McElroy T C, Kandl K L, Garcia J, Trexler J C
Department of Biological Sciences, Florida International University, University Park, Miami, FL 33199, USA.
Mol Ecol. 2003 Feb;12(2):355-68. doi: 10.1046/j.1365-294x.2003.01738.x.
The population genetics of aquatic animals in the Florida Everglades may be strongly influenced by extinction and colonization dynamics. We combined analyses of allozyme and microsatellite loci to test the hypothesis that two levels of population structure are present for spotted sunfish (Pisces: Centrarchidae: Lepomis punctatus) inhabiting the Everglades. We hypothesized that annual cycles of marsh dry-down increase local-scale genetic variation through a process of local extinction and colonization; we hypothesized that barriers to gene flow by levee/canal systems create a second, regional level of genetic variation. In 1996 and 1997, we sampled spotted sunfish from 11 Everglades sites that were distributed in three regions separated by levees. We documented patterns of genetic variation at 7 polymorphic allozyme loci and 5 polymorphic microsatellite loci. Most genetic variation was present among local populations, according to both types of genetic markers. Furthermore, samples from marsh sites were heterogeneous, while those from canals were not. These data supported our hypothesis that dry-down events and local population dynamics in the marsh have a significant effect on population genetic structure of spotted sunfish. We found no support for our hypothesis that water-management structures superimpose a second level of genetic structure on this species, possibly because canals obscure historical structure by facilitating gene flow or because the complete canal system has been in place for fewer than 20 generations of this species. Our data suggests a continent-island (canal-marsh) structure of populations with high gene flow among regions and recurrent mixing in marshes from canal and creek habitats.
佛罗里达大沼泽地水生动物的种群遗传学可能受到灭绝和定殖动态的强烈影响。我们结合等位酶和微卫星位点分析，以检验如下假说：栖息于大沼泽地的斑鳍太阳鱼（硬骨鱼纲：太阳鱼科：斑鳍太阳鱼）存在两个层次的种群结构。我们推测，沼泽干涸的年度周期通过局部灭绝和定殖过程增加了局部尺度的遗传变异；我们还推测，堤坝/运河系统造成的基因流动障碍形成了第二个区域层次的遗传变异。1996年和1997年，我们从大沼泽地的11个地点采集了斑鳍太阳鱼样本，这些地点分布在由堤坝分隔的三个区域。我们记录了7个多态性等位酶位点和5个多态性微卫星位点的遗传变异模式。根据这两种遗传标记，大多数遗传变异存在于局部种群之间。此外，来自沼泽地点的样本是异质的，而来自运河的样本则不是。这些数据支持了我们的假说，即沼泽中的干涸事件和局部种群动态对斑鳍太阳鱼的种群遗传结构有显著影响。我们没有找到证据支持我们的假说，即水资源管理结构在该物种上叠加了第二个层次的遗传结构，这可能是因为运河通过促进基因流动掩盖了历史结构，或者是因为完整的运河系统存在的时间还不到该物种20代。我们的数据表明，种群具有大陆 - 岛屿（运河 - 沼泽）结构，各区域间基因流动频繁，且来自运河和溪流栖息地的个体在沼泽中反复混合。
