Assemblages of drosophilids (Diptera, Drosophilidae) in mangrove forests: community ecology and species diversity

Brazilian fauna of drosophilids has been researched in various ecosystems, but those in mangrove forests remain overlooked in Brazil and elsewhere. The present study attempts to characterise the assemblages of drosophilids of this environment, based on 28 collections taken in three mangrove areas in Santa Catarina Island, southern Brazil. The three mangroves surveyed were different in their surroundings, which varied from highly urbanised areas to conservation areas with natural vegetation. Overall, 69 species were collected, and no remarkable difference was detected in species composition and abundances or in the richness, evenness and heterogeneity between sites. The species abundance distribution observed fitted to a theoretical lognormal distribution in the three mangroves. The species richness scored and the performance of the species richness estimators showed an unexpectedly high diversity, considering the very low floristic diversity and the harsh conditions of the environment. Regarding species composition and abundances, the drosophilid mangrove assemblages were shown to be more similar to those found in open environments, with a marked dominance of exotic species. Finally, considering the apparent lack of feeding and breeding sites, we suggest that mangrove forests are acting as sink habitats for the drosophilids populations.

Structure and diversity of endoparasitic infracommunities and the trophic level of Pseudoplatystoma corruscans and Schizodon borelli (Osteichthyes) of the high Paraná river

One hundred and ten specimens of Pseudoplatystoma corruscans (Pimelodidae) and 582 specimens of Schizodon borelli (Anostomidae) collected in the high Paraná River were analyzed. On necropsy 74% of P. corruscans were found to be parasitized; proteocephalidean cestodes presented the greatest number. With regard to S. borelli, the percentage of parasitism reached 19.42% and the nematode Cucullanus pinnai was the most abundant. The absence of correlation between the endoparasitic diversity and the standard length of the two host species indicates that each one presents homogeneity in alimentary behaviour during all its life time, permiting the uniform recruitment of the same species of endoparasites during all its ontogenetic development. Independence of diversity values in relation to sex of P. corruscans and S. borelli evidences that the ecological relationships are similar between males and females in these species. Both host's infrapopulations presented a typical overdispersed pattern of distribution with isolationist characteristics.

Cattle Dung Breeding Diptera in Pastures in Southeastern Brazil: Diversity, Abundance and Seasonallity

Diptera that breed in undisturbed cattle droppings in pastures present great diversity and abundance, and several species are of veterinary importance and may cause economic losses. To survey the diversity, abundance and seasonality of Diptera associated to this microhabitat, 83 samples of 10 dung pats each were taken from April 1992 to April 1994 in the vicinity of São Carlos, State of São Paulo, Southeastern Brazil. A total of 46,135 Diptera belonging to 20 families and at least 51 species were found to breed in the pats. The most abundant and diverse families were Sepsidae, Muscidae, Sarcophagidae and Sphaeroceridae. In general, the abundance was higher from October to March, the warm and wet months. The importance of some Diptera, both as horn fly enemies and as cattle dung decaying agents, is discussed.

Speech by Mr. Micheál Martin TD – Meeting The Challenges Of Cultural Diversity In The Irish Healthcare Sector

