Lee Taehwan, Foighil Diarmaid O
Museum of Zoology and Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, Michigan 48109-1079, USA.
Evolution. 2005 Oct;59(10):2139-58.
The well-documented Floridian Gulf/Atlantic marine genetic disjunction provides an influential example of presumed vicariant cladogenesis along a continental coastline for major elements of a diverse nearshore fauna. However, it is unclear if this disjunction represents a local anomaly for regionally distributed morphospecies, or if it is merely one of many such cryptic phylogenetic splits that underlay their assumed genetic cohesiveness. We aimed to place the previously characterized scorched mussel Gulf/Atlantic genetic disjunction into a regional phylogenetic perspective by incorporating genotypes of nominal conspecifics sampled throughout the Caribbean Basin as well as those of eastern Pacific potential geminate species. Our results show it to be one of multiple latent regional genetic disjunctions, involving five cryptic Caribbean species, that appear to be the product of a long history of regional cladogenesis. Disjunctions involving three stem lineages clearly predate formation of the Isthmus of Panama and of the Caribbean Sea, although four of the five cryptic species have within-basin sister relationships. Surprisingly, the Atlantic clade was also found to be widespread in the southern Caribbean, and ancestral demography calculations through time for Atlantic coast-specific genotypes are consistent with a northward range extension after the last glacial maximum. Our new data seriously undermine the hypothesis of a Floridian vicariant genesis and imply that the scorched mussel Gulf/Atlantic disjunction represents a case of geographic and temporal pseudocongruence. All five Caribbean Basin cryptic species exhibited an intriguing pattern of predominantly allopatric distribution characterized by distinct geographic areas of ecological dominance, often adjoining those of sister taxa. This pattern of distribution is consistent with allopatric speciation origins, coupled with restricted postspeciation range extensions. Several lines of indirect evidence favor the hypothesis that the predominantly allopatric distributions are maintained over evolutionary time scales, primarily by postrecruitment ecological filters rather than by oceanographic barriers to larval-mediated gene flow.
有充分记录的佛罗里达湾/大西洋海洋遗传间断为多样化近岸动物群的主要组成部分沿着大陆海岸线假定的间断性成种作用提供了一个有影响力的例子。然而，目前尚不清楚这种间断是区域分布形态物种的局部异常，还是仅仅是构成其假定遗传凝聚力的众多此类隐秘系统发育分裂之一。我们旨在通过纳入在整个加勒比海盆地采样的名义上的同种基因型以及东太平洋潜在的双生种的基因型，将先前表征的焦贻贝湾/大西洋遗传间断置于区域系统发育的视角下。我们的结果表明，它是多个潜在区域遗传间断之一，涉及五个隐秘的加勒比物种，似乎是区域成种作用悠久历史的产物。涉及三个干群谱系的间断显然早于巴拿马地峡和加勒比海的形成，尽管五个隐秘物种中有四个在盆地内有姐妹关系。令人惊讶的是，大西洋分支在加勒比海南部也很普遍，对大西洋海岸特定基因型随时间的祖先种群统计学计算与末次盛冰期后向北的范围扩展一致。我们的新数据严重削弱了佛罗里达间断起源的假说，并暗示焦贻贝湾/大西洋间断代表了地理和时间上的假一致性情况。所有五个加勒比海盆地隐秘物种都表现出一种有趣的主要异域分布模式，其特征是具有明显的生态优势地理区域，这些区域通常与姐妹类群的区域相邻。这种分布模式与异域物种形成起源一致，再加上物种形成后有限的范围扩展。几条间接证据支持这样的假说，即主要的异域分布在进化时间尺度上得以维持，主要是通过补充后生态筛选，而不是通过对幼虫介导的基因流动的海洋学障碍。
