Gargano Domenico, Bernardo Liliana, Rovito Simone, Passalacqua Nicodemo G, Abeli Thomas
Dipartimento di Biologia, Ecologia e Scienze della Terra dell'Università della Calabria, Via P. Bucci, I-87036 Arcavacata di Rende, Italy.
Department of Science, University of Roma Tre, Viale Guglielmo Marconi 446, 00146 Roma, Italy.
AoB Plants. 2022 May 12;14(3):plac022. doi: 10.1093/aobpla/plac022. eCollection 2022 Jun.
Assisted gene flow (AGF) can restore fitness in small plant populations. Due to climate change, current fitness patterns could vary in the future ecological scenario, as highly performant lineages can undergo maladaptation under the new climatic contexts. Peripheral populations have been argued to represent a potential source of species adaptation against climate change, but experimental evidence is poor. This paper considers the consequences of within- and between-population mating between a large core population and the southernmost population, the rare , to evaluate optimal AGF design under current and future conditions. We performed experimental self-pollinations and within- and between-population cross-pollinations to generate seed material and test its adaptive value to aridity. Seed germination, seedling growth and survival were measured under current and expected aridity. Effects of population type, pollination treatment and stress treatment on fitness components were analysed by generalized linear models. Relative measures of inbreeding depression and heterosis were taken under different stress treatments. Self-pollination reduced fitness for all the considered traits compared to within- and between-population cross-pollination. Under current aridity regime, the core population expressed higher fitness, and a larger magnitude of inbreeding depression. This indicated the core unit is close to its fitness optimum and could allow for restoring the fitness of the small peripheral population. Contrarily, under increased aridity, the fitness of outbred core lineages decreased, suggesting the rise of maladaptation. In this scenario, AGF from the small peripheral population enhanced the fitness of the core unit, whereas AGF from the core population promoted a fitness loss in the peripheral population. Hence, the small peripheral population could improve fitness of large core units versus climate change, while the contrary could be not true. Integrating reciprocal breeding programmes and fitness analyses under current and predicted ecological conditions can support optimal AGF design in a long-term perspective.
辅助基因流动（AGF）可以恢复小型植物种群的适合度。由于气候变化，当前的适合度模式在未来生态情景中可能会有所不同，因为高性能谱系在新的气候环境下可能会发生适应不良。边缘种群被认为是物种适应气候变化的潜在来源，但实验证据不足。本文考虑了一个大型核心种群与最南端稀有种群之间种群内和种群间交配的后果，以评估当前和未来条件下的最佳AGF设计。我们进行了实验性自花授粉以及种群内和种群间异花授粉，以产生种子材料并测试其对干旱的适应价值。在当前和预期干旱条件下测量种子发芽、幼苗生长和存活情况。通过广义线性模型分析种群类型、授粉处理和胁迫处理对适合度成分的影响。在不同胁迫处理下测量近交衰退和杂种优势的相对指标。与种群内和种群间异花授粉相比，自花授粉降低了所有考虑性状的适合度。在当前干旱条件下，核心种群表现出更高的适合度和更大程度的近交衰退。这表明核心种群接近其适合度最优值，并且可以恢复小型边缘种群的适合度。相反，在干旱增加的情况下，杂交核心谱系的适合度下降，表明适应不良的增加。在这种情况下，来自小型边缘种群的AGF提高了核心种群的适合度，而来自核心种群的AGF则导致边缘种群适合度下降。因此，小型边缘种群相对于气候变化可以提高大型核心种群的适合度，反之则不然。在当前和预测的生态条件下整合互交育种计划和适合度分析可以从长期角度支持最佳AGF设计。
