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5 resultados encontrados para: AUTOR: Paxton, Robert J.
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Recent low levels of differentiation in the native Bombus ephippiatus (Hymenoptera: Apidae) along two Neotropical mountain-ranges in Guatemala
Landaverde González, Patricia ; Baltz, Lucie M. (coaut.) ; Escobedo Kenefic, Natalia (coaut.) ; Mérida Rivas, Jorge Alfredo (coaut.) ; Paxton, Robert J. (coaut.) ; Husemann, Martin (coaut.) ;
Contenido en: Biodiversity and Conservation Vol. 27, no. 13 (November 2018), p. 3513-3531 ISSN: 1572-9710
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Resumen en: Inglés |
Resumen en inglés

Recent anthropogenic fragmentation has led to population differentiation threatening viability of many species, including species specialized on mountainous ecosystems. Bombus ephippiatus, a widespread species mostly found in mountains in the Neotropics, seems to use the highlands as island, and deforested lowland areas may represent barriers to their dispersal, leading to isolation and potentially loss of genetic diversity. Yet, lack of knowledge of its population structure does not allow adequate management and conservation. To fill this knowledge gap, we assessed the population structure and inferred dispersion of B. ephippiatus in two mountain-ranges in Guatemala (Volcanic Chain and Sierra de las Minas). This region is characterized by high topographic variation and considerable deforestation strain. We analyzed the effects of elevation and land-use on genetic differentiation of B. ephippiatus populations and inferred its demography in the region. Our results suggest that B. ephippiatus is able to disperse long distances across most landscape types, reflected by its high genetic diversity, high effective population size, considerable gene flow, low population differentiation, as well as the lack of isolation by distance. Hence, B. ephippiatus may be a resilient species for the provision of pollination services. However, we detected a subtle divergence of B. ephippiatus into two clusters, of which Sierra de las Minas has been identified as a regional hotspot of genetic and species endemism. Yet, differentiation is very recent and hence likely caused by lowland deforestation. The combined effects of current forest cover and elevation partially explain the observed subtle patterns of differentiation suggesting that the maintenance of suitable habitat is crucial to ensure population connectivity of this keystone pollinator.

Resumen en: Inglés |
Resumen en inglés

1. Traditional tropical agriculture often entails a form of slash-and-burn land management that may adversely affect ecosystem services such as pollination, which are required for successful crop yields. The Yucatán Peninsula of Mexico has a >4000 year history of traditional slash-and-burn agriculture, termed ‘milpa’. Hot ‘Habanero’ chilli is a major pollinator-dependent crop that nowadays is often grown in monoculture within the milpa system. 2. We studied 37 local farmers’ chilli fields (sites) to evaluate the effects of landscape composition on bee communities. At 11 of these sites, we undertook experimental pollination treatments to quantify the pollination of chilli. We further explored the relationships between landscape composition, bee communities and pollination service provision to chilli. 3. Bee species richness, particularly species of the family Apidae, was positively related to the amount of forest cover. Species diversity decreased with increasing proportion of crop land surrounding each sampling site. Sweat bees of the genus Lasioglossum were the most abundant bee taxon in chilli fields and, in contrast to other bee species, increased in abundance with the proportion of fallow land, gardens and pastures which are an integral part of the milpa system. 4. There was an average pollination shortfall of 21% for chilli across all sites; yet the shortfall was unrelated to the proportion of land covered by crops. Rather, chilli pollination was positively related to the abundance of Lasioglossum bees, probably an important pollinator of chilli, as well indirectly to the proportion of fallow land, gardens and pastures that promote Lasioglossum abundance.

5. Synthesis and applications. Current, low-intensity traditional slash-and-burn (milpa) agriculture provides Lasioglossum spp. pollinators for successful chilli production; fallow land, gardens and pasture therefore need to be valued as important habitats for these and related ground-nesting bee species. However, the negative impact of agriculture on total bee species diversity highlights how agricultural intensification is likely to reduce pollination services to crops, including chilli. Indeed, natural forest cover is vital in tropical Yucat an to maintain a rich assemblage of bee species and the provision of pollination services for diverse crops and wild flowers.

