Phylogeography of Plathymenia reticulata (Leguminosae) reveals patterns of recent range expansion towards northeastern Brazil and southern Cerrados in Eastern Tropical South America

Little is known about past vegetation dynamics in Eastern Tropical South America (ETSA). Here we describe patterns of chloroplast (cp) DNA variation in Plathymenia reticulata, a widespread tree in the ETSA Atlantic Forest and Cerrado biomes, but not found in the xeromorphic Caatinga. Forty one populations, comprising 220 individuals, were analysed by sequencing the trnS‐trnG and trnL‐trnL‐trnF cpDNA regions. Combined, they resulted in 18 geographically structured haplotypes. The central region of the sampling area, comprising Minas Gerais and Goiás Brazilian states, is a centre of genetic diversity and probably the most longstanding area of the distribution range of the species. In contrast, populations from northeastern Brazil and the southern Cerrados showed very low diversity levels, almost exclusively with common haplotypes which are also found in the central region. Coupled with a long‐branched star‐like network, these patterns suggest a recent range expansion of P. reticulata to those regions from central region sources. The recent origin of the species (in the early Pleistocene) or the extinction of some populations due to drier and cooler climate during the last glacial maximum could have been responsible for that phylogeographic pattern. The populations from northeastern Brazil originated from two colonization routes, one eastern (Atlantic) and one western (inland). Due to its high diversity and complex landscape, the central region, especially central‐north Minas Gerais (between 15°–18° S and 42°–46° W), should be given the highest priority for conservation.     

Retracted: MHC diversity and differential exposure to pathogens in kestrels (Aves: Falconidae)

Pathogen diversity is thought to drive major histocompatibility complex (MHC) polymorphism given that host’s immune repertories are dependent on antigen recognition capabilities. Here, we surveyed an extensive community of pathogens (n = 35 taxa) and MHC diversity in mainland versus island subspecies of the Eurasian kestrel Falco tinnunculus and in a sympatric mainland population of the phylogenetically related lesser kestrel Falco naumanni. Insular subspecies are commonly exposed to impoverished pathogen communities whilst different species’ ecologies and contrasting life‐history traits may lead to different levels of pathogen exposure. Although specific host traits may explain differential particular infections, overall pathogen diversity, richness and prevalence were higher in the truly cosmopolitan, euriphagous and long‐distance disperser Eurasian kestrel than in the estenophagous, steppe‐specialist, philopatric but long‐distance migratory lesser kestrel. Accordingly, the continental population of Eurasian kestrels displayed a higher number (64 vs. 49) as well as more divergent alleles at both MHC class I and class II loci. Detailed analyses of amino acid diversity revealed that significant differences between both species were exclusive to those functionally important codons comprising the antigen binding sites. The lowest pathogen burdens and the smallest but still quite divergent set of MHC alleles (n = 16) were found in island Eurasian kestrels, where the rates of allele fixation at MHC loci seem to have occurred faster than at neutral markers. The results presented in this study would therefore support the role of pathogen diversity and abundance in shaping patterns of genetic variation at evolutionary relevant MHC genes.     

Ant diversity in an Amazonian savanna: Relationship with vegetation structure,disturbance by fire,and dominant ants

Abstract The savannas of South America support a relatively diverse ant fauna, but little is known about the factors that influence the structure and dynamics of these assemblages. In 1998 and 2002, we surveyed the ground‐dwelling ant fauna and the fauna associated with the woody vegetation (using baits and direct sampling) from an Amazonian savanna. The aim was to evaluate the influence of vegetation structure, disturbance by fire and dominant ants on patterns of ant species richness and composition. Variations in the incidence of fires among our 39 survey plots had no or only limited influence on these patterns. In contrast, spatial variations in tree cover and cover by tall grasses (mostly Trachypogon plumosus), significantly affected ant species composition. Part of the variation in species richness among the study plots correlated with variations in the incidence of a dominant species (Solenopsis substituta) at baits. Ant species richness and composition also varied through time, possibly as an indirect effect of changes in vegetation cover. In many plots, and independently of disturbance by fire, there was a major increase in cover by tall grasses, which occupied areas formerly devoid of vegetation. Temporal changes in vegetation did not directly explain the observed increase in the number of ant species per plot. However, the incidence of S. substituta at baits declined sharply in 2002, especially in plots where changes in vegetation cover were more dramatic, and that decline was correlated with an increase in the number of ground‐dwelling species, a greater turnover of bait‐recruiting species and the appearance of the little fire ant Wasmannia auropunctata. The extent to which these changes in fact resulted from the relaxation of dominance by S. substituta is not clear. However, our results strongly suggest that the ant fauna of Amazonian savannas is affected directly and indirectly by the structure of the vegetation.     

