Thurman C L, Alber R E, Hopkins M J, Shih Hsi-Te
Department of Biology, University of Northern Iowa, 1227 West 27th St., Cedar Falls, IA 50614-0421, USA. E-mail:
Division of Paleontology, American Museum of Natural History, Central Park West at 79th Street, New York, NY 10024-5192, USA. E-mail:
Zool Stud. 2021 Apr 29;60:e19. doi: 10.6620/ZS.2021.60-19. eCollection 2021.
For this study, in addition to museum vouchers, 1437 specimens of (Holthuis, 1967) were collected from crab colonies at 105 locations in the western Atlantic Ocean to examine diversity in a species with a large geographic range. Both allometric and geometric morphometry were coupled with the molecular analysis of DNA to give a broader perspective of intraspecific variability in this species. A total of 1153 specimens from the Caribbean Sea and the Atlantic coast of South America demonstrated that from both regions are very similar in their pattern of growth. The average carapace width (CW) for Caribbean is larger than the average for South American males and females. However, size distribution based on CW is unimodal in Caribbean and bimodal in South American populations. The carapace length-width ratio is about 0.68 in females and 0.66 in males. South American males express asymmetric elongation of the cheliped in smaller CW intervals than Caribbean males. In a sample of 259 females, carapace shape is distinct between South American and Caribbean populations. Caribbean populations have less swelling in the branchial regions than South American populations. The swelling correlates primarily with geographic region and to a lesser degree with substrate and salinity. Molecular data from the 16S rDNA and cytochrome oxidase subunit I () reveal three clades within . Two clades are distributed in the Caribbean and the third in eastern South America. The timing of divergence between Caribbean and South American clades is coincident with an increased rate of water and sediment outflow from the Amazon as inferred from the geologic record. Current patterns and associated gene flow within the Caribbean were subsequently influenced by the closing of the Isthmus of Panama. We speculate that various populations may employ different larval dispersion mechanisms resulting in genetic heterogeneity. Consequently, there is considerable biological divergence among populations of in the Caribbean and South America.
在本研究中，除了博物馆标本外，还从西大西洋105个地点的蟹群中采集了1437份（霍尔特休斯，1967年）标本，以研究一个地理分布范围广的物种的多样性。将异速生长和几何形态测量与DNA分子分析相结合，以便更全面地了解该物种的种内变异性。来自加勒比海和南美洲大西洋海岸的1153份标本表明，来自这两个地区的在生长模式上非常相似。加勒比地区的平均头胸甲宽度（CW）大于南美洲雄性和雌性的平均宽度。然而，基于CW的大小分布在加勒比地区是单峰的，而在南美洲种群中是双峰的。雌性的头胸甲长宽比约为0.68，雄性为0.66。南美洲雄性在比加勒比地区雄性更小的CW区间内表现出螯足的不对称伸长。在259只雌性样本中，南美洲和加勒比地区种群的头胸甲形状明显不同。加勒比地区种群鳃区的肿胀程度低于南美洲种群。这种肿胀主要与地理区域相关，在较小程度上与底物和盐度有关。来自16S rDNA和细胞色素氧化酶亚基I（）的分子数据揭示了内的三个进化枝。两个进化枝分布在加勒比地区，第三个分布在南美洲东部。从地质记录推断，加勒比地区和南美洲进化枝之间的分歧时间与亚马逊河的水和沉积物流出速率增加相吻合。巴拿马地峡的关闭随后影响了加勒比地区内的当前模式和相关的基因流动。我们推测，不同种群可能采用不同的幼体扩散机制，从而导致遗传异质性。因此，加勒比地区和南美洲的种群之间存在相当大的生物学差异。
