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Divergent sympatric lineages of the A tlantic and I ndian O cean crinoid T ropiometra carinata
Author(s) -
Torrence Kathleen G.,
Correia Monica D.,
Hoffman Eric A.
Publication year - 2012
Publication title -
invertebrate biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.486
H-Index - 42
eISSN - 1744-7410
pISSN - 1077-8306
DOI - 10.1111/j.1744-7410.2012.00275.x
Subject(s) - biology , sympatric speciation , sympatry , phylogenetic tree , evolutionary biology , phylogeography , biological dispersal , reproductive isolation , species complex , ecology , zoology , gene , genetics , population , demography , sociology
The shallow water comatulid crinoid T ropiometra carinata is native to both the A tlantic and I ndian O ceans, a distribution anomalous among shallow water crinoids and many other broadcast spawning species. Given this species' short pelagic larval duration, the findings of previous work that suggest that the B enguela upwelling is a significant barrier to gene flow in broadcast spawning species, and T . carinata 's unexpected geographic distribution, we predicted that the crinoids presently recognized as T . carinata consisted of a species complex. To test this prediction, we sequenced a portion of the mitochondrial cytochrome oxidase 1 gene from 30 individuals of T . carinata collected from B razil, the M ozambique C hannel, M adagascar, and R eunion I sland. We found that nucleotide divergence ranged 0.02–3.10% among haplotypes. Moreover, while a B ayesian phylogenetic tree indicated that there were two substantially divergent genetic lineages, there was no evidence to support that T . carinata is comprised of a species complex due to isolation‐by‐distance. Surprisingly, both lineages were found in sympatry in both the A tlantic and I ndian O ceans. Likewise, a 95% parsimony haplotype network revealed that identical haplotypes are found in both oceans, suggesting that a species complex may indeed exist, just not one caused by geographic isolation. We discuss possible explanations for this unexpected genetic structure, such as natural dispersal or human‐mediated movement, and how the genetic structure found here is relevant to other marine organisms and to cryptic speciation.