Analysis of genetic diversity and spatial structure in Tunisian populations of Hordeum marinum ssp. marinum based on molecular markers

Hordeum marinum commonly known as sea barley is a salinity-tolerant species of grass. In the current study, 150 lines from ten populations of H. marinum ssp. marinum collected from five Tunisian bioclimatic sites were screened for polymorphism with 13 selected random amplified polymorphic DNA primers. Results exhibited a high level of polymorphism (160 polymorphic bands with an average of 12.46 per primer) and a high level of genetic diversity in all the studied populations (on average UHe = 0.247 and I = 0.358). High discrimination capacity was found for the 13 primers and a combination of three allowed assignation of a unique profile for each of the 150 lines. The partition of genetic diversity with Analysis of Molecular Variance suggested that the majority of genetic variation (67%) was within populations. The components between-populations within ecoregions and between-ecoregions explained 21 and 12%, respectively, of the total genetic variance. There was no significant association of population differentiation (ФPT) with geographical distance or altitudinal difference. Results also showed that the 150 lines grouped into three clusters with no respect to geographic origin. A sub-set of 13 lines was identified, which captured the maximum genetic diversity of the entire collection. The genetic variation found in this collection of H. marinum is deemed to be useful in formulating conservation strategies for this species.

Contrasting patterns of taxonomic, phylogenetic and functional variation along a Costa Rican altitudinal gradient in the plant family Melastomataceae

The functional composition of plant communities in montane regions has been studied for decades, and most recent analyses find that environmentally favourable landscapes at lower altitudes tend to be dominated by species with resource-acquisitive traits, while more resource-conservative taxa dominate higher-altitude communities. However, it is unclear the extent to which this pattern is driven by co-gradient variation within clades or changes in clade representation across the gradient. To test for co-gradient variation, species composition, phylogenetic structure and functional traits were quantified for 97 species within the plant family Melastomataceae at five locations across a 2500-m altitudinal gradient along Volcán Barva in Costa Rica. Average melastome leaf force to punch, specific leaf area and leaf size vary with altitude, while four other functional traits do not. Taxonomic dissimilarity between communities was correlated with altitudinal difference, while phylogenetic dissimilarity was correlated with altitudinal dissimilarity only when measured with a metric that emphasizes shallow turnover of the tips of the phylogeny. These results highlight how species turnover may be more pronounced than functional or phylogenetic variation along altitudinal gradients. In addition, these results highlight the conservation value of lowland tropical forests, which here harbour a disproportionate amount of phylogenetic and functional diversity.

Topographic descriptors and thermal inversions amid the plateaus and mountains of the Jura (France)

Sixteen temperature measurement sites under forest cover are distributed across the plateaus and mountains of the Jura (France). They are composed of pairs of stations located, one at the bottom of a topographic trough, the other at least 50 m higher in altitude. Three descriptors (station elevation, altitudinal difference (amplitude) between the two stations of each site, and topographical context) are used to explain how the frequency, intensity, and duration of inversions are spatially structured. Depending on whether one considers: 1) tn (minimum temperature) or tx (maximum temperature), 2) frequency or intensity, the sign of the correlation values changes. This reflects the fact that not all inversions can be explained in the same way. Elevation moderately explains the three characters of the inversions. Amplitude mainly explains their frequency (R = -0.83 for daily minima [tn]) and their intensity (R = 0.62 for daily maxima [tx]). The magnitude of the topographic depressions where the low stations are located mainly explains the tn inversions while the magnitude of the eminences where the high stations are located mainly explains the tx inversions. Finally, a multiple regression where the explanatory variables correspond to the topographic descriptors makes it possible to model the three inversion indicators.

Variasi Morfologi Bambu Tali [Gigantochloa apus (Schult.F.) Kurz.] pada berbagai ketinggian tempat di Sub Daerah Aliran Sungai Pelus

A study on the morphological variation of tali bamboo [Gigantochloa apus (Schult.f.) Kurz] has been conducted at various altitudes of Sub Watershed Pelus Banyumas, Central Java. This study was aimed at determining the morphological variations in relation to altitudes above sea levels. The method used was survey with stratified sampling. The variables measured included culm diameter, culm internode length, culm sheath length and width, ovate-triangular blade length and width, leaf blade length and width, stem color and hairs, and altitude. The results of this study indicated that the altitudinal difference effect some morphological characteristics of tali bamboos such as: 1) green young seedling with black hairs found at 200-299 m and 300-399 m asl. 2) morphological variations are effected by altitude. Tali bamboo grows optimally at the altitude of 400 to 499 m asl. The results of regression analysis showed that the altitude has a relatively close correlation with somes of morphological character of tali bamboo.

Performance of ASTER and SRTM DEMs, and their potential for assessing glacial lakes in the Lunana region, Bhutan Himalaya

To assess the potential volume of a glacial lake outburst flood (GLOF) more precisely than in previous studies, we analyze ground survey data and remote-sensing digital elevation models (DEMs) around glacial lakes in the Lunana region, Bhutan. Based on a DEM generated from differential GPS ground surveys, we first evaluate the relative accuracies of DEMs produced by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) and the Shuttle Radar Topography Mission (SRTM). Root-mean-square errors of the altitudinal difference between these DEMs and ground survey data were 11.0 m for ASTER and 11.3 m for SRTM. These errors are similar to those of previous studies. We show that a topographical classification allows a better estimate of elevation on lakes/ponds, riverbeds and glaciers due to their flat surfaces, while the relative accuracy is worse over moraines and hill slopes due to their narrow ridges and steep slopes. Using the optical satellite images and the ground survey data, we re-evaluate the GLOF volume in 1994 as (17.2 ± 5.3) × 106 m3. We show GLOF-related information such as distance, altitudinal difference and gradient at possible outburst points where the lake level is higher than the neighboring riverbed and/or glacial lake.