Department of Organismal Biology, Uppsala University, Norbyvägen 18D, SE-752 36, Uppsala, Sweden.
Department of Ecology and Genetics, Uppsala University, Norbyvägen 18D, SE-752 36, Uppsala, Sweden.
ISME J. 2019 Mar;13(3):780-788. doi: 10.1038/s41396-018-0294-7. Epub 2018 Nov 9.
Trade-offs among traits influencing fitness are predicted by life history theory because resources allocated to one function are unavailable to another. Here we examine the relationship between two such traits, asexual reproduction and growth rate, in the filamentous fungus Neurospora crassa, where shared genetic and physiological factors and a source-sink energetic relationship between growth and reproduction may constrain the evolution of these traits. To test growth-reproduction relationships in this species, we independently selected on mycelial growth rate or asexual spore production in a heterogeneous lab-derived population and evaluated the response of the non-selected traits. Combined with phenotypes for the 20 wild strains used to produce the heterogeneous population and the genome-wide genotypes of 468 strains, these data show that growth and reproduction are highly plastic in N. crassa and do not trade off either among wild strains or after laboratory selection in two environments. Rather, we find no predictable growth-reproduction relationship in the environments tested, indicating an effective absence of genetic constraint between these traits. Our results suggest that growth rate and asexual reproduction may not respond predictably to environmental change and suggest that reliance on a single trait as a proxy for fitness in fungal studies may be inadvisable.
由于资源分配到一个功能就无法用于另一个功能，因此影响适合度的性状之间的权衡是由生活史理论预测的。在这里，我们研究了丝状真菌粗糙脉孢菌（Neurospora crassa）中两个这样的性状之间的关系，即无性繁殖和生长速率，其中共享的遗传和生理因素以及生长和繁殖之间的源-汇能量关系可能会限制这些性状的进化。为了在该物种中检验生长-繁殖关系，我们在异质实验室衍生群体中独立选择菌丝生长速率或无性孢子产生，然后评估非选择性状的响应。结合用于产生异质群体的 20 个野生株系的表型以及 468 个株系的全基因组基因型，这些数据表明，生长和繁殖在粗糙脉孢菌中具有高度可塑性，无论是在野生株系之间还是在两种环境中的实验室选择后都没有发生权衡。相反，我们在测试的环境中没有发现可预测的生长-繁殖关系，这表明这些性状之间不存在有效的遗传限制。我们的研究结果表明，生长速率和无性繁殖可能不会对环境变化做出可预测的响应，并表明在真菌研究中依赖单一性状作为适合度的替代可能是不可取的。
