7,289 research outputs found
Intervista sulla destra con Franco Cardini:
No full textA short interview with Franco Cardini about the Right
Análise do polimorfismo de inversões cromossômicas em populações de Drosophila polymorpha do sul da ilha de Santa Catarina - Florianópolis
No full textTCC(graduação) - Universidade Federal de Santa Catarina. Centro de Ciências Biológicas. Biologia.O grupo cardini do subgênero Drosophila apresenta quesitos muito interessantes principalmente no que se refere à distribuição, pigmentação e padrões evolutivos. Sua distribuição abrange a região Neotropical e, apesar de sua alta representatividade nesta região, ainda há poucos estudos sobre o grupo. A espécie D. polymorpha pertencente a este grupo tem recebido recentemente grande atenção dos pesquisadores devido aos seus polimorfismos: pigmentação e inversão cromossômica paracêntrica. No Brasil, estudos apontam sua maior abundância na região Sul e em levantamentos taxonômicos na região de Florianópolis, tem sido uma das espécies de drosofilídeos mais abundante. Os polimorfismos de inversão cromossômica em espécies de Drosophila constituem um dos sistemas mais estudados em evolução e dados recentes apontam D. polymorpha como uma das espécies mais polimórficas do grupo cardini. O presente estudo teve como objetivo analisar o polimorfismo de inversões cromossômicas em D. polymorpha na Caiera da Barra do Sul, área de Mata Atlântica do extremo sul da região insular de Florianópolis. As 6 isolinhagens cultivadas em laboratório foram obtidos a partir da captura com rede sobre iscas de banana fermentada deixadas no campo por no mínimo três dias. As lâminas com os cromossomos politênicos foram obtidas a partir das larvas de terceiro estágio destas linhagens. Duas inversões, XA e IIRE sendo esta última descrita pela primeira vez na literatura. O estudo contribui no complemento do mapa cromossômico da espécie, com informações citogenéticas agregadas a aspectos ecológicos do grupo bem como para futuras pesquisas sobre sua história evolutiva
Descrição do comportamento de corte em duas espécies do grupo Cardini de Drosophila (Diptera: Drosophilidae)
No full textTCC(graduação) - Universidade Federal de Santa Catarina. Centro de Ciências Biológicas. Biologia.Foram observados 200 casais de Drosophila cardinoides e 200 casais de Drosophila polymorpha a fim de descrever o comportamento de corte destas espécies. A análise foi feita pela observação dos casais por um tempo mínimo de 50 minutos, ou até que o casal terminasse a cópula. Ambas as espécies demonstraram ser extremamente similares e seguiram os comportamentos já descritos para o gênero. Esta observação permitiu também determinar os tempos médios de latência, corte e cópula em 4,5 min, 12 min e 18 min para D. cardinoides e 3,5 min, 17 min e 26 min para D. polymorpha. A avaliação do comportamento de corte como barreira reprodutiva em Drosophila já foi bastante estudada dentre as espécies do grupo melanogaster. Estes dados foram importantes para o desenvolvimento desta área, mas não exprimem necessariamente toda a variação encontrada no gênero. Trabalhos feitos com espécies do grupo cardini sobre hibridização exploraram apenas as questões associadas a morfologia das moscas e negligenciam outras barreiras reprodutivas como, por exemplo, o comportamento. As observações feitas neste trabalho sugerem que a corte não deva ser uma barreira reprodutiva importante entre estas espécies. Pois, além das já conhecidas semelhanças morfológicas, estas espécies apresentam muitas semelhanças comportamentais na corte. Dentre as variações observadas na corte das espécies de Drosophila, uma das principais é a forma de vibração das asas. Os sons desta vibração são produzidos por complexos movimentos das asas associados a forma da mesma. A covariação entre a forma da asa e o sucesso do acasalamento tem sido descrito para várias espécies de Drosophila. Por isso, dados da morfometria geométrica das asas contribuem muito para o entendimento de como variações na forma das asas influenciam no acasalamento e o sucesso reprodutivo dos indivíduos. As correlações entre tamanho macho/fêmea de casais com e sem sucesso na copula de D. cardinoides e D. polymorpha não foram significativas. Do mesmo modo, não há diferença no tamanho médio entre os machos que conseguiram ou não copular. Tais dados levam a pensar que a relação entre o tamanho do corpo e o sucesso masculino é complexa e pode não ser tão forte como pensado inicialmente, sugerindo que a seleção sexual direcional para aumento do tamanho do corpo masculino não é universal em Drosophila.In order to describe the courtship behavior of Drosophila cardinoides and D. polymorpha, 200 couples of each species were observed. The couples were observed for at least 50 minutes, or until the end of copulation. Both species were shown to be extremely similar, following the behavior already described for the genus. This observation also allowed us to determine the average latency, courtship and copulation times, being 4.5 min, 12 min and 18 min, respectively, for