Successive Invasion-Mediated Interspecific Hybridizations and Population Structure in the Endangered Cichlid Oreochromis mossambicus

Hybridization between invasive and native species accounts among the major and pernicious threats to biodiversity. The Mozambique tilapia Oreochromis mossambicus, a widely used freshwater aquaculture species, is especially imperiled by this phenomenon since it is recognized by the IUCN as an endangered taxon due to genetic admixture with O. niloticus an invasive congeneric species. The Lower Limpopo and the intermittent Changane River (Mozambique) drain large wetlands of potentially great importance for conservation of O. mossambicus, but their populations have remained unstudied until today. Therefore we aimed (1) to estimate the autochthonous diversity and population structure among genetically pure O. mossambicus populations to provide a baseline for the conservation genetics of this endangered species, (2) to quantify and describe genetic variation of the invasive populations and investigate the most likely factors influencing their spread, (3) to identify O. mossambicus populations unaffected by hybridization. Bayesian assignment tests based on 423 AFLP loci and the distribution of 36 species-specific mitochondrial haplotypes both indicate a low frequency of invasive and hybrid genotypes throughout the system, but nevertheless reveal evidence for limited expansion of two alien species (O. niloticus and O. andersonii) and their hybrids in the Lower Limpopo. O. mossambicus populations with no traces of hybridization are identified. They exhibit a significant genetic structure. This contrasts with previously published estimates and provides rather promising auspices for the conservation of O. mossambicus. Especially, parts of the Upper Changane drainage and surrounding wetlands are identified as refugial zones for O. mossambicus populations. They should therefore receive high conservation priority and could represent valuable candidates for the development of aquaculture strains based on local genetic resources.© 2013 Firmat et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited

SINUSOIDAL PREDICTOR METHOD WITHIN A FULLY SEPARATED MODELER/SOLVER FRAMEWORK TO SPEED EMT SIMULATIONS SUBJECT TO OSCILLATING FORCING TERM

With the introduction of renewable energy sources into the power system, transmission system operators need extremely reliable and flexible simulation tools that should also be fast. Sinusoidal predictor method, aims to meet this need by simulating the full-waveform of AC power systems by integrating the arising systems of DAE by trying to free the time step limitation introduced by the frequency of some electrical components. The searched solution is split in a predicted sinusoidal part and a corrector DAE solution part. This paper presents the mathematical convergence of this approach leading to the choice of computing Fourier coefficients by minimizing a function that captures the distance of the desired sinusoidal part of the solution with respect to its oscillating steady state. Using the Dynaωo framework that aims to completely separate the modeling and the solving aspects of power systems, It details latest developments of an add-on in the IDA solver of SUNDIALS and the implementation optimisations. Results on performance speed up of the method computational time using much larger time steps than those used by classical DAE integration methods