Genetic diversity in Atlantic Forest trees: fragmentation effects on Astronium graveolens (Anacardiaceae) and Metrodorea nigra (Rutaceae), species with distinct seed dispersal strategies

We explore the genetic structure and variability in autochorous Metrodorea nigra (Rutaceae) and anemochorous Astronium graveolens (Anacardiaceae), two species affected by deforestation in the Atlantic Forest of Brazil. The effects of deforestation and the depletion of the habitat within the remaining patches of forest are evaluated by comparing the variability between saplings and adults of each of these two species. The results indicate that the depletion of forest land and the deteriorating condition of the remaining fragments of forest may reduce the level of endogamous breeding in wind‐dispersed species. In autochorous species, the fragmentation of forest land has less notable effects on genetic attributes, but pollen flow could be decreased as a result of the reduced number of insects flying between the forest remnants. © 2010 The Linnean Society of London, Botanical Journal of the Linnean Society, 2010, 164 , 326–336.     

Turtle groups or turtle soup: dispersal patterns of hawksbill turtles in the Caribbean

Despite intense interest in conservation of marine turtles, spatial ecology during the oceanic juvenile phase remains relatively unknown. Here, we used mixed stock analysis and examination of oceanic drift to elucidate movements of hawksbill turtles (Eretmochelys imbricata) and address management implications within the Caribbean. Among samples collected from 92 neritic juvenile hawksbills in the Cayman Islands we detected 11 mtDNA control region haplotypes. To estimate contributions to the aggregation, we performed ‘many‐to‐many’ mixed stock analysis, incorporating published hawksbill genetic and population data. The Cayman Islands aggregation represents a diverse mixed stock: potentially contributing source rookeries spanned the Caribbean basin, delineating a scale of recruitment of 200–2500 km. As hawksbills undergo an extended phase of oceanic dispersal, ocean currents may drive patterns of genetic diversity observed on foraging aggregations. Therefore, using high‐resolution Aviso ocean current data, we modelled movement of particles representing passively drifting oceanic juvenile hawksbills. Putative distribution patterns varied markedly by origin: particles from many rookeries were broadly distributed across the region, while others would appear to become entrained in local gyres. Overall, we detected a significant correlation between genetic profiles of foraging aggregations and patterns of particle distribution produced by a hatchling drift model (Mantel test, r = 0.77, P < 0.001; linear regression, r = 0.83, P < 0.001). Our results indicate that although there is a high degree of mixing across the Caribbean (a ‘turtle soup’), current patterns play a substantial role in determining genetic structure of foraging aggregations (forming turtle groups). Thus, for marine turtles and other widely distributed marine species, integration of genetic and oceanographic data may enhance understanding of population connectivity and management requirements.     

Reproduction of Antarctic Benthic Marine Invertebrates: Tempos, Modes, and Timing

Work on the life histories of common antarctic benthic marineinvertebrates over the past several decades demands a revisionof several widely held paradigms. First, contrary to expectationsderived from work on temperate species, there is little or noevidence for temperature adaptation with respect to reproduction(gametogenesis), development, and growth. It remains to be determinedwhether the slow rates of these processes reflect some inherentinability to adapt to low temperatures, or are a response tofeatures of the antarctic marine environment not directly relatedto low temperature, such as low food resources. Secondly, contraryto the widely accepted opinion designated as "Thorson's rule,"pelagic development is common in many groups of shallow-watermarine invertebrates. In fact in some groups, such as asteroids,pelagicdevelopment is as prevalent in McMurdo Sound, the southern-mostopen-water marine environment in the world, as in central California.In other taxonomic groups, especially gastropods, there doesseem to be a genuine trend toward non-pelagic development fromtropical to antarctic latitudes. Although this trend has beenpredicted by theoretical models, its underlying causes appearto be group specific rather than general. Thirdly, pelagic lecithotrophicdevelopment, often considered to be of negligible importance,occurs in many shallow-water antarctic marine macroinvertebrates.Pelagic lecithotrophy may be an adaptation to a combinationof poor food conditions in antarctic waters most of the yearand slow rates of development. Nevertheless, some of the mostabundant and widespread antarctic marine invertebrates havepelagic planktotrophic larvae that take very long times to completedevelopment to metamorphosis. These species areparticularlyprevalent in productive regions of shallow water (<30 m),which are frequently disturbed by anchor ice formation, andthe production of numerous pelagic planktotrophic larvaemayrepresent a strategy for colonization. Although planktotrophiclarvae tend to be seasonal in occurrence, their production isnot linked particularly closely to the mid-summer pulse of phytoplanktonproduction. These larvae show no evidence of starvation, evenduring times when phytoplankton abundance is very low, and theymay depend on unusual sources of food, such as bacteria. Howthey escape the selective conditions that apparently led toa predominance of non-feeding modes of development in antarcticmarine invertebrates remains as a major challenge for antarcticmarine biology.     

