72 research outputs found

    Evolutionary history and diversity in the ball roller beetle Canthon cyanellus

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    To understand the evolutionary history of species, it is necessary to know the mechanisms for reproductive isolation, divergence-time between populations, and the relative action of the evolutionary forces (e.g., mutation, genetic drift, gene flow) within and between populations of the same, or closely related species. Although Canthon is one of the more diverse genera of neotropical beetles, insufficient research has been done to comprehend the divergent patterns that explain its speciation process. The absence of diagnostic morphological characters and the wide geographic variation of qualitative traits in Scarabaeinae obscures species delimitation, genealogical limits between populations, and its taxonomy. Canthon cyanellus is one of the best-known species in ecological and evolutionary aspects. It is a widely distributed species in the tropical forests of America. Also, the current deforestation has facilitated its incursion into open areas. Individuals from different populations have similar morphological characters but show wide variation in body color throughout their distribution, which makes it difficult to delimit the subspecies that comprise it. Recently, studies have been carried out to elucidate the pre-and postzygotic isolation mechanisms between populations and the historical biogeographical processes favoring cladogenesis events during the Pleistocene. Morphological variation of the male genitalia does not correspond to the phylogeographic structure. However, the morphological differences in one of the pieces of the endophallic sclerites have allowed a preliminary delimitation of some genetically differentiated clades. Finally, we consider that the joint analysis of traditional morphological taxonomy and phylogeography is important to understand the speciation process in the C. cyanellus complex

    Phylogeographic structure of Canthon cyanellus (Coleoptera: Scarabaeidae), a Neotropical dung beetle in the Mexican Transition Zone: Insights on its origin and the impacts of Pleistocene climatic fluctuations on population dynamics

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    Canthon cyanellus is a roller dung beetle with a wide distribution range in the tropical forests of the New World. In Mexico, it inhabits the Pacific and the Gulf coasts, the Yucatan Peninsula and the south mainly in the State of Chiapas. This species shows a wide geographical variation in cuticle color, which has been used as defining trait for subspecies. In this study we analyzed the phylogeographic and demographic history of the Mexican populations of C. cyanellus using DNA sequences of the nuclear ITS2, and the mitochondrial COI and 16S genes. We found that not all the current valid subspecies are supported by the molecular analysis. The populations are genetically and geographically structured in five lineages. The diversification events that gave origin to the main lineages within this species complex occurred during the Pleistocine in a time range of 1.63–0.91 Myr. The demographic history of these lineages suggests post-glacial expansions toward the middle and the end of the Pleistocene. The combined data of mitochondrial and nuclear DNA suggest that the phylogeographic structure and demographic history of the C. cyanellus populations are the result of: the geological and volcanic activity that occurred from the end of the Pliocene to the Pleistocene; and the contraction and expansion of tropical forests due to the glacial and inter-glacial cycles during the Pleistocene. Landscape changes derived from historical events have affected the demographic history of the populations of this species. The results presented here point to the need to review the taxonomic status and delimitation of the lineages encompassed in the Canthon cyanellus complex.This work was financial supported by the Consejo Nacional de Ciencia y Tecnología, México (CONACyT, grant number CB-168373, 257039). This paper constitutes a partial fulfilment of the Graduate Program in Biodiversidad: Conservación y Gestión de las Especies y sus Hábitat of the Centro Iberoamericano de la Biodiversidad (CIBIO), Universidad de Alicante, España

    Speciation in the Emerald Toucanet (*Aulacorhynchus prasinus*) complex

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    We analyzed genetic variation in the Emerald Toucanet (Aulacorhynchus prasinus), a species complex that ranges primarily along the montane forests of southern and eastern Mexico south to Bolivia. Segments of three mitochondrial DNA genes (cytochrome b, ND2, and ND3) were sequenced for a total of 1,159 base pairs. Using maximum parsimony, maximum likelihood, and Bayesian analysis,we found a set of seven differentiated populations that correspond to clear geographic breaks throughout the highlands of the Neotropics. These genetically distinct populations also correspond with the geographic breaks found in previous analyses of morphological data. Molecular evidence suggests species treatment for four of the Central American clades and three South American clades. Received 19 June 2006, accepted 28 January 2007

