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Genetic Diversity in Salix gordejevii Populations from Different Environmental Gradients in Horqin Sandy Land, Northern China

Huang Wen-Da, Zhao Xue-Yong, Zhao Xin, Luo Ya-Yong, Feng Jing, Su Na, He Yuan-Zheng

Polish Journal of Ecology

2019

Vol. 67, nr 3

175--185

Salix gordejevii (Salicaceae) is a climax and dominant sand-fixing shrub species native to the northern China. We assessed S. gordejevii population genetic variation in different environmental gradients in Horqin Sandy Land, Northern China using inter-simple sequence repeat (ISSR) markers, and investigated the possible existence of relationships between genetic diversity and environmental gradients. The results showed that S. gordejevii populations in general have high genetic diversity. An analysis of molecular variation (AMOVA) revealed relatively high levels (> 89.91%) of within-population genetic variation. Based on cluster analysis, the 12 studied S. gordejevii populations can be clustered into three clades. Genetic diversity and differentiation of S. gordejevii populations are affected from different environmental gradients. Genetic diversity of all populations was affected by habitat environment change, and was well-correlated with the humidity gradients. These results have important implications for restoration and management of degraded ecosystems in arid and semi-arid areas.

Diatom assemblages as indicators of salinity gradients : a case study from a coastal lake

Rzodkiewicz M., Gąbka M., Szpikowska G., Woszczyk M.

Oceanological and Hydrobiological Studies

2017

Vol. 46, No. 3

325--339

In order to understand the variability of diatoms in coastal lakes and its relationship to salinity, the authors have conducted a two-year study at Lake Resko Przymorskie (the Southern Baltic coast), which has a salinity between 1.9-4.8 PSU. Redundancy analysis (RDA) was used to describe the relationship between the species composition and selected variables. Four of the 10 measured variables of surface water chemistry (Cl- and PO43- concentrations, temperature, and pH) significantly explained 23% of the variation in the diatom species composition. We found 82 taxa of diatoms (mostly tychoplanktonic) and determined the optimum and tolerance levels of salinity for predominant taxa (49 species with minimum 2% abundance). The optimum chloride concentration for the predominant diatoms ranged from 1471 to 2961 mg Cl- l-1. The most abundant brackish water species was Pseudostaurosiropsis geocollegarum. Brackish-freshwater diatoms were represented by Cyclotella atomus, Cyclotella meneghiniana, Diatoma tenuis and Staurosira subsalina. The most abundant fresh-brackish water diatoms were Amphora pediculus, Fragilaria sopotensis, Hippodonta hungarica, Pseudostaurosira brevistriata and Staurosira construens. Freshwater taxa accounted for as little as 1% of the population. This study provides new data on the ecology of coastal lakes and the possibility of using diatom-based transfer functions in the reconstruction of past environmental changes.

Altitudinal gradients in a volcanic island : effect on biodiversity and species richness of the dipteran fauna

Ferreira T., Ribeiro E., Duarte-Rodrigues P. P., Boavida M.

Polish Journal of Ecology

2012

Vol. 60, nr 3

591-599

Although research on environmental gradients is relatively common, the altitudinal gradient is one of the least explored. The discrepancies between earlier studies attributing highest diversity to lowest altitude and more recent studies where this altitudinal pattern is not maintained justify the pertinence of investigating the way diversity gradually changes with altitude. The studied altitudinal gradient is located inside the volcanic cone, on one of volcanic island Azores, and the investigated altitudes were 450, 600 and 800 meters a.s.l. Malaise traps were used to capture insects and Diptera were selected for this study. Application of the Zipt-Mandelbrot model to rank-abundance curves of Diptera sampled at three different altitudes, as well as analyses of richness, diversity and evenness, led to the conclusion that medium altitude was the stratum with the highest niche diversity, the highest specific diversity and the highest predictability. Non-metric multidimensional scaling allowed an excellent separation of the three altitudes sampled, suggesting that habitat characteristics significantly differ with altitude. The study, undertaken in a volcanic island of the Azores, Atlantic Ocean, will have heuristic interest to the scientific community in general and especially to those researchers studying environmental gradients. The results of this research will underpin further work on the insect biodiversity in the Azores Archipelago.