On the gains of committing to inefficiency: Corruption, deforestation and low land productivity in Latin America

We present a new explanation and empirical evidence showing that rural subsidies to large farmers tend to be associated with low land productivity and excessive deforestation. We develop a lobbying model where wealthy farmers trade bribes or political contributions to government politicians in exchange for subsidies; farmers are able to tilt the terms of the bargaining game with policy makers in their favor by pre-committing to an inefficient choice of semi-fixed inputs. Government proneness to accept political contributions or bribes and its willingness to provide subsidies cause farmers to adopt inefficient modes of production as a mechanism to capture such subsidies. Our predictions are consistent with stylized facts on land use in Latin America, and suggest that subsidy schemes have been counterproductive—distorting and constraining development, and triggering excessive depletion of natural resources. We validate some of the predictions of the model through econometric analyses using a new data set for nine countries in Latin America.     

Heavy metals and organic carbon in sediments from the Tuy River basin,Venezuela

The Tuy River basin, located in north-central Venezuela with an annual average temperature of 27°C and precipitation of 140 cm, was selected to conduct a geochemical study of bottom sediments, with the object of establishing the natural and human influences in the abundance and distribution of Fe, Mn, Cr, Co, Cu, Ni, Pb, Zn and organic carbon. The basin is lithologically divided into two sub-basins, north and south. The north sub-basin drains a iow-grade metasedimentary terrain with a population density of 800 persons km^–2 and approximateiy 600 industrial sites, while the south sub-basin in underlain by metavolcanic and ultramafic rocks, with a population density of less than 10 persons km^–2.Stream bottom sediment samples (150) were collected during the years of 1979–1986 in 16 unpolluted sites and 13 polluted sites. The sediments were air dried at room temperature and sieved through a 120 stainless steel mesh (125 m). Samples of grain size smaller than 125 m were analysed, the heavy metals being determined by atomic absorption spectrometry and the organic carbon (Corg) by dry combustion.The higher concentrations of heavy metals and organic carbon found in the pristine areas were in the south sub-basin, especially in those areas with higher annual precipitation and tropical forest. This indicated that the metavolcanic and ultramafic rocks yield higher concentrations of heavy metals than the metasedimentary rocks. It was also noted that the higher concentrations of Cr and Ni are associated with the ultramafic rocks. The results obtained from the sediment samples collected in the polluted sites showed that the elements Pb, Zn and Corg are enriched up to 4 times as a result of ail the human activities taking place in the basin. Organic carbon is an excellent indicator of domestic wastewater, Pb and Zn are good indicators of the automotive traffic and industrial effluents. The concentrations of each heavy metal did not show any significant correlation with grain size fractions; however, the concentration of organic carbon did show a negative correlation with grain size. The lithological, climatic and vegetation influence in the abundance of heavy metals and organic carbon in stream sediments clearly indicates the necessity of establishing background levels for the area under study when carrying out studies in environmental geochemistry.     

Population genetics of the swimming crab<Emphasis Type="Italic"> Callinectes bellicosus</Emphasis> (Brachyura: Portunidae) from the eastern Pacific Ocean

The population genetics and historical demography of the swimming crab Callinectes bellicosus from the eastern Pacific were assessed using mitochondrial DNA (mtDNA) sequences from portions of the cytochrome c oxidase subunit I (COI) and cytochrome b (Cytb) genes. Analysis of molecular variance of sequence data from crabs collected from nine localities, ranging from the upper to lower Gulf of California and the outer coast of the Baja California peninsula, revealed an absence of population structure, suggesting a high level of gene flow over a wide geographic area. Maximum-likelihood estimates of long-term effective population size obtained with the program FLUCTUATE, in addition to highly significant values obtained from neutrality tests (Tajimas D, Fu and Lis D, and Fus F_S) and mismatch analysis, are consistent with a population expansion dating to the Pleistocene epoch. Phylogenetic analysis of C. bellicosus sequences using both neighbor-joining and Bayesian methods revealed a widely distributed subclade (clade II) cryptically embedded at low frequency in the main (clade I) population. Although sequence divergence between the two clades was low (1.1% COI; 0.6% Cytb), statistical support for the split was high. The Kimura-2-parameter genetic distance between C. bellicosus and the sympatric and morphologically similar C. arcuatus was high (d=0.17) and similar to the genetic distance between C. bellicosus and the allopatric C. sapidus from the western Atlantic (d=0.18), suggesting an ancient (Miocene) divergence of C. bellicosus and C. arcuatus.Communicated by P.W. Sammarco, Chauvin     

Accumulation of mesozooplankton in a wake area as a causative mechanism of the “island-mass effect”

Mesozooplankton biomass (as displacement volume and protein content) and electron-transport system (ETS) activity have been studied in the coastal waters around the Canary Islands. Increases in biomass and ETS activity, on a unit volume basis, were observed in the wakes of the islands. The biomass values obtained in the leeward area for Gran Canaria Island were up to ten times higher than those observed for typical oceanic waters around this archipelago. Sampling was performed in May 1986 at the end of the characteristic vertical mixing period in these waters. Relatively strong winds were recorded prior to sampling. Specific ETS activity was higher at the windward stations on the island shelf. This correlates with the observation in a recent study of increased primary production on the shelf area, where turbulence produced by the northerly trade winds has a marked effect. The persistence of this turbulence during a prolonged wind-pulse results in an accumulation of organisms in the wake of the islands due to current dynamics. This process is proposed as being an important causative mechanism of the island-mass effect. Different biomass values were recorded between circular and oblong islands. The latter are oriented towards the current and the northerly trade winds, and display significantly lower biomass values than the former.     