It gives me great pleasure to accept the invitation to address this conference on “Meeting the Challenges of Cultural Diversity in the Irish Healthcare Sector” which is being organised by the Irish Health Services Management Institute in partnership with the National Consultative Committee on Racism and Interculturalism. The conference provides an important opportunity to develop our knowledge and understanding of the issues surrounding cultural diversity in the health sector from the twin perspectives of patients and staff. Cultural diversity has over recent years become an increasingly visible aspect of Irish society bringing with it both opportunities and challenges. It holds out great possibilities for the enrichment of all who live in Ireland but it also challenges us to adapt creatively to the changes required to realise this potential and to ensure that the experience is a positive one for all concerned but particularly for those in the minority ethnic groups. In the last number of years in particular, the focus has tended to be on people coming to this country either as refugees, asylum seekers or economic migrants. Government figures estimate that as many as 340,000 immigrants are expected in the next six years. However ethnic and cultural diversity are not new phenomena in Ireland. Travellers have a long history as an indigenous minority group in Ireland with a strong culture and identity of their own. The changing experience and dynamics of their relationship with the wider society and its institutions over time can, I think, provide some valuable lessons for us as we seek to address the more numerous and complex issues of cultural diversity which have arisen for us in the last decade. Turning more specifically to the health sector which is the focus of this conference, culture and identity have particular relevance to health service policy and provision in that The first requirement is that we in the health service acknowledge cultural diversity and the differences in behaviours and in the less obvious areas of values and beliefs that this often implies. Only by acknowledging these differences in a respectful way and informing ourselves of them can we address them. Our equality legislation – The Employment Equality Act, 1998 and the Equal Status Act, 2000 – prohibits discrimination on nine grounds including race and membership of the Traveller community. The Equal Status Act prohibits discrimination on an individual basis in relation to the nine grounds while for groups it provides for the promotion of equality of opportunity. The Act applies to the provision of services including health services. I will speak first about cultural diversity in relation to the patient. In this respect it is worth mentioning that the recognition of cultural diversity and appropriate responses to it were issues which were strongly emphasised in the public consultation process which we held earlier this year in the context of developing National Anti-Poverty targets for the health sector and also our new national health strategy. Awareness and sensitivity training for staff is a key requirement for adapting to a culturally diverse patient population. The focus of this training should be the development of the knowledge and skills to provide services sensitive to cultural diversity. Such training can often be most effectively delivered in partnership with members of the minority groups themselves. I am aware that the Traveller community, for example, is involved in in-service training for health care workers. I am also aware that the National Consultative Committee on Racism and Interculturalism has been involved in training with the Eastern Regional Health Authority. We need to have more such initiatives. A step beyond the sensitivity training for existing staff is the training of members of the minority communities themselves as workers in our health services. Again the Traveller community has set an example in this area with its Primary Health Care Project for Travellers. The Primary Health Care for Travellers Project was established in 1994 as a joint partnership initiative with the Eastern Health Board and Pavee Point, with ongoing technical assistance being provided from the Department of Community Health and General Practice, Trinity College, Dublin. This project was the first of its kind in the country and has facilitated The project included a training course which concentrated on skills development, capacity building and the empowerment of Travellers. This confidence and skill allowed the Community Health Workers to go out and conduct a baseline survey to identify and articulate Travellers’ health needs. This was the first time that Travellers were involved in this process; in the past their needs were assumed. The results of the survey were fed back to the community and they prioritised their needs and suggested changes to the health services which would facilitate their access and utilisation. Ongoing monitoring and data collection demonstrates a big improvement in levels of satisfaction and uptake and ulitisation of health services by Travellers in the pilot area. This Primary Health Care for Travellers initiative is being replicated in three other areas around the country and funding has been approved for a further 9 new projects. This pilot project was the recipient of a WHO 50th anniversary commemorative award in 1998. The project is developing as a model of good practice which could inspire further initiatives of this type for other minority groups. Access to information has been identified in numerous consultative processes as a key factor in enabling people to take a proactive approach to managing their own health and that of their families and in facilitating their access to health services. Honouring our commitment to equity in these areas requires that information is provided in culturally appropriate formats. The National Health Promotion Strategy 2000-2005, for example, recognises that there exists within our society many groups with different requirements which need to be identified and accommodated when planning and implementing health promotion interventions. These groups include Travellers, refugees and asylum seekers, people with intellectual, physical or sensory disability and the gay and lesbian community. The Strategy acknowledges the challenge involved in being sensitive to the potential differences in patterns of poor health among these different groups. The Strategic aim is to promote the physical, mental and social well-being of individuals from these groups. The objective of the Strategy on these issues are: While our long term aim may be to mainstream responses so that our health services is truly multicultural, we must recognise the need at this point in time for very specific focused responses particularly for groups with poor health status such as Travellers and also for refugees and asylum seekers. In the case of refugees and asylum seekers examples of targeted services are screening for communicable diseases – offered on a voluntary basis – and psychological support services for those who have suffered trauma before coming here. The two approaches of targeting and mainstreaming are not mutually exclusive. A combination of both is required at this point in time but the balance between them must be kept under constant review in the light of changing needs. A major requirement if we are to meet the challenge of cultural diversity is an appropriate data and research base. I think it is important that we build up our information and research data base in partnership with the minority groups themselves. We must establish what the health needs of diverse groups are; we must monitor uptake of services and how well we are responding to needs and we must monitor outcomes and health status. We must also examine the impact of the policies in other sectors on the health of minority groups. The National Health Information Strategy, currently being developed, and the recently published National Strategy for Health Research – Making Knowledge Work for Health provide important frameworks within which we can improve our data and research base. A culturally diverse health sector workforce – challenges and opportunities The Irish health service can benefit greatly from successful international recruitment. There has been a strong non-national representation amongst the medical profession for more than 30 years. More recently there have been significant increases in other categories of health service workers from overseas. The Department recognises the enormous value that overseas recruitment brings over a wide range of services and supports the development of effective and appropriate recruitment strategies in partnership with health service employers. These changes have made cultural diversity an important issue for all health service organisations. Diversity in the workplace is primarily about creating a culture that seeks, respects, values and harnesses difference. This includes all the differences that when added together make each person unique. So instead of the focus being on particular groups, diversity is about all of us. Change is not about helping “them” to join “us” but about critically looking at “us” and rooting out all aspects of our culture that inappropriately exclude people and prevent us from being inclusive in the way we relate to employees, potential employees and clients of the health service. International recruitment benefits consumers, Irish employees and the overseas personnel alike. Regardless of whether they are employed by the health service, members of minority groups will be clients of our service and consequently we need to be flexible in order to accommodate different cultural needs. For staff, we recognise that coming from other cultures can be a difficult transition. Consequently health service employers have made strong efforts to assist them during this period. Many organisations provide induction courses, religious facilities (such as prayer rooms) and help in finding suitable accommodation. The Health Service Employers Agency (HSEA) is developing an equal opportunities/diversity strategy and action plans as well as training programmes to support their implementation, to ensure that all health service employment policies and practices promote the equality/diversity agenda to continue the development of a culturally diverse health service. The management of this new environment is extremely important for the health service as it offers an opportunity to go beyond set legal requirements and to strive for an acceptance and nurturing of cultural differences. Workforce cultural diversity affords us the opportunity to learn from the working practices and perspectives of others by allowing personnel to present their ideas and experience through teamwork, partnership structures and other appropriate fora, leading to further improvement in the services we provide. It is important to ensure that both personnel units and line managers communicate directly with their staff and demonstrate by their actions that they intend to create an inclusive work place which doesn´t demand that minority staff fit. Contented, valued employees who feel that there is a place for them in the organisation will deliver a high quality health service. Your conference here today has two laudable aims – to heighten awareness and assist health care staff to work effectively with their colleagues from different cultural backgrounds and to gain a greater understanding of the diverse needs of patients from minority ethnic backgrounds. There is a synergy in these aims and in the tasks to which they give rise in the management of our health service. The creative adaptations required for one have the potential to feed into the other. I would like to commend both organisations which are hosting this conference for their initiative in making this event happen, particularly at this time – Racism in the Workplace Week. I look forward very much to hearing the outcome of your deliberations. Thank you.