Activation of Brain Succinate Dehydrogenase by Lithium

IN spite of the widespread use of lithium salts as therapeutic and prophylactic agents against manic-depressive psychosis^{1, 2}, little is known about the mechanism of lithium effects^{3, 4}. Li⁺ stimulates noradrenergic neurones³, increases the uptake of this amine by isolated rat brain synaptosomes^{5, 6}, increases serotonin uptake into platelets obtained from manic-depressive patients⁷ and increases the levels of serotonin and tryptophan in rat brain⁸. On the other hand, Lallier observed inhibitory action of LiCl on dehydrogenase activity in homogenates of Rana fusca⁹. We have investigated whether long term treatment with Li⁺ affects brain succinate dehydrogenase activity.     

Borate promotes the formation of a complex between legume AGP‐extensin and Rhamnogalacturonan II and enhances production of Rhizobium capsular polysaccharide during infection thread development in Pisum sativum symbiotic root nodules

The capacity to bind to biomolecules is considered to be the basis for any physiological role of boron (B). Legume arabinogalactan protein‐extensin (AGPE), a major component of the infection thread matrix of legume nodules is a potential B‐ligand. Therefore, its role in infection threads development was investigated in Pisum sativum grown under B deficiency. Using the AGPE‐specific antibody MAC265, immunochemical analysis revealed that a 175 kDa MAC265 antigen was abundant in +B but much weaker in –B nodule extracts. A B‐dependent complex involving AGPE and rhamnogalacturonan II (RGII) could be co‐purified using anti‐RGII antiserum. Following fractionation of –B nodules, MAC265 antigens were mostly associated with the bacterial pellet. Immunogold staining confirmed that AGPE was closely associated with the surface of rhizobia in the lumen of threads in ?B nodules whereas in +B nodules, AGPE was separated from the bacterial surface by a sheath of capsular polysaccharide. Interestingly, colonies of rhizobia grown in free‐living culture without B developed low capsule production. Therefore, we propose that B could be important for apical growth of infection threads by strengthening thread wall through a B‐dependent AGPE‐RGII interaction and by promoting bacterial advance through a B‐dependent production of a stable rhizobial capsule that prevents AGPE attachment.     

An integrated greenhouse gas assessment of an alternative to slash-and-burn agriculture in eastern Amazonia

Fires set for slash‐and‐burn agriculture contribute to the current unsustainable accumulation of atmospheric greenhouse gases, and they also deplete the soil of essential nutrients, which compromises agricultural sustainability at local scales. Integrated assessments of greenhouse gas emissions have compared intensive cropping systems in industrialized countries, but such assessments have not been applied to common cropping systems of smallholder farmers in developing countries. We report an integrated assessment of greenhouse gas emissions in slash‐and‐burn agriculture and an alternative chop‐and‐mulch system in the Amazon Basin. The soil consumed atmospheric methane (CH₄) under slash‐and‐burn treatment and became a net emitter of CH₄ to the atmosphere under the mulch treatment. Mulching also caused about a 50% increase in soil emissions of nitric oxide and nitrous oxide and required greater use of fertilizer and fuel for farm machinery. Despite these significantly higher emissions of greenhouse gases during the cropping phase under the alternative chop‐and‐mulch system, calculated pyrogenic emissions in the slash‐and‐burn system were much larger, especially for CH₄. The global warming potential CO₂‐equivalent emissions calculated for the entire crop cycles were at least five times lower in chop‐and‐mulch compared with slash‐and‐burn. The crop yields were similar for the two systems. While economic and logistical considerations remain to be worked out for alternatives to slash‐and‐burn, these results demonstrate a potential ‘win‐win’ strategy for maintaining soil fertility and reducing net greenhouse gas emissions, thus simultaneously contributing to sustainability at both spatial scales.     

Biogeographical and evolutionary patterns in the Macaronesian shield-backed katydid genus Calliphona Krauss, 1892 (Orthoptera: Tettigoniidae) and allies as inferred from phylogenetic analyses of multiple mitochondrial genes

Abstract.  We investigated the phylogenetic patterns, evolutionary processes, and their taxonomic implications, of two closely related shield-backed katydid genera endemic to the Macaronesian archipelagos: the monotypic Psalmatophanes Chopard, 1938 endemic to Madeira and Calliphona Krauss, 1892, which includes three species restricted to the Canary Islands. Two main hypotheses have been proposed to explain the origin and colonization pathways of these two genera: a single origin with subsequent sequential colonization of the islands, or three independent colonization waves from continental Africa. We used DNA sequence information from the mitochondrial genes cox1, tRNAleucine, rrnL and nad1 to infer phylogenetic relationships among Psalmatophanes and Calliphona species. Our results provide support for the independent colonization of Madeira and the Canary Islands, and suggest that Psalmatophanes is actually more closely related to the continental genus Tettigonia than to the Canarian representatives. Deep genetic divergence among Canarian species provides further support for the assignment of the Canarian species into two subgenera. Tree topology along with Bayesian-based estimates of lineage age suggest a pattern of colonization from Tenerife to La Palma, and from Tenerife to Gran Canaria with subsequent dispersal to La Gomera. We report the first collection of a Calliphona specimen in the island of El Hierro, which molecular data suggest is a recent immigrant from La Gomera. We hypothesize that the patterns of distribution and genetic divergence exhibited by Calliphona in the Canary Islands are compatible with a taxon cycle process. Our results have further implications for the higher level phylogeny of the subfamily Tettigoniinae and suggest that some of the tribes as currently delimited may not correspond to natural groups.