Remarkable genetic homogeneity in Hoplosternum littorale

[bekateen]

Thiago E. Parente, Daniel A. Moreira, Paulo A. Buckup, Paula C. C. de Andrade, Maithê G. P. Magalhães, Carolina Furtado, Marcelo R. Britto, & Adalberto L. Val. 2017. Remarkable genetic homogeneity supports a single widespread species of Hoplosternum littorale (Siluriformes, Callichthyidae) in South America. Conservation Genetics Resources, 2 September 2017, 1–7.
DOI 10.1007/s12686-017-0831-0
https://doi.org/10.1007/s12686-017-0831-0

ABSTRACT

Hoplosternum littorale

is a widespread, non-migratory, air-breathing armored catfish (Callichthyidae, Siluriformes) present in most river drainages of tropical South America. This species has invaded aquatic habitats out of its native range. The distribution and unity of this species is supported by strong morphological evidences, but only few molecular data are available. As for February 2017, 45 partial mitochondrial gene sequences for H. littorale were deposited at the U.S. National Center for Biotechnology Information (NCBI) GenBank. The nearly complete mitochondrial genomes from two individuals of H. littorale sampled in geographically isolated populations were sequenced and compared to the intraspecific divergence encountered in a related species,

Corydoras nattereri

. Tamura-Nei corrected distances between the mitochondrial genomes from the two H. littorale was 0.004, equivalent to the distance found among individuals from the same population of C. nattereri (0.002) and considerably smaller than the distance between C. nattereri and C. schwartzi (0.123). An insertion of 30 nucleotides between the ATPase 6 and the COIII genes was identified in H. littorale. This insertion is homologous to the one previously noted in two species of Corydoras. This work supports H. littorale as a single and widespread species of Callichthyidae catfish. The new genetic resources for H. littorale are now available to support further studies with larger sampling sizes.

• Keywords: Next-generation sequencing, Biodiversity, Distribution, Dispersal, Speciation, Fish, Teleostei, Neotropical region, Mitochondrial genome

[Bas Pels]

Remarkable indeed

Who would have guessed that a species, found all over South America, is a real species indeed? I think anyone would have assumed it is one species for lack of sufficient research.

Well, apparently, sufficient research is now done, and it is still one species. Still, in a few remote areas, the fishes can have changed more

[bekateen]

In every genetic study, unless it's genome based, I often question whether the results would differ if the investigators picked a different set of genes. But since I'm not a geneticist, I trust they've done their homework on this if their paper is peer-reviewed and in a legit journal.

This type of study also really pushes our beliefs about how reliable watersheds are when used to separate similar forms (e.g., aeneus corys, etc.)

Cheers, Eric

[Bas Pels]

With Central American cichlids this is often the case. I myself think that this is the result of much hybridising between species/populations, resulting in new species.

If you take one of mothers genes, the species looks related to a whole other group than if one of fathers genes was searched.

But as far as I know, within catfish this is less a problem.

Still, if you have an A or a T on one gene, which can swap, it is impossible to say there have been 100 or 2 swaps. But this number is, clearly very significant when you talk about relatedness.

I studied Chemistry, once, but oddly enough, I am much easier to convince populations are not the same species by morfometric studies than by a dumb gene counter