Reconciling the evolutionary origin of bread wheat (Triticum aestivum)

The origin of bread wheat (Triticum aestivum; AABBDD) has been a subject of controversy and of intense debate in the scientific community over the last few decades. In 2015, three articles published in New Phytologist discussed the origin of hexaploid bread wheat (AABBDD) from the diploid progenitors Triticum urartu (AA), a relative of Aegilops speltoides (BB) and Triticum tauschii (DD). Access to new genomic resources since 2013 has offered the opportunity to gain novel insights into the paleohistory of modern bread wheat, allowing characterization of its origin from its diploid progenitors at unprecedented resolution. We propose a reconciled evolutionary scenario for the modern bread wheat genome based on the complementary investigation of transposable element and mutation dynamics between diploid, tetraploid and hexaploid wheat. In this scenario, the structural asymmetry observed between the A, B and D subgenomes in hexaploid bread wheat derives from the cumulative effect of diploid progenitor divergence, the hybrid origin of the D subgenome, and subgenome partitioning following the polyploidization events.

[The gonotrophic cycle and the daily rhythm of bites of Anopheles gambiae (Giles) 1902 and Anopheles nili (Theobald), 1904]

The authors have elaborated a formula to calculate the average number of times an anopheline parous female bites in one day ("L") according to its gonotrophic cycle and more specially to its behaviour before and after oviposition (parameters "alpha" and "A". The formula was applied to Anopheles gambiae observed at Djoumouna village (L = 0.40) and to Anopheles nili observed at M'Pola village (L = 0.30). The value obtained has then to be multiplied by the anthropophilic index to obtain the "a" parameter of MacDonald (1957) when studying malaria transmission in a village. On the other hand such a formula allowed a better evaluation of biting frequency of a vector, thus of risks of transmission of diseases, according to the respective situation of human houses and water storages. An important point which ahs to be born in mind when planning artificial permanent reservoirs.