scholarly journals Calibration of diversity indexes and search for ecologically tolerable levels of abiotic factors (case study: water objects of the Don river)

2009 ◽  
Vol 1 (2) ◽  
pp. 199-207
Author(s):  
E. A. Zaburdaeva
Keyword(s):  
2020 ◽  
Author(s):  
Ana Paula S Carvalho ◽  
Ryan A St Laurent ◽  
Emmanuel F A Toussaint ◽  
Caroline Storer ◽  
Kelly M Dexter ◽  
...  

Abstract Understanding the evolutionary mechanisms governing the uneven distribution of species richness across the tree of life is a great challenge in biology. Scientists have long argued that sexual conflict is a key driver of speciation. This hypothesis, however, has been highly debated in light of empirical evidence. Recent advances in the study of macroevolution make it possible to test this hypothesis with more data and increased accuracy. In the present study, we use phylogenomics combined with four different diversification rate analytical approaches to test whether sexual conflict is a driver of speciation in brush-footed butterflies of the tribe Acraeini. The presence of a sphragis, an external mating plug found in most species among Acraeini, was used as a proxy for sexual conflict. Diversification analyses statistically rejected the hypothesis that sexual conflict is associated with shifts in diversification rates in Acraeini. This result contrasts with earlier studies and suggests that the underlying mechanisms driving diversification are more complex than previously considered. In the case of butterflies, natural history traits acting in concert with abiotic factors possibly play a stronger role in triggering speciation than does sexual conflict. [Acraeini butterflies; arms race; exon capture phylogenomics; Lepidoptera macroevolution; sexual selection; sphragis.]


Author(s):  
Subhas Chandra Bastola

The purpose of this study is to quantify species diversity of birds in the study area and to explore the biotic and abiotic factors affecting the bird population. This study was carried out by using the fixed point counting method. The study area was situated in Annapurna Rural Municipality of Kaski district. A total of 147 bird species belonging to 46 families and 14 orders were identified in the study area. It was found that Muscicapidae was the largest family and Passeriformes the largest order. Among the reported species, 50% were residents, 31% were full-migrants, 18% were altitudinal migrants and the remaining were 1% nomadic. Habitats of birds included the forest 68%, the scrubland 17 %, the grassland 7% and the wetland 6 % of the study area. Similarly, the rocky area and artificial area covered 1% of the total species. The results showed that most of the bird species i.e. 136 were least concerned, 4 of them were nearly threatened, 3 of them were endangered, 3 were critically endangered and only one species was vulnerable. The most important threats included hunting and trapping, killing for fun, shift in crop production, use of insecticides and pesticides, improved storage devices, habitat destruction, developmental activities, tourism, buried carcasses and predatory.


Author(s):  
Olivier Chabrerie ◽  
François Massol ◽  
Benoit Facon ◽  
Romain Thevenoux ◽  
Manon Hess ◽  
...  

Biological invasions have reached an unprecedented level and the number of introduced species is still increasing worldwide. Despite major advances in invasion science, the determinants of success of introduced species, the magnitude and dimensions of their impact, and the mechanisms sustaining successful invasions are still debated. Empirical studies show divergent impacts of non-native populations on ecosystems and contrasting effects of biotic and abiotic factors on the dynamics of non-native populations; this is hindering the emergence of a unified theory of biological invasions. We propose a synthesis that merges perspectives from population, community, and ecosystem levels. Along a timeline of ecosystem transformation driven by non-native species, from historical to human-modified ecosystems, we order invasion concepts and theories to clarify their chaining and relevance during each step of the invasion process. This temporal sorting of invasion concepts shows that each concept is relevant at a specific stage of the invasion. Concepts and empirical findings on non-native species may appear contradictory. However, we suggest that, when mapped onto an invasion timeline, they may be combined in a complementary way. An overall scheme is proposed to summarise the theoretical dynamics of ecosystems subjected to invasions. For any given case study, this framework provides a guide through the maze of theories and should help choose the appropriate concepts according to the stage of invasion.


2018 ◽  
Vol 44 (6) ◽  
pp. 1314-1326 ◽  
Author(s):  
Sannan Zahid Mansoor ◽  
Sana Louie ◽  
Ana T. Lima ◽  
Philippe Van Cappellen ◽  
Bruce MacVicar

2014 ◽  
Vol 8 (2) ◽  
pp. 4-9
Author(s):  
Sambit Dutta ◽  
Souvik Das ◽  
Abhijit Sarkar ◽  
Jayanta Tarafdar ◽  
Ashim Chowdhury

Rhizoctonia solani Kuhn, is one of the most important pathogen of rice causing the sheath blight disease which accounts for heavy crop losses in all the major rice growing areas of the world, including tropical Asia. The proliferation of this soil borne pathogen depends on many abiotic factors. The two most common factors associated with the growth and spread of the pathogen is pH and temperature which has been studied in the present study. Both pH and temperature had significant effect on the growth of the fungal mycelial and sclerotial formation. A non-linear regression model for growth of the fungal mycelia revealed that growth occurred best at pH 6.0 and temperature 30°C for all treatments studied. No growth was observed below 15°C. In agricultural fields sclerotia, forms the means for the spread of the pathogen causing secondary disease incidence as well as survival of the pathogen in harsher conditions. Sclerotia formed between the temperatures of 20°C and 30°C, with an optimum at 30°C and pH 6.0. DOI: http://dx.doi.org/10.3126/ijls.v8i2.10226    International Journal of Life Sciences Vol.8(2): 2014; 4-9


2009 ◽  
Vol 36 (6) ◽  
pp. 706-717 ◽  
Author(s):  
A. P. Levich ◽  
E. A. Zaburdaeva ◽  
V. N. Maksimov ◽  
N. G. Bulgakov ◽  
S. V. Mamikhin

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