Hu Xin-Sheng, He Fangliang
Department of Renewable Resources, 751 General Service Building, University of Alberta, Edmonton, Alberta, Canada, T6G 2H1.
J Theor Biol. 2006 Jun 21;240(4):662-72. doi: 10.1016/j.jtbi.2005.11.002. Epub 2005 Dec 20.
The distinct processes of gene flow via seeds and pollen in hermaphrodite plants provide a biological basis for interpreting their different roles in expanding a species' range. A species' range is primarily expanded through the colonization process by seed dispersal and followed by the joint effects of both seed and pollen flow. Here we examined the effects of seed and pollen flow on shaping a species' distribution in one-dimensional space. Our results demonstrate that pollen flow can enhance range expansion when immigrating genes are adaptive to recipient populations, but can shrink a species' range when immigrating genes are maladaptive. The incompletely purging of maladaptive genes from immigrating pollen grains at the gametophyte stage can reinforce the biological barrier to range expansion. The linkage disequilibria attained by immigrating seeds and pollen grains indirectly amplify the effects of the reaction component and further limit a species' range. The cumulative effect from multiple loci each with a small effect can be substantial on altering a species' range when these genes are maladaptive. These theoretical predictions can help understand the role of pollen flow that is incapable of colonizing new habitats in range expansion.
雌雄同体植物中通过种子和花粉进行的基因流动的不同过程，为解释它们在扩大物种分布范围中所起的不同作用提供了生物学基础。一个物种的分布范围主要通过种子传播的定殖过程来扩大，随后是种子和花粉流动的共同作用。在这里，我们研究了种子和花粉流动对一维空间中物种分布形成的影响。我们的结果表明，当迁入的基因适应受体种群时，花粉流动可以增强分布范围的扩大，但当迁入的基因不适应时，花粉流动会缩小物种的分布范围。在配子体阶段，迁入花粉粒中不适应基因的不完全清除会加强对分布范围扩大的生物屏障。迁入种子和花粉粒所达到的连锁不平衡间接放大了反应成分的影响，并进一步限制了物种的分布范围。当这些基因不适应时，多个位点各自具有较小影响的累积效应在改变物种分布范围方面可能是巨大的。这些理论预测有助于理解无法在新栖息地定殖的花粉流动在分布范围扩大中的作用。
