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Tierney SM Sanjur O Grajales GG Santos LM Bermingham E Wcislo WT 《Proceedings. Biological sciences / The Royal Society》2012,279(1729):794-803
Most bees rely on flowering plants and hence are diurnal foragers. From this ancestral state, dim-light foraging in bees requires significant adaptations to a new photic environment. We used DNA sequences to evaluate the phylogenetic history of the most diverse clade of Apoidea that is adapted to dim-light environments (Augochlorini: Megalopta, Megaloptidia and Megommation). The most speciose lineage, Megalopta, is distal to the remaining dim-light genera, and its closest diurnal relative (Xenochlora) is recovered as a lineage that has secondarily reverted to diurnal foraging. Tests for adaptive protein evolution indicate that long-wavelength opsin shows strong evidence of stabilizing selection, with no more than five codons (2%) under positive selection, depending on analytical procedure. In the branch leading to Megalopta, the amino acid of the single positively selected codon is conserved among ancestral Halictidae examined, and is homologous to codons known to influence molecular structure at the chromophore-binding pocket. Theoretically, such mutations can shift photopigment λ(max) sensitivity and enable visual transduction in alternate photic environments. Results are discussed in light of the available evidence on photopigment structure, morphological specialization and biogeographic distributions over geological time. 相似文献
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Carolina Camargo Jorge H. Maldonado Elvira Alvarado Rocío Moreno-Sánchez Sandra Mendoza Nelson Manrique Andrés Mogollón Juan D. Osorio Alejandro Grajales Juan Armando Sánchez 《Biodiversity and Conservation》2009,18(4):935-956
Climate change is posing new challenges to conservation because management policies on protected coral reefs are less effective
than they were before the current ecosystem degradation. Coral reefs, the most diverse and complex marine ecosystem provide
economic services for millions, but are seriously threatened worldwide because reef-building corals are experiencing bleaching
phenomena and a steady decline in abundance. The resources of a Marine Protected Area (MPA) in Cartagena, Colombia, are in
constant decline, despite a current management plan and on-site staff, urging new conservation actions. A multidisciplinary
team gathered to evaluate management effectiveness including biophysical, socioeconomic and governance indicators. Coral cover
and fish diversity and abundance were low both inside and outside the MPA, which suggests a limited efficiency of management.
Currently, the MPA is a reef with low coral cover and high algae cover as well as large dead coral areas, which are generally
signs of highly degraded reef habitats. Live coral cover in the MPA was represented by pioneer coral species such as Agaricia tenuifolia and Porites astreoides. Nonetheless, 35% of the scleractinian species sampled in the area harbored more than one zooxanthellae symbiont, which suggests
potential resistance and resilience against coral bleaching. Maintenance of trophic structure and functional diversity is
an important endeavor that should be a priority for management in order to allow ecosystem resilience. Social and governance
indicators showed low-income levels and few opportunities for communities living in and around the park, low governability,
weak communication among stakeholders and with authorities at different levels. As a result, problems related to over exploitation
of resources were commonplace in the MPA. These results reflect low adaptive capacity of communities to comply with restrictive
conservation rules, showing that establishment of a protected area is a necessary but insufficient condition to guarantee
conservation goals. Ignoring the role of local communities only will exacerbate the problems associated with natural resources.
Involvement of communities in strategic ecosystems management appears to be a requisite to improve effectiveness of protected
areas, and participatory strategies, such as co-management, offer opportunities to improve governability while letting communities
adapt to MPA needs. 相似文献
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