Browsing by Author "Robalo, Joana Isabel"
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- Absence of consistent genetic differentiation among several morphs of Actinia (Actiniaria: Actiniidae) occurring in the portuguese coastPublication . Pereira, Ana Martins; Brito, Cristiana Maria; Sanches, Joana; Santos, Carla Sousa; Robalo, Joana IsabelActinia equina, the beadlet sea anemone, is a very labile species, displaying variable colour patterns, broad habitat choice and diverse modes of reproduction. Historically, studies using genetic markers such as allozymes and differences in habitat choice lead several authors to propose that different colour morphs could represent different species. One of the species defined was A. fragacea. In this paper, the relationships between brown, red and green colour morphs of A. equina and A. fragacea were studied, using two DNA fragments (one mitochondrial and one nuclear). Individuals were sampled from three different areas in Portugal separated by a maximum distance of 500 km. This is the first study applying direct sequencing of selected gene fragments to approach the validity of Actinia morphs as different genetic entities. The results show that, at least in the Portuguese coast, these colour morphs do not correspond to the two valid species recognized in the literature. The existence of cryptic species is discussed.
- Alguns aspectos do comportamento social do tritão-verde triturus marmoratus (latreille, 1800) em cativeiroPublication . Robalo, Joana Isabel; Almada, Vítor CarvalhoDescrevem-se os comportamentos sociais observados em grupos mistos de T. marmoratus da Serra de Sintra, mantidos num cativeiro de grandes dimensões durante várias semanas. Reconhecem-se padrões de comportamento descritos para esta espécie e para outras do género Triturus. Descrevem-se, aparentemente pela primeira, vez os seguintes comportamentos: Walk I, Land-over, Stand-on, Show, Erect-body, Yawn, Circle e Dig. As fêmeas parecem ter um papel mais activo na côrte do que se considera habitualmente, nomeadamente através de iniciativas como Walk I, Land-over e Show. As frequências dos comportamentos para cada sexo e as principais interacções entre os indivíduos, foram analisadas utilizando uma estatística de simulação. Alguns padrões, habitualmente classificados como comportamentos sexuais masculinos, ocorrem em ambos os sexos e têm possivelmente outras funções sociais. Alguns comportamentos desencadeiam respostas diferentes de acordo com o sexo dos indivíduos intervenientes na interacção.
- Analysis of conditional contingency using ACTUS2 with examples from studies of animal behaviorPublication . Estabrook, George F.; Almada, Vítor Carvalho; Robalo, Joana IsabelIn this paper we present ACTUS2, the second version of ACTUS (Analysis of Contingency Tables Using Simulation). ACTUS2 has many new features, including analysis of data in which dependencies that make some combinations of properties impossible are hypothesized. Because ACTUS2 explicitly simulates such hypotheses, it can be used without loss of accuracy to analyze small amounts of data in large tables with many zeros or very low frequencies. We illustrate these features with two studies of animal behavior: interactions of male individuals with other individuals in groups of captive, mature Triturus marmoratus pygmaeus (newts); and agonistic interactions between pairs of male juvenile Diplodus sargus (the sparid fish, white sea-bream). Both significantly frequent, and significantly infrequent, co-occurrences that had biologically meaningful interpretations were revealed.
- Are local extinctions and recolonizations continuing at the colder limits of marine fish distributions? Halobatrachus didactylus (Bloch & Schneider, 1801), a possible candidatePublication . Robalo, Joana Isabel; Crespo, Ana Maria Azambuja Farinha da Conceição Pereira; Castilho, Rita; Francisco, Sara Martins; Amorim, Maria Clara Pessoa; Almada, Vítor CarvalhoIn this paper, we compare the populations of the Lusitanian toadfish Halobatrachus didactylus along the Portuguese shore, using a putative fragment of the mitochondrial control region and the first intron of the S7 ribosomal protein gene. This demersal species ranges from the tropical West African coast to the Iberian Peninsula and the Mediterranean, having its northern limit in the Tagus River. For the putative control region, a single haplotype occurs in all fish from Tagus and Sado (the location immediately to the south) with a clear increase in diversity to the South, peaking at Algarve (south Portugal). The data seem to point to a very recent Holocenic colonization of Tagus and Sado from the South (possibly Algarve). We suggest that even small oscillations in sea surface temperature (SST) may cause local extinctions and subsequent recolonizations in populations of thermophilic fish that are at the cold limit of their distributions.
