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Thacker C.E.,Vertebrates Ichthyology | Roje D.M.,Vertebrates Ichthyology | Roje D.M.,American Museum of Natural History
Systematics and Biodiversity | Year: 2011

The teleost family Gobiidae includes at least 1120 described species of fishes, distributed worldwide in both tropical and temperate habitats. The majority of gobies inhabit marine environments, in particular Old World coral reefs. However, a radiation of gobiids inhabits the rivers and near-shore habitats of Europe and Asia, and a variety of genera are also found in the seas of the New World. This study builds on previous work in which gobiids were placed among their gobioid relatives by adding additional taxa as well as additional markers, providing a much more comprehensive portrait of gobiid intrarelationships and including all major lineages of gobies. We used DNA sequences from both mitochondrial (ND1, ND2, COI) and nuclear (RAG2, Rhodopsin, RNF213) genes to infer phylogeny among 127 representatives of 100 species of gobies, using two gobionellid species as outgroups. We delineated 13 lineages within Gobiidae, including one clade of shrimp-associated gobies represented by the genera Cryptocentrus, Mahidolia and Stonogobiops and a second separate shrimp-associated goby clade including Amblyeleotris, Ctenogobiops and Vanderhorstia. The Mediterranean, Ponto-Caspian and Eastern Atlantic gobies are resolved in a clade along with two genera known from the Western Indian Ocean. Invasion of the New World is shown to have occurred multiple times among the sampled taxa, in the American seven-spined gobies, the Coryphopterus, Lophogobius and Rhinogobiops radiation (sister to Fusigobius) and separately in the wormfishes Cerdale and Microdesmus, resolved in a clade alongside the Indo-Pacific Gunnellichthys, Ptereleotris and Nemateleotris. The cosmopolitan genera Bathygobius and Priolepis represent further separate radiations, and Lythrypnus shows complex relationships with both Priolepis and Trimma. © 2011 The Natural History Museum.

Thompson A.R.,National Oceanic and Atmospheric Administration | Adam T.C.,University of California at Santa Barbara | Hultgren K.M.,Smithsonian Institution | Hultgren K.M.,Seattle University | Thacker C.E.,Vertebrates Ichthyology
American Naturalist | Year: 2013

Elucidating patterns and causes of interaction among mutualistic species is a major focus of ecology, and recent meta-analyses of terrestrial networks show that network-level reciprocal specialization tends to be higher in intimate mutualisms than in nonintimate mutualisms. It is largely unknown, however, whether this pattern holds for and what factors affect specialization in marine mutualisms. Here we present the first analysis of network specialization ('H2) for marine mu-tualistic networks. Specialization among eight Indo-Pacific networks of obligate mutualistic gobies and shrimps was indistinguishable from that among comparably intimate terrestrial mutualisms (ants-myrmecophytes) and higher than that among nonintimate ones (seed dispersers). Specialization was affected by variability in habitat use for both gobies and shrimps and by phylogenetic history for shrimps. Habitat use was phylogenetically conserved among shrimp, and thus effects of shrimp phylogeny on partner choice were mediated in part by habitat. By contrast, habitat use and pairing patterns in gobies were not related to phylogenetic history. This asymmetry appears to result fromevolutionary constraints on partner use in shrimps and convergence among distantly related gobies to utilize burrows provided by multiple shrimp species. Results indicate that the evolution of mutualism is affected by life-history characteristics that transcend environments and that different factors constrain interactions in disparate ecosystems. © 2013 by The University of Chicago.

Thacker C.E.,Vertebrates Ichthyology | Thompson A.R.,Vertebrates Ichthyology | Thompson A.R.,Southwest Fisheries Science Center | Adam T.C.,University of California at Santa Barbara | Chen J.-P.,Taiwan Ocean Research Institute
Ichthyological Research | Year: 2010

Ctenogobiops is a genus of Indo-Pacific gobies that form obligate, mutualistic associations with shrimp in the genus Alpheus. This study provides a molecular phylogenetic analysis of eight Ctenogobiops species: C. aurocingulus, C. crocineus, C. feroculus, C. formosa, C. maculosus, C. mitodes, C. tangaroai, and C. tongaensis. We recover two clades within the genus, one consisting of C. feroculus and C. aurocingulus, the second including the remaining species arrayed as follows: (C. tongaensis (C. mitodes (C. formosa (C. maculosus (C. crocineus, C. tangaroai))))). Recovery of C. maculosus and C. crocineus as distinct taxa suggests that these species are not synonymous, although sampling in this study is limited. Species of Ctenogobiops are morphologically very similar to each other, with generally consistent meristic character states present throughout the genus. Recognition of species is based primarily on slight variations in color pattern, shape of the dorsal fin, and size of the gill opening. Comparison of our specimens of C. mitodes with accounts of C. pomastictus confirms that color pattern variations and lateral scale counts are more reliable indicators of species identity than relative dorsal fin spine length, particularly for smaller specimens. We evaluate the distribution of morphological characters in the context of the new phylogenetic hypothesis, and provide a summary of distinguishing characters for Ctenogobiops species. In this case, as in other instances of diverse reef-dwelling fish taxa, molecular data are ideal for inferring phylogenetic relationships, whereas morphological data remain the most expedient way to identify species. © 2010 The Ichthyological Society of Japan.

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