Isolation of polymorphic microsatellite markers in the sub‐Saharan tree,Acacia (Senegalia) mellifera (Fabaceae: Mimosoideae)

We isolated 11 polymorphic microsatellite markers from Acacia mellifera, a savannah woodland tree in sub‐Saharan Africa and southern Arabia. The loci were screened for polymorphism using 48 Kenyan individuals. Allelic diversity ranged from three to 19 per locus and the polymorphic information content varied from 0.287 to 0.893. These loci will be useful in studies of genetic structure, gene flow and breeding systems.     

Benefits,costs and reactivity of inducible defences: an experimental test with rotifers

1. A key aspect of the ecology and evolution of adaptive prey responses to predator risk is the timing by which the former develop a defensive trait in response to inducing signals released by the latter. This property, called reactivity, has been shown to affect population stability and persistence. 2. Theoretically, the minimal predator density required by prey to exhibit induced defences is expected to increase with the effectiveness of the defence and decrease with its cost. Likewise, the time required for the prey population to exhibit an induced defence is expected to increase together with cost. 3. The freshwater rotifers Brachionus calyciflorus and B. havanaensis and their predator Asplanchna brightwelli were used to test the hypothesis that prey species exhibiting defences that offer a larger fitness benefit and lower fitness cost are more reactive to predator signals, in terms of requiring shorter exposure time and lower signal concentration to trigger a morphological defence reaction. 4. Our results showed that both prey species exhibited costly and effective defences after induction by predator infochemicals. Faster reactions were observed at higher levels of predator cues. Nevertheless, the observed relationship between reactivity and benefit/cost of defences did not agree with our expectations. 5. To our knowledge, this is the first study in which the timing of induction of morphological defences is experimentally assessed over a gradient of risk signals. We propose new research directions to disentangle the mechanisms and project the consequences of prey decisions at the morphological level.     

Laboratory and field evaluations of chemical and plant‐derived potential repellents against Culicoides biting midges in northern Spain

The efficacy of 23 compounds in repelling Culicoides biting midges (Diptera: Ceratopogonidae), particularly Culicoides obsoletus (Meigen) females, was determined by means of a Y‐tube olfactometer. The 10 most effective compounds were further evaluated in landing bioassays. The six most promising compounds (including chemical and plant‐derived repellents) were evaluated at 10% and 25% concentrations in field assays using Centers for Disease Control (CDC) light traps. At least three compounds showed promising results against Culicoides biting midges with the methodologies used. Whereas olfactometer assays indicated DEET at 1 µg/µL to be the most effective repellent, filter paper landing bioassays showed plant‐derived oils to be better. Light traps fitted with polyester mesh impregnated with a mixture of octanoic, decanoic and nonanoic fatty acids at 10% and 25% concentrations collected 2.2 and 3.6 times fewer midges than control traps and were as effective as DEET, which is presently considered the reference standard insect repellent. The best plant‐derived product was lemon eucalyptus oil. Although these have been reported as safe potential repellents, the present results indicate DEET and the mixture of organic fatty acids to be superior and longer lasting.     

Earliest South American paucituberculatans and their significance in the understanding of ‘pseudodiprotodont’ marsupial radiations

We describe the oldest Paucituberculata marsupials, from the La Barda and Las Flores localities (Argentina; Late Palaeocene, and Early–Middle Eocene), as well as from the Itaboraí Basin (Brazil; Late Palaeocene). The new taxa are represented by very scarce, although well‐preserved, dental remains. A parsimony analysis was performed in order to evaluate the phylogenetic affinities of these taxa. Representatives of both Riolestes capricornicus gen. et sp. nov. and Bardalestes hunco gen. et sp. nov. appear to be basal paucituberculatans, and their molar features give clues on the early evolution of the representatives of this order. Within the Paucituberculata we recognize two major clades: Caenolestoidea and Palaeothentoidea. We conclude that ‘pseudodiprotodont’ marsupials of the traditional literature (i.e. Polydolopimorphia + Paucituberculata) do not form a natural group. © 2009 The Linnean Society of London, Zoological Journal of the Linnean Society, 2009, 155 , 867–884.     

