Research Center in Biodiversity and Genetic Resources

Porto, Portugal

Research Center in Biodiversity and Genetic Resources

Porto, Portugal
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Rat M.,University of Cape Town | van Dijk R.E.,University of Sheffield | Covas R.,University of Cape Town | Covas R.,Research Center in Biodiversity and Genetic Resources | And 3 more authors.
Behavioral Ecology and Sociobiology | Year: 2015

In animal societies, individuals face the dilemma of whether to cooperate or to compete over a shared resource. Two intertwined mechanisms may help to resolve this enduring evolutionary dilemma by preventing conflicts and thereby mediating the costs of living in groups: the establishment of dominance hierarchies and the use of ‘badge-of-status’ for signalling dominance. We investigated these two mechanisms in the sociable weaver (Philetairus socius), a colonial and social passerine which cooperates over multiple tasks. We examined the sociable weavers’ dominance structure in 2 years by recording 2563 agonistic interactions between 152 individuals observed at a feeder at eight colonies. We tested which individual traits, including sex, age, relatedness and two melanin-based plumage traits, predicted variation in social status. First, using social network analysis, we found that colonies were structured by strongly ordered hierarchies which were stable between years. Second, medium-ranked birds engaged more in aggressive interactions than highly ranking individuals, suggesting that competition over food is most pronounced among birds of intermediate social status. Third, we found that colony size and kinship influenced agonistic interactions, so aggression was less pronounced in smaller colonies and among relatives. Finally, within- and between-individual variation in social status and the presence of an individual at the feeder were associated with variation in bib size, as predicted by the badge-of-status hypothesis. These results suggest that dominance hierarchies and bib size mediate conflicts in sociable weaver societies. © 2014, Springer-Verlag Berlin Heidelberg.

Paquet M.,French National Center for Scientific Research | Covas R.,Research Center in Biodiversity and Genetic Resources | Covas R.,University of Cape Town | Covas R.,University of Porto | And 3 more authors.
PLoS ONE | Year: 2013

In egg laying species, breeding females may adjust the allocation of nutrients or other substances into eggs in order to maximise offspring or maternal fitness. Cooperatively breeding species offer a particularly interesting context in which to study maternal allocation because helpers create predictably improved conditions during offspring development. Some recent studies on cooperative species showed that females assisted by helpers produced smaller eggs, as the additional food brought by the helpers appeared to compensate for this reduction in egg size. However, it remains unclear how common this effect might be. Also currently unknown is whether females change egg composition when assisted by helpers. This effect is predicted by current maternal allocation theory, but has not been previously investigated. We studied egg mass and contents in sociable weavers (Philetairus socius). We found that egg mass decreased with group size, while fledgling mass did not vary, suggesting that helpers may compensate for the reduced investment in eggs. We found no differences in eggs' carotenoid contents, but females assisted by helpers produced eggs with lower hormonal content, specifically testosterone, androstenedione (A4) and corticosterone levels. Taken together, these results suggest that the environment created by helpers can influence maternal allocation and potentially offspring phenotypes. © 2013 Paquet et al.

Covas R.,Research Center in Biodiversity and Genetic Resources | Covas R.,University of Porto | Covas R.,French National Center for Scientific Research | Covas R.,University of Edinburgh
Proceedings of the Royal Society B: Biological Sciences | Year: 2012

Island environments typically share characteristics such as impoverished biotas and less-seasonal climates, which should be conducive to specific adaptations by organisms. However, with the exception of morphological studies, broad-scale tests of patterns of adaptation on islands are rare. Here, I examine reproductive patterns in island birds worldwide. Reproductive life histories are influenced by latitude, which could affect the response to insularity; therefore, I additionally test this hypothesis. Island colonizers showed mostly bi-parental care, but there was a significant increase in cooperative breeding on islands. Additionally, I found support for previous suggestions of reduced fecundity, longer developmental periods and increased investment in young on islands. However, clutch size increased with latitude at a rate nearly five times faster on the mainland than on the islands revealing a substantially stronger effect of insularity at higher latitudes. Latitude and insularity may also interact to determine egg volume and incubation periods, but these effects were less clear. Analyses of reproductive success did not support an effect of reduced nest predation as a driver of reproductive change, but this requires further study. The effect of latitude detected here suggests that the evolutionary changes associated with insularity relate to environmental stability and improved adult survival. © 2011 The Royal Society.

