Browsing by Author "Brito, Alberto"
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- Establishment of a coastal fish in the Azores : Recent colonisation or sudden expansion of an ancient relict population?Publication . Stefanni, Sergio; Castilho, Rita; Sala-Bozano, Maria; Robalo, Joana Isabel; Francisco, Sara Martins; Santos, Ricardo Serrão; Marques, N.; Brito, Alberto; Almada, Vítor Carvalho; Mariani, StefanoThe 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 ∼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.
- Genetic divergence in the Atlantic-Mediterranean Montagu's blenny Coryphoblennius galerita revealed by molecular and morphological charactersPublication . Domingues, Vera dos Santos; Faria, Cláudia Barreiros Macedo de; Stefanni, Sergio; Santos, Ricardo Serrão; Brito, Alberto; Almada, Vítor CarvalhoCoryphoblennius galerita is a small intertidal fish with a wide distribution and limited dispersal ability, occurring in the northeastern Atlantic and Mediterranean. In this study, we examined Atlantic and Mediterranean populations of C. galerita to assess levels of genetic divergence across populations and to elucidate historical and contemporary factors underlying the distribution of the genetic variability. We analyse three mitochondrial and one nuclear marker and 18 morphological measurements. The combined dataset clearly supports the existence of two groups of C. galerita : one in the Mediterranean and another in the northeastern Atlantic. The latter group is subdivided in two subgroups: Azores and the remaining northeastern Atlantic locations. Divergence between the Atlantic and the Mediterranean can be the result of historical isolation between the populations of the two basins during the Pleistocene glaciations. Present-day barriers such as the Gibraltar Strait or the ‘Almeria-Oran jet’ are also suggested as responsible for this isolation. Our results show no signs of local extinctions during the Pleistocene glaciations, namely at the Azores, and contrast with the biogeographical pattern that has been observed for Atlantic– Mediterranean warm-water species, in which two groups of populations exist, one including the Mediterranean and the Atlantic coast of western Europe, and another encompassing the western tropical coast of Africa and the Atlantic islands of the Azores, Madeira and Canaries. Species like C. galerita that tolerate cooler waters, may have persisted during the Pleistocene glaciations in moderately affected locations, thus being able to accumulate genetic differences in the more isolated locations such as the Azores and the Mediterranean. This study is one of the first to combine morphological and molecular markers (mitochondrial and nuclear) with variable rates of molecular evolution to the study of the relationships of the Atlantic and Mediterranean populations of a cool-water species.
- Historical population dynamics and demography of the eastern Atlantic pomacentrid Chromis limbata (Valenciennes, 1833)Publication . Domingues, Vera dos Santos; Santos, Ricardo Serrão; Brito, Alberto; Almada, Vítor CarvalhoRecent studies have focused on the relationship between the marine fauna of the eastern Atlantic and the Mediterranean Sea, but within the Atlantic, little is known about genetic relationships between populations of the Macaronesian islands. In this study, we tested whether the paleo-climatology and paleo-oceanography of the region could predict the genetic relationships among three eastern Atlantic populations (Azores, Madeira, and Canaries) of a damselWsh, Chromis limbata, and compared our results with its Mediterranean and adjacent Atlantic sister species, Chromis chromis. We combined phylogeographic and coalescent approaches using the fast evolving mitochondrial control region gene. No population structure was found for the three archipelagos. The coalescence time estimated for C. limbata (0.857–1.17Mya) was much greater than that estimated for C. chromis. We propose that this diVerence reXects diVerences in glaciating extents in the Northeastern Atlantic and the Mediterranean. Diversity indexes (Hd and genetic distances) together with historical demographic parameters of C. limbata ( and g) revealed a more stable population history when compared to C. chromis. Our results suggest that the Macaronesian populations of C. limbata have probably been less aVected by the last glaciation than the Mediterranean populations of C. chromis. Migration across the three archipelagos was estimated and a prevailing northwest trend was detected. This result supports the idea of a colonization of the Azores by warm water Wsh from Madeira or the westernmost Canary islands which acted as major glacial refugia for the tropical and subtropical marine fauna during the glaciations.
- Mitochondrial and nuclear markers reveal isolation by distance and effects of Pleistocene glaciations in the northeastern Atlantic and Mediterranean populations of the white seabream (Diplodus sargus, L.)Publication . Domingues, Vera dos Santos; Santos, Ricardo Serrão; Brito, Alberto; Alexandrou, Markos; Almada, Vítor CarvalhoPhylogeography of Diplodus sargus from the northeastern Atlantic and the Mediterranean was assessed using sequences from the mitochondrial control region and the first intron of the S7 ribosomal protein gene. The relationship between genetic and geographic distances supported an isolation by distance model, with the Azores having a peripheral position. The geographic distribution of the genetic diversity, together with the historical demography of the populations studied can be explained by the effect of the Pleistocene glaciations in the northeastern Atlantic warm water fauna. D. sargus might have disappeared from western Europe during glacial peaks and suffered considerable demographic reductions in the Canaries and Mauritania, surviving in less affected areas such as Madeira, Azores and the Mediterranean. The mismatch analysis and the Fu's Fs values provide clear evidence of expansion in western Iberia (S. Pedro), Canaries, Mauritania and also in the eastern Mediterranean. Atlantic and Mediterranean populations of D. sargus showed no signs of genetic differentiation. D. sargus are active swimmers that can undergo extensive movements along the shores. This and the presence of planktonic eggs and larvae would allow rapid mixing between Mediterranean and Atlantic fish, erasing signs of population differentiation.
