Lake Erie Center

Systematics of the Neogobiin Gobies

The primary focus of this project is to elucidate and reconstruct the evolutionary history and phylogenetic relationships of the "neogobiin" gobies.  The "neogobiins" are small (10-30 cm total length) benthic fishes that are members of the teleost family Gobiidae, one of the largest fish families with ~1950 species in 210 genera that are found in freshwater, brackish, and marine systems worldwide.  Gobies include some of the smallest and lightest vertebrates in the world (Pandaka pygmaea, Schindleria brevipinguis, and Trimmatom nanus are all sexually mature at <10mm), as well as species that scale waterfalls 10,000X their body length during migration between juvenile and adult habitats (Hawaiian amphidromous gobies).  The lack of understanding of goby biology and ecology, as well as the high degree of morphological reduction within the group, has presented a major problem in describing the phylogenetic relationships within and among goby groups. 

The "neogobiin" gobies, as well as other Ponto-Caspian gobiids, are an especially understudied group within the Gobiidae.  The "neogobiins" are a small species flock containing ~20 broadly euryhaline species inhabiting freshwater, brackish, and marine habitats within the Ponto-Caspian basin.  In addition, the "neogobiins" are a major component of the Ponto-Caspian fish fauna that has been introduced outside of its native range into central and western Europe and the North American Laurentian Great Lakes.  The geologic history of the Ponto-Caspian basin is marked by large fluctuations in salinity corresponding to glacial cycles and an intermittent connection with the world ocean, which is evident today in the broad salinity tolerances exhibited by many Ponto-Caspian taxa.  This increased euryhalinity has likely augmented the invasion success of many introduced Ponto-Caspian species, including the neogobiins.

Despite their prominent position in the invasive Ponto-Caspian fish fauna, little is known about the systematics of the "neogobiin gobies". Detailed studies of the morphology, osteology, and systematics of the group have only recently (~20 years) been undertaken, but have yet to present a clear picture of neogobiin systematics. Several studies have questioned the validity of the various neogobiin genera, and the placement of the neogobiins as a whole within the larger framework of goby systematics has not been resolved. In addition, few studies have investigated multiple neogobiin species simultaneously or utilized a molecular approach to neogobiin systematics.

This project utilizes both DNA sequence data as well as morphological data to infer the phylogenetic relationships among the neogobiin species and other Ponto-Caspian and Mediterranean gobiid outgroups. To date, we have sequenced ~1200 base pairs from each of two mitochondrial (cyt b and COI) and two nuclear (RAG1 and ribosomal S7 protein intron 1) gene from 19 of the ~20 species of neogobiin gobies as well as 11 outgroup species. Our current phylogenetic hypothesis is seen in the tree below, with several interesting features. First is the finding that Neogobius, sensu Miller (2003), is paraphyletic. As the type species for the genus Neogobius is N. fluviatilis, this generic name must be restricted to the clade containing N. fluviatilis as well as two additional species: N. melanostomus and N. caspius. The former subgenera Babka (N. gymnotrachelus) and Ponticola (all remaining species formerly in Neogobius) are thus elevated to generic level. In addition, N. caspius has not been grouped with N. fluviatilis or N. melanostomus by other authors, although some prior morhological similarites have been discussed. Additional research in our laboratory on the population genetics of N. fluviatilis and N. melanostomus has revealed that these taxa likely include separate species/sub-species in both the Black and Caspian Sea basins, and indicates that a taxonomic revision for these taxa is warranted as well. Finally, these molecular data also show that the "neogobiins" and benthophilines (another Ponto-Caspian endemic gobiid species flock, containing the genera Anatirostrum, Benthophilus, Benthophiloides, and Caspiosoma) do share a common ancestor and together are highly divergent from other gobiid groups, which has been suggested by other authors but not evaluated with any phylogenetic study to date. We have resurrected and redescribed the subfamily Benthophilinae Beling and Iljin (1927) to comprise these endemic Ponto-Caspian goby species flocks.

Sampling site map

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Figure 1. Current range (excluding introduced range in North America) of nominal species of the subfamily Benthophilinae (hatched area; based on Miller, 2003), and locations of taxa sampled in the present study. K-M = Kumo-Manych Depression.

Fig 2 NS 2009

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Figure 2. Maximum likelihood phylogeny (PhyML; Guindon and Gascuel, 2003) of the subfamily Benthophilinae and outgroups based on combined analysis of four gene regions. Numbers at nodes indicate likelihood bootstrap support (2000 pseudoreplications), with * = 100%.

NS2009 Fig3

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Figure 3. Chronogram for the subfamily Benthophilinae and related Ponto-Caspian gobies, derived from a penalized likelihood analysis of divergence time (r8s; Sanderson, 2003) and maximum likelihood analysis of the extended cyt b dataset. Nodes with fixed ages in divergence time analysis are lettered; numbers at nodes indicate support values from phylogenetic analyses of the extended cyt b dataset (likelihood bootstrap).

NS2009 Fig4

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Figure 4. Maximum likelihood phylogeny of the goby subfamily Benthophilinae and other gobioids based on COI sequence data from the present study and from Thacker (2003). Numbers above branches indicate likelihood bootstrap support. In clades spanning multiple families/subfamilies, symbols adjacent to species names indicate familial/subfamilial membership. Pertinent clade described in Thacker (2003) is labeled (IIB).


Neilson, M.E. and C. A. Stepien.  2009. Escape from the Ponto-Caspian: Evolution and biogeography of an endemic goby species flock (Benthophilinae: Gobiidae: Teleostei). Molecular Phylogenetics and Evolution, 52:84-102


Matt Neilson

Last Updated: 3/22/15