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*En hemeroteca, SIBE-Tapachula
Number of honeybee colonies in areas with high and low beekeeping activity in Southern Mexico
Moritz, Robin F. A ; Bernhard Kraus, F. (coaut.) ; Huth Schwarz, Anett (coaut.) ; Wolf, Stephan (coaut.) ; Castillo Carrillo, Claudia A. (coaut.) ; Paxton, Robert J. (coaut.) ; Vandame, Rémy (coaut.) ;
Contenido en: Apidologie Vol. 44, no. 1, (January 2013), p. 113-120 ISSN: 0044-8435
Bibliotecas: Tapachula
SIBE Tapachula
51504-10 (Disponible)
Disponibles para prestamo: 1
Nota: En hemeroteca, SIBE-Tapachula
Resumen en: Inglés |
Resumen en inglés

The number of colonies in feral and managed honeybee populations (Apis mellifera) was determined for various sampling locations in Chiapas and Yucatan (Mexico) to assess the impact of apiculture on feral honeybee populations. We used a comparative sampling approach determining the number of colonies in similar habitats and landscapes but with different intensity of beekeeping. Sampling sites included nature reserves, and mango and shaded coffee plantations. The agricultural sites were all set in high-diversity landscapes with plenty of surrounding secondary forest. The number of colonies was determined by genotyping drones caught on drone congregation areas and assigning the drone genotypes to mother queens each heading a colony. We used three sets of linked markers each to achieve sufficient resolution for a precise colony assignment. The estimated colony numbers ranged from 34 to 54 colonies, with an average of 38.3 ± 6.9 colonies in areas with high and 43.5 ± 6.6 colonies in areas with low beekeeping activity. There was no significant difference in colony numbers between the sites with high and low beekeeping activity suggesting that the managed honeybee populations do not substantially add to the overall number of honeybee colonies supported in the wild. This might indicate that restrictions on apicultural activities to prevent any potential conservation conflict with native pollinators might not be useful, since honeybee colonies are very abundant in many different landscapes in Southern Mexico independent of apiculture.

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Efecto del uso del suelo en paisajes cafetaleros para la conservación de abejas nativas
Florez, Jaime Alberto (autor) ; Vandame, Rémy (autor) ; Ayala Barajas, Ricardo (autor) ; Paxton, Robert J. (autor) ;
Disponible en línea
Contenido en: Memorias del VII seminario mesoamericano sobre abejas nativas San Cristóbal de Las Casas, Chiapas, México : El Colegio de la Frontera Sur : Unión de Cooperativas Tosepan, 2011 p. 196-199
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Memorias: VI congreso mesoamericano sobre abejas nativas [Recurso electrónico] / editado por Carmen Lucía Yurrita
Congreso Mesoamericano sobre Abejas Nativas (VI : 2009 : Antigua Guatemala) ; Yurrita, Carmen Lucía (ed.) ;
Guatemala, Guatemala : Universidad de San Carlos de Guatemala, Centro de Estudios Conservacionistas :: Florida Center for Instructional Technology , [2009]
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Resumen en español

Las abejas constituyen un grupo de insectos importante, tanto ecológica como económicamente, debido a su participación en los procesos de polinización de una gran variedad de plantas silvestres y cultivadas. Además, el grupo de las abejas sociales es de especial interés para los humanos debido a su capacidad de almacenar miel y polen en sus colmenas. En la región mesoamericana este último grupo, comúnmente conocido como abejas sin aguijón, es especialmente importante ya que constituye, para muchas comunidades rurales, una fuente alternativa de alimento y medicina. Actualmente, la diversidad biológica nativa de la mayor parte del planeta está amenazada debido a la pérdida de hábitat natural, pero también por causa de la introducción de especies no nativas. Debido a esto, se hace necesario difundir los conocimientos que se generan sobre la diversidad biológica de nuestros países, para poder emplearlas de una manera racional.