Origin and number of founders in an introduced insular primate: estimation from nuclear genetic data
Origin and number of founders in an introduced insular primate: estimation from nuclear genetic data
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DOI：
10.1111/j.1365-294x.2007.03645.x
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发表时间：
2008-02-01
影响因子：
4.9
通讯作者：
Crouau-Roy, B.
中科院分区：
文献类型：
--
作者：
Bonhomme, M.;Blancher, A.;Crouau-Roy, B.
食蟹猴 (Macaca fasciculis) 于 400 至 500 年前被引入毛里求斯岛，并在可能的最初建国事件后经历了强劲的种群扩张。然而，实际上，人们对岛上殖民者的地理起源、引入了多少个体以及随后的人口扩张是否消除了这一假定瓶颈的任何信号知之甚少。在这项研究中，我们询问毛里求斯人口当前的核基因组是否保留了使我们能够回答这些问题的特征。总共对 81 个不相关的毛里求斯个体和来自东南亚（爪哇岛、菲律宾群岛和印度支那半岛）假定地理来源的 173 个个体的 21 个多态性常染色体和性连锁微卫星进行了调查。我们发现（i）根据我们使用的标记，毛里求斯人口更接近不同的人口，这表明可能是混合起源，其中爪哇很可能发挥了主要作用； (ii) 多样性水平低于其他群体，但使用汇总统计或完全似然方法没有明确且一致的瓶颈信号。然而，汇总统计数据强烈表明，毛里求斯并未处于突变漂移平衡，并且倾向于扩张而不是瓶颈。这表明，在短时间内，很难从基于突变漂移理论的遗传数据中推断出种群数量下降后的增长。然后，我们使用简单的贝叶斯拒绝算法来估计不同人口统计模型（指数模型、逻辑模型和带滞后的逻辑模型）和纯遗传漂变下的创始人数量。这种新方法使用毛里求斯和源人口的当前人口规模估计和预期杂合性。我们的结果表明，简单的指数增长不太可能，并且在逻辑模型下，种群数量可能已从最初的 10-15 人有效数量扩大。这些数据也与具有不同滞后值的逻辑增长一致，表明我们不能排除过去的人口波动。
Cynomolgus macaques (Macaca fascicularis) were introduced on the island of Mauritius between 400 and 500 years ago and underwent a strong population expansion after a probable initial founding event. However, in practice, little is known of the geographical origin of the individuals that colonized the island, on how many individuals were introduced, and of whether the following demographic expansion erased any signal of this putative bottleneck. In this study, we asked whether the current nuclear genome of the Mauritius population retained a signature that would allow us to answer these questions. Altogether, 21 polymorphic autosomal and sex-linked microsatellites were surveyed from 81 unrelated Mauritius individuals and 173 individuals from putative geographical sources in Southeast Asia: Java, the Philippines islands and the Indochinese peninsula. We found that (i) the Mauritius population was closer to different populations depending on the markers we used, which suggests a possible mixed origin with Java playing most probably a major role; and (ii) the level of diversity was lower than the other populations but there was no clear and consistent bottleneck signal using either summary statistics or full-likelihood methods. However, summary statistics strongly suggest that Mauritius is not at mutation-drift equilibrium and favours an expansion rather than a bottleneck. This suggests that on a short time scale, population decline followed by growth can be difficult to deduce from genetic data based on mutation-drift theory. We then used a simple Bayesian rejection algorithm to estimate the number of founders under different demographic models (exponential, logistic and logistic with lag) and pure genetic drift. This new method uses current population size estimates and expected heterozygosity of Mauritius and source population(s). Our results indicate that a simple exponential growth is unlikely and that, under the logistic models, the population may have expanded from an initial effective number of individuals of 10-15. The data are also consistent with a logistic growth with different lag values, indicating that we cannot exclude past population fluctuation.