Percorrer por autor "Robalo, J. I."
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- Establishment of a coastal fish in the Azores: recent colonisation or sudden expansion of an ancient relict population?Publication . Stefanni, S.; Castilho, Rita; Sala-Bozano, M.; Robalo, J. I.; Francisco, S. M.; Santos, R. S.; Marques, N.; Brito, A.; Almada, V. C.; Mariani, S.The processes and timescales associated with ocean-wide changes in the distribution of marine species have intrigued biologists since Darwin's earliest insights into biogeography. The Azores, a mid-Atlantic volcanic archipelago located >1000 km off the European continental shelf, offers ideal opportunities to investigate phylogeographic colonisation scenarios. The benthopelagic sparid fish known as the common two-banded seabream (Diplodus vulgaris) is now relatively common along the coastline of the Azores archipelago, but was virtually absent before the 1990s. We employed a multiple genetic marker approach to test whether the successful establishment of the Azorean population derives from a recent colonisation from western continental/island populations or from the demographic explosion of an ancient relict population. Results from nuclear and mtDNA sequences show that all Atlantic and Mediterranean populations belong to the same phylogroup, though microsatellite data indicate significant genetic divergence between the Azorean sample and all other locations, as well as among Macaronesian, western Iberian and Mediterranean regions. The results from Approximate Bayesian Computation indicate that D. vulgaris has likely inhabited the Azores for similar to 40 (95% confidence interval (CI): 5.5-83.6) to 52 (95% CI: 6.32-89.0) generations, corresponding to roughly 80-150 years, suggesting near-contemporary colonisation, followed by a more recent demographic expansion that could have been facilitated by changing climate conditions. Moreover, the lack of previous records of this species over the past century, together with the absence of lineage separation and the presence of relatively few private alleles, do not exclude the possibility of an even more recent colonisation event.
- Facultative cleaning behaviour of juvenile Diplodus sargus (Sparidae) and its ecological role in marine temperate watersPublication . Neto, J.; Vieira, D.; Abecasis, David; Marques, J.; Gordo, L.; Robalo, J. I.; Bispo, R.; Araújo, M.; Almada, F.The diversity and abundance of cleaner species have been frequently associated with ectoparasite load and ecological wealth of tropical fish communities. Cleaning behaviour in temperate regions has received less attention, with few labrid species being described as cleaners. The context and frequency of cleaning behaviour by juvenile white seabream Diplodus sargus are described. Surface observations from pontoons in yachting marinas were carried out based on a method used in a recent first report of cleaning behaviour by this northeastern Atlantic and Mediterranean sparid. A total of 51 h of observations revealed that these juveniles (<10 cm total length [TL]) display similar or higher cleaning rates (13.1 cleaning events per hour) compared to other temperate cleaners. The high cleaning rates, high abundance of young D. sargus on rocky shores along their distribution area and preferential targeting of adults by coastal fisheries highlight the ecological importance of D. sargus. The most common client species include grey mullets (Mugilidae), which represent 93.5% of total cleaning events registered. Regarding TL, clients were 4.6 to 6.6 times larger than cleaners. Environmental factors such as water temperature (14.0-24.0°C), wave exposure (6.0-17.0 s) and wind speed (2.0-8.0 m s-1) influence white seabream cleaning rates. Thus, a combination of factors may affect the health of temperate client fish communities. On a different perspective, these results also highlight the potential of juvenile D. sargus in integrated multitrophic aquaculture. In conclusion, white seabream cleaning behaviour plays an important role in temperate fish communities and its relevance in different habitats should be further assessed.
- Genetic evidence fails to discriminate between Macroramphosus gracilis Lowe 1839 and Macroramphosus scolopax Linnaeus 1758 in Portuguese watersPublication . Robalo, J. I.; Sousa-Santos, C.; Cabral, H.; Castilho, Rita; Almada, V. C.Fish belonging to the genus Macroramphosus are distributed throughout the Atlantic, Indian and PaciWc oceans. Some authors consider this genus monotypic, Macroramphosus scolopax being the only valid species. Other authors consider (based on several morphological and ecological characters) that another species (Macroramphosus gracilis) exists and occurs frequently in sympatry with the Wrst one. Intermediate forms are also reported in literature. In this paper, using the mitochondrial control region and the nuclear Wrst S7 intron markers, we failed to Wnd genetic diVerences between individuals considered to belong to both species as well as the intermediate forms. Our results suggest that in the northeastern Atlantic, Macroramphosus is represented by a single species, M. scolopax, with diVerent morphotypes interbreeding in the sampling areas.
- Unexpected high genetic diversity at the extreme Northern geographic limit of Taurulus bubalis (Euphrasen, 1786)Publication . Almada, V. C.; Almada, Frederico; Francisco, S. M.; Castilho, Rita; Robalo, J. I.The longspined bullhead (Taurulus bubalis, Euphrasen 1786) belongs to the family Cottidae and is a rocky shore species that inhabits the intertidal zones of the Eastern Atlantic since Iceland, southward to Portugal and also the North Sea and Baltic, northward to the Gulf of Finland, with some occurrences in the northern Mediterranean coasts eastward to the Gulf of Genoa. We analysed the phylogeographic patterns of this species using mitochondrial and nuclear markers in populations throughout most of its distributional range in west Europe. We found that T. bubalis has a relatively shallow genealogy with some differentiation between Atlantic and North Sea. Genetic diversity was homogeneous across all populations studied. The possibility of a glacial refugium near the North Sea is discussed. In many, but not all, marine temperate organisms, patterns of diversity are similar across the species range. If this phenomenon proves to be most common in cold adapted species, it may reflect the availability of glacial refugia not far from their present-day northern limits.