. high potential growth rate) regrow more vigorously than species with high WD when pre‐fire individuals were tall. In contrast, when pre‐fire individuals were small, WD had no influence on sprout vigour. A trade‐off between allocation of biomass to underground reserves and shoot growth seems to be responsible for the patterns obtained. For small individuals, below‐ground reserves seem to play a more important role than inherent growth rate (here measured through WD) in determining the sprouting vigour, while for large individuals, growth rate seems more important than reserves.     

Small‐scale spatial variation in evolvability for life‐history traits in the storm petrel

The evolutionary potential in the timing of recruitment and reproduction may be crucial for the ability of populations to buffer against environmental changes, allowing them to avoid unfavourable breeding conditions. The evolution of a trait in a local population is determined by its heritability and selection. In the present study, we performed pedigree‐based quantitative genetic analyses for two life‐history traits (recruiting age and laying date) using population data of the storm petrel over an 18‐year period in two adjacent breeding colonies (only 150 m apart) that share the same environmental conditions. In both traits, natal colony effect was the main source of the phenotypic variation among individuals, and cohort variance for recruitment age and additive genetic variance for laying date were natal colony‐specific. We found significant heritability only in laying date and, more specifically, only in birds born in one of the colonies. The difference in genetic variance between the colonies was statistically significant. Interestingly, selection on earlier breeding birds was detected only in the colony in which heritable variation in laying date was found. Therefore, local evolvability for a life‐history trait may vary within a unexpectedly small spatial scale, through the diversifying natural selection and insulating gene flow. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 106 , 439–446.     

Resource density regulates the foraging investment in higher termite species

1. Resource density can regulate the area that animals use. At low resource density, there is a conflict in terms of balance between costs of foraging and benefits acquired. The foraging of the higher termite Nasutitermes aff. coxipoensis consists of searching throughout trails and a building galleries phase. 2. In this study, a manipulative field experiment was used to test the hypothesis that colonies of N. aff. coxipoensis forage towards a more profitable balance between the establishment of trails and gallery construction at low resource density. 3. The experiment was conducted in north‐eastern Brazil. Seven experimental plots were established with a continuous increase in resource density (sugarcane baits). Entire colonies of N. aff. coxipoensis were transplanted from their original sites to the experimental plot, totalling 35 nests. The number, branches and total length of trails and galleries were quantified. 4. The results show that N. aff. coxipoensis optimises its foraging output, intensifying the establishment of trails at the cost of gallery construction when resource density is low. The number of trails, the number of trail branches and the total length of trails decreased with increasing resource density. Interestingly, at low resource density, the search effort was concentrated on forming longer and a greater number of trails, a small proportion of which were converted into galleries. The opposite relationship was observed at high resource density. 5. These results suggest an optimisation of search efforts during foraging depending on resource density, a mechanism that may help researchers to understand the use of space by higher termite species.     

Brood parasitism is associated with increased bacterial contamination of host eggs: bacterial loads of host and parasitic eggs

Factors related to bacterial environment of nests are of primary interest for understanding the causes of embryo infection and the evolution of antimicrobial defensive traits in birds. Nest visitors such as parasites could act as vectors for bacteria and/or affect the hygienic conditions of nests and hence influence the nest bacterial environment. In the present study, we explored some predictions of this hypothetical scenario in the great spotted cuckoo (Clamator glandarius)–magpie (Pica pica) system of brood parasitism. Great spotted cuckoos visit the nests of their magpie hosts and frequently damage some of the host eggs when laying eggs or on subsequent visits. Therefore, it represents a good system for testing the effect of nest visitors on the bacterial environment of nests. In accordance with this hypothesis, we found that the bacterial load of magpie eggshells was greater in parasitized nests, which may suggest that brood parasitism increases the probability of bacterial infection of magpie eggs. Moreover, comparisons of bacterial loads of cuckoo and magpie eggs revealed that: (1) cuckoo eggshells harboured lower bacterial densities than those of their magpie hosts in the same nests and (2) the prevalence of bacteria inside unhatched eggs was higher for magpies than for great spotted cuckoos. These interspecific differences were predicted because brood parasitic eggs (but not host eggs) always experience the bacterial environments of parasitized nests. Therefore, the results obtained in the present study suggest that parasitic eggs are better adapted to environments with a high risk of bacterial contamination than those of their magpie hosts. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 103 , 836–848.     

High European sauropod dinosaur diversity during Jurassic–Cretaceous transition in Riodeva (Teruel, Spain)

Abstract:  Up to now, more than 40 dinosaur sites have been found in the latest Jurassic – earliest Cretaceous sedimentary outcrops (Villar del Arzobispo Formation) of Riodeva (Iberian Range, Spain). Those already excavated, as well as other findings, provide a large and diverse number of sauropod remains, suggesting a great diversity for this group in the Iberian Peninsula during this time. Vertebrae and ischial remains from Riodevan site RD-13 are assigned to Turiasaurus riodevensis (a species described in RD-10, Barrihonda site), which is part of the Turiasauria clade. This is the first time that a taxon is attributed to Turiasaurus genus out of its type site. A Neosauropod caudal vertebra from the RD-11 site has been classified as Diplodocinae indet., supporting the previous attribution on an ilion also found in Riodeva (CPT-1074) referring to the Diplodocidae clade. New remains from the RD-28, RD-41 and RD-43 sites, of the same age, among which there are caudal vertebrae, are assigned to Macronaria. New sauropod footprints from the Villar del Arzobispo Formation complete the extraordinary sauropod record coming to light in the area. The inclusion of other sauropods from different contemporaneous exposures in Teruel within the Turiasauria clade adds new evidence of a great diversity of sauropods in Iberia during the Jurassic–Cretaceous transition. Turiasauria distribution contributes to the understanding of European and global palaeobiogeography.