Carreira Valeria Paula, Mensch Julián, Hasson Esteban, Fanara Juan José
Departamento de Ecología, Genética y Evolución, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Autónoma de Buenos Aires, Argentina.
Instituto de Ecología, Genética y Evolución de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, Ciudad Autónoma de Buenos Aires, Argentina.
PLoS One. 2016 Jul 26;11(7):e0160069. doi: 10.1371/journal.pone.0160069. eCollection 2016.
Body size is a complex character associated to several fitness related traits that vary within and between species as a consequence of environmental and genetic factors. Latitudinal and altitudinal clines for different morphological traits have been described in several species of Drosophila and previous work identified genomic regions associated with such variation in D. melanogaster. However, the genetic factors that orchestrate morphological variation have been barely studied. Here, our main objective was to investigate genetic variation for different morphological traits associated to the second chromosome in natural populations of D. melanogaster along latitudinal and altitudinal gradients in Argentina. Our results revealed weak clinal signals and a strong population effect on morphological variation. Moreover, most pairwise comparisons between populations were significant. Our study also showed important within-population genetic variation, which must be associated to the second chromosome, as the lines are otherwise genetically identical. Next, we examined the contribution of different candidate genes to natural variation for these traits. We performed quantitative complementation tests using a battery of lines bearing mutated alleles at candidate genes located in the second chromosome and six second chromosome substitution lines derived from natural populations which exhibited divergent phenotypes. Results of complementation tests revealed that natural variation at all candidate genes studied, invected, Fasciclin 3, toucan, Reticulon-like1, jing and CG14478, affects the studied characters, suggesting that they are Quantitative Trait Genes for morphological traits. Finally, the phenotypic patterns observed suggest that different alleles of each gene might contribute to natural variation for morphological traits. However, non-additive effects cannot be ruled out, as wild-derived strains differ at myriads of second chromosome loci that may interact epistatically with mutant alleles.
体型是一个复杂的性状，与多个与适应性相关的性状相关联，由于环境和遗传因素，这些性状在物种内部和物种之间存在差异。在几种果蝇中已经描述了不同形态性状的纬度和海拔梯度变化，并且先前的研究确定了与黑腹果蝇这种变异相关的基因组区域。然而，协调形态变异的遗传因素几乎没有得到研究。在这里，我们的主要目标是研究阿根廷黑腹果蝇自然种群中沿着纬度和海拔梯度与第二条染色体相关的不同形态性状的遗传变异。我们的结果揭示了微弱的渐变信号以及种群对形态变异的强烈影响。此外，种群之间的大多数成对比较都是显著的。我们的研究还显示了重要的种群内遗传变异，由于这些品系在其他方面基因相同，所以这种变异一定与第二条染色体相关。接下来，我们研究了不同候选基因对这些性状自然变异的贡献。我们使用一系列携带位于第二条染色体上候选基因突变等位基因的品系以及六个来自自然种群且表现出不同表型的第二条染色体替代品系进行了定量互补试验。互补试验结果表明，所研究的所有候选基因invected、Fasciclin 3、巨嘴鸟、类网织蛋白1、jing和CG14478的自然变异都会影响所研究的性状，这表明它们是形态性状的数量性状基因。最后，观察到的表型模式表明，每个基因的不同等位基因可能对形态性状的自然变异有贡献。然而，不能排除非加性效应，因为野生来源的品系在无数个第二条染色体位点上存在差异，这些位点可能与突变等位基因发生上位性相互作用。
