Department of Biology & S.L. Welsh Herbarium, 4102 LSB, Brigham Young University, Provo, Utah 84602 USA.
Rancho Santa Ana Botanic Garden, 1500 North College Avenue, Claremont, California 91711 USA.
Am J Bot. 2017 Nov;104(11):1729-1744. doi: 10.3732/ajb.1700183.
Following establishment after long-distance dispersal, species may experience stasis, accumulate changes leading to new species identity, diversify into multiple species, interact with related species to form novel species, and even become extirpated. We examined each species of temperate Polemoniaceae in South America via the literature and new analyses to better understand the fates of species in this family after their dispersal from North America.
We reviewed literature for the 15 species of Polemoniaceae in South America amphitropically disjunct from their relatives in North America. We conducted DNA sequence analyses to infer relationships, timing of dispersal, and processes involved since dispersal in Microsteris gracilis, three Gilia, two Giliastrum, and three Collomia. Analyses included construction of haplotype networks and phylogenetic trees using maximum likelihood and Bayesian inference.
For all species examined in detail, origins in South America are compatible with dispersal via epizoochory from ca. 0.092-19.46 million years ago. Most species in South America are unique relative to their North American congeners, yet few have radiated into two or more species. Relative stasis, divergence, and hybridization with, and without, allopolyploid formation have occurred postdispersal in Polemoniaceae, as well as extirpation following at least brief establishment.
Polemoniaceae that have established in South America share many features likely inherited from their North American progenitors, but some traits may have arisen in situ in specific taxa, such as cleistogamy, self-incompatibility, and the annual habit, evidencing the rich nature of diversification processes.
物种在长距离扩散后建立种群，可能会经历停滞期，积累导致新物种形成的变化，多样化形成多个物种，与相关物种相互作用形成新物种，甚至灭绝。我们通过文献和新的分析研究了南美的每一种温带 Polemoniaceae 物种，以更好地了解该科物种在从北美扩散后的命运。
我们查阅了文献中记录的在南美洲与北美的亲缘物种呈间断分布的 15 种 Polemoniaceae 物种。我们进行了 DNA 序列分析，以推断在 Microsteris gracilis、三种 Gilia、两种 Giliastrum 和三种 Collomia 中，自扩散以来的亲缘关系、扩散时间和涉及的过程。分析包括使用最大似然法和贝叶斯推断构建单倍型网络和系统发育树。
对于所有详细研究的物种，其在南美洲的起源与约 0.092-19.46 百万年前通过动物传播的扩散是兼容的。在南美的大多数物种相对于其北美的同属物种是独特的，但很少有物种辐射形成两个或更多的物种。在 Polemoniaceae 中，扩散后发生了相对停滞、分化和与杂交，以及没有发生异源多倍体形成，还有在至少短暂建立后灭绝。
在南美洲建立的 Polemoniaceae 物种共享许多可能从其北美的祖先遗传而来的特征，但有些特征可能是在特定分类群中就地产生的，例如闭花受精、自交不亲和性和一年生习性，这证明了多样化过程的丰富性。