- Asexual origin of brooding in the sea anemones Actinia equina and A. schmidti: Molecular evidence from the portuguese shorePublication . Pereira, Ana Martins; Cadeireiro, Emília Margarida; Robalo, Joana IsabelReproduction by sexual or asexual viviparity is a common phenomenon in some anemone species. In this short communication, the origin of the brooded young of Actinia equina and A. schmidti from the Portuguese shore was investigated. DNA was extracted from 56 brooding adult Actinia sp. and the nuclear gene that codes for the 28S ribosomal subunit was sequenced. Species identity was then assessed using GenBank. In total, 50 individuals were A. schmidti, five were A. equina and one had a hybrid origin. Three adult anemones (the hybrid, one A. equina and one A. schmidti) possessed two different 28S sequences and so their offspring was selected for further analysis using the same molecular procedure. Each brooded polyp was found to possess the exact same sequence as its parent, strongly suggesting the asexual origin of broods in A. equina and A. schmidti.
- Asymmetrical dispersal and putative isolation-by-distance of an intertidal blenniid across the atlantic–mediterranean dividePublication . Castilho, Rita; Cunha, Regina L.; Faria, Cláudia Barreiros Macedo de; Velasco, Eva Maria; Robalo, Joana IsabelTransition zones are of high evolutionary interest because unique patterns of spatial variation are often retained. Here, we investigated the phylogeography of the peacock blenny, Salaria pavo, a small marine intertidal fish that inhabits rocky habitats of the Mediterranean and the adjacent Atlantic Ocean. We screened 170 individuals using mitochondrial and nuclear sequence data from eight locations. Four models of genetic structure were tested: panmixia, isolation-by-distance, secondary contact and phylogeographic break. Results indicated clear asymmetric migration from the Mediterranean to the Atlantic but only marginally supported the isolation-by-distance model. Additionally, the species displays an imprint of demographic expansion compatible with the last glacial maximum. Although the existence of a refugium in the Mediterranean cannot be discarded, the ancestral lineage most likely originated in the Atlantic, where most of the genetic diversity occurs.
- Broad-scale sampling of primary freshwater fish populations reveals the role of intrinsic traits, inter-basin connectivity, drainage area and latitude on shaping contemporary patterns of genetic diversityPublication . Santos, Carla Sousa; Robalo, Joana Isabel; Pereira, Ana Martins; Branco, Paulo; Santos, José Maria; Ferreira, Maria Teresa; Sousa, Mónica; Doadrio, IgnacioBackground. Worldwide predictions suggest that up to 75% of the freshwater fish species occurring in rivers with reduced discharge could be extinct by 2070 due to the combined effect of climate change and water abstraction. The Mediterranean region is considered to be a hotspot of freshwater fish diversity but also one of the regions where the effects of climate change will be more severe. Iberian cyprinids are currently highly endangered, with over 68% of the species raising some level of conservation concern. Methods. During the FISHATLAS project, the Portuguese hydrographical network was extensively covered (all the 34 river basins and 47 sub-basins) in order to contribute with valuable data on the genetic diversity distribution patterns of native cyprinid species. A total of 188 populations belonging to 16 cyprinid species of Squalius, Luciobarbus, Achondrostoma, Iberochondrostoma, Anaecypris and Pseudochondrostoma were characterized, for a total of 3,678 cytochrome b gene sequences. Results. When the genetic diversity of these populations was mapped, it highlighted differences among populations from the same species and between species with identical distribution areas. Factors shaping the contemporary patterns of genetic diversity were explored and the results revealed the role of latitude, inter-basin connectivity, migratory behaviour, species maximum size, species range and other species intrinsic traits in determining the genetic diversity of sampled populations. Contrastingly, drainage area and hydrological regime (permanent vs. temporary) seem to have no significant effect on genetic diversity. Species intrinsic traits, maximum size attained, inter-basin connectivity and latitude explained over 30% of the haplotype diversity variance and, generally, the levels of diversity were significantly higher for smaller sized species, from connected and southerly river basins. Discussion. Targeting multiple co-distributed species of primary freshwater fish allowed us to assess the relative role of historical versus contemporary factors affecting genetic diversity. Since different patterns were detected for species with identical distribution areas we postulate that contemporary determinants of genetic diversity (species' intrinsic traits and landscape features) must have played a more significant role than historical factors. Implications for conservation in a context of climate change and highly disturbed habitats are detailed, namely the need to focus management and conservation actions on intraspecific genetic data and to frequently conduct combined genetic and demographic surveys.
