Ecological Factors and the Variability of Gene-Pools in Drosophila

Author(s):  
John Beardmore
2021 ◽  
Vol 2 ◽  
Author(s):  
Ludwig Triest ◽  
Jasper Dierick ◽  
Thi Thuy Hang Phan ◽  
Quang Doc Luong ◽  
Nguyen Quang Huy ◽  
...  

Lagoonal environments exhibit high levels of instability depending on hydrological, climatic and ecological factors, thereby influencing the distribution and structure of submerged plant communities. Conditions typically fluctuate widely due to the interaction of freshwater from rivers with saltwater from the sea, as well as from aquaculture activities that together influence submerged hydrophyte community spatial and temporal variability depending on plant survival strategies. Ruppia species feature either underwater pollination mediated by an air bubble or by the release of pollen floating at the water surface, the former promoting self-pollination. Tropical Asian Ruppia brevipedunculata Yu and den Hartog was assumed to pollinate below the water surface and identified as a separate lineage among selfed Ruppia taxa. We used nine nuclear microsatellites to estimate inbreeding levels and connectivity of R. brevipedunculata within a large SE Asian lagoon complex. Ruppia brevipedunculata meadows were strongly inbred as could be derived from the many monomorphic or totally fixed loci for unique alleles in different parts of the lagoon, which appears consistent with selfing behavior. Those from aquaculture ponds were highly inbred (FIS = 0.620), though less than open lagoon sites that showed nearly total inbreeding (FIS = 0.942). Ruppia brevipedunculata from two major lagoon parts were highly differentiated with spatially structured gene pools and a strong barrier between parts of the lagoon over a 30 km distance. Migration-n analysis indicated unidirectional though limited gene flow and following potential hydrological connectivity. Overall, private alleles under homozygote conditions explained a stronger genetic differentiation of populations situated inside aquaculture ponds than of open lagoon populations. Kinship values were only relevant up to 5 km distance in the open lagoon. Within a confined area of aquaculture ponds featuring dense vegetation in stagnant water, there would be opportunity for mixed pollination, thereby explaining the higher diversity of unique multilocus genotypes of aquaculture pond habitats. Low connectivity prevents gene pools to homogenize however promoted sites with private alleles across the lagoon. Complex hydrodynamic systems and human-made habitats enclosed by physical structures impose barriers for propagule dispersal though may create refugia and contribute to conserving regional genetic diversity.


2018 ◽  
Vol 65 (3-4) ◽  
pp. 129-146 ◽  
Author(s):  
Tamar Krugman ◽  
Eviatar Nevo ◽  
Alex Beharav ◽  
Hanan Sela ◽  
Tzion Fahima

The Institute of Evolution Wild Cereal Gene Bank (ICGB) at the University of Haifa, Israel, harbors extensive collections of wild emmer wheat (WEW), Triticum dicoccoides, and wild barley (WB), Hordeum spontaneum, the primary progenitors of wheat and barley, respectively. The ICGB also includes minor collections of 10 species of Aegilops, wild oat (Avena barbata), and Brachypodium stacei and B. hybridum (previously distachyon). Here, we describe the WEW and WB collections, explain sampling strategies, and introduce related studies. Natural populations were sampled across Israel along aridity gradients, occurring from north to south and from west to east, and in local microsites with variable (or contrasting) ecological factors. The collection sites varied greatly in terms of climatic (rainfall, temperature and humidity), edaphic (soil types), and topography (altitude, slope) variables. Thus, the ICGB collections represent wild cereals adapted to a wide range of habitats and eco-geographical conditions. We have collected and preserved these unique gene pools since mid-70th, and further used them for theoretical and applied studies in population genetics, evolution, domestication, adaptation to local and regional habitats, and coping mechanisms for a plethora of biotic and abiotic stresses. Our studies revealed that WEW and WB populations from Israel harbor high adaptive genetic diversity that can serve as a reservoir of beneficial alleles to improve important agronomic traits such as disease resistance, drought tolerance and improved grain protein content. These mostly untapped genetic resources could contribute to increasing world food production for the constantly rising human population.


2019 ◽  
Vol 3 (3) ◽  
pp. 69-93
Author(s):  
Young-soo Kim ◽  
◽  
Su-yon Kim ◽  
Won-sup Ryu ◽  
Soo-eun Park ◽  
...  

2006 ◽  
pp. 43-57 ◽  
Author(s):  
H. N. Lysenko ◽  
I. A. Korotchenko

Changes in the set of syntaxa have been traced for the plant cover of the «Mikhaylovskaya Tselina» meadow-steppe (an isolated part of the Ukrainian Steppe Nature Reserve, Sumy Region, Ukraine) with the help of the Braun-Blanquet approach. The area vegetation syntaxa prodromus includes 2 classes, 2 rders, 3 alliances, 9 associations, and 6 subasso­ciations, 2 of the latter described anew. The plant cover is highly dynamic and undergoes expressed meso­phytization, especially within the area where strict protection has been maintained since 1961. Amplitudes of the principal ecological factors and also peculiarities of their shift under exogenic regulation are determined with the help of the method of synecological phyto­indication (i. e. not single species but total species sets of communities serve as indicators). The essential transformations of the reserve meadow steppes are probably caused by the «insular» character of the reserve, its small size, also by the poorness of the set of natural grazers and hence the inadequacy of regulation by means of mowing.


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