- Molecular validation of the specific status of Parablennius sanguinolentus and Parablennius parvicornis (Pisces: Blenniidae)Publication . Almada, Frederico José Oliveira de; Almada, Vítor Carvalho; Domingues, Vera dos Santos; Brito, Alberto; Santos, Ricardo SerrãoParablennius sanguinolentus and P. parvicornis have been classified as either two distinct species or as two sub-species depending on the different criteria used to classify them. An analysis of fragments of mitochondrial 12S and 16S rDNA showed that the genetic distance between samples of P. sanguinolentus and P. parvicornis is similar or higher than those found for other blenniids that are widely recognized as distinct species. These results, together with the distinct geographical distributions and meristic differences, support the conclusion that P. sanguinolentus and P. parvicornis should be considered as two different species.
- On the phylogenetic affinities of Centrolabrus trutta and Centrolabrus caeruleus (Perciformes: Labridae) to the genus Symphodus: Molecular, meristic and behavioural evidencesPublication . Almada, Vitor; Almada, Frederico José Oliveira de; Henriques, Miguel; Santos, Ricardo Serrão; Brito, AlbertoPhylogenetic analysis of partial 12S and 16S mitochondrial rDNA regions, together with meristic and ethological data, has revealed that Centrolabrus trutta (Lowe, 1833), a species occurring in the Canaries and Madeira, and its close relative Centrolabrus caeruleus (Azevedo, 1999) from the Azores, are more closely related to most species of the genus Symphodus than to Centrolabrus exoletus (Linnaeus, 1758). Underwater behavioural observations showed that C. trutta, like C. caeruleus, shares with most Symphodus species sexual dichromatism, male nest building and male parental care of the eggs, traits that are absent in C. exoletus. The low number of base substitutions found between C. trutta and C. caeruleus indicates that these species are very closely related. The 16S rDNA data suggest that C. trutta, C. caeruleus and S. roissali form a monophyletic group. The analysis of the 16S rDNA data also showed that S. melanocercus is the sister species of C. exoletus and it is not closely related to the species of Symphodus included in this study. Lack of nest building and parental behaviour in S. melanocercus, and its marked divergence to other members of the genus Symphodus in meristic characters, also stress its affinity with C. exoletus and its separation from the remaining species of Symphodus. Our data and the evidence available in the literature led us to propose the inclusion of C. trutta and C. caeruleus in the genus Symphodus, while S. melanocercus must be transferred to the genus Centrolabrus.
- Phylogenetic relationships of Gymnothorax bacalladoi Böhlke and Brito (1987) a poorly known moray of the Macaronesian islandsPublication . Almada, Vítor Carvalho; Pérez-Portela, Rocío; Robalo, Joana Isabel; Brito, AlbertoInexistente
- Phylogenetic relationships of the North-eastern Atlantic and Mediterranean forms of Atherina (Pisces, Atherinidae)Publication . Francisco, Sara Martins; Congiu, Leonardo; Stefanni, Sergio; Castilho, Rita; Brito, Alberto; Ivanova, P. P.; Levy, André; Cabral, Henrique; Kilias, Georgio; Doadrio, Ignacio; Almada, Vítor CarvalhoInexistente
- Phylogeography and demographic history of Atherina presbyter (Pisces: Atherinidae) in the North-eastern Atlantic based on mitochondrial DNAPublication . Francisco, Sara Martins; Castilho, Rita; Soares, Miguel; Congiu, Leonardo; Brito, Alberto; Vieira, Maria Natividade; Almada, Vítor CarvalhoA fragment of the mitochondrial control region was used to assess phylogeographic patterns and historical demography of the sand-smelt Atherina presbyter in the North-eastern Atlantic, covering its geographical range. A striking result is the highly marked diVerentiation between the Canary Islands population and western European ones. A genetic structure among European populations of A. presbyter was revealed, with a pattern of isolation-by-distance or a gradient eVect at a scale of hundreds kilometres, an uncommon pattern likely related to the biological and life-history traits of the sand-smelt. The northern European populations present a much lower genetic diversity when compared to southern populations, which is consistent with a recent colonization from southern populations. The results showed signs of Pleistocene signatures, with the population age estimates for the European populations being clearly older than the Last Glacial Maximum (18,000 years bp). Nevertheless, paleotemperature reconstructions show that the sand-smelt could not have inhabited the western European shores during the last glacial phase.
- Phylogeography and demography of the Blenniid Parablennius parvicornis and its sister species P. sanguinolentus from the northeastern Atlantic Ocean and the western Mediterranean SeaPublication . Domingues, Vera dos Santos; Stefanni, Sergio; Brito, Alberto; Santos, Ricardo Serrão; Almada, Vítor CarvalhoInexistente