Centre for Sustainable Ecosystem Solutions and School of Biological Sciences, University of Wollongong, Wollongong, NSW, Australia.
Mol Ecol. 2018 Apr;27(7):1541-1555. doi: 10.1111/mec.14552. Epub 2018 Apr 10.
Many plant species have pollination and seed dispersal systems and evolutionary histories that have produced strong genetic structuring. These genetic patterns may be consistent with expectations following recent anthropogenic fragmentation, making it difficult to detect fragmentation effects if no prefragmentation genetic data are available. We used microsatellite markers to investigate whether severe habitat fragmentation may have affected the structure and diversity of populations of the endangered Australian bird-pollinated shrub Grevillea caleyi R.Br., by comparing current patterns of genetic structure and diversity with those of the closely related G. longifolia R.Br. that has a similar life history but has not experienced anthropogenic fragmentation. Grevillea caleyi and G. longifolia showed similar and substantial population subdivision at all spatial levels (global F' = 0.615 and 0.454; S = 0.039 and 0.066), marked isolation by distance and large heterozygous deficiencies. These characteristics suggest long-term effects of inbreeding in self-compatible species that have poor seed dispersal, limited connectivity via pollen flow and undergo population bottlenecks because of periodic fires. Highly structured allele size distributions, most notably in G. caleyi, imply historical processes of drift and mutation were important in isolated subpopulations. Genetic diversity did not vary with population size but was lower in more isolated populations for both species. Through this comparison, we reject the hypothesis that anthropogenic fragmentation has impacted substantially on the genetic composition or structure of G. caleyi populations. Our results suggest that highly self-compatible species with limited dispersal may be relatively resilient to the genetic changes predicted to follow habitat fragmentation.
许多植物物种具有授粉和种子传播系统以及进化历史，这些系统和历史产生了强烈的遗传结构。这些遗传模式可能与最近人为破碎化后的预期一致，如果没有预先破碎化的遗传数据，就很难检测到破碎化的影响。我们使用微卫星标记来研究严重的生境破碎化是否可能影响濒危的澳大利亚鸟类授粉灌木 Grevillea caleyi R.Br. 的种群结构和多样性，通过比较当前遗传结构和多样性模式与具有相似生活史但未经历人为破碎化的密切相关的 G. longifolia R.Br. 的模式。Grevillea caleyi 和 G. longifolia 在所有空间水平上都表现出相似且显著的种群细分（全球 F' = 0.615 和 0.454；S = 0.039 和 0.066），标志着隔离距离和大的杂合子缺失。这些特征表明，在自交亲和物种中，长期存在近交的影响，这些物种的种子传播能力差，通过花粉流的连通性有限，并且由于周期性的火灾而经历种群瓶颈。高度结构化的等位基因大小分布，尤其是在 G. caleyi 中，暗示了历史上的漂变和突变过程在孤立的亚种群中很重要。遗传多样性与种群大小无关，但对于两个物种来说，在更孤立的种群中，遗传多样性较低。通过这种比较，我们拒绝了人为破碎化对 G. caleyi 种群遗传组成或结构产生重大影响的假设。我们的研究结果表明，具有有限传播能力的高度自交亲和物种可能对预计随生境破碎化而发生的遗传变化具有相对弹性。
