Rios Rodrigo S, Salgado-Luarte Cristian, Gianoli Ernesto
Departamento de Biología, Universidad de La Serena, La Serena, Chile.
Departamento de Biología, Universidad de La Serena, La Serena, Chile; Departamento de Botánica, Universidad de Concepción, Concepción, Chile.
PLoS One. 2014 Jun 10;9(6):e99871. doi: 10.1371/journal.pone.0099871. eCollection 2014.
The climbing habit is an evolutionary key innovation in plants because it is associated with enhanced clade diversification. We tested whether patterns of species divergence and variation of three ecophysiological traits that are fundamental for plant adaptation to light environments (maximum photosynthetic rate [A(max)], dark respiration rate [R(d)], and specific leaf area [SLA]) are consistent with this key innovation. Using data reported from four tropical forests and three temperate forests, we compared phylogenetic distance among species as well as the evolutionary rate, phylogenetic distance and phylogenetic signal of those traits in lianas and trees. Estimates of evolutionary rates showed that R(d) evolved faster in lianas, while SLA evolved faster in trees. The mean phylogenetic distance was 1.2 times greater among liana species than among tree species. Likewise, estimates of phylogenetic distance indicated that lianas were less related than by chance alone (phylogenetic evenness across 63 species), and trees were more related than expected by chance (phylogenetic clustering across 71 species). Lianas showed evenness for R(d), while trees showed phylogenetic clustering for this trait. In contrast, for SLA, lianas exhibited phylogenetic clustering and trees showed phylogenetic evenness. Lianas and trees showed patterns of ecophysiological trait variation among species that were independent of phylogenetic relatedness. We found support for the expected pattern of greater species divergence in lianas, but did not find consistent patterns regarding ecophysiological trait evolution and divergence. R(d) followed the species-level pattern, i.e., greater divergence/evolution in lianas compared to trees, while the opposite occurred for SLA and no pattern was detected for A(max). R(d) may have driven lianas' divergence across forest environments, and might contribute to diversification in climber clades.
攀缘习性是植物进化中的一项关键创新，因为它与进化枝多样化的增强有关。我们测试了物种分化模式以及植物适应光照环境的三个生态生理特征（最大光合速率[A(max)]、暗呼吸速率[R(d)]和比叶面积[SLA]）的变化是否与这一关键创新一致。利用来自四个热带森林和三个温带森林报告的数据，我们比较了藤本植物和树木之间物种的系统发育距离以及这些特征的进化速率、系统发育距离和系统发育信号。进化速率估计表明，R(d)在藤本植物中进化得更快，而SLA在树木中进化得更快。藤本植物物种间的平均系统发育距离是树木物种间的1.2倍。同样，系统发育距离估计表明，藤本植物之间的亲缘关系比随机情况下更少（63个物种的系统发育均匀度），而树木之间的亲缘关系比随机预期更多（71个物种的系统发育聚类）。藤本植物在R(d)上表现出均匀度，而树木在该特征上表现出系统发育聚类。相比之下，对于SLA，藤本植物表现出系统发育聚类，而树木表现出系统发育均匀度。藤本植物和树木在物种间表现出与系统发育相关性无关的生态生理特征变化模式。我们发现支持藤本植物中物种分化更大的预期模式，但未发现关于生态生理特征进化和分化的一致模式。R(d)遵循物种水平模式，即与树木相比，藤本植物中的分化/进化更大，而SLA则相反，并且未检测到A(max)的模式。R(d)可能推动了藤本植物在不同森林环境中的分化，并可能有助于攀缘植物进化枝多样化。
