Magalhaes Ivan L F, Oliveira Ubirajara, Santos Fabrício R, Vidigal Teofânia H D A, Brescovit Antonio D, Santos Adalberto J
Departamento de Zoologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Av. Antônio Carlos 6627, 31270-901, Belo Horizonte, Minas Gerais, Brazil; División Aracnología, Museo Argentino de Ciencias Naturales 'Bernardino Rivadavia', Av. Angel Gallardo 470, C1405DJR, Buenos Aires, Argentina.
Mol Ecol. 2014 Nov;23(21):5323-36. doi: 10.1111/mec.12937. Epub 2014 Oct 13.
The Brazilian Caatinga is part of the seasonally dry tropical forests, a vegetation type disjunctly distributed throughout the Neotropics. It has been suggested that during Pleistocene glacial periods, these dry forests had a continuous distribution, so that these climatic shifts may have acted as important driving forces of the Caatinga biota diversification. To address how these events affected the distribution of a dry forest species, we chose Sicarius cariri, a spider endemic to the Caatinga, as a model. We studied the phylogeography of one mitochondrial and one nuclear gene and reconstructed the paleodistribution of the species using modelling algorithms. We found two allopatric and deeply divergent clades within S. cariri, suggesting that this species as currently recognized might consist of more than one independently evolving lineage. Sicarius cariri populations are highly structured, with low haplotype sharing among localities, high fixation index and isolation by distance. Models of paleodistribution, Bayesian reconstructions and coalescent simulations suggest that this species experienced a reduction in its population size during glacial periods, rather than the expansion expected by previous hypotheses on the paleodistribution of dry forest taxa. In addition to that, major splits of intraspecific lineages of S. cariri took place in the Pliocene. Taken together, these results indicate S. cariri has a complex diversification history dating back to the Tertiary, suggesting the history of dry forest taxa may be significantly older than previously thought.
巴西卡廷加是季节性干燥热带森林的一部分，这种植被类型在新热带界呈间断分布。有人提出，在更新世冰川期，这些干燥森林曾连续分布，因此这些气候变化可能是卡廷加生物群多样化的重要驱动力。为了探究这些事件如何影响一种干燥森林物种的分布，我们选择了卡廷加特有的蜘蛛卡里里刺客蛛作为模型。我们研究了一个线粒体基因和一个核基因的系统地理学，并使用建模算法重建了该物种的古分布。我们在卡里里刺客蛛中发现了两个异域且差异很大的分支，这表明目前所认定的该物种可能由不止一个独立进化的谱系组成。卡里里刺客蛛种群结构高度分化，各地之间单倍型共享率低，固定指数高且存在距离隔离。古分布模型、贝叶斯重建和溯祖模拟表明，该物种在冰川期种群数量减少，而非如先前关于干燥森林类群古分布的假说所预期的那样扩张。除此之外，卡里里刺客蛛种内谱系的主要分化发生在上新世。综合来看，这些结果表明卡里里刺客蛛具有可追溯到第三纪的复杂多样化历史，这表明干燥森林类群的历史可能比先前认为的要长得多。