Brown T.A.,University of Manchester | Cappellini E.,Copenhagen University | Kistler L.,Pennsylvania State University | Lister D.L.,University of Cambridge | And 3 more authors.
Vegetation History and Archaeobotany | Year: 2014

The scope and ambition of biomolecular archaeology is undergoing rapid change due to the development of new ‘next generation’ sequencing (NGS) methods for analysis of ancient DNA in archaeological specimens. These methods have not yet been applied extensively to archaeobotanical material but their utility has been demonstrated with desiccated, waterlogged and charred remains. The future use of NGS is likely to open up new areas of investigation that have been difficult or impossible with the traditional approach to aDNA sequencing. Species identification should become more routine with archaeobotanical explants, not just with charred grain but with most if not all species likely to be encountered in an archaeobotanical setting. Distinctions between different subspecies groups such as cereal landraces will also be possible in the near future. Phenotypic characterization, in which aDNA sequencing is used to infer the biological characteristics of an archaeological specimen, will become possible, improving our understanding of traits such as flowering behaviour of cereals, and when combined with studies of preserved RNA and protein will enable complex phenotypes such as environmental tolerance and nutritional quality to be assessed. The sequencing of entire ancient plant genomes is also likely to have significant impact. As with past studies of ancient plant DNA, realization of the new potential provided by NGS will require productive collaboration between archaeologists and geneticists within the archaeobotanical research community. © 2014, Springer-Verlag Berlin Heidelberg.

Xavier J.R.,University of Amsterdam | Xavier J.R.,Research Center in Biodiversity and Genetic Resources | Rachello-Dolmen P.G.,University of Amsterdam | Parra-Velandia F.,National University of Colombia | And 3 more authors.
Molecular Phylogenetics and Evolution | Year: 2010

Over the past several decades molecular tools have shown an enormous potential to aid in the clarification of species boundaries in the marine realm, particularly in morphologically simple groups. In this paper we report a case of cryptic speciation in an allegedly cosmopolitan and ecologically important species-the excavating sponge Cliona celata (Clionaidae, Hadromerida). In the Northeast Atlantic and Mediterranean C. celata displays a discontinuous distribution of its putative growth stages (boring, encrusting, and massive) leading us to investigate its specific status. Phylogenetic reconstructions of mitochondrial (COI, Atp8) and nuclear (28S) gene fragments revealed levels of genetic diversity and divergence compatible with interspecific relationships. We therefore demonstrate C. celata as constituting a species complex comprised of at least four morphologically indistinct species, each showing a far more restricted distribution: two species on the Atlantic European coasts and two on the Mediterranean and adjacent Atlantic coasts (Macaronesian islands). Our results provide further confirmation that the different morphotypes do indeed constitute either growth stages or ecologically adapted phenotypes as boring and massive forms were found in two of the four uncovered species. We additionally provide an overview of the cases of cryptic speciation which have been reported to date within the Porifera, and highlight how taxonomic crypsis may confound scientific interpretation and hamper biotechnological advancement. Our work together with previous studies suggests that overconservative systematic traditions but also morphological stasis have led to genetic complexity going undetected and that a DNA-assisted taxonomy may play a key role in uncovering the hidden diversity in this taxonomic group. © 2010 Elsevier Inc. All rights reserved.