Effect of adults on juvenile reproduction of Calomys venustus (Muridae: Sigmodontinae)

Abstract We tested the hypothesis that adult overwintering Calomys venustus inhibit maturation and reproduction in young‐of‐the‐year from the first cohort. The study was carried out in four 0.25‐ha enclosures (two control and two experimental), each situated on natural pasture. This study was conducted between August 1997 and March 1999 and had two parts: removal of overwintering male (ROM) and removal of overwintering female (ROF). For the ROM treatment overwintering males were removed immediately after the first cohort of juveniles were born, in the ROF treatment overwintering females were removed after the first cohort were weaned. Weekly censuses were taken for three successive days over 6 weeks. The sexual maturation and reproductive condition of juveniles were compared between treatments (overwintering male or female removal) using repeated‐measures anova . The repeated measures factor was the age of juveniles. Removal of overwintering males and females did not affect sexual maturation of juveniles, however, overwintering males influenced the onset of reproductive activity of juvenile females at the beginning of the breeding period.     

Production via good manufacturing practice of exofucosylated human mesenchymal stromal cells for clinical applications

Background

The regenerative and immunomodulatory properties of human mesenchymal stromal cells (hMSCs) have raised great hope for their use in cell therapy. However, when intravenously infused, hMSCs fail to reach sites of tissue injury. Fucose addition in α(1,3)-linkage to terminal sialyllactosamines on CD44 creates the molecule known as hematopoietic cell E-/L-selectin ligand (HCELL), programming hMSC binding to E-selectin that is expressed on microvascular endothelial cells of bone marrow (BM), skin and at all sites of inflammation. Here we describe how this modification on BM-derived hMSCs (BM-hMSCs) can be adapted to good manufacturing practice (GMP) standards.

Sex,life history and morphology drive individual variation in flight performance of an insect parasitoid

1. The movement of organisms can be driven by multiple factors and has implications for fitness and the spatial distribution of populations. Insects spend a large proportion of their adult lives foraging by flying for resources; however, their capability and motivation to move can vary across individuals. 2. The aims of this study were to examine interindividual and sex differences in flight performance and flight characteristics, using a flight mill bioassay, in Megarhyssa nortoni (Hymenoptera; Ichneumonidae), a parasitoid of the invasive woodwasp Sirex noctilio (Hymenoptera: Siricidae), one of the most important pests of pine afforestation worldwide. We also assessed the influence of morphological traits in combination with sex on flight and explored the cost of flight on longevity and mass loss. 3. The results show a difference between sexes in flight characteristics and performance. Females show greater total distance flown than males, and have a better capacity to undergo sustained flight. Sexual size dimorphism was also found and it was noted that size positively affects distances travelled. Females have a longer life span than males, yet no differences were noted in longevity within sex between individuals that did not fly and those that flew. Age did not influence flight performance of females or impacted on post‐flight longevity. Females lost less body mass than males even after flying longer distances. 4. These results suggest that sex‐specific behaviours probably govern flight abilities together with (and not only because of) morphological traits. The paper discusses sex‐specific life‐history strategies in parasitoids and their implications for biocontrol programmes.     

Why do some species in arid lands increase under grazing? Mechanisms that favour increased abundance of Maireana pyramidata in overgrazed chenopod shrublands of South Australia

