DEMOGRAPHIC SOURCE-SINK DYNAMICS RESTRICT LOCAL ADAPTATION IN ELLIOTT'S BLUEBERRY (VACCINIUM ELLIOTTII)
DEMOGRAPHIC SOURCE-SINK DYNAMICS RESTRICT LOCAL ADAPTATION IN ELLIOTT'S BLUEBERRY (VACCINIUM ELLIOTTII)
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DOI：
10.1111/j.1558-5646.2009.00825.x
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发表时间：
2010-02-01
期刊：
影响因子：
3.3
通讯作者：
Geber, Monica A.
中科院分区：
文献类型：
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作者：
Anderson, Jill T.;Geber, Monica A.
在异质景观，趋异选择有利于当地适应的生态型的演变，特别是当栖息地间的基因流是最小的。然而，如果栖息地的大小或质量不同，源汇动态可以塑造进化轨迹。美国东南部的高地和低地森林在地下水位深度、光照、土壤条件和植物群落方面存在差异。我们进行了多年的相互移植实验，以测试埃利奥特的蓝莓（湿地越橘）是否在当地适应这些对比鲜明的环境。此外，我们将幼苗和插条暴露于温室中的长时间干旱和洪水中，以评估对非生物胁迫的适应性反应。与当地适应的预测相反，湿地植物的家庭表现出显着更高的生存率和生长在高地比低地森林和干旱比洪水条件下，无论原产地的栖息地。中性的人口分化是最小的，这表明广泛的栖息地迁移。种群密度、生殖产量和遗传多样性均显著高于洼地。这些差异可能导致从高地到低地的不对称基因流动。因此，对边缘生境的适应可能会受到小种群、有限的适应性和从良性生境移民的限制。我们的研究强调了人口统计学和遗传多样性在局部（mal）适应进化中的重要性。
In heterogeneous landscapes, divergent selection can favor the evolution of locally adapted ecotypes, especially when interhabitat gene flow is minimal. However, if habitats differ in size or quality, source-sink dynamics can shape evolutionary trajectories. Upland and bottomland forests of the southeastern USA differ in water table depth, light availability, edaphic conditions, and plant community. We conducted a multiyear reciprocal transplant experiment to test whether Elliott's blueberry (Vaccinium elliottii) is locally adapted to these contrasting environments. Additionally, we exposed seedlings and cuttings to prolonged drought and flooding in the greenhouse to assess fitness responses to abiotic stress. Contrary to predictions of local adaptation, V. elliottii families exhibited significantly higher survivorship and growth in upland than in bottomland forests and under drought than flooded conditions, regardless of habitat of origin. Neutral population differentiation was minimal, suggesting widespread interhabitat migration. Population density, reproductive output, and genetic diversity were all significantly greater in uplands than in bottomlands. These disparities likely result in asymmetric gene flow from uplands to bottomlands. Thus, adaptation to a marginal habitat can be constrained by small populations, limited fitness, and immigration from a benign habitat. Our study highlights the importance of demography and genetic diversity in the evolution of local (mal)adaptation.