Sarria M.P.,CIIMAR – Interdisciplinary Center of Marine and Environmental | Sarria M.P.,University of Porto | Santos M.M.,CIIMAR – Interdisciplinary Center of Marine and Environmental | Reis-Henriques M.A.,CIIMAR – Interdisciplinary Center of Marine and Environmental | And 4 more authors.
Chemosphere | Year: 2011

Endocrine disrupting chemical (EDC) effects during early life have the potential to modulate population structure, either directly through increased mortality or by causing inappropriate aggregation events, thus affecting the number of young that will reach adulthood. An alteration in the dispersal and recruitment patterns can also impair the connectivity among geographically distant populations. However, the detection of EDC-induced effects occurring after egg hatch, when newborns increase their chances of contacting with environmentally dispersed contaminants, is not a simple process as effects might be masked by the large natural mortality rates that usually occur during fish early life.Since there is a lack of information regarding the impact of EDCs on fish early life dispersal patterns, particularly on vertical migrations patterns, the effects of environmentally relevant concentrations of EE2 on the vertical distribution of newborn fish was assessed through an ex situ exposure experiment. Syngnathus abaster newborns were exposed to EE2 (nominal concentrations of 8, 12 and 36ngL-1) and the dynamics of their vertical distribution was monitored for up to 40d. No significant differences in overall mortality were observed between treatments or in the dynamics of the registered death curves. Nevertheless, an alteration in the distribution patterns was observed. The commonly benthic newborn tended to shift their vertical distribution towards the surface, in a dose-dependent manner. Curiously, a follow up of the exposed pipefish confirmed that EE2 effects were also noticeable upon sexual maturity, namely by the alteration of several primary and secondary sexual characters. The observation that vertical distributional patterns, at least in pipefish, are clearly altered at environmentally relevant EE2 concentrations indicates that EDC's impact in fish larvae behaviour should be considered when addressing the effects of contaminants, given the obvious implications on population connectivity, stability and persistence. © 2011 Elsevier Ltd.

Soares J.,CIIMAR – Interdisciplinary Center of Marine and Environmental | Soares J.,University of Porto | Castro L.F.C.,CIIMAR – Interdisciplinary Center of Marine and Environmental | Reis-Henriques M.A.,CIIMAR – Interdisciplinary Center of Marine and Environmental | And 4 more authors.
Ecotoxicology | Year: 2012

Parental full life-cycle exposure to ethinylestradiol (EE 2) significantly affects embryo development and survival. One of the possible mechanisms of action of EE 2 may involve the impairment of an organism's ability to repair DNA damage. DNA repair mechanisms have sophistically evolved to overcome DNA damaging hazards that threaten the integrity of the genome. In the present study, changes in the transcription levels of key genes involved in two of the most thoroughly studied DNA repair systems in mammals were evaluated in adult zebrafish (Danio rerio) gonad upon full life-cycle exposure to chronic environmentally low levels of EE 2 (i.e., 0.5, 1 and 2 ng/L EE 2). Real time PCR was used to analyse the expression levels of nucleotide excision repair genes (NER) as well as the tumor suppressor p53 and downstream selected effectors, i.e., p21 (cyclin-dependent kinase inhibitor), GADD45a (growth arrest and DNA damage induced 45, alpha), bax (bcl2-associated X protein) and p53 key regulator MDM2 (murine double minute 2 protein). NER genes transcription levels in gonads did not differ significantly among treatments. In contrast, the number of transcripts of p53 gene was significantly increased in male gonads at all EE 2 exposure concentrations and in females at 1 ng/L EE 2. Despite the increase in p53 transcripts, transcription levels of p21, GADD45α and bax genes were not affected upon EE 2 treatment, whereas MDM 2 gene expression significantly increased in females at the intermediate EE 2 dose (1 ng/L). Overall, the present study indicate that chronic low levels of EE 2 significantly modulates the transcription of p53, a key gene involved in DNA repair, particularly in male zebrafish gonads, which supports the hypothesis of an impact of EE2 in male gonad DNA repair pathways. © Springer Science+Business Media, LLC 2012.