Heterozygote excess in ancient populations of the critically endangered Dioon caputoi (Zamiaceae,Cycadales) from central Mexico

Dioon caputoi is a long‐lived cycad known from only four populations that range in size from 50 to 120, mostly adult individuals. Dioon caputoi has the most narrow geographical range of all Dioon spp. (less than 10 km), existing completely within the boundaries of the Tehuacán–Cuicatlán Biosphere Reserve, Mexico. Negative inbreeding values were found in all four populations (F_IT = ?0.242) and within subpopulations (F_IS = ?0.379). Only c. 10% of the total genetic variation was partitioned among populations (F_ST = 0.099). We also found that most mean values of genetic variation (A = 1.91 ± 0.12; P = 78.9 ± 10.2; H_E = 0.35 ± 0.01) are within the range reported for other Dioon species with larger populations and with wider geographical ranges. These results support recent findings that rare plant species maintain high levels of genetic diversity. The heterozygote excess found at all loci is discussed in detail from a neutral evolutionary perspective, leaving arguments as working hypotheses for further research. © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society, 2008, 158 , 436–447.     

The Triassic fish faunas of the Cuyana Basin,Western Argentina

Abstract: The continental deposits of the Cuyana Basin, western Argentina, have yielded the most diverse, but so far almost unstudied, Triassic ichthyofaunas of South America. Here, we review these faunas and show that only eight of the 29 named taxa can be considered valid, including the chondrostean Neochallaia, the acrolepid Challaia, Guaymayenia, a taxon of uncertain affinities, and five species of the perleidiform family Pseudobeaconiidae. The first three taxa most probably come from Middle Triassic sediments, while the pseudobeaconiids are of Late Triassic age. Other material, although not diagnostic, probably represents other species, and thus, the diversity of actinopterygians in the Cuyana basin is certainly higher than currently recognized. For the Late Triassic fish fauna, the absence of crown‐group neopterygians and a single record of a sarcopterygian is noteworthy and probably indicates some degree of endemism in this fauna, also supported by the high abundance of pseudobeaconiids, which are unknown from other areas. Furthermore, on the basis of the age indicated by the fishes and the available geological information, we discuss the age of the local fauna of the Cerro Bayo, close to the city of Mendoza, and the Agua de la Zorra Formation, Uspallata.     

Characterization of Acanthamoeba Isolates from Dust of a Public Hospital in Curitiba, Paraná, Brazil

ABSTRACT. Occurrence of Acanthamoeba in the hospital environment may represent a health risk for patients, since these organisms can cause severe opportunistic illness, such as keratitis, and also can harbor pathogenic agents. We analyzed the dust from some environments of a public hospital in Curitiba, Parana State, Brazil. Two distinct populations of Acanthamoeba were isolated in five locations and morphologically classified as group I and group II according to Pussard and Pons. Isolates were identified as Acanthamoeba by PCR using primers to amplify a region of 18S rDNA, which showed variation in the product length among the isolates. A cloned culture of group II showed greater growth at 37 °C and in media with 0.1, 0.5, and 1.0 M mannitol, which are the physiological characteristics of pathogenic Acanthamoeba . Monitoring the presence of Acanthamoeba in hospital units, as well as evaluating the pathogenicity of the isolates, can be an approach to alert the health professionals to improve the disinfection procedures and minimize the risks of treating this problematic disease caused by this protozoan.     

Climatic niche and neutral genetic diversity of the six Iberian pine species: a retrospective and prospective view

Quaternary climatic fluctuations have left contrasting historical footprints on the neutral genetic diversity patterns of existing populations of different tree species. We should expect the demography, and consequently the neutral genetic structure, of taxa less tolerant to particular climatic extremes to be more sensitive to long‐term climate fluctuations. We explore this hypothesis here by sampling all six pine species found in the Iberian Peninsula (2464 individuals, 105 populations), using a common set of chloroplast microsatellite markers, and by looking at the association between neutral genetic diversity and species‐specific climatic requirements. We found large variation in neutral genetic diversity and structure among Iberian pines, with cold‐enduring mountain species (Pinus uncinata, P. sylvestris and P. nigra) showing substantially greater diversity than thermophilous taxa (P. pinea and P. halepensis). Within species, we observed a significant positive correlation between population genetic diversity and summer precipitation for some of the mountain pines. The observed pattern is consistent with the hypotheses that: (i) more thermophilous species have been subjected to stronger demographic fluctuations in the past, as a consequence of their maladaptation to recurrent glacial cold stages; and (ii) altitudinal migrations have allowed the maintenance of large effective population sizes and genetic variation in cold‐tolerant species, especially in more humid regions. In the light of these results and hypotheses, we discuss some potential genetic consequences of impending climate change.