Ecological implications of a flower size/number trade-off in tropical forest trees

Peer reviewedPublisher PD

High levels of genetic differentiation and selfing in the Brazilian cerrado fruit tree Dipteryx alata Vog. (Fabaceae)

Dipteryx alata is a native fruit tree species of the cerrado (Brazilian savanna) that has great economic potential because of its multiple uses. Knowledge of how the genetic variability of this species is organized within and among populations would be useful for genetic conservation and breeding programs. We used nine simple sequence repeat (SSR) primers developed for Dipteryx odorata to evaluate the genetic structure of three populations of D. alata located in central Brazil based on a leaf sample analysis from 101 adults. The outcrossing rate was evaluated using 300 open-pollinated offspring from 25 seed-trees. Pollen dispersal was measured by parentage analysis. We used spatial genetic structure (SGS) to test the minimal distance for harvesting seeds in conservation and breeding programs. Our data indicate that the populations studied had a high degree of genetic diversity and population structure, as suggested by the high level of divergence among populations . The estimated outcrossing rate suggested a mixed mating system, and the intrapopulation fixation index was influenced by SGS. We conclude that seed harvesting for genetic conservation and breeding programs requires a minimum distance between trees of 196 m to avoid collecting seeds from related seed-trees

Disturbance Alters the Phylogenetic Composition and Structure of Plant Communities in an Old Field System

The changes in phylogenetic composition and structure of communities during succession following disturbance can give us insights into the forces that are shaping communities over time. In abandoned agricultural fields, community composition changes rapidly when a field is plowed, and is thought to reflect a relaxation of competition due to the elimination of dominant species which take time to re-establish. Competition can drive phylogenetic overdispersion, due to phylogenetic conservation of ‘niche’ traits that allow species to partition resources. Therefore, undisturbed old field communities should exhibit higher phylogenetic dispersion than recently disturbed systems, which should be relatively ‘clustered’ with respect to phylogenetic relationships. Several measures of phylogenetic structure between plant communities were measured in recently plowed areas and nearby ‘undisturbed’ sites. There was no difference in the absolute values of these measures between disturbed and ‘undisturbed’ sites. However, there was a difference in the ‘expected’ phylogenetic structure between habitats, leading to significantly lower than expected phylogenetic diversity in disturbed plots, and no difference from random expectation in ‘undisturbed’ plots. This suggests that plant species characteristic of each habitat are fairly evenly distributed on the shared species pool phylogeny, but that once the initial sorting of species into the two habitat types has occurred, the processes operating on them affect each habitat differently. These results were consistent with an analysis of correlation between phylogenetic distance and co-occurrence indices of species pairs in the two habitat types. This study supports the notion that disturbed plots are more clustered than expected, rather than ‘undisturbed’ plots being more overdispersed, suggesting that disturbed plant communities are being more strongly influenced by environmental filtering of conserved niche traits

Contrasting Genetic Structure in Two Co-Distributed Species of Old World Fruit Bat

The fulvous fruit bat (Rousettus leschenaulti) and the greater short-nosed fruit bat (Cynopterus sphinx) are two abundant and widely co-distributed Old World fruit bats in Southeast and East Asia. The former species forms large colonies in caves while the latter roots in small groups in trees. To test whether these differences in social organization and roosting ecology are associated with contrasting patterns of gene flow, we used mtDNA and nuclear loci to characterize population genetic subdivision and phylogeographic histories in both species sampled from China, Vietnam and India. Our analyses from R. leschenaulti using both types of marker revealed little evidence of genetic structure across the study region. On the other hand, C. sphinx showed significant genetic mtDNA differentiation between the samples from India compared with China and Vietnam, as well as greater structuring of microsatellite genotypes within China. Demographic analyses indicated signatures of past rapid population expansion in both taxa, with more recent demographic growth in C. sphinx. Therefore, the relative genetic homogeneity in R. leschenaulti is unlikely to reflect past events. Instead we suggest that the absence of substructure in R. leschenaulti is a consequence of higher levels of gene flow among colonies, and that greater vagility in this species is an adaptation associated with cave roosting

Collaboration with general practitioners: preferences of medical specialists – a qualitative study

BACKGROUND: Collaboration between general practitioners (GPs) and specialists has been the focus of many collaborative care projects during the past decade. Unfortunately, quite a number of these projects failed. This raises the question of what motivates medical specialists to initiate and continue participating with GPs in new collaborative care models. The following question is addressed in this study: What motivates medical specialists to initiate and sustain new models for collaborating with GPs? METHODS: We conducted semi-structured interviews with eighteen medical specialists in the province of Groningen, in the North of The Netherlands. The sampling criteria were age, gender, type of hospital in which they were practicing, and specialty. The interviews were recorded, fully transcribed, and analysed by three researchers working independently. The resulting motivational factors were grouped into categories. RESULTS: 'Teaching GPs' and 'regulating patient flow' (referrals) appeared to dominate when the motivational factors were considered. In addition, specialists want to develop relationships with the GPs on a more personal level. Most specialists believe that there is not much they can learn from GPs. 'Lack of time', 'no financial compensation', and 'no support from colleagues' were considered to be the main concerns to establishing collaborative care practices. Additionally, projects were often experienced as too complex and time consuming whereas guidelines were experienced as too restrictive. CONCLUSION: Specialists are particularly interested in collaborating because the GP is the gatekeeper for access to secondary health care resources. Specialists feel that they are able to teach the GPs something, but they do not feel that they have anything to learn from the GPs. With respect to professional expertise, therefore, specialists do not consider GPs as equals. Once personal relationships with the GPs have been established, an informal network with incidental professional contact seems to be sufficient to satisfy the collaborative needs of the specialist. The concerns seem to outweigh any positive motivational forces to developing new models of collaborative practice

