Candidate transcriptomic sources of inbreeding depression in Drosophila melanogaster

The genomic causes of inbreeding depression are poorly known. Several studies have found widespread transcriptomic alterations in inbred organisms, but it remains unclear which of these alterations are causes of the depression and which are mere responses to the ensuing physiological stress induced by increased homozygosity due to inbreeding. Attempting to differentiate causes from responses, we made a c-DNA microarray analysis of inbreeding depression in Drosophila melanogaster. The rationale of the experiment was that, while depression is a general phenomenon involving reductions in fitness in different inbred lines, its first genetic causes would be different for each inbred line, as they are expected to be caused by the fixation of rare deleterious genes. We took four sets of inbred sublines, each set descending from a different founding pair obtained from a large outbred stock, and compared the expression of the three most depressed sublines and the three least depressed sublines from each set. Many changes in expression were common to all sets, but fourteen genes, grouped in four expression clusters, showed strong set-specific changes, and were therefore possible candidates to be sources of the inbreeding depression observed.This work was funded by Xunta de Galicia (INCITE08PXIB200119PR and Grupos de Referencia Competitiva, 2010/80), Ministerio de Ciencia y Tecnología (CGL2009-13278-C02, CGL2012-39861-C02) and Fondos Feder: “Unha maneira de facer Europa”S

Diagnóstico y propuesta metodológica en la planificación de la demanda de una empresa de alimentos

RESUMEN : El presente trabajo plantea diagnosticar y proponer una metodología de planificación de la demanda, a una empresa de alimentos que desarrolla y comercializa ingredientes y soluciones de la industria alimenticia, donde sus productos están enfocados estratégicamente en olor, color y sabor. Actualmente la empresa no tiene establecido una metodología que le permita planear la demanda incluyendo un amplio portafolio donde cuentan con aproximadamente 6000 SKU, que generan así un alto grado de complejidad en la administración del portafolio. Basados en rango de tiempo histórico de las unidades vendidas se realiza una segmentación de los SKU por canales y sub canales, tomando el sub canal SAVORY como muestra, para ejecutar un comparativo de cuatro metodologías de planeación de demanda, siendo ellas; metodología mínimos y máximos, metodología forecast medio, metodología tradicional (SOR) y la metodología de demand driven, con el fin de encontrar la herramienta metodológica que permita estabilizar y disminuir los inventarios e incidir en un adecuado comportamiento en relación al crecimiento de ventas

An empirical test of the estimation of historical effective population size using Drosophila melanogaster

The availability of a large number of high-density markers (SNPs) allows the estimation of historical effective population size (Ne) from linkage disequilibrium between loci. A recent refinement of methods to estimate historical Ne from the recent past has been shown to be rather accurate with simulation data. The method has also been applied to real data for numerous species. However, the simulation data cannot encompass all the complexities of real genomes, and the performance of any estimation method with real data is always uncertain, as the true demography of the populations is not known. Here, we carried out an experimental design with Drosophila melanogaster to test the method with real data following a known demographic history. We used a population maintained in the laboratory with a constant census size of about 2800 individuals and subjected the population to a drastic decline to a size of 100 individuals. After a few generations, the population was expanded back to the previous size and after a few further generations again expanded to twice the initial size. Estimates of historical Ne were obtained with the software GONE both for autosomal and X chromosomes from samples of 17 individuals sequenced for the whole genome. Estimates of the historical effective size were able to infer the patterns of changes that occurred in the populations showing generally good performance of the method. We discuss the limitations of the method and the application of the software carried out so farMinisterio de Ciencia, Innovación y Universidades | Ref. PID2020-114426GB- C21Ministerio de Educación, Cultura y Deporte | Ref. FPU16/02299Ministerio de Ciencia, Innovación y Universidades | Ref. FPU18/04642Universidade de Vigo/CISUG | Ref. Financiamiento de acceso abiertoCRUE-CSIC | Ref. Financiamiento de acceso abiertoXunta de Galicia | Ref. ED431C 2020-0

Long-term exhaustion of the inbreeding load in Drosophila melanogaster

Inbreeding depression, the decline in fitness of inbred individuals, is a ubiquitous phenomenon of great relevance in evolutionary biology and in the fields of animal and plant breeding and conservation. Inbreeding depression is due to the expression of recessive deleterious alleles that are concealed in heterozygous state in noninbred individuals, the so-called inbreeding load. Genetic purging reduces inbreeding depression by removing these alleles when expressed in homozygosis due to inbreeding. It is generally thought that fast inbreeding (such as that generated by full-sib mating lines) removes only highly deleterious recessive alleles, while slow inbreeding can also remove mildly deleterious ones. However, a question remains regarding which proportion of the inbreeding load can be removed by purging under slow inbreeding in moderately large populations. We report results of two long-term slow inbreeding Drosophila experiments (125–234 generations), each using a large population and a number of derived lines with effective sizes about 1000 and 50, respectively. The inbreeding load was virtually exhausted after more than one hundred generations in large populations and between a few tens and over one hundred generations in the lines. This result is not expected from genetic drift alone, and is in agreement with the theoretical purging predictions. Computer simulations suggest that these results are consistent with a model of relatively few deleterious mutations of large homozygous effects and partially recessive gene actionAgencia Estatal de Investigación (AEI) | Ref. PGC2018-095810-B-I00Agencia Estatal de Investigación (AEI) | Ref. PID2020-114426GB-C21Xunta de Galicia | Ref. ED431C 2020-0

Population genomics of parallel evolution in gene expression and gene sequence during ecological adaptation

Natural selection often produces parallel phenotypic changes in response to a similar adaptive challenge. However, the extent to which parallel gene expression differences and genomic divergence underlie parallel phenotypic traits and whether they are decoupled or not remains largely unexplored. We performed a population genomic study of parallel ecological adaptation among replicate ecotype pairs of the rough periwinkle (Littorina saxatilis) at a regional geographical scale (NW Spain). We show that genomic changes underlying parallel phenotypic divergence followed a complex pattern of both repeatable differences and of differences unique to specific ecotype pairs, in which parallel changes in expression or sequence are restricted to a limited set of genes. Yet, the majority of divergent genes were divergent either for gene expression or coding sequence, but not for both simultaneously. Overall, our findings suggest that divergent selection significantly contributed to the process of parallel molecular differentiation among ecotype pairs, and that changes in expression and gene sequence underlying phenotypic divergence could, at least to a certain extent, be considered decoupled processesMinisterio de Economía y Competitividad | Ref. BFU2013- 44635-PMinisterio de Economía y Competitividad | Ref. CGL2016-75482-PMinisterio de Economía y Competitividad | Ref. CGL2016-75904-C2-1Xunta de Galicia | Ref. ED431C 2016-037Xunta de Galicia | Ref. INCITE09 310 006 PRSwedish Research Councils VR | Ref. Linnaeus grant Formas 217-2008-171

Genética de la conservación: la aplicación de los conceptos de la evolución a la conservación de la diversidad biológica

La comprensión de las fuerzas de cambio evolutivo que actúan sobre las poblaciones, en conjunción con las técnicas más modernas de análisis genético, lleva aplicándose en los últimos veinte años al servicio de la conservación de la biodiversidad. Esta nueva aplicación de la genética ha recibido el nombre de genética de la conservación