在通过自交繁殖的物种中,与异交相关的特征通常会退化,一种叫做自交综合症的现象。在秀丽隐杆线虫中,自交综合征影响许多与交配有关的特征,使交叉受精效率很低。在这项研究中,我们调查了通过强制性异交进行遗传修饰以繁殖的种群中杂交受精效率的演变。在基因改造之后,强制复制异交维持了100多代,在最佳(20°C)或高温(24°C)下,作为更广泛的实验进化计划的一部分。随后,在不断变化的种群中测定受精率,以及他们的祖先,他们引入了强制性的异交,但没有经历实验进化。通过跟踪年龄同步种群中受精雌性的比例来测量受精有效性,从成年以来的8小时。为了检查我们测量的鲁棒性,在两个或三个独立的重复区块中测定每个进化的种群.的确,我们在施肥轨迹中发现了高水平的区块间变异性,以及不断发展的人口与其祖先之间差异的估计。我们还确定了五个似乎进化出受精效率提高的种群,相对于他们的祖先。然而,由于上述的高可变性,这组人群应该被视为候选人,需要进一步的复制来确认或反驳它们与祖先的分歧。此外,我们还讨论了我们对受精轨迹的其他观察。
In species reproducing by selfing, the traits connected with outcrossing typically undergo degeneration, a phenomenon called selfing syndrome. In Caenorhabditis elegans nematodes, selfing syndrome affects many traits involved in mating, rendering cross-fertilization highly inefficient. In this study, we investigated the evolution of cross-fertilization efficiency in populations genetically modified to reproduce by obligatory outcrossing. Following the genetic modification, replicate obligatorily outcrossing were maintained for over 100 generations, at either optimal (20 °C) or elevated (24 °C) temperatures, as a part of a broader experimental evolution program. Subsequently, fertilization rates were assayed in the evolving populations, as well as their ancestors who had the obligatory outcrossing introduced but did not go through experimental evolution. Fertilization effectivity was measured by tracking the fractions of fertilized females in age-synchronized populations, through 8 h since reaching adulthood. In order to check the robustness of our measurements, each evolving population was assayed in two or three independent replicate blocks. Indeed, we found high levels of among-block variability in the fertilization trajectories, and in the estimates of divergence between evolving populations and their ancestors. We also identified five populations which appear to have evolved increased fertilization efficiency, relative to their ancestors. However, due to the abovementioned high variability, this set of populations should be treated as candidate, with further replications needed to either confirm or disprove their divergence from ancestors. Furthermore, we also discuss additional observations we have made concerning fertilization trajectories.