Combined use of gliadins and SSRs to analyse the genetic variability of the Spanish collection of cultivated diploid wheat (Triticum monococcum L. ssp. monococcum)

This work studied the combined use of gliadins and SSRs to analyse inter- and intra-accession variability of the Spanish collection of cultivated einkorn (Triticum monococcum L. ssp. monococcum) maintained at the CRF-INIA. In general, gliadin loci presented higher discrimination power than SSRs, reflecting the high variability of the gliadins. The loci on chromosome 6A were the most polymorphic with similar PIC values for both marker systems, showing that these markers are very useful for genetic variability studies in wheat. The gliadin results indicated that the Spanish einkorn collection possessed high genetic diversity, being the differentiation large between varieties and small within them. Some associations between gliadin alleles and geographical and agro-morphological data were found. Agro-morphological relations were also observed in the clusters of the SSRs dendrogram. A high concordance was found between gliadins and SSRs for genotype identification. In addition, both systems provide complementary information to resolve the different cases of intra-accession variability not detected at the agro-morphological level, and to identify separately all the genotypes analysed. The combined use of both genetic markers is an excellent tool for genetic resource evaluation in addition to agro-morphological evaluation

Genetic hitchhiking and resistance evolution to transgenic Bt toxins: insights from the African stalk borer Busseola fusca (Noctuidae)

Since transgenic crops expressing Bacillus thuringiensis (Bt) toxins were first released, resistance evolution leading to failure in control of pests populations has been observed in a number of species. Field resistance of the moth Busseola fusca was acknowledged 8 years after Bt maize was introduced in South Africa. Since then, field resistance of this corn borer has been observed at several locations, raising questions about the nature, distribution and dynamics of the resistance trait. Using genetic markers, our study identified four outlier loci clearly associated with resistance. In addition, genetic structure at neutral loci reflected extensive gene flow among populations. A realistically parameterised model suggests that resistance could travel in space at speed of several kilometres a year. Markers at outlier loci delineated a geographic region associated with resistance spread. This was an area of approximately 100 km radius, including the location where resistance was first reported. Controlled crosses corroborated these findings and showed significant differences of progeny survival on Bt plants depending on the origin of the resistant parent. Last, our study suggests diverse resistance mutations, which would explain the widespread occurrence of resistant larvae in Bt fields across the main area of maize production in South Africa

Motives and preferences of general practitioners for new collaboration models with medical specialists: a qualitative study

BACKGROUND: Collaboration between general practitioners (GPs) and specialists has been the focus of many collaborative care projects during the past decade. Unfortunately, quite a number of these projects failed. This raises the question of what motivates GPs to initiate and continue participating with medical specialists in new collaborative care models. The following two questions are addressed in this study: What motivates GPs to initiate and sustain new models for collaborating with medical specialists? What kind of new collaboration models do GPs suggest? METHODS: A qualitative study design was used. Starting in 2003 and finishing in 2005, we conducted semi-structured interviews with a purposive sample of 21 Dutch GPs. The sampling criteria were age, gender, type of practice, and practice site. The interviews were recorded, fully transcribed, and analysed by two researchers working independently. The resulting motivational factors and preferences were grouped into categories. RESULTS: 'Developing personal relationships' and 'gaining mutual respect' appeared to dominate when the motivational factors were considered. Besides developing personal relationships with specialists, the GPs were also interested in familiarizing specialists with the competencies attached to the profession of family medicine. Additionally, they were eager to increase their medical knowledge to the benefit of their patients. The GPs stated a variety of preferences with respect to the design of new models of collaboration. CONCLUSION: Developing personal relationships with specialists appeared to be one of the dominant motives for increased collaboration. Once the relationships have been formed, an informal network with occasional professional contact seemed sufficient. Although GPs are interested in increasing their knowledge, once they have reached a certain level of expertise, they shift their focus to another specialty. The preferences for new collaboration models are diverse. A possible explanation for the differences in the preferences is that professionals are more knowledge driven than organisation driven as the acquiring of new knowledge is considered more important than the route by which this is achieved. A new collaboration model seems a way to acquire knowledge. Once this is achieved the importance of a model possibly diminishes, whereas the professional relationships last