    Relación entre las funciones ejecutivas y el nivel de actividad física en estudiantes de la ESO y Bachillerato

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    The objective of this work was to know the relationship between the level of physical activity and executive functions (cognitive flexibility and inhibition); and the differences according to gender, age and type of sport practiced in students aged between 12 and 17 years old. The research sample consisted of 71 students (28 boys and 43 girls). The level of physical activity was evaluated through the Physician-based Assessment and Counseling for Exercise, cognitive flexibility through the Design Fluency Test, and for the inhibitory mechanisms the Stroop Test was used. The results of this work showed that there is a positive and significant relationship between hours of physical activity and cognitive flexibility in adolescents. In terms of gender, boys obtained significantly higher values of hours of physical activity. In addition, older students had significantly higher scores on executive functions. Finally, the students of collective sports show significantly higher values of hours of physical activity practice and cognitive flexibility.Centrándonos en estudiantes con edades comprendidas entre 12 y 17 años de edad, el objetivo de este trabajo fue conocer la relación entre el nivel de actividad física y las funciones ejecutivas (flexibilidad cognitiva e inhibición); así como las diferencias en función del género, edad y tipo de deporte practicado. La muestra de la investigación estuvo compuesta por 71 estudiantes (28 chicos y 43 chicas). El nivel de actividad física fue evaluado mediante el Physician-based Assessment and Counseling for Exercise, la flexibilidad cognitiva a través del Design Fluency Test, y para los mecanismos inhibitorios se utilizó el Test Stroop. Los resultados de este trabajo mostraron que existe una relación positiva y significativa entre las horas de actividad física y la flexibilidad cognitiva en adolescentes. En función del género, los chicos obtuvieron valores significativamente más altos de horas de actividad física. Además, los estudiantes de mayor edad presentaron unas puntuaciones significativamente mayores en las funciones ejecutivas. Finalmente, los estudiantes de deportes colectivos muestran valores significativamente mayores de horas de práctica de actividad física y de flexibilidad cognitiva

    In Vitro Studies of Endophytic Bacteria Isolated from Ginger (Zingiber officinale) as Potential Plant-Growth-Promoting and Biocontrol Agents against Botrytis cinerea and Colletotrichum

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    Agriculture currently confronts a multitude of challenges arising from the excessive utilization of chemical pesticides and the proliferation of phytopathogenic fungi strains that exhibit resistance to commonly employed active compounds in the field. Botrytis cinerea and Colletotrichum acutatum are phytopathogenic fungi that inflict substantial economic losses within agriculture and food due to their high impacts on crops both pre- and post-harvest. Furthermore, the emergence of fungal strains that are resistant to commercial fungicides has exacerbated this problem. To explore more environmentally sustainable alternatives for the control of these pathogens, an investigation into the endophytic bacteria associated with ginger (Zingiber officinale Rosc.) was conducted. The primary focus of this study involved evaluating their inhibitory efficacy against the fungi and assessing their potential for promoting plant growth. The endophytic bacteria genera Lelliottia, Lysinibacillus, Kocuria, Agrococcus, Acinetobacter, Agrobacterium, Zymobacter, and Mycolicibacterium were identified. All isolates showed remarkable in vitro antagonistic ability against B. cinerea (>94%) and C. acutatum (>74%). Notably, the Lelliottia amnigena J29 strain exhibited a notable proficiency in producing extracellular enzymes and indole compounds (IAA), solubilizing phosphate and potassium, and forming biofilm. Furthermore, the Lysinibacillus capsici J26, Agrococcus citreus J28, and Mycolicibacterium sp. J5 strains displayed the capacity for atmospheric nitrogen fixation and siderophore production. These findings underscore the agricultural and biotechnological potential of endophytic bacteria derived from ginger plants and suggest the feasibility of developing alternative approaches to manage these two phytopathogenic fungi

