Genetic and functional leaf traits variability of Quercus laurina along an oak diversity gradient in Mexico

The ecological literature has documented the effects of plant hybridization on phenotypic variation, and dominant, intermediate, or novel morphological, chemical and physiological traits in hybrids. It is important to understand the ecological consequences of hybridization by evaluating their impact on phenotypic expression of functional traits. We evaluated the relationship between genetic diversity of Quercus laurina and functional foliar traits along an oak diversity gradient. We selected five study sites that represent an oak diversity gradient where Q. laurina is present. Using chloroplast and nuclear microsatellites, we evaluated genetic diversity, measured functional foliar traits of Q. laurina in each site and assessed the effects of local climate variables on the oak community and functional traits. We found a greater abundance of Q. laurina in all study sites. We did not find a relationship between the number of accompanying red oak species and the population genetic diversity in Q. laurina, but higher genetic diversity was found in all study sites in comparison with European oak species. Sites with more oak species had more variation of foliar functional traits. Our results do not support the hypothesis that predicts higher levels of genetic diversity of Q. laurina in communities with greater oak diversity from the same section, but we demonstrated an increase in the foliar functional traits of Q. laurina associated with oak richness and climate variables. We highlight the need to consider environmental and ecological variables linkages as regulatory mechanisms of the phenotypic plasticity expressed in changes of some functional attributes of oaks.

     

Phylogeographic patterns and possible incipient domestication of <Emphasis Type="Italic">Jacaratia mexicana</Emphasis> A. DC. (Caricaceae) in Mexico

Jacaratia mexicana A. DC. (Caricaceae) is a tropical tree distributed throughout Mexico and Mesoamerica. Some evidence in Mexico indicates the presence of an incipient domestication process in this species. Phylogeographical analyses can potentially determine contemporary patterns of gene flow, isolation between population lineages, as well as historical processes such as population bottlenecks or expansions on their geographical areas. In this study we reconstruct the phylogeographical patterns in populations of J. mexicana A. DC., in order to find differences between genetic variation among wild and cultivated populations utilizing chloroplast DNA and nuclear DNA sequences. We generate a Bayesian phylogenetic tree, to estimate the divergence time between clades using calibrated mutation rates. We also infer the demographic history of these populations using neutrality tests among wild and cultivated accessions. We identified higher levels of haplotype and nucleotide diversity for the cpDNA and ITS types in wild populations than in domesticated populations. These results indicate a reduction of genetic diversity derived from human selection on domestication traits. Neutrality test suggests population expansion detected by the significant negative values of Fu’s Fs in the cultivated populations of this specie. These process results in an excess of rare polymorphism with the fixation of certain advantageous mutation throughout time, this implication are in accordance with the role of the strong selection in the fruit traits of J. mexicana. The dated phylogeny constructed with BEAST program indicated a dispersion pattern for the J. mexicana ancestors across the South Pacific and South Eastern populations during the late Pliocene. Posterior dispersion and divergence in the clades from Central Mexico and North Pacific are in agreement with the episodes of mountain-building in different regions of Mexico.     

Land cover and conservation in the area of influence of the Chamela-Cuixmala Biosphere Reserve,Mexico

Tropical deforestation and habitat fragmentation in areas around conservation areas have been an important element for discussion in the conservation and policy-making community. In this paper, we evaluate land cover change processes around one of the most important tropical dry forest reserves in the Americas: the Chamela-Cuixmala Biosphere Reserve, Mexico. The analysis is conducted at three scales: regional scale (coast of the State of Jalisco), proximity to the reserve (via a 30-km buffer zone analysis), and inside the Biosphere Reserve. The proximity analysis is complemented by a unique data set that represents the extent and boundaries of Ejidos (local land management units) in the region. Results indicate that areas surrounding the reserve have low deforestation, with Ejidos and buffer areas having more forest cover as they get closer to the reserve. The nature of this important phenomenon is discussed in the context of the socio-economic conditions of the local communities. Our work suggests that the creation of a network of “Ejidos’ Conservation Areas”, in the context of an approach that will recognize payments for environmental services provided to local communities, could contribute to the conservation and maintenance of the rich biodiversity in a region that has one of the highest levels of endemism in the world.     

Morphological changes in the lungs of meconium-stained piglets.

Meconium staining of the skin is a common event associated with fetal hypoxia, stillbirths, weak-born piglets, and neonatal mortality. Aspiration of meconium leads to meconium aspiration syndrome (MAS). This study was undertaken to assess the relationship between the degree of meconium staining of the skin at birth, meconium aspiration, and pulmonary changes in porcine neonates. A total of 353 farrowing sows and 3,693 born piglets were monitored during parturition and for 15 days after delivery. Umbilical cords were classified as normal or ruptured. Meconium staining in the skin was graded as nonstained, mildly, moderately, and severely stained. Mortality from birth to 15 days of age was 8.4%. The lungs from 60 meconium-stained piglets and 60 lungs from nonstained piglets were collected and microscopically examined for meconium aspiration and inflammation. Rupture of the umbilical cord was significantly higher (P < 0.01) in meconium-stained piglets. Microscopically, 32% and 40% of the lungs had evidence of meconium for the stained and nonstained groups, respectively. The microscopic grade of meconium aspiration and inflammatory cells was not different between nonstained and meconium-stained piglets. Aspiration of meconium induced a granulomatous response in the lungs. It was concluded that the grade of meconium staining is a good indicator of fetal hypoxia, but not a good predictor for meconium aspiration and MAS in piglets.