Eduardo F. Balart

Molecular phylogeny of grunts (Teleostei, Haemulidae), with an emphasis on the ecology, evolution, and speciation history of New World species

BackgroundThe fish family Haemulidae is divided in two subfamilies, Haemulinae and Plectorhynchinae (sweetlips), including approximately 17 genera and 145 species. The family has a broad geographic distribution that encompasses contrasting ecological habitats resulting in a unique potential for evolutionary hypotheses testing. In the present work we have examined the phylogenetic relationships of the family using selected representatives of additional Percomorpha based on Bayesian and Maximum likelihood methods by means of three mitochondrial genes. We also developed a phylogenetic hypothesis of the New World species based on five molecular markers (three mitochondrial and two nuclear) as a framework to evaluate the evolutionary history, the ecological diversification and speciation patterns of this group.ResultsMitochondrial genes and different reconstruction methods consistently recovered a monophyletic Haemulidae with the Sillaginidae as its sister clade (although with low support values). Previous studies proposed different relationships that were not recovered in this analysis. We also present a robust molecular phylogeny of Haemulinae based on the combined data of two nuclear and three mitochondrial genes. All topologies support the monophyly of both sub-families (Haemulinae, Plectorhinchinae). The genus Pomadasys was shown to be polyphyletic and Haemulon, Anisotremus, and Plectorhinchus were found to be paraphyletic. Four of seven presumed geminate pairs were indeed found to be sister species, however our data did not support a contemporaneous divergence. Analyses also revealed that differential use of habitat might have played an important role in the speciation dynamics of this group of fishes, in particular among New World species where extensive sample coverage was available.ConclusionsThis study provides a new hypothesis for the sister clade of Hamulidae and a robust phylogeny of the latter. The presence of para- and polyphyletic genera underscores the need for a taxonomic reassessment within the family. A scarce sampling of the Old World Pomadasys species prevents us to definitively point to a New World origin of the sub-familiy Hamulinae, however our data suggest that this is likely to be the case. This study also illustrates how life history habitat influences speciation and evolutionary trajectories.

Switch between Morphospecies of Pocillopora Corals

Pocillopora corals are the main reef builders in the eastern tropical Pacific. The validity of Pocillopora morphospecies remains under debate because of disagreements between morphological and genetic data. To evaluate the temporal stability of morphospecies in situ, we monitored the shapes of individual colonies in three communities in the southern Gulf of California for 44 months. Twenty-three percent of tagged colonies of Pocillopora damicornis changed to Pocillopora inflata morphology during this time. This switch in identity coincided with a shift to a higher frequency of storms and lower water turbidity (i.e., lower chlorophyll a levels). Seven months after the switch, P. inflata colonies were recovering their original P. damicornis morphology. All colonies of both morphospecies shared a common mitochondrial identity, but most P. damicornis colonies undergoing change were at a site with low-flow conditions. This is the first in situ study to document switching between described morphospecies, and it elucidates the influence of temporal shifts in environmental conditions on morphologically plastic responses.

Morphological variation and different branch modularity across contrasting flow conditions in dominant Pocillopora reef-building corals

Pocillopora corals, the dominant reef-builders in the Eastern Tropical Pacific, exhibit a high level of phenotypic plasticity, making the interpretation of morphological variation and the identification of species challenging. To test the hypothesis that different coral morphospecies represent phenotypes that develop in different flow conditions, we compared branch characters in three Pocillopora morphospecies (P.damicornis, P. verrucosa, and P. meandrina) from two communities in the Gulf of California exposed to contrasting flow conditions. Morphological variation and branch modularity (i.e., the tendency of different sets of branch traits to vary in a coordinated way) were assessed in colonies classified as Pocillopora type 1 according to two mitochondrial regions. Our results can be summarized as follows. (1) Pocillopora type 1 morphospecies corresponded to a pattern of morphological variation in the Gulf of California. Overall, P.damicornis had the thinnest branches and its colonies the highest branch density, followed by P.verrucosa, and then by P.meandrina, which had the thickest branches and its colonies the lowest branch density. (2) The differentiation among morphospecies was promoted by different levels of modularity of traits. P.verrucosa had the highest coordination of traits, followed by P.damicornis, and P.meandrina. (3) The variation and modularity of branch traits were related to water flow condition. Morphology under the high-flow condition was more similar among morphospecies than under the low-flow condition and seemed to be related to mechanisms for coping with these conditions. Our results provide the first evidence that in scleractinian corals different levels of modularity can be promoted by different environmental conditions.