D. cardinoides and 3.5 min, 17 min and 26 min for D. polymorpha. The assessment of courtship behavior in Drosophila as a reproductive barrier has been widely studied among the species of the melanogaster group. These data were important for the development in this area, but do not necessarily express the whole range found within the genre. Previous work involving hybridization of species from the cardini group only explored the issues associated with the flies’ morphology and neglected other reproductive barriers such as the behavior. The observations made in this study suggest that the courtship should not be a major reproductive barrier between these species. Therefore, besides the well-known morphological similarities, these species present many behavioral similarities in courtship. A major form of courtship variation observed in Drosophila species is related to the wing fluttering. Complex wing movements associated with its shape are responsible for producing a vibration sound. The covariation between wing shapes and mating success has been reported for various species of Drosophila. Therefore, data from geometric morphometric wings contribute a lot to the understanding as to how variations in wing shape influence the mating and reproductive success of the studied individuals. According to our results, there is no significant correlation between male/female size and success in copulation for D. cardinoides and D. polymorpha. Also, no differences in mean size were observed between copulating and non copulating flies. Such data leads us to assume that the relationship between body size and male success is complex and may not be as strong as originally thought, suggesting that directional sexual selection related to increasing male body size is not universal in Drosophil
As fast as a hare: Did intraspecific morphological change bring the Hallands Väderö Island population of Lepus timidus close to interspecific differences in less than 150 years?
No full text: The study of insular variation has fascinated generations of biologists and has been central to evolutionary biology at least since the time of Wallace and Darwin. In this context, using 3D geometric morphometrics, I investigate whether the population of mountain hares (Lepus timidus Linnaeus, 1758) introduced in 1857 on the Swedish island of Hallands Väderö shows distinctive traits in cranial size and shape. I find that size divergence follows the island rule, but is very small. In contrast, shape differences, compared to the mainland population, are almost as large as interspecific differences among lineages separated by hundreds of thousands of years of a largely independent evolutionary history. Even if, contrary to what is documented in the scientific literature, mountain hares were present in HV before 1857, the evolutionary history of this population could not have start earlier than the end of the last glaciation (i.e., at least one order of magnitude more recently than the separation of L. timidus from other hare species in this study). My results, thus, suggest that the insular population is a significant evolutionary unit and a potentially important component of the diversity of Swedish mountain hares. This is interesting for evolutionary biologists, but even more relevant for conservationists trying to protect the disappearing population of southern Swedish L. timidus, threatened by changes in climate and the environment, as well as by disease and the introduced European hare (Lepus europaeus Pallas, 1778). Island populations of mountain hares, thus, represent a potential source for future reintroductions on the mainland and, as my research shows, an important component of variability to maximize the preservation of the evolutionary potential in a species facing huge environmental changes.The study of insular variation has fascinated generations of biologists and has been central to evolutionary biology at least since the time of Wallace and Darwin. In this context, using 3D geometric morphometrics, I investigate whether the population of mountain hares (Lepus timidus Linnaeus, 1758) introduced in 1857 on the Swedish island of Hallands Väderö shows distinctive traits in cranial size and shape. I find that size divergence follows the island rule, but is very small. In contrast, shape differences, compared to the mainland population, are almost as large as interspecific differences among lineages separated by hundreds of thousands of years of a largely independent evolutionary history. Even if, contrary to what is documented in the scientific literature, mountain hares were present in HV before 1857, the evolutionary history of this population could not have start earlier than the end of the last glaciation (i.e., at least one order of magnitude more recently than the separation of L. timidus from other hare species in this study). My results, thus, suggest that the insular population is a significant evolutionary unit and a potentially important component of the diversity of Swedish mountain hares. This is interesting for evolutionary biologists, but even more relevant for conservationists trying to protect the disappearing population of southern Swedish L. timidus, threatened by changes in climate and the environment, as well as by disease and the introduced European hare (Lepus europaeus Pallas, 1778). Island populations of mountain hares, thus, represent a potential source for future reintroductions on the mainland and, as my research shows, an important component of variability to maximize the preservation of the evolutionary potential in a species facing huge environmental changes
