Moreno-Letelier Alejandra, Ortíz-Medrano Alejandra, Piñero Daniel
Departamento de Ecología Evolutiva, Instituto de Ecologia, Universidad Nacional Autonoma de México, México D.F., Mexico.
PLoS One. 2013 Oct 29;8(10):e78228. doi: 10.1371/journal.pone.0078228. eCollection 2013.
Solving relationships of recently diverged taxa, poses a challenge due to shared polymorphism and weak reproductive barriers. Multiple lines of evidence are needed to identify independently evolving lineages. This is especially true of long-lived species with large effective population sizes, and slow rates of lineage sorting. North American pines are an interesting group to test this multiple approach. Our aim is to combine cytoplasmic genetic markers with environmental information to clarify species boundaries and relationships of the species complex of Pinus flexilis, Pinus ayacahuite, and Pinus strobiformis.
Mitochondrial and chloroplast sequences were combined with previously obtained microsatellite data and contrasted with environmental information to reconstruct phylogenetic relationships of the species complex. Ecological niche models were compared to test if ecological divergence is significant among species.
Separately, both genetic and ecological evidence support a clear differentiation of all three species but with different topology, but also reveal an ancestral contact zone between P. strobiformis and P. ayacahuite. The marked ecological differentiation of P. flexilis suggests that ecological speciation has occurred in this lineage, but this is not reflected in neutral markers. The inclusion of environmental traits in phylogenetic reconstruction improved the resolution of internal branches. We suggest that combining environmental and genetic information would be useful for species delimitation and phylogenetic studies in other recently diverged species complexes.
由于共享多态性和较弱的生殖隔离，解决最近分化的分类群之间的关系具有挑战性。需要多条证据来识别独立进化的谱系。对于有效种群规模大、谱系分选速率慢的长寿物种来说尤其如此。北美松树是测试这种多方法的一个有趣群体。我们的目的是将细胞质遗传标记与环境信息相结合，以阐明柔枝松、阿亚卡维松和球果松物种复合体的物种界限和关系。
将线粒体和叶绿体序列与先前获得的微卫星数据相结合，并与环境信息进行对比，以重建该物种复合体的系统发育关系。比较生态位模型，以检验物种间的生态分化是否显著。
分别来看，遗传和生态证据均支持所有三个物种的明显分化，但拓扑结构不同，同时还揭示了球果松和阿亚卡维松之间的一个祖先接触区。柔枝松显著的生态分化表明该谱系中发生了生态物种形成，但这在中性标记中并未体现。在系统发育重建中纳入环境特征提高了内部分支的分辨率。我们认为，将环境和遗传信息相结合，对于其他最近分化的物种复合体的物种界定和系统发育研究将是有用的。