Diversification of the pectoral fin shape in damselfishes (Perciformes, Pomacentridae) of the Eastern Pacific

Fin shape strongly influences performance of locomotion across all swimming styles. In this study, we focused on the diversity of the pectoral fin morphology in damselfishes of the Eastern Pacific. Underwater observations and a review of literature allowed the characterization of ten behavioral groups. Territorial and non-territorial species were discriminated easily with traditional morphometrics. Five ecomorphological groups were recognized by geometric morphometric analyses. Geometric data segregated the outgroup from the damselfishes and allowed the distinction of mean morphologies from extreme ones within territorial and non-territorial species. Additionally, geometric morphometric data split Abudefduf into two groups: (1) A. troschelii is similar to C. atrilobata and (2) A. concolor and A. declivifrons are close to Stegastes. Solitary territorial species (e.g., Stegastes) show rounded and high fins whereas non-territorial species living in groups (e.g., Chromis) present long and curved pectoral fins. In the range of morphological variation, the morphologies of Microspathodon (elongate with highly curved hydrodynamic trailing edge) and Azurina (long, slender and angular) represent the extreme morphologies within territorial and non-territorial species, respectively. Our study revealed a strong relationship between the pectoral fin shape and the behavioral diversification in damselfishes.

The cerato-mandibular ligament: a key functional trait for grazing in damselfishes (Pomacentridae)

IntroductionThe success of a taxonomic group can be promoted by a key character that allows the group to interact with its environment in a different way and to potentially occupy new niches. The Pomacentridae possess a synapomorphic trait, the cerato-mandibular (c-md) ligament, which joins the hyoid bar to the inner part of the lower jaw. It has previously been shown that this ligament is a key trait in communication in damselfishes because it enables them to slam the oral jaws shut causing teeth collision and sound production. This specific behavior of mouth closing could, however, also be used for other tasks, such as feeding. Many territorial damselfishes are referred to as farmers, due to their ability to manage algal crops on which they feed. This study hypothesizes that the c-md ligament provides an advantage for grazing filamentous algae, and should thus be considered a key trait for farming behavior.ResultsThe kinematic patterns associated with sound production and biting filamentous algae or attached animal prey are all based on the same mechanism and are associated with a slam of the oral jaws. We observed that transection of the c-md ligaments makes the fish unable to perform such actions. We also counted biting rates on filamentous algae in fish with and without the c-md ligament and observed a drop of more than 80% in the latter.ConclusionThis study shows that the c-md ligament is a key trait both for sound production and for grazing activities in damselfishes. The buccal jaw slam enables the fish to perform accurate strikes on small filamentous algae. This kind of bite probably plays a major role in farming activity and allows grazing damselfishes to occupy distinct niches, possibly increasing their competitive evolutionary success.

Clarifying the taxonomic status of Merluccius spp. in the northeastern Pacific: a combined morphological and molecular approach

The taxonomic status of hake (Merluccius spp.) in the northeastern Pacific is unclear. Hakes in this region are Merluccius productus, M. angustimanus, M. hernandezi, and a morphotype known as dwarf hake. Of these, only the first two species are currently valid. Descriptions in previous studies have been limited by overlapping morphological characteristic, lack of biological material, and limited numbers of sampling localities. To clarify their taxonomy, 461 hake were obtained from eight localities along the North American coast for morphological and mitochondrial DNA sequence analyses (cytochrome b, cytochrome c oxidase subunit I, and 16S ribosomal rDNA). Morphological and molecular analyses suggest that hake in this region represent a continuum of a single species with some levels of morphological and genetic intra-specific variation. In light of these results, we propose that M. productus is the only species of hake present along the North American and northern Central American coast.