Un breve diálogo intergeneracional: Entrevista a Juan Carlos Radovich por Laura Cardini
No full textThis article consists of an interview conducted by Laura Cardini from the Universidad Nacional de Rosario with Juan Carlos Radovich from the Universidad de Buenos Aires, two professionals who belong to different generations of anthropologists, in which various topics related to professional training processes are discussed according to the different historical contexts; compulsory readings and silenced readings at different moments of professional training. Additionally, they reflect on the transformations different Anthropologies suffered in light of local itineraries and contexts. Finally, they discuss the place Ethnography holds in professional work and the role played by Runa journal as a formative reading, along with the challenges faced by local Anthropologies in today’s world.O presente trabalho apresenta uma entrevista feita por Laura Cardini, da Universidade Nacional de Rosario, a Juan Carlos Radovich, da Universidade de Buenos Aires - antropólogos pertencentes a gerações distintas - em que discutem vários temas, como os processos de formação profissional de acordo com as circunstâncias históricas vividas, as leituras obrigatórias e as leituras silenciadas em diferentes momentos. Além disso, refletem sobre as transformações sofridas pelas diferentes antropologias de acordo com os itinerários e contextos locais, abordam o lugar da Etnografia no trabalho profissional e o papel desempenhado pela revista Runa como leitura formativa. Finalmente, discutem os desafios enfrentados pelas Antropologias locais no mundo atual.En esta entrevista realizada por Laura Cardini (de la Universidad Nacional de Rosario) a Juan Carlos Radovich (de la Universidad de Buenos Aires) —antropólogxs pertenecientes a distintas generaciones— discuten diversas temáticas, entre las que se encuentran los procesos de formación profesional según las coyunturas históricas vividas, las lecturas obligadas y las lecturas silenciadas en distintos momentos. Reflexionan, asimismo, sobre las transformaciones sufridas por las distintas Antropologías según los itinerarios y contextos locales, abordan el lugar de la Etnografía en el trabajo profesional y el papel jugado por la revista Runa como lectura formativa. Finalmente, debaten sobre los desafíos que enfrentan las Antropologías locales en el mundo actual
Less tautology, more biology? A comment on “high-density” morphometrics
No full textIn the context of geometric morphometric analyses of modularity and integration using Procrustes methods, some researchers have recently claimed that “high-density geometric morphometric data exceed the traditional landmark-based methods in the characterization of morphology and allow more nuanced comparisons across disparate taxa” and also that, using “high-density” data (i.e., with dozens or hundreds of semilandmarks), “potential issues [with tests of modularity and integration] are unlikely to obscure genuine biological signal”. I show that the first claim is invalidly tautological and, therefore, flawed, while the second one is a speculation. “High-density” geometric morphometrics is a potentially useful tool for the quantification of continuous morphological variation in evolutionary biology, but cannot be said to represent absolute accuracy, simply because more measurements increase information, but do not by default imply that this information is accurate. Semilandmarks are an analytical expedient to break the continuity of regions devoid of clearly corresponding landmarks, but the shape variables which they generate are a function of the specific choice of the placement and possible mathematical manipulation of these points. Not only there are infinite ways of splitting a curve or surface into discrete points, but also none of the methods to slide the semilandmarks increases the accuracy of their mapping onto the underlying biological homology: indeed, none of them is based on a biological model, and the assumption of universal equivalence between geometric and biological correspondence is unverified, if at all verifiable. Besides, in the specific context of modularity and integration using Procrustes geometric morphometrics, the limited number of scenarios simulated until now may provide interesting clues, but do not yet allow strong statements and clear generalizations. The Procrustes superimposition does alter the ‘true’ covariance