Weinrich Mason T, Rosenbaum Howard, Scott Baker C, Blackmer Alexis L, Whitehead Hal
Whale Center of New England, PO Box 159, Gloucester, MA 01930, USA.
J Hered. 2006 May-Jun;97(3):226-34. doi: 10.1093/jhered/esj018. Epub 2006 Feb 17.
Humpback whales on their feeding grounds in the Gulf of Maine typically form fluid fission/fusion groups of two to three individuals characterized by noncompetitive and, at times, cooperative behavior. Here we test the hypothesis that, despite the apparent absence of close kinship bonds, the fluid associations between feeding whales are influenced by "maternal lineages" as represented by mtDNA haplotypes. Using skin samples collected with a biopsy dart, variation in the hypervariable segment of the mtDNA control region identified 17 unique haplotypes among 159 individually identified whales from the southern Gulf of Maine. The haplotypes of a further 143 individuals were inferred from known direct maternal (cow-calf) relationships. The frequencies of associations among these 302 individuals were calculated from 21,617 sighting records collected from 1980 to 1995, excluding associations between a cow and her dependent calf. For groups of two where the haplotypes of both individuals were known (n = 3,151), individuals with the same haplotype were together significantly more often (26%) than expected by random association (20%). To account for different group sizes and associations with individuals of unknown haplotype and sex, we used Monte Carlo simulations to test for nonrandom associations in the full data set, as well as known female-only (n = 1,512), male-only (n = 730), and mixed-sex (n = 2,745) groups. Within-haplotype associations were significantly more frequent than expected at random for all groups (P = .002) and female-only groups (P = .011) but not male-only groups, while mixed-sex groups approached significance (P = .062). A Mantel test of individual pairwise association indices and haplotype identity confirmed that within-haplotype associations were more frequent than expected for all sex combinations except male-male associations, with females forming within-haplotype associations 1.7 times more often than expected by random assortment. Partial matrix correlations and permutation analyses indicated that the skew toward within-haplotype associations could not be accounted for by short-term temporal co-occurrence or fine-scale spatial distributions of individuals with shared haplotypes. While the mechanism by which individuals with a common mtDNA haplotype assort remains unknown, our results strongly suggest an influence of maternal lineages on the social organization of humpback whales within a regional feeding ground.
在缅因湾觅食地的座头鲸通常会形成由两到三个个体组成的流动裂变/融合群体，其特点是没有竞争行为，且有时会有合作行为。在这里，我们检验了这样一个假设：尽管明显不存在紧密的亲属关系，但觅食鲸鱼之间的流动关联受到线粒体DNA单倍型所代表的“母系血统”的影响。我们使用活检镖采集的皮肤样本，通过线粒体DNA控制区高变区的变异，在来自缅因湾南部的159头个体识别鲸鱼中确定了17种独特的单倍型。另外143头个体的单倍型是根据已知的直接母系（母鲸-幼鲸）关系推断出来的。这302头个体之间的关联频率是根据1980年至1995年收集的21617条目击记录计算得出的，不包括母鲸与其依赖幼鲸之间的关联。对于两个个体单倍型都已知的成对组合（n = 3151），具有相同单倍型的个体在一起的频率（26%）显著高于随机关联预期的频率（20%）。为了考虑不同的群体规模以及与单倍型和性别未知个体的关联，我们使用蒙特卡罗模拟来检验整个数据集以及已知的仅雌性（n = 1512）、仅雄性（n = 730）和混合性别（n = 2745）群体中的非随机关联。所有群体（P = 0.002）和仅雌性群体（P = 0.011）中，单倍型内关联的频率显著高于随机预期，但仅雄性群体则不然，而混合性别群体接近显著水平（P = 0.062）。对个体成对关联指数和单倍型同一性的曼特尔检验证实，除了雄性-雄性关联外，所有性别组合中，单倍型内关联都比预期更频繁，雌性形成单倍型内关联的频率比随机分类预期的高1.7倍。部分矩阵相关性和置换分析表明，单倍型内关联的偏差不能用短期时间共现或共享单倍型个体的精细空间分布来解释。虽然具有共同线粒体DNA单倍型的个体聚集在一起的机制尚不清楚，但我们的结果强烈表明母系血统对区域觅食地内座头鲸的社会组织有影响。
