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Search Results: 1 - 10 of 191 matches for " Christiana Klingenberg "
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The type specimens of fungus growing ants, Attini (Hymenoptera, Formicidae, Myrmicinae) deposited in the Museu de Zoologia da Universidade de S?o Paulo, Brazil
Klingenberg, Christiana;Brand?o, Carlos Roberto F.;
Papéis Avulsos de Zoologia (S?o Paulo) , 2005, DOI: 10.1590/S0031-10492005000400001
Abstract: we present here a list of the attini type material deposited in the formicidae collection of the museu de zoologia da universidade de s?o paulo (mzsp), brazil. in total, the attini (fungus-growing and leaf-cutting ants) collection includes types of 105 nominal species, of which 74 are still valid, whereas 31 are considered synonyms. the majority of the types in the mzsp collection are syntypes (74), but in the collection there are 4 species represented only by holotypes, 12 by holotypes and paratypes, 13 species only by paratypes, and 2 species by the lectotype and one paralectotype as well. all holotypes and paratypes refer to valid species. the aim of this type list is to facilitate consultation and to encourage further revisionary studies of the attini genera.
Cyatta abscondita: Taxonomy, Evolution, and Natural History of a New Fungus-Farming Ant Genus from Brazil
Jeffrey Sosa-Calvo, Ted R. Schultz, Carlos R. F. Brand?o, Christiana Klingenberg, Rodrigo M. Feitosa, Christian Rabeling, Maurício Bacci, Cauê T. Lopes, Heraldo L. Vasconcelos
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0080498
Abstract: Cyatta abscondita, a new genus and species of fungus-farming ant from Brazil, is described based on morphological study of more than 20 workers, two dealate gynes, one male, and two larvae. Ecological field data are summarized, including natural history, nest architecture, and foraging behavior. Phylogenetic analyses of DNA sequence data from four nuclear genes indicate that Cyatta abscondita is the distant sister taxon of the genus Kalathomyrmex, and that together they comprise the sister group of the remaining neoattine ants, an informal clade that includes the conspicuous and well-known leaf-cutter ants. Morphologically, Cyatta abscondita shares very few obvious character states with Kalathomyrmex. It does, however, possess a number of striking morphological features unique within the fungus-farming tribe Attini. It also shares morphological character states with taxa that span the ancestral node of the Attini. The morphology, behavior, and other biological characters of Cyatta abscondita are potentially informative about plesiomorphic character states within the fungus-farming ants and about the early evolution of ant agriculture.
There's something afoot in the evolution of ontogenies
Christian Klingenberg
BMC Evolutionary Biology , 2010, DOI: 10.1186/1471-2148-10-221
Abstract: The interplay between selective forces and the developmental processes that produce selectable variation is the focus of much attention in evolutionary biology. In a new article, Adams and Nistri [1] pursue this line of investigation by examining the evolution of growth processes in the foot of European cave salamanders. Foot morphology is particularly important in this group of salamanders because the degree of webbing between the toes has been related to their ability to cling to rocks or other substrates. Adams and Nistri use the methods of geometric morphometrics to quantify foot shape in general and to derive a measure of the degree of webbing of the feet.For the clade of salamanders included in the study, an isometric growth trajectory, where the degree of webbing of the foot is constant over ontogeny, appears to be the ancestral condition [1]. There were at least two evolutionary changes of allometry: one lineage evolved an allometric growth pattern, where the degree of foot webbing increases with size, and a species in this lineage later reverted to an isometric mode of growth. Adams and Nistri [1] interpret the switch to allometric growth as a possible adaptation for climbing. Moreover, the ontogenetic trajectories of the different species resulted in a clear convergence from different juvenile foot morphologies toward a shared adult morphology with extensive webbing. This convergence suggests an adaptive explanation, where the common morphology corresponds to a functional optimum [1]. Overall, there appears to be a considerable degree of ontogenetic plasticity that provides opportunities for adaptive evolution.This paper is one of a growing trend for studies at the interface of evolution and development to use morphometric methods to quantify shape [2]. Allometry and its role in evolution have long been recognized as factors that potentially can influence evolutionary processes [3-5]. In recent years, a variety of studies have provided evidence that this i
Grand challenges in computational physics
Christian Klingenberg
Frontiers in Physics , 2013, DOI: 10.3389/fphy.2013.00002
Abstract:
Novas tendências no estudo do conhecimento, economia & sociedade