structure of the data and sliding semilandmarks further contributes to this change. Although we hope that this might only add a negligible source of inaccuracy, and simulations using landmarks (but no semilandmarks yet) suggest that this might be the case, it is too early to confidently share the view, expressed by the promoters of high-density methods, that this is “Not-Really-a-Problem”. The evidence is very preliminary and the dichotomy may not be this simple, with the magnitude (from negligible to large) and direction (inflation of modularity, integration, or both) of a potential bias in the tests likely to vary in ways specific to the data being analysed. We need more studies that provide robust and generalizable evidence, without indulging in invalid tautology and over-interpretation. With both landmarks and semilandmarks, what is measured should be functional to the specific hypothesis and we should be clear on where the treatment of the data is pure mathematics and where there is a biological model that supports the maths
Erratum to: Larger mammals have longer faces because of size-related constraints on skull form (Nature Communications, (2013), 4, 1, (2458), 10.1038/ncomms3458)
No full textIn Table 1 of this article, the descriptions of landmarks 14, 15, and 36 are incorrect. Landmarks 14 and 36 should read “Posterior extremity of occipital condyle along margin of foramen magnum” and landmark 15 should read “Opisthion”. A correct version of Table 2 appears in the Author Correction associated with this article; the error has not been fixed in the original article
Modern morphometrics and the study of population differences: Good data behind clever analyses and cool pictures?
No full textThe study of phenotypic variation in time and space is central to evolutionary biology. Modern geometric morphometrics is the leading family of methods for the quantitative analysis of biological forms. This set of techniques relies heavily on technological innovation for data acquisition, often in the form of 2D or 3D digital images, and on powerful multivariate statistical tools for their analysis. However, neither the most sophisticated device for computerized imaging nor the best statistical test can produce accurate, robust and reproducible results, if it is not based on really good samples and an appropriate use of the ‘measurements’ extracted from the data. Using examples mostly from my own work on mammal craniofacial variation and museum specimens, I will show how easy it is to forget these most basic assumptions, while focusing heavily on analytical and visualization methods, and much less on the data that generate potentially powerful analyses and visually appealing diagrams
Allometry and phylogenetic divergence: Correspondence or incongruence?
No full textThe potential connection between trends of within species variation, such as those of allometric change in morphology, and phylogenetic divergence has been a central topic in evolutionary biology for more than a century, including in the context of human evolution. In this study, I focus on size-related shape change in craniofacial proportions using a sample of more than 3200 adult Old World monkeys belonging to 78 species, of which 2942 specimens of 51 species are selected for the analysis. Using geometric morphometrics, I assess whether the divergence in the direction of static allometries increases in relation to phyletic differences. Because both small samples and taxonomic sampling may bias the results, I explore the sensitivity of the main analyses to the inclusion of more or less taxa depending on the choice of a threshold for the minimum sample size of a species. To better understand the impact of sampling error, I also use randomized subsampling experiments in the largest species samples. The study shows that static allometries vary broadly in directions without any evident phylogenetic signal. This variation is much larger than previously found in ontogenetic trajectories of Old World monkeys, but the conclusion of no congruence with phylogenetic divergence is the same. Yet, the effect of sampling error clearly contributes to inaccuracies and tends to magnify the differences in allometric change. Thus, morphometric research at the boundary between micro- and macro-evolution in primates, and more generally in mammals, critically needs very large and representative samples. Besides sampling error, I suggest other non-mutually exclusive explanations for the lack of correspondence between allometric and phylogenetic divergence in Old World monkeys, and also discuss why directions might be more variable in static compared to ontogenetic trajectories. Even if allometric variation may be a poor source of information in relation to phylogeny, the evolution of allometry is a fascinating subject and the study of size-related shape changes remains a fundamental piece of the puzzle to understand morphological variation within and between species in primates and other animals
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