Genetically based demographic reconstructions require careful consideration of generation time
Genetically based demographic reconstructions require careful consideration of generation time
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基于遗传的人口重建需要仔细考虑世代时间
DOI：
10.1016/j.cub.2022.03.048
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发表时间：
2022
期刊：
影响因子：
9.2
通讯作者：
Kirkland, Steve
中科院分区：
文献类型：
--
作者：
Bakker, Victoria J.;Finkelstein, Myra E.;D’Elia, Jesse;Doak, Daniel F.;Kirkland, Steve
世代时间(G)，通常定义为个体在种群中繁殖的平均年龄，是使用聚代模型进行基于基因的人口重建的关键组成部分。在他们最近发表于《当代生物学》的研究中，Robinson等人1提出了这样一种重建方法，对了解安第斯秃鹫（Vultur gryphus）、加利福尼亚秃鹫（Gymnogyps californianus）和土耳其秃鹫（Cathartes aura）的历史种群规模具有重要意义。然而，我们认为，不正确的世代时间估计使他们的发现受到质疑，即现在极度濒危的加利福尼亚秃鹰曾经在数量上超过了土耳其秃鹫——目前美洲数量最多、分布最广的秃鹫。Robinson等人1使用G表示10岁的秃鹰——不到真实值的一半，我们估计的真实值为~ 25岁（表S1）。这种较短的世代时间夸大了他们对历史有效种群大小（N e）的估计，并且他们对不同生活史的物种使用相同的G，使得他们的相对丰度比较有缺陷。在这里，我们重新评估了Robinson等人的研究结果1，以强调在人口重建中仔细估计G的重要性，特别是对于具有保护意义的物种。基于基因的人口统计重建利用当代个体的基因多样性模式，以及估计的突变率，来推断过去的N - e随时间2。这些重建的突变率通常来自序列分化和分类群之间估计的分化时间，每年产生突变，然后转换为每代突变率。对于固定的年突变率，增加G线性降低N e估计值，但不影响估计N e趋势的整体形状2,3。因此，当比较物种之间过去的种群轨迹或当绝对历史N e为当前的保护决策提供信息时，G的错误说明尤其有问题。
Generation time (G), generally defined as the mean age at which individuals reproduce in a population, is a critical component of genetically based demographic reconstructions using coalescent models. In their recent study in Current Biology, Robinson et al. 1 present such a reconstruction with implications for understanding historical population sizes of Andean condors (Vultur gryphus), California condors (Gymnogyps californianus) and turkey vultures (Cathartes aura). However, here we argue that incorrect generation time estimates call into question their finding that the now critically endangered California condor once outnumbered the turkey vulture—currently the most abundant and widespread vulture in the Americas. Robinson et al. 1 use a G for condors of 10 years—less than half the true value, which we estimate to be∼ 25 years (Table S1). This shorter generation time inflates their historical effective population size (N e) estimates, and their use of the same G for species with different life histories makes their relative abundance comparisons flawed. Here, we re-evaluate the findings of Robinson et al. 1 to highlight the importance of carefully estimating G in demographic reconstructions, especially for species of conservation concern.Genetically based demographic reconstructions use genetic diversity patterns in contemporary individuals, along with an estimated mutation rate, to infer past N e over time 2. Mutation rates for these reconstructions are frequently derived from sequence divergence and estimated divergence times among taxa, yielding mutations per year, which is then converted to a per-generation mutation rate. For a fixed per-year mutation rate, increasing G linearly decreases N e estimates but does not affect the overall shape of estimated N e trends 2, 3. Therefore, misspecifications of G are especially problematic when comparing past population trajectories among species or when absolute historical N e informs current conservation decisions.
影响因子：
3.1
作者：
D'Elia, Jesse;Haig, Susan M.;Miller, Mark P.
通讯作者：
Miller, Mark P.