Crozier R H, Smith B H, Crozier Y C
School of Zoology, University of New South Wales, Kensington, N.S.W., 2033, Australia.
Department of Entomology, University of Kansas, Lawrence, KS, 66045.
Evolution. 1987 Jul;41(4):902-910. doi: 10.1111/j.1558-5646.1987.tb05863.x.
Lasioglossum zephyrum is a primitively eusocial bee, which nests in small colonies of up to 20 individuals. The nests occur in patchily distributed aggregations of from a few to over 1,000 nests along periodically disturbed stream and river banks in eastern North America. We used five polymorphic allozyme loci to test for geographic structure and estimate relatedness in eight patches of nests from five aggregations in Douglas Co., Kansas. Autocorrelation analysis of gene frequencies, plus a multilocus G test, revealed a low but significant tendency for differentiation among nests within patches, among patches within aggregations, and among aggregations. Small numbers of nests restricted estimation of relatedness to three patches, of which only one had a sample size large enough to yield confidence limits narrow enough to be informative. The limits from this patch of 20 nests are 0.64 < 0.8245 < 1.01. While these limits are consistent with the true value being 0.75 (that expected under male-haploidy if each nest results from the reproduction of a single, once-mated female), the occurrence of some nests with three or more genotypes shows that nest makeup is more complex than this, so that a lower value, say 0.7, is more plausible. This value is sufficiently high to indicate that kin selection is probably important in these populations.
西风细舌蜂是一种原始的群居蜜蜂，其巢穴中的小群体规模可达20只个体。这些巢穴分布在北美东部周期性受到干扰的溪流和河岸沿线，形成了从几个到1000多个巢穴的零散聚集区。我们使用了五个多态性等位酶位点，对堪萨斯州道格拉斯县五个聚集区的八个巢穴斑块进行地理结构测试并估计亲缘关系。对基因频率进行自相关分析，再加上多位点G检验，结果显示在斑块内的巢穴之间、聚集区内的斑块之间以及聚集区之间存在低但显著的分化趋势。少量的巢穴使得亲缘关系的估计仅限于三个斑块，其中只有一个斑块的样本量足够大，能够得出足够窄且有信息量的置信区间。来自这个有20个巢穴的斑块的置信区间为0.64 < 0.8245 < 1.01。虽然这些区间与真实值为0.75（如果每个巢穴都由一只单次交配的雌蜂繁殖产生，在雄蜂单倍体情况下预期的值）一致，但出现一些具有三种或更多基因型的巢穴表明巢穴组成比这更复杂，所以较低的值，比如0.7，可能更合理。这个值足够高，表明亲缘选择在这些种群中可能很重要。