Reproduction and life-cycle of the beachflea (<Emphasis Type="Italic">Orchestia gammarellus</Emphasis> (Pallas) (Crustacea: Amphipoda) at thermal and non-thermal sites in the intertidal of Iceland: how important is temperature?

The littoral fringe beachflea Orchestia gammarellus (Pallas) is a seasonal breeder over much of its range. Previous studies indicated that temperature was the most important factor initiating breeding while photoperiod appeared inconsequential. We tested the effect of temperature by comparing two populations at non-thermal sites with two populations at thermal sites in Iceland. At the non-thermal sites the species is probably close to its lower temperature tolerance limits, while potentially able to choose optimal temperatures at all times of the year at the thermal sites. The species was a seasonal breeder at all sites, but the breeding season started 2–3 months earlier at thermal sites. Breeding ended at about the same time at all sites. We conclude that photoperiod probably governs breeding season under constant thermal conditions, and this is also supported by observations on laboratory stocks. At the thermal sites the animals became sexually mature in a year or less, as is the case where the species has been studied at lower latitudes, while at the non-thermal sites Icelandic animals, apparently uniquely, need 2 years to become sexually mature.     

Chemical ornaments of male lizards <Emphasis Type="Italic">Psammodromus algirus</Emphasis> may reveal their parasite load and health state to females

Evidence for parasite-mediated sexual selection has been found in many species that use visual ornaments to attract females. However, in many animals, variation in female responses to scents of parasitized males suggests that parasitic infections might also affect information conveyed by pheromones (i.e., chemical ornaments). Thus, pheromones might also function in parasite-mediated sexual selection. We show here that female lizards Psammodromus algirus responded differently to femoral gland secretions of males according to the parasite load and health of these males. Scents of healthier males elicited more tongue flicks (a chemosensory behavior) by females, suggesting that these scents were more attractive. Chemical analyses showed that parasite load and the T-cell-mediated immune response were related to the variability in the proportions of some lipids in secretions of males. Further trials testing the chemosensory responses of females to chemical standards indicated that females actually discriminated the chemicals related to males’ health from other chemicals found in secretions. We suggest that these chemical ornaments may provide reliable information on the health and degree of parasitic infection of a male.     

Fly ash content and distribution in lake sediments around a large power station: inferences from magnetic susceptibility analysis

The bulk magnetic susceptibility of sediments from artificial and natural lakes around a large coal-fired power station in NE Spain has been measured. Higher magnetic susceptibility values are found in lake sediments located SE of the power station. This distribution of susceptibility values is compatible with environmental and meterological studies of emissions from the power station, which indicate a dominant SE plume direction. Mineralogical studies, by means of X-ray diffraction and scanning electron microscopy, show that the highest susceptibility values found in the sediments are caused by magnetic iron spinels in the fly ash that is transferred to the environment by the power station particulate emissions. After the quantitative mineralogical studies of fly ash, two different methods of fly ash content determination in the sediments have been devised, showing very similar results. The low background magnetic susceptibility of the sediments in the study area and the high susceptibility resulting from the input of magnetic fly ash particles allows both delimitation of the polluted area around the power station, and quantification of the fly ash input into the natural sediments.     

Spatial distribution of the infaunal benthic communities of the Ría de Muros,north-west Spain

Benthic samples were collected at 13 stations in the Ría de Muros, north-west Spain. There are three major communities: (1) in the southern and outer part of the ría, an Amphiura filiformis—Thyone fusus community, inhabiting sandy sediments with low organic content; (2) in the middle part of the ría, and Amphiura chiajei—Maldane glebifex community, inhabiting muddy sediments that are not anoxic (sulphide not detected); (3) in Muros Bay and the inner part of the ría, a Spiochaetopterus costarum community, inhabiting anoxic sediments with high organic content. Biomass is very high (up to 46.2 g ash-free dry wt) in the first two communities. In the Spiochaetopterus costarum community, biomass and diversity are much lower, probably because of oxygen deficiency.     

Individual dispersal status influences space use of conspecific residents in the common lizard, Lacerta vivipara

The effects of immigration on the behaviour of residents may have important implications for the local population characteristics. A manipulative laboratory experiment with yearlings of the common lizard (Lacerta vivipara) was performed to test whether the introduction of dispersing or philopatric individuals influences the short-term spacing behaviour of resident individuals. Staged encounters were carried out to induce interactions within dyads. The home cage of each responding individual was connected by a corridor to an unfamiliar “arrival cage” to measure the latency to leave their own home cage after each encounter. Our results showed that the time that pairs spent in close proximity was longer when a dispersing individual was introduced in the home cage. The latency to leave the home cage was longer after the introduction of a dispersing individual. These response variables were not influenced by the relative body sizes of contestants nor by the level of aggression towards each other. In contrast, the aggressive response was significantly influenced by the residency asymmetry established experimentally (“owner” of the home cage vs introduced individual). Our results suggest that the space use by resident individuals is influenced by the dispersal status of conspecifics. The potential ultimate causes driving this effect are discussed.