- Chondrostoma oligolepis, new replacement name for Leuciscus macrolepidotus Steindachner, 1866 (Teleostei: Cyprinidae)Publication . Robalo, Joana Isabel; Doadrio, Ignacio; Almada, Vítor Carvalho; Kottelat, MauriceInexistente
- Climate change and genetic structure of leading edge and rear end populations in a northwards shifting marine fish species, the corkwing wrasse (Symphodus melops)Publication . Knutsen, Halvor; Jorde, Per Erik; Gonzalez, Enrique Blanco; Robalo, Joana Isabel; Albretsen, Jon; Almada, Vítor CarvalhoOne mechanism by which marine organisms may respond to climate shifts is range shifts. The corkwing wrasse (Symphodus melops) is a temperate fish species, inhabiting the coasts of Europe, that show strong indications of current as well as historical (ice-age) range shifts towards the north. Nine neutral microsatellite DNA markers were screened to study genetic signatures and spatial population structure over the entire geographic and thermal gradient of the species from Portugal to Norway. A major genetic break (FST = 0.159 average among pairs) was identified between Scandinavian and more southern populations, with a marked reduction (30% or more) in levels of genetic variability in Scandinavia. The break is probably related to bottleneck(s) associated with post-glacial colonization of the Scandinavian coasts, and indicates a lack of present gene flow across the North Sea. The lack of gene flow can most likely be attributed to the species’ need for rocky substrate for nesting and a relatively short pelagic larval phase, limiting dispersal by ocean currents. These findings demonstrate that long-distance dispersal may be severely limited in the corkwing wrasse, and that successful range-shifts following present climate change may be problematic for this and other species with limited dispersal abilities, even in the seemingly continuous marine environment.
- Competition among european robins Erithacus rubecula in the winter quarters: Sex is the best predictor of priority of access to experimental food resourcesPublication . Campos, Ana R.; Catry, Paulo; Ramos, Jaime; Robalo, Joana IsabelCompetition for resources by individuals of different sexes, ages, body sizes or geographical originsmay have varied implications, from demography to the evolution ofmigratory systems. European robins Erithacus rubecula display segregation by habitat in relation to sex, age, body size and geographic origin in the winter quarters. Here we report on an experiment to investigate the existence of asymmetries in the priority of access to food resources among unconstrained individuals in their natural environment. Feeders with mealwormswere provided in an areawith a high density of wintering robins and, after 15 days of provisioning, were replaced by a spring trap thatwas operated during a whole day. The first individuals to be caught in each trap were heavier and had higher fat andmuscle scores than last-caught individuals. Based on this and on behavioural observations, we conclude that first-caught individuals had priority of access to feeders. First- and lastcaught individuals did not differ in body size, wingtip shape or age ratios. However, whilst 35% of the first-caught individuals weremales, only 6%of the last-caught individuals weremales. This suggests that sex is an important predictor of the outcomes of competition in an area where multiple robin populations coexist in winter, while, at least on sites where no strictly sedentary individuals are present, geographic origin may be relatively unimportant.