Ruiz-García Manuel, Chacón Diego, Plese Tinka, Schuler Ingrid, Shostell Joseph Mark
a Departamento de Biología, Facultad de Ciencias , Pontificia Universidad Javeriana , Bogotá , DC , Colombia.
b Fundación AIUNAU , Medellín , Colombia.
Mitochondrial DNA A DNA Mapp Seq Anal. 2018 Mar;29(2):281-299. doi: 10.1080/24701394.2016.1275602. Epub 2017 Jan 27.
We sequenced the complete mitogenome of 39 sloths (19 Bradypus variegatus, 4 B. tridactylus, 1 B. pygmaeus, 1 B. torquatus, 4 Choloepus didactylus, and 10 C. hoffmanni). A Bayesian tree (BI) indicated a temporal split between Bradypus and Choloepus around 31 million years ago (MYA, Oligocene) and the other major splits within each genera during the Miocene and Pliocene. A haplotype network (MJN) estimated a lower temporal split between the sloth genera (around 23.5 MYA). Both methods detected the ancestor of B. torquatus as the first to diverge within Bradypus (21 for BI and 19 MJN), followed by that of the ancestor of B. tridactylus. The split of B. pygmaeus from the common ancestor with B. variegatus was around 12 MYA (BI) or 4.3 MYA (MJN). The splits among the previous populations of B. variegatus began around 8 MYA (BI) or 3.6 MYA (MJN). The trans-Andean population was the first to diverge from the remaining cis-Andean populations of B. variegatus. The genetic differentiation of the trans-Andean B. variegatus population relative to the cis-Andean B. variegatus is similar to that found for different species of sloths. The mitogenomic analysis resolved the differentiation of C. hoffmanni from the C. didactylus individuals of the Guiana Shield. However, one C. didactylus from the Colombian Amazon specimen was inside the C. hoffmanni clade. This could be the first example of possible natural hybridization in the Amazon of both Choloepus taxa or the existence of un-differentiable phenotypes of these two species in some Amazonian areas.
我们对39只树懒的完整线粒体基因组进行了测序（19只鬃毛三趾树懒、4只三趾树懒、1只侏儒三趾树懒、1只鬃毛树懒、4只二趾树懒和10只霍氏树懒）。贝叶斯树（BI）表明，三趾树懒属和二趾树懒属在约3100万年前（渐新世）出现了时间上的分化，每个属内的其他主要分化发生在中新世和上新世。单倍型网络（MJN）估计树懒属之间的时间分化较低（约2350万年前）。两种方法都检测到鬃毛树懒是三趾树懒属中第一个分化出来的（贝叶斯树为21，单倍型网络为19），其次是三趾树懒的祖先。侏儒三趾树懒与鬃毛三趾树懒的共同祖先的分化时间约为1200万年前（贝叶斯树）或430万年前（单倍型网络）。鬃毛三趾树懒先前种群之间的分化始于约800万年前（贝叶斯树）或360万年前（单倍型网络）。安第斯山脉以西的种群是第一个从安第斯山脉以东的鬃毛三趾树懒种群中分化出来的。安第斯山脉以西的鬃毛三趾树懒种群相对于安第斯山脉以东的鬃毛三趾树懒种群的遗传分化，与不同树懒物种之间的遗传分化相似。线粒体基因组分析解决了圭亚那地盾上霍氏树懒与二趾树懒个体之间的分化问题。然而，来自哥伦比亚亚马逊标本的一只二趾树懒位于霍氏树懒分支内。这可能是这两个二趾树懒属在亚马逊地区可能存在自然杂交的首个例子，或者是这两个物种在亚马逊某些地区存在无法区分的表型的证据。
