Valentin Rafael E, Lockwood Julie L, Mathys Blake A, Fonseca Dina M
Department of Ecology, Evolution and Natural Resources Rutgers University New Brunswick NJ USA.
Division of Mathematics, Computer and Natural Sciences Ohio Dominican University Columbus OH USA.
Ecol Evol. 2018 May 1;8(11):5291-5302. doi: 10.1002/ece3.4021. eCollection 2018 Jun.
There is increasing evidence that exotic populations may rapidly differentiate from those in their native range and that differences also arise among populations within the exotic range. Using morphological and DNA-based analyses, we document the extent of trait divergence among native North American and exotic Hawaiian populations of northern cardinal (). Furthermore, using a combination of historical records and DNA-based analyses, we evaluate the role of founder effects in producing observed trait differences. We measured and compared key morphological traits across northern cardinal populations in the native and exotic ranges to assess whether trait divergence across the Hawaiian Islands, where this species was introduced between 1929 and 1931, reflected observed variation across native phylogeographic clades in its native North America. We used and added to prior phylogenetic analyses based on a mitochondrial locus to identify the most likely native source clade(s) for the Hawaiian cardinal populations. We then used Approximate Bayesian Computation (ABC) to evaluate the role of founder effects in producing the observed differences in body size and bill morphology across native and exotic populations. We found cardinal populations on the Hawaiian Islands had morphological traits that diverged substantially across islands and overlapped the trait space of all measured native North American clades. The phylogeographic analysis identified the eastern North American clade () as the most likely and sole native source for all the Hawaiian cardinal populations. The ABC analyses supported written accounts of the cardinal's introduction that indicate the original 300 cardinals shipped to Hawaii were simultaneously and evenly released across Hawaii, Kauai, and Oahu. Populations on each island likely experienced bottlenecks followed by expansion, with cardinals from the island of Hawaii eventually colonizing Maui unaided. Overall, our results suggest that founder effects had limited impact on morphological trait divergence of exotic cardinal populations in the Hawaiian archipelago, which instead reflect postintroduction events.
越来越多的证据表明，外来种群可能会迅速与其原生范围内的种群产生分化，并且在其外来范围内的种群之间也会出现差异。通过形态学和基于DNA的分析，我们记录了北美本土和夏威夷外来种群的北方主红雀（Cardinalis cardinalis）的性状分化程度。此外，结合历史记录和基于DNA的分析，我们评估了奠基者效应在产生观察到的性状差异中所起的作用。我们测量并比较了原生和外来范围内北方主红雀种群的关键形态性状，以评估在1929年至1931年间引入该物种的夏威夷群岛上，性状分化是否反映了其北美原生地各系统发育分支中观察到的变异。我们在先前基于线粒体基因座的系统发育分析基础上进行补充，以确定夏威夷主红雀种群最可能的原生源分支。然后，我们使用近似贝叶斯计算（ABC）来评估奠基者效应在产生原生和外来种群间观察到的体型和喙形态差异中所起的作用。我们发现，夏威夷群岛上的主红雀种群具有在各岛屿间显著分化的形态性状，并且与所有测量的北美本土分支的性状空间有重叠。系统发育地理分析确定北美东部分支（Cardinalis cardinalis）是所有夏威夷主红雀种群最可能且唯一 的原生源。ABC分析支持了关于主红雀引入的书面记录，这些记录表明最初运往夏威夷的300只主红雀是同时且均匀地在夏威夷岛、考艾岛和瓦胡岛放生的。每个岛屿上的种群可能经历了瓶颈期后再扩张，夏威夷岛的主红雀最终独自殖民了毛伊岛。总体而言，我们的结果表明，奠基者效应对外来主红雀种群在夏威夷群岛的形态性状分化影响有限，这些分化反而反映了引入后的事件。