Van Der Valk T.,Leiden University | Van Der Meijden A.,Research Center in Biodiversity and Genetic Resources
Toxicon | Year: 2014

The LD50 is an important metric for venom studies and antivenom development. It has been shown that several variables in the protocol influence the LD50 value obtained, such as venom source, extraction and treatment and administration route. These inconsistencies reduce the utility of the results of these test for comparative studies. In scorpion venom LD 50 assays, often only the soluble fraction of the venom is used, whereas other studies use the whole venom. We here tested the toxicity of the soluble fraction in isolation, and of the whole venom in two different systems: chick embryos and mealworms Tenebrio molitor. Ten microliters of venom solutions from Hadrurus arizonensis, Leiurus quinquestriatus, Androctonus australis, Grosphus grandidieri and Heterometrus laoticus were applied to five day old chicken embryos at stage 25-27. Our results showed no significant differences between the LD50 based on the whole venom versus that of only the soluble fraction and in the chicken embryo assay in four of the five scorpion species tested. H. laoticus however, showed a significantly lower LD 50 value for the whole venom than the soluble fraction. In assays on mealworms however, this pattern was not seen. Nonetheless, caution may be warranted when using LD50 values obtained from only the soluble fraction. The LD50 values of the five species in this study, based on the chicken embryo assay, showed good correlation with values from the literature based on mouse studies. This suggests that the chick embryo assay may be an economic alternative to rodent assays for scorpion LD50 studies. © 2014 Elsevier Ltd. All rights reserved.

Van Der Meijden A.,Research Center in Biodiversity and Genetic Resources | Coelho P.,Research Center in Biodiversity and Genetic Resources | Rasko M.,Research Center in Biodiversity and Genetic Resources
Toxicon | Year: 2015

Scorpions have been shown to control their venom usage in defensive encounters, depending on the perceived threat. Potentially, the venom amount that is injected could be controlled by reducing the flow speed, the flow duration, or both. We here investigated these variables by allowing scorpions to sting into an oil-filled chamber, and recording the accreting venom droplets with high-speed video. The size of the spherical droplets on the video can then be used to calculate their volume. We recorded defensive stings of 20 specimens representing 5 species. Significant differences in the flow rate and total expelled volume were found between species. These differences are likely due to differences in overall size between the species. Large variation in both venom flow speed and duration are described between stinging events of single individuals. Both venom flow rate and flow duration correlate highly with the total expelled volume, indicating that scorpions may control both variables in order to achieve a desired end volume of venom during a sting. © 2015 Elsevier Ltd. All rights reserved.

Silva K.,University of Porto | Silva K.,CIIMAR – Interdisciplinary Center of Marine and Environmental | Vieira M.N.,University of Porto | Vieira M.N.,CIIMAR – Interdisciplinary Center of Marine and Environmental | And 3 more authors.
Animal Behaviour | Year: 2010

The operational sex ratio (OSR) is thought to be a major factor influencing the intensity of mating competition and sexual selection. Even though many studies on species with conventional sex roles have shown that alterations in the OSR can either intensify male-male competition or promote female-female competitive interactions, sometimes resulting in a reversal of sex roles, it is not known how, and how quickly, individuals with reversed sex roles respond to fluctuations in this ratio. We tested for a direct influence of adult sex ratios (as a direct estimation of the OSR) on the reproductive behaviour of the sex role-reversed black striped pipefish, Syngnathus abaster. Although imbalances in the OSR effectively modulated the expression of sex roles, with males and females varying in the degree of choosiness and competitive displays, alterations in the sex ratios did not promote a similar response pattern in both sexes. A surplus of males resulted in a reversion to conventional sex roles observed when both sexes coexist in similar numbers, with males competing intensely and exhibiting a conspicuous ornament towards other males. An excess of females, in contrast, did not result in an overall increase in female competitive interactions. Only small, less attractive, females were more prone to compete as the proportion of males decreased. Large females, however, seemed to rely on their greater mating prospects, thereby avoiding the hypothetical costs of intrasexual competition. © 2010 The Association for the Study of Animal Behaviour.

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