Mee Jonathan A, Ly Carolyn, Pigott Grace C
Department of Biology, Mount Royal University, Calgary, Alberta, Canada.
Evol Lett. 2024 Oct 18;9(1):115-124. doi: 10.1093/evlett/qrae053. eCollection 2025 Feb.
The genetic basis of phenotypic or adaptive parallelism can reveal much about constraints on evolution. This study investigated the genetic basis of a canonically parallel trait: pelvic spine reduction in sticklebacks. Pelvic reduction has a highly parallel genetic basis in threespine stickleback in populations around the world, always involving a deletion of the pel1 enhancer of . We conducted a genome-wide association study to investigate the genetic basis of pelvic spine reduction in 3 populations of brook stickleback in Alberta, Canada. Pelvic reduction did not involve in any of the 3 populations. Instead, pelvic reduction in 1 population involved a mutation in an exon of , and it involved a mutation in an intron of in the other two populations. Hence, the parallel phenotypic evolution of pelvic spine reduction across stickleback genera, and among brook stickleback populations, has a nonparallel genetic basis. This suggests that there may be redundancy in the genetic basis of this adaptive polymorphism, but it is not clear whether a lack of parallelism indicates a lack of constraint on the evolution of this adaptive trait. Whether different pleiotropic effects of different mutations have different fitness consequences or whether certain pelvic reduction mutations confer specific benefits in certain environments remains to be determined.
表型或适应性平行现象的遗传基础能够揭示许多关于进化限制的信息。本研究调查了一种典型平行性状的遗传基础：棘鱼的骨盆刺减少。在世界各地的三刺棘鱼种群中，骨盆减少具有高度平行的遗传基础，总是涉及到pel1增强子的缺失。我们进行了一项全基因组关联研究，以调查加拿大艾伯塔省3个溪棘鱼种群中骨盆刺减少的遗传基础。在这3个种群中，骨盆减少均未涉及到[具体基因缺失情况]。相反，其中1个种群的骨盆减少涉及到[基因名称]一个外显子中的突变，而另外两个种群的骨盆减少涉及到[基因名称]一个内含子中的突变。因此，棘鱼属间以及溪棘鱼种群间骨盆刺减少的平行表型进化具有非平行的遗传基础。这表明这种适应性多态性的遗传基础可能存在冗余，但尚不清楚缺乏平行性是否表明对这种适应性性状的进化缺乏限制。不同突变的不同多效性效应是否具有不同的适合度后果，或者某些骨盆减少突变在某些环境中是否赋予特定益处，仍有待确定。
