The exchangeability of shape

<p>Abstract</p> <p>Background</p> <p>Landmark based geometric morphometrics (GM) allows the quantitative comparison of organismal shapes. When applied to systematics, it is able to score shape changes which often are undetectable by traditional morphological studies and even by classical morphometric approaches. It has thus become a fast and low cost candidate to identify cryptic species. Due to inherent mathematical properties, shape variables derived from one set of coordinates cannot be compared with shape variables derived from another set. Raw coordinates which produce these shape variables could be used for data exchange, however they contain measurement error. The latter may represent a significant obstacle when the objective is to distinguish very similar species.</p> <p>Results</p> <p>We show here that a single user derived dataset produces much less classification error than a multiple one. The question then becomes how to circumvent the lack of exchangeability of shape variables while preserving a single user dataset. A solution to this question could lead to the creation of a relatively fast and inexpensive systematic tool adapted for the recognition of cryptic species.</p> <p>Conclusions</p> <p>To preserve both exchangeability of shape and a single user derived dataset, our suggestion is to create a free access bank of reference images from which one can produce raw coordinates and use them for comparison with external specimens. Thus, we propose an alternative geometric descriptive system that separates 2-D data gathering and analyzes.</p

Clasificación de imágenes LANDSAT-TM para la estimación de superficie de regadío en la Vega Baja y Campo de Elche, unidad hidrogeológica 07.24 (Alicante)

Se presenta el trabajo realizado para la estimación de las superficies de regadío en la Vega Baja y Campo de Elche (Alicante). Esta actividad se enmarca en los trabajos de carácter hidrogeológico que el Instituto Tecnológico y Geominero de España está realizando en la zona. La discriminación de las superficies regadas se ha realizado mediante técnicas de clasificación digital de dos imágenes Landsat TM registradas en primavera y verano. La utilización combinada de estas imágenes ha permitido discriminar cítricos, especies arbóreas de hoja caduca, cultivos de huerta y herbáceos. Los resultados obtenidos se han utilizado para estimar los retornos de riego en el modelo matemático que se está elaborando para simular el funcionamiento hidrogeológico del acuífero

Cartografía del vertido de iodos de la mina de Aznalcóllar mediante imágenes Daedalus ATM.C.

A raíz del accidente de la mina de Aznalcóllar, se han realizado varias campañas de vuelos multiespectrales Daedalus-1268 sobre las áreas afectadas. El objeto de estos vuelos ha sido tanto el control y seguimiento de los trabajos de limpieza de los Iodos vertidos en el cauce del río Guadiamar, como la detección de la contaminación remanente una vez finalizadas estas tareas. Se han efectuado correcciones geométricas a partir de fotografía área ortorectificada y correcciones radiométricas aplicando distintos modelos basados en transferencia radiativa y en medidas in situ de radiometría. Los análisis químicos, mineralógicos y de reflectividad de muestras de Iodos y alteraciones han permitido interpretar el comportamiento espectral de estos materiales y los datos multiespectrales. Los mapas generados a partir de la clasificación digital de las imágenes han permitido controlar la progresión de la limpieza de los Iodos y la localización precisa de las costras de sales

Geoelectrical characterization of superficial deposits in Western Antarctica (Livingston Island, South Shetland Islands)

The geophysical study of superficial deposits (mainly gravels) in ice-free areas near the seashore in the South Shetland Islands (Antarctica) allows establishing the possible existence of permafrost and buried ice bodies. In this work we have investigated the internal structure of Quaternary sediments using the resistivity method (vertical electric sounding, V.E.S.), with the purpose of establishing the resistivity values of the different materials and their geometry. We present here the results obtained from 1 7 vertical electric soundings carried out in Caleta Española, (north coast of Hurd Peninsula), and in the surroundings of Caleta del Glaciar Rocoso (south coast of Hurd Peninsula), both in Livingston Island. Vertical electric soundings interpretation has allowed us to characterise different units from the resistivity values (active layer, permafrost, buried ice, Quaternary deposits and their basement), and to establish the inter-phase between sea water and continental water. Moreover, with the resistivity method we have deduced the spatial distribution of some of these beds. In this way the permafrost (with resistivity values ranging between 13000 and 35000 Q*m), and the associated active layer, is restrained to shallow depths ( 60000 Q*m) and has been only found in the studied rock glacie

Phenotypic variability confirmed by nuclear ribosomal DNA suggests a possible natural hybrid zone of Triatoma brasiliensis species complex

Triatoma brasiliensis macromelasoma occurs in Pernambuco state, Brazil, which is situated between the distribution areas of Triatoma brasiliensis brasiliensis (north) and Triatoma juazeirensis (south). T. b. macromelasoma displays greater variations in its chromatic phenotype than either T. b. brasiliensis or T. juazeirensis, and patterns reminiscent of one or the other. Experimental crosses from each of these members of the T. brasiliensis species complex generated fertile offspring suggesting that viable hybrids could be present in nature, despite their significant genetic distances. Considering the geographical position of occurrence of the T. b. macromelasoma (in Pernambuco) it was proposed to be an area capable of supporting natural hybridization between T. b. brasiliensis and T. juazeirensis. Since phenotypic variability is expected, this study investigated the existence of intermediate chromatic phenotypes for T. b. macromelasoma in various locations in areas between the T. b. brasiliensis and T. juazeirensis occurrences. Thirteen different color patterns were for the first time characterized and nine of those displayed intermediate phenotypes. Molecular analysis performed using ribosomal DNA intergenic region, grouped all within the T. brasiliensis complex. The intermediate chromatic phenotypes, molecular analysis and experimental crosses all support the distinction of a zone of hybridization that gave rise to the T. b. macromelasoma through homoploidal evolution

Dispersion capacity of Triatoma sherlocki, Triatoma juazeirensis and laboratory-bred hybrids

Flight dispersion is recognized as one of the most important mechanisms for triatomine house infestation. Triatoma sherlocki and T. juazeirensis are closely related species that occur within the same ecotope and their possible reproductive boundaries are unknown. T. sherlocki has shorter wings than T. juazeirensis: a characteristic that possibly implies in reduced flight dispersion, however, this species has been found to invade and colonize homes in Bahia, Brazil. Here, we tested the flight potential of T. sherlocki, compared to that of T. juazeirensis and laboratory-bred hybrids. insects were kept in an apparatus designed to distinguish flyers from nonflyers. Fifty-one and 53% of T. juazeirensis and hybrids were flyers respectively, whereas no T. sherlocki were recorded to fly. Morphometric analysis of the main structures associated with the locomotor abilities showed that hybrids exhibited intermediate size for most of characters. The width of pronotum of both hybrids and T. juazeirensis was significantly larger than T. sherlocki. We suggested that lack of flight ability of T. sherlocki is possibly a result of reduced wing size and distinct shape, combined with undeveloped flight muscles in a shorter thoracic box. The mobility of T. sherlocki might be compensated by its significantly longer legs, and may possibly increase its ability to invade human dwellings by active dispersion. What is more, this study showed that hybrids between T. sherloki and T. juazeirensis have intermediate morphological characters that may give them higher fitness than their parents, and thus may advance the process of house infestation by either fight or walking in case of an eventual natural hybridization. (C) 2011 Elsevier B.V. All rights reserved.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP