在生物地理学中,替代和长距离分散通常被描述为竞争场景。然而,它们是相关的概念,两者都依靠集体地质,生态,和系统发育证据。这可以用淡水鱼来说明,当淡水连接暂时存在并随后被切断(替代)时,它们可能会移民到岛屿,或通过不寻常的方式,当海洋间隙交叉(长距离扩散)。海洋屏障对淡水鱼有很强的过滤作用,将移民限制在最有能力传播海洋的人。对于大安的列斯群岛的淡水鱼来说,替代和分散的作用是有争议的。我们回顾了三个活跃的假设[白垩纪代际,大安的列斯群岛-埃夫斯岭(加兰迪亚),长距离扩散],并由于对淡水鱼使用陆地跨度的支持有限,因此提出长距离扩散是适当的模型。大安的列斯淡水鱼有六个潜在的来源生物区域(根据动物群相似性定义):墨西哥北部海湾,墨西哥西部海湾,MayaTerrane,ChortisBlock,东巴拿马,和南美洲北部。大安的列斯群岛的动物由从许多这些生物区迁徙的分类群组成,但是岛屿和大陆鱼类动物区系之间存在强烈的成分不和谐(>90%的安的列斯物种是鲤科动物,与墨西哥北部海湾和南美洲北部的<10%相比,在其他地方≤50%),与长距离扩散的假设一致。祖先地区重建分析表明,在过去的5100万年中,有16或17起移民事件,其中有14或15个是鲤鱼齿形。已发布的每个移民事件的差异估计和证据表明,它们发生在不同的时间和不同的途径,可能是在暴风雨中从河流中排出或冲入大海的植被筏。如果是,洋流可能为从一个陆地流向另一个陆地时的移民提供了关键途径。另一方面,当在陆块之间垂直流动时,水流会产生分散障碍。除了高耐盐性,Cyprinodontiforms集体表现出各种适应性,可以增强其与筏一起生活的能力(小体型,胎生,低代谢,两栖,滞育,自我受精)。这些适应措施也可能帮助移民在抵达后建立岛屿人口,并在此后长期持续下去。Cichiclids可能使用了伪桥(尼加拉瓜崛起)到达大安的列斯群岛。Gars(Lepisosteidae)可能已经越过佛罗里达海峡到达古巴,一个相对较短的杂交,对于几个鲤鱼状移民来说,这不是基因流动的障碍。的确,第四纪移民的广泛分布(Cyprinodon,甘布西亚,Kryptolebias),在大安的列斯群岛和邻近的生物区域中,意味着长距离扩散不一定抑制适应良好的物种,即使这对所有其他淡水鱼来说似乎几乎是不可能的。
In biogeography, vicariance and long-distance dispersal are often characterised as competing scenarios. However, they are related concepts, both relying on collective geological, ecological, and phylogenetic evidence. This is illustrated by freshwater fishes, which may immigrate to islands either when freshwater connections are temporarily present and later severed (vicariance), or by unusual means when ocean gaps are crossed (long-distance dispersal). Marine barriers have a strong filtering effect on freshwater fishes, limiting immigrants to those most capable of oceanic dispersal. The roles of vicariance and dispersal are debated for freshwater fishes of the Greater Antilles. We
review three active hypotheses [Cretaceous vicariance, Greater Antilles-Aves Ridge (GAARlandia), long-distance dispersal] and propose long-distance dispersal to be an appropriate model due to limited support for freshwater fish use of landspans. Greater Antillean freshwater fishes have six potential source bioregions (defined from faunal similarity): Northern Gulf of México, Western Gulf of México, Maya Terrane, Chortís Block, Eastern Panamá, and Northern South America. Faunas of the Greater Antilles are composed of taxa immigrating from many of these bioregions, but there is strong compositional disharmony between island and mainland fish faunas (>90% of Antillean species are cyprinodontiforms, compared to <10% in Northern Gulf of México and Northern South America, and ≤50% elsewhere), consistent with a hypothesis of long-distance dispersal. Ancestral-area reconstruction analysis indicates there were 16 or 17 immigration events over the last 51 million years, 14 or 15 of these by cyprinodontiforms. Published divergence estimates and evidence available for each immigration event suggests they occurred at different times and by different pathways, possibly with rafts of vegetation discharged from rivers or washed to sea during storms. If so, ocean currents likely provide critical pathways for immigration when flowing from one landmass to another. On the other hand, currents create dispersal barriers when flowing perpendicularly between landmasses. In addition to high salinity tolerance, cyprinodontiforms collectively display a variety of adaptations that could enhance their ability to live with rafts (small body size, viviparity, low metabolism, amphibiousness, diapause, self-fertilisation). These adaptations likely also helped immigrants establish island populations after arrival and to persist long term thereafter. Cichlids may have used a pseudo bridge (Nicaragua Rise) to reach the Greater Antilles. Gars (Lepisosteidae) may have crossed the Straits of Florida to Cuba, a relatively short crossing that is not a barrier to gene flow for several cyprinodontiform immigrants. Indeed, widespread distributions of Quaternary migrants (Cyprinodon, Gambusia, Kryptolebias), within the Greater Antilles and among neighbouring bioregions, imply that long-distance dispersal is not necessarily inhibitory for well-adapted species, even though it appears to be virtually impossible for all other freshwater fishes.