4.4 | Population subdivision of Ocyropsis
The high levels of within-species diversity of Ctenophores make theCOI fragment, and possibly mitochondrial sequencing in general, a good marker for population genetics. Mitochondrial sequencing revealed many morphologically cryptic but genetically distinct species. Within Lobata, phylogenetic relationships were better supported and many cryptic species complexes were revealed for those with both sympatric distributions and allopatric isolation (Figure 4b).
The genus Ocyropsis was a good example. Currently,Ocyropsis contains two robustly described species, each with two subspecies based on coloration, including O. crystallina crystallina and O. maculata maculata. These have sympatric distributions and were both described from the Atlantic Ocean (near Europe), but are thought to be distributed worldwide. Two other subspecies were described from the Gulf of Mexico, including O. crystallina guttata which we sequenced one specimen form Florida. TheCOI fragment for specimens of O. maculata maculatasequenced from Florida, Australia, and Tahiti were closely related and all represented one MOTU. In contrast, specimens of O. crystallina crystallina sequenced from Florida, the Gulf of California, and Hawaii, represented three distinct lineages. Unfortunately, specimens from other regions were not available for sequencing. Regardless, theOcyropsis genus represents just one interesting dichotomy where one subspecies such as O. crystallina crystallina may have many genetic and morphological distinctions that lead to many named subspecies, yet O. maculata maculata, a closely related species within the genus has a nearly worldwide distribution (Johnson et al., in prep).