    Morbillivirus and Pilot Whale Deaths, Mediterranean Sea

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    An outbreak of a lethal morbillivirus infection of long-finned pilot whales occurred in the Mediterranean Sea from the end of October 2006 through April 2007. Sequence analysis of a 426-bp conserved fragment of the morbillivirus phosphoprotein gene indicates that the virus is more closely related to dolphin morbillivirus than to pilot whale morbillivirus

    Management of acromegaly in Latin America: expert panel recommendations

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    Although there are international guidelines orienting physicians on how to manage patients with acromegaly, such guidelines should be adapted for use in distinct regions of the world. A panel of neuroendocrinologists convened in Mexico City in August of 2007 to discuss specific considerations in Latin America. Of major discussion was the laboratory evaluation of acromegaly, which requires the use of appropriate tests and the adoption of local institutional standards. As a general rule to ensure diagnosis, the patient’s GH level during an oral glucose tolerance test and IGF-1 level should be evaluated. Furthermore, to guide treatment decisions, both GH and IGF-1 assessments are required. The treatment of patients with acromegaly in Latin America is influenced by local issues of cost, availability and expertise of pituitary neurosurgeons, which should dictate therapeutic choices. Such treatment has undergone profound changes because of the introduction of effective medical interventions that may be used after surgical debulking or as first-line medical therapy in selected cases. Surgical resection remains the mainstay of therapy for small pituitary adenomas (microadenomas), potentially resectable macroadenomas and invasive adenomas causing visual defects. Radiotherapy may be indicated in selected cases when no disease control is achieved despite optimal surgical debulking and medical therapy, when there is no access to somatostatin analogues, or when local issues of cost preclude other therapies. Since not all the diagnostic tools and treatment options are available in all Latin American countries, physicians need to adapt their clinical management decisions to the available local resources and therapeutic options

    Phylogenetic Relationships among the Trogons

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    AVIFAUNA DE LOS BOSQUES DE CACTACEAS COLUMNARES DEL VALLE DE TEHUACAN, PUEBLA

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    We present a list of the avifauna of the columnar cacti forests of central México in the Tehuacán Valley. We found 90 species grouped into 13 orders and 27 families. Residents (56 species) are mostiy species of insectivorous and frugivorous-granivorous birds. Migrant birds are aiso pnmarily insectivorous. Another group of species moves locally between habitats during time of resource abundance. These species are common to the surrounding tropical deciduous forests that move constantly between habitats. The avifauna of the Tehuacan Valley share about 30% of the species with North American deserts (Sonoran, Chihuahuan, Mohave and Great Basin) and 33% with tropical deciduous forests in México. This asseiritjiage of species from different habitats is probably the cause of the high bird diversity found in the Valley.Se presenta una lista de la avifauna de los bosques de cactáceas columnares y hábitats adyacentes en una zona árida del centro de México, en el Valle de Tehuacán, Puebla. Se encontraron 90 especies de aves pertenecientes a 1 3 órdenes y 27 familias. De éstas, 56 son residentes en la zona siendo en su mayoría insectívoras y frugívoro-granívoras. las migratorias son también predominantemente insectívoras. Otro grupo de especies, está formado por aquellas que se mueven localmente y están en el valle durante las temporadas de abundancia de recursos. Son especies típicas de las selvas bajas caducifolias que probablemente se mueven constantemente entre hábitats. la avifauna del Valle de Tehuacán, Puebla, comparte con los desiertos de Norte América (Sonorense, Chihuahuense, Mohave y Gran Cañón) alrededor del 30% de sus especies. De igual forma, comparte el 33% de las especies con la selva baja caducifolia. Esta es probablemente la causa de su alta diversidad avifaunística presentándose un mosaico de especies características de otros sistemas
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