Feder Jeffrey L, Chilcote Charley A, Bush Guy L
Department of Zoology, Michigan State University, E. Lansing, Michigan, 48824.
Evolution. 1990 May;44(3):595-608. doi: 10.1111/j.1558-5646.1990.tb05940.x.
In the preceding study (Feder et al., 1990), we report that paired apple and hawthorn infesting populations of Rhagoletis pomonella are genetically differentiated for six allozymes. Here, we show that patterns of intra- and inter-host allele frequency variation seen for these six loci across the eastern United States are consistent on a more fine grained spatial scale in western Michigan. Malic enzyme, Aconitase-2, Mannose phosphate isomerase, and Hydroxyacid dehydrogenase all displayed significant linear relationships with latitude among five "regional" hawthorn populations sampled along a north-south transect between the cities of Cadillac and Portage, Michigan. Clines were not as evident among "regional" apple populations in western Michigan, although allele frequencies for Malic enzyme , Mannose phosphate isomerase and Aconitase-2 varied with latitude among six "local" apple populations within a 60 km area near the town of Grant. Significant allele frequency differences were observed between hawthorn and apple populations at all "regional" and "local" collecting sites analyzed in the study (a total of 20 different apple and hawthorn populations). As was the case in the geographic survey of the eastern United States, the magnitude and pattern of inter-host frequency differences at "regional" and "local" sites were a function of latitude. Host related genetic differentiation was consistent on a "microgeographic" scale as well. Allele frequencies for Malic enzyme and Aconitase-2 were significantly higher over a four-year period (1984 to 1987) for flies sampled from individual hawthorn trees (N = 6) than apple trees (N = 7) within an old field (0.09-km area) located near Grant. The fine level of genetic subdivision between hawthorn and apple populations of R. pomonella in western Michigan substantiates the existence of host associated polymorphism in the fly and supports a sympatric mode of divergence for the "apple race".
在之前的研究中（费德等人，1990年），我们报告称，苹果实蝇和山楂实蝇的成对侵染种群在六种等位酶上存在遗传分化。在此，我们表明，在美国东部，这六个基因座的宿主内和宿主间等位基因频率变化模式，在密歇根州西部更精细的空间尺度上是一致的。苹果酸酶、乌头酸酶-2、磷酸甘露糖异构酶和羟酸脱氢酶，在密歇根州凯迪拉克市和波蒂奇市之间沿南北样带采样的五个“区域”山楂种群中，均与纬度呈现出显著的线性关系。在密歇根州西部的“区域”苹果种群中，渐变群并不那么明显，尽管苹果酸酶、磷酸甘露糖异构酶和乌头酸酶-2的等位基因频率，在格兰特镇附近60公里区域内的六个“本地”苹果种群中随纬度而变化。在该研究分析的所有“区域”和“本地”采集地点（总共20个不同的苹果和山楂种群），山楂种群和苹果种群之间均观察到显著的等位基因频率差异。与美国东部的地理调查情况一样，“区域”和“本地”地点的宿主间频率差异的幅度和模式是纬度的函数。宿主相关的遗传分化在“微观地理”尺度上也是一致的。在格兰特附近一块旧田地（0.09平方公里区域）内，在四年时间（1984年至1987年）里，从单个山楂树（N = 6）采集的果蝇中，苹果酸酶和乌头酸酶-2的等位基因频率显著高于从苹果树上（N = 7）采集的果蝇。密歇根州西部苹果实蝇山楂种群和苹果种群之间精细的遗传细分，证实了该果蝇中存在宿主相关多态性，并支持“苹果小种”的同域分化模式。