While the abundance of some plant species decreases under high grazing intensity, others become more abundant. Release from competition by decreaser species contributes to this pattern in mesic systems, but this may not be the case in xeric systems where competition may be less intense. Here we examine three mechanisms that may be involved: (i) increased recruitment and growth because of soil changes produced by grazing, for example, increased soil nutrient availability through dung accumulation; (ii) increased recruitment favoured by the breaking up of the lichen crust; and (iii) reduced competition because of the decline of decreaser species. We used field and glasshouse experiments to determine the possible contribution of these mechanisms to the increase of the chenopod Maireana pyramidata around a watering point in a chenopod shrubland of South Australia. There was no evidence of nutrient accumulation close to the watering point, and while seedlings of M. pyramidata responded to nutrient addition, their growth was the same in soil collected from areas with different grazing intensity. While a broken lichen crust increased the emergence of both M. pyramidata and the decreaser Atriplex vesicaria, the effect was larger for the former. We found no competition between seedlings of the two species or between juveniles of A. vesicaria and seedlings of M. pyramidata in glasshouse experiments. Adult plants of both A. vesicaria and M. pyramidata produced similar growth reduction in seedlings of M. pyramidata. Furthermore, a field removal experiment failed to detect any competitive effect of A. vesicaria on M. pyramidata. Our data indicate that the disintegration of the soil crust by grazer activities can be a major factor controlling floristic changes in overgrazed rangelands. These results imply that factors that control establishment may be more important than competition in shaping shrub population dynamics in these systems. Ground surface itself can affect establishment opportunities, and this should be taken into account in management and restoration efforts in arid lands.     

Environmental controls and patterns of cumulative radial increment of evergreen tree species in montane,temperate rainforests of Chiloé Island,southern Chile

We investigated the local environmental controls on daily fluctuations of cumulative radial increment and cambial hydration of three dominant, evergreen tree species from montane, Coastal rainforests of Chiloé Island, Chile (42° 22′ S). During 2 years (1997–1998 and 1998–1999) we recorded hourly cumulative radial increments using electronic band dendrometers in the long‐lived conifer Fitzroya cupressoides (Cupressaceae), the evergreen broad‐leaved Nothofagus nitida (Nothofagaceae), and the narrow‐leaved conifer Podocarpus nubigena (Podocarpaceae). We also measured soil and cambial tissue hydration using capacitance sensors, together with air and soil temperature and rainfall during the period of the study. In addition, we collected cores of these tree species to evaluate how dendrometer measurements reflect annual tree ring width. One‐year long daily time series of cumulative radial increments suggests that radial growth of Fitzroya cupressoides was initiated slowly in early spring, with a maximum in early summer. Multiple regressions showed positive relations between daily precipitation and radial index (i.e. the difference in cumulative radial increment of two consecutive days) in the three species. According to path analysis there was a significant direct effect of changes in tree hydration on radial index of the three focal species. In emergent, pioneer species such as Nothofagus and Fitzroya, radial index was negatively affected by changes in maximum air temperature and photosynthetically active radiation, probably because of high evapotranspiration demand on warm sunny days. The shade‐tolerant species Podocarpus nubigena was positively affected by photosynthetically active radiation. Our diel scale findings support the use of tree ring widths for reconstructing past climate in these southern temperate forests and provide evidence that rainforest trees may be highly sensitive to future declines in rainfall and temperature increases during summer.     

Genetic and morphological differentiation of the mangrove crab Perisesarma guttatum (Brachyura: Sesarmidae) along an East African latitudinal gradient

The genetic structure and morphometric differentiation of mangrove crab Perisesarma guttatum populations were examined among shelf connected locations along a latitudinal gradient on the East African coast. Over 2200 specimens were sampled from 23 mangrove sites for geometric morphometrics analysis. Population genetic analyses of mitochondrial cytochrome c oxidase subunit I (COI) DNA sequences were used to evaluate connectivity among populations. A total of 73 haplotypes were detected, and almost no haplotypes were found in common between two highly supported phylogeographic clades: southern Mozambique (Inhaca Island and Maputo Bay) and a northern clade that included north Mozambique, Tanzania and Kenya. These two clades were identified based on the species' populations pairwise genetic differentiation and geographical location. Φ_ST values were considerably high between the two clades, indicating the presence of significant population genetic structure between Kenya and South Mozambique. However, each clade was composed of genetically similar populations along the latitudinal gradient, and no significant population structure was found within each clade because the Φ_st values were not significant. The morphometric analysis corroborated the division into two clades (i.e. Inhaca Island/Maputo Bay and northern populations) and also detected less shape variation among populations that were few kilometres apart. The significant spatial genetic structuring between the southern and the northern populations of P. guttatum along the geographic gradient under study, combined with morphological differences, suggests that these populations may be considered as cryptic species. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 99 , 28–46.