High Divergence of Cuticular Hydrocarbons and Hybridization Success in Two Allopatric Seven-Spot Ladybugs.

The seven-spotted ladybug is a widespread species in the Palearctic, and also acclimated in the Nearctic. It has been classified into different species on the basis of certain morphological characteristics, the geographical origin, and the genitalia structure of both sexes. The morphotypes of North Africa and the Canary Islands are separated, under the name of Coccinella algerica Kovár, 1977, from the rest of the Palearctic and Nearctic populations of Coccinella septempunctata Linnaeus, 1758. In this study, we investigated, on one hand, whether potential reproductive barriers have been established during evolution between the geographically isolated North African and the European seven-spotted ladybugs by performing reciprocal crosses. On the other hand, we assessed their cuticular hydrocarbon (CHC) divergence by GC-MS. The 33 CHCs indentified are with a skeleton of 23 to 32 carbon atoms. These CHCs are linear alkanes (24.9 ± 3.6%) and methyl-branched alkanes (75.1 ± 3.6%) including monomethylalkanes (48.8 ± 2.4%), dimethylalkanes (24.6 ± 4.0%) and trimethylalkanes (2.0 ± 1.0%). Although all the CHC compounds identified are present in the two seven-spotted ladybugs and their F1 and F2 hybrids, their profiles diverged significantly. However, these chemical divergences have not altered the sexual communication to cause reproductive isolation. The two ladybugs interbreed and leave viable and fertile offspring, with even a heterosis effect on reproductive performances, without phenotypic degradation after the F1 generation. So, these chemical differences are just an intraspecific variability in response to heterogeneous environments. The two types of ladybugs can be considered as two different races of the same species with reduced genetic divergence.

Qualitative analysis of a fractional-order two-strain epidemic model with vaccination and general non-monotonic incidence rate.

In this paper, a fractional-order two-strain epidemic model with vaccination and general non-monotonic incidence rate is analyzed. The studied problem is formulated using susceptible, infectious and recovered compartmental model. A Caputo fractional operator is incorporated in each compartment to describe the memory effect related to an epidemic evolution. First, the global existence, positivity and boundedness of solutions of the proposed model are proved. The basic reproduction numbers associated with studied problem are calculated. Four steady states are given, namely the disease-free equilibrium, the strain 1 endemic equilibrium, the strain 2 endemic equilibrium, and the endemic equilibrium associated with both strains. By considering appropriate Lyapunov functions, the global stability of the equilibrium points is proven according to the model parameters. Our modeling approach using a generalized non-monotonic incidence functions encloses a variety of fractional-order epidemic models existing in the literature. Finally, the theoretical findings are illustrated using numerical simulations.

STR-based genetic structure of the Berber population of Bejaia (Northern Algeria) and its relationships to various ethnic groups.

Patterns of genetic variation in human populations have been described for decades. However, North Africa has received little attention and Algeria, in particular, is poorly studied, Here we genotyped a Berber-speaking population from Algeria using 15 short tandem repeat (STR) loci D8S1179, D21S11, D7S820, CSF1PO, D3S1358, TH01, D13S317, D16S539, D2S1338, D19S433, vWA, TPOX, D18S51, D5S818 and FGA from the commercially available AmpF/STR Identifiler kit. Altogether 150 unrelated North Algerian individuals were sampled across 10 administrative regions or towns from the Bejaia Wilaya (administrative district). We found that all of the STR loci met Hardy-Weinberg equilibrium expectations, after Bonferroni correction and that the Berber-speaking population of Bejaia presented a high level of observed heterozygosity for the 15 STR system (>0.7). Genetic parameters of forensic interest such as combined power of discrimination (PD) and combined probability of exclusion (PE) showed values higher than 0.999, suggesting that this set of STRs can be used for forensic studies. Our results were also compared to those published for 42 other human populations analyzed with the same set. We found that the Bejaia sample clustered with several North African populations but that some geographically close populations, including the Berber-speaking Mozabite from Algeria were closer to Near-Eastern populations. While we were able to detect some genetic structure among samples, we found that it was not correlated to language (Berber-speaking versus Arab-speaking) or to geography (east versus west). In other words, no significant genetic differences were found between the Berber-speaking and the Arab-speaking populations of North Africa. The genetic closeness of European, North African and Near-Eastern populations suggest that North Africa should be integrated in models aiming at reconstructing the demographic history of Europe. Similarly, the genetic proximity with sub-Saharan Africa is a reminder of the links that connect all African regions.

Impact of water deficit intensity on durum wheat seminal roots.

Experiments were performed under controlled conditions to study seminal roots traits of durum wheat genotypes grown under four water conditions. Seminal root length, root-to-shoot dry matters ratio and piliferous layer cell size were measured. Root volume was assessed at three soil depths. Water stress has affected significantly root traits and piliferous layer cell size and this impact depends on its intensity. Severe water stress reduced markedly root traits. Water treatment by genotype interaction was observed. Middle-East genotypes responded differently from Algerian ones. Our results and those obtained elsewhere on the same genotypes for other physiological traits are discussed.

Early water-deficit effects on seminal roots morphology in barley.

In order to study seminal roots morphology in barley grown under different water treatments, experiments were carried out under glasshouse-controlled conditions. Eight genotypes were cultivated under four water treatments (100, 75, 50 and 25% of field capacity). Seminal root length and root-to-shoot dry matters' ratio were measured. Root volume was assessed at three soil depths. Results showed broad genotypic differences for all traits. The effect of low and moderate water deficit was slight. In contrast, the impact of severe water treatment was strongly marked on all traits. The impact of water deficit intensity on root traits at different soil depths is discussed.