Spatio-temporal dynamics of the Allonemobius fasciatus-A. socius mosaic hybrid zone:: a 14-year perspective
Spatio-temporal dynamics of the Allonemobius fasciatus-A. socius mosaic hybrid zone:: a 14-year perspective
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DOI：
10.1046/j.1365-294x.2001.01215.x
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发表时间：
2001-03-01
影响因子：
4.9
通讯作者：
Howard, DJ
中科院分区：
文献类型：
--
作者：
Britch, SC;Cain, ML;Howard, DJ
对混合区的长期研究可以为长期以来引起进化论者关注的许多问题提供有价值的见解。这些问题的范围从混合区的稳定性和命运到混合区的相对适应性。在本文中，我们报告了对 Allonemobius fasciatus-Allonemobius socius 混合区进行 14 年调查的结果。 1986 年和 1987 年对种群进行了集中收集，然后在 20 世纪 80 年代末和整个 90 年代进行了零星收集。通过记录这段时间内该区域附近和区域内种群遗传组成的变化，我们评估了： 两个物种之间生殖隔离的强度；与杂种和纯种个体相对应的基因型类别的相对生长率（可以被认为是相对适应性的替代）；并且，单年和多年相对增长率测量可以预测混合种群遗传组成随时间变化的能力。简而言之，我们发现纯种和杂交个体的相对增长率存在很大的逐年变化。这种差异可能反映了这样一个事实：这两个物种都处于其活动范围的边缘，并且可能处于其应对环境扰动的能力的极限。由于这种变化，即使是多年的相对增长率估计也常常无法准确预测混合种群未来的基因型组成。尽管我们预测个体种群动态的能力有限，但一些趋势是显而易见的。 A. socius，南部物种，沿着阿巴拉契亚山脉横断面的频率明显增加，表明该区域正在向北移动。相比之下，该区域沿东海岸横断面似乎更加稳定。在混合种群中，性状指数概况通常是双峰的，并且随着时间的推移保持稳定，这表明两个物种之间相对较强的生殖隔离，这种隔离没有得到加强，也没有被打破。
Long-term studies of hybrid zones can provide valuable insight into a number of questions that have long attracted the attention of evolutionists. These questions range from the stability and fate of hybrid zones to the relative fitness of hybrids. In this paper we report the results of a 14-year survey of the Allonemobius fasciatus-Allonemobius socius hybrid zone. Populations were collected intensively in 1986 and 1987 and then more sporadically through the end of the 1980s and throughout the 1990s. By documenting changes in the genetic composition of populations near and within the zone during this period of time we assessed: the strength of the reproductive isolation between the two species; the relative growth rates (which can be considered a surrogate of relative fitness) of genotype classes corresponding to hybrids and to pure species individuals; and, the power of single-year and multi-year measurements of relative growth rates to predict changes in the genetic composition of mixed populations through time. In brief, we found very large year-to-year variation in the relative growth rates of pure species and hybrid individuals. This variation may reflect the fact that both species are at the edge of their range and perhaps at the limits of their ability to deal with environmental perturbations. As a consequence of the variation, even multi-year estimates of relative growth rates often provided imprecise predictions regarding the future genotypic composition of mixed populations. Despite our limited ability to predict the dynamics of individual populations, some trends are apparent. A. socius, the southern species, has clearly increased in frequency along a transect through the Appalachian Mountains, indicating that the zone is moving north in this region. In contrast, the zone appeared to be more stable along the East Coast transect. Within mixed populations, character-index profiles are often bimodal and stable through time, indicating relatively strong reproductive isolation between the two species that is not being reinforced, nor is it breaking down.