Michalak Katarzyna, Czesny Sergiusz, Epifanio John, Snyder Randal J, Schultz Eric T, Velotta Jonathan P, McCormick Stephen D, Brown Bonnie L, Santopietro Graciela, Michalak Pawel
Virginia Bioinformatics Institute, Virginia Tech, Blacksburg, Virginia.
J Exp Zool A Ecol Genet Physiol. 2014 Apr;321(4):233-40. doi: 10.1002/jez.1854. Epub 2014 Jan 30.
Predicting the success of a species' colonization into a novel environment is routinely considered to be predicated on niche-space similarity and vacancy, as well as propagule pressure. The role genomic variation plays in colonization success (and the interaction with environment) may be suggested, but has not rigorously been documented. To test an hypothesis that previously observed ecotype-specific polymorphisms between anadromous and landlocked alewife (Alosa pseudoharengus) populations are an adaptive response to osmoregulatory challenges rather than a result of allele sampling at founding, we examined multiple anadromous and landlocked (colonized) populations for their allelic profiles at a conserved region (3'-UTR end) of a β-thymosin gene whose protein product plays a central role in the organization of cytoskeleton. The putatively ancestral β-thymosin allele was prevalent in anadromous populations, whereas a newly derived allele was overrepresented in landlocked populations; a third allele was exclusive to the anadromous populations. We also conducted a complementary set of salinity exposure experiments to test osmoregulatory performance of the alewife ecotypes in contrasting saline environments. The pattern of variation and results from these challenges indicate a strong association of β-thymosin with colonization success and a transition from species with an anadromous life history to one with only a freshwater component.
预测一个物种在新环境中定殖成功通常被认为取决于生态位空间相似性、空位以及繁殖体压力。基因组变异在定殖成功（以及与环境的相互作用）中所起的作用虽可能被提及，但尚未得到严格记录。为了检验一个假设，即先前观察到的溯河洄游型和陆封型美洲河鲱（Alosa pseudoharengus）种群之间的生态型特异性多态性是对渗透调节挑战的适应性反应，而非建立种群时等位基因抽样的结果，我们研究了多个溯河洄游型和陆封型（定殖的）种群在β - 胸腺素基因保守区域（3'-UTR末端）的等位基因谱，该基因的蛋白质产物在细胞骨架组织中起核心作用。推测的祖先β -胸腺素等位基因在溯河洄游型种群中普遍存在，而一个新衍生的等位基因在陆封型种群中占比过高；第三个等位基因仅存在于溯河洄游型种群中。我们还进行了一组补充的盐度暴露实验，以测试美洲河鲱生态型在不同盐度环境下的渗透调节性能。这些挑战的变异模式和结果表明β -胸腺素与定殖成功以及从具有溯河洄游生活史的物种向仅具有淡水成分的物种转变之间存在强烈关联。
