Genetic structure and population differentiation of the Mediterranean pioneer spiny broom Calicotome villosa across the Strait of Gibraltar

The region around the Strait of Gibraltar is considered to be one of the most relevant 'hot spots' of biodiversity in the Mediterranean Basin due to its historical, biogeographical, and ecological features. Prominent among these is its role as a land bridge for the migration and differentiation of species during the Pleistocene, as a consequence of the lowering of sea level and climate changes associated with the Ice Ages. In the present study, we report a multilevel hierarchical investigation of the genetic diversity of Calicotome villosa, a common pioneer legume shrub, at the regional scale. The results of genetic analysis of progeny arrays are consistent with a predominantly outcrossing mating system in all the populations analysed. Geographically, a pattern of population isolation by distance was found, but the Strait accounted for only approximately 2% of the among-population genetic differentiation. Consequently, extensive historical gene flow appears to be the rule for this species in this area. According to the natural history traits of C. villosa (pollination, dispersal, and colonization ability), we hypothesize that gene flow must be strongly influenced by seed dispersal because pollen flow is very limited. Based on the history of trade and land use, cattle and human movements across the Strait must have strongly favoured seed dispersal. We review and discuss these results and compare them with those of other reported studies of genetic and phylogenetic differentiation across the Strait of Gibraltar. It is stressed that colonization ability, which depends upon seed dispersal and life form, can be a more critical factor in gene flow than pollination.Junta de Andalucía PB0551-95, PB1144-98BOS, 2003-07924-CO2-01 to J.A

Renal control of disease tolerance to malaria

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Spreading recruitment over time to cope with environmental variability

10 paginas, 3 figuras, 2 tablas.-- El PDF es la versión de autor.Seedling establishment is one of the most vulnerable life cycle stages, and a key component for the population dynamics in short-lived plants. In unpredictable environments, timing of emergence is critical for the success of plant performance, and different adaptive bet-hedging strategies have evolved to reduce the risk of failure in recruitment. In this study we describe the spatio-temporal pattern of seedling emergence (overall rate and timing) and survival in four contrasting Mediterranean habitats for Plantago coronopus, a small herb with dimorphic seeds. We then explore the importance of spreading germination within years, as well as the role of the two types of seeds from a broader temporal perspective. Populations strongly differed for all recruitment components analyzed in a given year, but this spatial differentiation diluted when a longer period was considered. Apical (smaller) seeds germinated later and in a significantly lower proportion than basal (larger) seeds. Both late emergents and seedlings from apical seeds had lower survival probability in a rainy year. However, our results suggest that in a population having the lowest production of apical seeds, late emergents coming from apical seeds may constitute a large fraction of yearly recruitment and that their performance was non-significantly different from that of early emergents over the 4-year study period. This study provides evidence of the importance of two related traits (spreading seedling emergence through time by producing dimorphic seeds) as bet-hedging strategies to cope with environmental unpredictability. This is at least partly accomplished by increasing the potential of recruitment in favourable years, instead of buffering such important process in extremely bad years.This study was funded by the Spanish Ministry of Science, under projects BOS2002-01162 and CGL2006-08507 to MBG.Peer reviewe

Natural variation of fecundity components in a widespread plant with dimorphic seeds

6 páginas, 3 figuras, 2 tablas.-- El PDF es la versión pre-print.The number and size of seeds are the basis of the quantity and quality components of female reproductive fitness in plants, playing a central role in the evolutionary ecology of life history diversification. In this study we show and analyze the natural variability of several fecundity variables (fruit set, seed production per fruit, seed size, total seed production per plant, and proportion of small seeds) in Plantago coronopus, a widespread, short-lived herb with dimorphic seeds. The structure of such variability was examined at the individual, population (eight locations with different environments within the same region), and life history levels (annual vs perennial), and correlated to soil fertility. There was no divergence associated to the life history for any of the variables studied. Total seed production (the quantity component of female fitness) was correlated with maternal resources, while the size of the large mucilaginous, basal seeds, and the proportion of the small apical seeds (quality component) were more associated to environmental resources. Thus, internal and external resources shape different fitness components, maximizing seed production, and fitting the size and proportion of different kind of seeds to local conditions irrespective of life history. P. coronopus illustrates the versatility of short-lived widespread plants to combine fecundity traits in a flexible manner, in order to increase fitness at each of the many possible habitats they occupy over heterogeneous environments.This study has been funded by the Spanish Ministry of Science, projects BOS2002- 01162 and CGL2006-08507 to MBG, and CGL2006-13847-CO2 to JA.Peer reviewe

Genetic differentiation and phylogeography of roe deer in Spain, as suggested by mitochondrial DNA and microsatellite analysis

Current population structure patterns of roe deer Capreolus capreolus in Spain were assessed through the analysis of mitochondrial and nuclear DNA. Restriction fragment length polymorphism was detected in the D‐loop and NADH‐dehydrogenase ND1 segments of mitochondrial DNA. Nuclear variation was investigated using 12 microsatellite loci. A total of 126 roe deer were analysed from fourteen sampling sites across the Iberian peninsula, including the Andalusian population from Sierra de Cádiz, which represents the southwestern limit of the distribution of C. capreolus. Results from both mitochondrial and microsatellite variation revealed a considerable level of structuring for roe deer populations throughout the Spanish range. In particular, evidence was provided from mtDNA of a genetic differentiation of roe deer populations in northern Spain from those occurring in southern areas, with a particular distinctiveness of the Andalusian roe deer. Concordant results were obtained from classical clustering analysis based on microsatellite loci. Furthermore, a Bayesian approach to microsatellite data proved more efficiently that northern roe deer are in turn genetically heterogenous, comprising at least three subpopulations. The phylogeographic pattern suggests a history of long‐term isolation of the two main groups of roe deer populations, possibly as a consequence of the climatic changes in the Late Pleistocene. The occurrence of two genetic lineages calls for different strategies of conservation and management of this species in the Iberian Peninsula, according to the geographic distribution of populations.Peer reviewe

Ferritin regulates organismal energy balance and thermogenesis

Objective: The ferritin heavy/heart chain (FTH) gene encodes the ferroxidase component of the iron (Fe) sequestering ferritin complex, which plays a central role in the regulation of cellular Fe metabolism. Here we tested the hypothesis that ferritin regulates organismal Fe metabolism in a manner that impacts energy balance and thermal homeostasis. Methods: We developed a mouse strain, referred herein as FthR26 fl/fl, expressing a tamoxifen-inducible Cre recombinase under the control of the Rosa26 (R26) promoter and carrying two LoxP (fl) sites: one at the 5′end of the Fth promoter and another the 3' end of the first Fth exon. Tamoxifen administration induces global deletion of Fth in adult FthR26Δ/Δ mice, testing whether FTH is required for maintenance of organismal homeostasis. Results: Under standard nutritional Fe supply, Fth deletion in adult FthR26Δ/Δ mice led to a profound deregulation of organismal Fe metabolism, oxidative stress, inflammation, and multi-organ damage, culminating in death. Unexpectedly, Fth deletion was also associated with a profound atrophy of white and brown adipose tissue as well as with collapse of energy expenditure and thermogenesis. This was attributed mechanistically to mitochondrial dysfunction, as assessed in the liver and in adipose tissue. Conclusion: The FTH component of ferritin acts as a master regulator of organismal Fe homeostasis, coupling nutritional Fe supply to organismal redox homeostasis, energy expenditure and thermoregulation. Keywords: Iron metabolism, Redox homeostasis, Adipose tissue, Energy expenditure, Adipose tissue, Mitochondri