Annotated checklist of marine fishes from the Sanctuary of Bahía Chamela, Mexico with occurrence and biogeographic data

Abstract An annotated checklist of marine fishes of the Sanctuary of Islands and Islets of Bahía Chamela in the central Mexican Pacific is presented. Records of fish species were obtained by different methods including visual census, sampling with anesthetics, fisherman-nets, and trawling with a biological dredge. Additional records were obtained from natural history collections and publications. The list comprises 196 species in 64 families and 141 genera. The Carangidae is the most speciose family with 11 species, followed by the Labridae with 10 and the Pomacentridae with nine. Fourteen species are endemic in Mexican Pacific waters, but none is restricted to Bahía Chamela. The most dominant species recorded during underwater surveys were Epinephelus labriformis, Stegastes flavilatus, and Halichoeres dispilus. Most species are of tropical affinities distributed throughout the tropical eastern Pacific (123), eastern Pacific (23), and Mexican Pacific (14). Other species are known from the eastern and Indo-Pacific regions (18), eastern Pacific and western Atlantic oceans (2), and some are circumtropical (9). A new record of the Gulf Brotula Ogilbia ventralis is provided for the Bahía Chamela and its geographical distribution is extended to Mexican central Pacific.

The complete mitochondrial DNA of endemic Eastern Pacific coral (Porites panamensis)

Abstract The mitogenome of the endemic coral Porites panamensis (Genbank accession number KJ546638) has a total length of 18,628 bp, and the arrangement consist of 13 protein-coding genes, 2 ribosomal RNA (rRNA) genes and 2 transfer RNA (tRNA) genes. Gene order was equal to other scleractinian coral mitogenomes.

On the first record of a potentially harmful fish, Sparus aurata in the Gulf of California

The record of free and healthy Mediterranean gilt-head seabream Sparus aurata Linnaeus, 1758 in waters of the Gulf of California, México is documented for the first time. Consequences of this introduction are briefly outlined.

Comparison of ecological diversity and species composition of macroalgae, benthic macroinvertebrates, and fish assemblages between two tropical rocky reefs

En el medio marino, las costas rocosas son reconocidas por su alta diversidad de especies y particularmente las zonas de transicion representan areas de mezcla biotica, provocado por las variaciones naturales historicas y ecologicas que permiten la presencia de taxones de diferentes regiones y que presentan rasgos biologicos diferentes. Un estudio intensivo permitio describir los ensambles de macroalgas, macroinvertebrados (moluscos, crustaceos y equinodermos) y de peces en dos arrecifes rocosos: Islas Marietas y Tehuamixtle, en la zona de transicion tropical-templado en el norte del Pacifico de Mexico, utilizando indices ecologicos tradicionales (riqueza, diversidad y uniformidad) y complementando con indices de distincion taxonomica. Se colecto el material biologico de 10 cuadrantes (25 × 25 cm) ubicados aleatoriamente a lo largo de dos transectos de 50 m paralelos a la linea de costa, a una profundidad de entre 6 y 12 m. Se identificaron 204 especies: 22 macroalgas, 55 moluscos, 78 crustaceos, 11 equinodermos y 38 peces. La estructura de la comunidad de macroalgas, macroinvertebrados y peces fue similar entre los sitios. Macroalgas, moluscos y peces fueron mas diversos en verano y crustaceos y equinodermos fueron mas diversos en el invierno. Los resultados y la literatura sugieren un patron latitudinal de menores cambios estacionales en equinodermos y crustaceos en las altas respecto a bajas latitudes en el Pacifico mexicano.