Christiana Freitas
Sociedade e Estado , 2002, DOI: 10.1590/s0102-69922002000100010
Abstract:
Contemporary Art and Political Violence: The Role of Art in the Rehabilitation and Healing of Communities Affected by Political Violence
Christiana Spens
Journal of Terrorism Research , 2013,
Abstract: This paper will investigate how contemporary artists who use political violence as a subject matter in their work explain the relationship between art and that form of violence. Referring to interviews with Anita Glesta and George Gittoes, the potential of art as a means of healing communities and individuals affected by terrorism will be explored, alongside related issues of voyeurism, sensationalism and commercialism in art. The study will refer to the ideas of Collingwood and Tolstoy, chosen so as to represent two main schools of thought regarding artistic responsibility & morality and the appropriate intentions of artists. I will explain that both theories can be applied harmoniously to contemporary practise, to the understanding of the role and responsibility of contemporary artists, and discourse around the wider social value of contemporary art
Beyond bilateral symmetry: geometric morphometric methods for any type of symmetry
Yoland Savriama, Christian Klingenberg
BMC Evolutionary Biology , 2011, DOI: 10.1186/1471-2148-11-280
Abstract: We generalize the morphometric methods currently used for the shape analysis of bilaterally symmetric objects so that they can be used for analyzing any type of symmetry. Our framework uses a mathematical definition of symmetry based on the theory of symmetry groups. This approach can be used to divide shape variation into a component of symmetric variation among individuals and one or more components of asymmetry. We illustrate this approach with data from a colonial coral that has ambiguous symmetry and thus can be analyzed in multiple ways. Our results demonstrate that asymmetric variation predominates in this dataset and that its amount depends on the type of symmetry considered in the analysis.The framework for analyzing symmetry and asymmetry is suitable for studying structures with any type of symmetry in two or three dimensions. Studies of complex symmetries are promising for many contexts in evolutionary biology, such as fluctuating asymmetry, because these structures can potentially provide more information than structures with bilateral symmetry.Morphological symmetry results from the repetition of parts in different orientations or positions and is widespread in the body plans of most organisms. For example, the human body is bilaterally symmetric in external appearance because the same anatomical parts are repeated on the left and right sides. Likewise, many flowers are radially symmetric because sets of petals and other organs are repeated in circular patterns. The evolution of morphological symmetry is of interest in its own right [1-8] and variation among repeated parts, such as fluctuating asymmetry, has been widely used for research in evolutionary biology [9-12]. For instance, fluctuating asymmetry can be viewed as a measure of developmental instability [13] and has been related to measures of environmental stress [14], hybridization [15,16], or fitness [17]. In a different context, fluctuating asymmetry can also be used to investigate the develop
Reflection of a wave off a surface
Brendan Guilfoyle,Wilhelm Klingenberg
Mathematics , 2004,
Abstract: Recent advances in twistor theory are applied to geometric optics in ${\Bbb{R}}^3$. The general formulae for reflection of a wavefront in a surface are derived and in three special cases explicit descriptions are provided: when the reflecting surface is a plane, when the incoming wave is a plane and when the incoming wave is spherical. In each case particular examples are computed exactly and the results plotted to illustrate the outgoing wavefront.
Generalised Surfaces in ${\Bbb{R}}^3$
Brendan Guilfoyle,Wilhelm Klingenberg
Mathematics , 2004,
Abstract: The correspondence between 2-parameter families of oriented lines in ${\Bbb{R}}^3$ and surfaces in $T{\Bbb{P}}^1$ is studied, and the geometric properties of the lines are related to the complex geometry of the surface. Congruences generated by global sections of $T{\Bbb{P}}^1$ are investigated and a number of theorems are proven that generalise results for closed convex surfaces in ${\Bbb{R}}^3$.
Reflection in a Translation Invariant Surface
Brendan Guilfoyle,Wilhelm Klingenberg
Mathematics , 2005,
Abstract: We prove that the focal set generated by the reflection of a point source off a translation invariant surface consists of two sets: a curve and a surface. The focal curve lies in the plane orthogonal to the symmetry direction containing the source, while the focal surface is translation invariant. This is done by constructing explicitly the focal set of the reflected line congruence (2-parameter family of oriented lines in ${\Bbb{R}}^3$) with the aid of the natural complex structure on the space of all oriented affine lines.
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