Bats of Borneo: diversity, distributions and representation in protected areas

Protected areas are valuable in conserving tropical biodiversity, but an insufficient understanding of species diversity and distributions makes it difficult to evaluate their effectiveness. This is especially true on Borneo, a species rich island shared by three countries, and is particularly concerning for bats, a poorly known component of mammal diversity that may be highly susceptible to landscape changes. We reviewed the diversity, distributions and conservation status of 54 bat species to determine the representation of these taxa in Borneo's protected areas, and whether these reserves complement each other in terms of bat diversity. Lower and upper bound estimates of bat species composition were characterised in 23 protected areas and the proposed boundaries of the Heart of Borneo conservation area. We used lower and upper bound estimates of species composition. By using actual inventories, species representation was highly irregular, and even if some reserves were included in the Heart of Borneo, the protected area network would still exhibit low complementarity. By inferring species presence from distributions, composition between most reserves was similar, and complementarity was much higher. Predicting species richness using abundance information suggested that bat species representation in reserves may lie between these two extremes. We recommend that researchers better sample biodiversity over the island and address the conservation threats faced in Borneo both within and outside protected areas. While the Heart of Borneo Initiative is commendable, it should not divert attention from other conservation areas.

Antiretroviral resistance and genetic diversity of human immunodeficiency virus type 1 isolates from the Federal District, Central Brazil

In the context of universal access to antiretroviral therapy, the surveillance of human immunodeficiency virus type 1 (HIV-1) genetic diversity and resistance becomes pivotal. In this work our purpose was to describe the genetic variability; prevalence of drug-resistance mutations; and genotypic resistance profiles in HIV-1 infected individuals under antiretroviral treatment, from the Federal District, Brasília, Central Brazil. The entire viral protease and codons 19 to 234 of the reverse transcriptase gene from 45 HIV-1 isolates were amplified and sequenced for subtyping and genotyping. By phylogenetic analysis, 96% of the samples clustered with subtype B and the remaining 4% with HIV-1 subtype F sequences. One major protease inhibitor resistance-associated mutation, I50V, was detected in 38% of the samples. Minor mutations were also found at the protease gene: L10I/V (7%), K20M (2%), M36I (11%), L63P (20%), A71T (2%), and V77I (7%). Many mutations associated with reduced susceptibility to nucleoside or non-nucleoside reverse transcriptase inhibitors were detected: M41L (11%), E44D (4%), D67N (11%), T69D (2%), K70R (11%), L74V (2%), L100I (4%), K103N (18%), V118I (9%), Y181C (11%), M184V (18%), G190A (4%), T215Y (4%), and K219E (4%). This study has shown that 84% of the studied population from the Federal District, showing evidences of therapy failure, presented viral genomic mutations associated with drug resistance. The main antiretrovirals to which this population showed resistance were the PI amprenavir (38%), the NNRTIs delavirdine, nevirapine (31%), and efavirenz (24%), and the NRTIs lamivudine (18%), abacavir, and zidovudine (13%).

Genetic diversity of NS3 protease from Brazilian HCV isolates and possible implications for therapy with direct-acting antiviral drugs

The hepatitis C virus (HCV) NS3 protease has been one of the molecular targets of new therapeutic approaches. Its genomic sequence variability in Brazilian HCV isolates is poorly documented. To obtain more information on the magnitude of its genetic diversity, 114 Brazilian HCV samples were sequenced and analysed together with global reference sequences. Genetic distance (d) analyses revealed that subtype 1b had a higher degree of heterogeneity (d = 0.098) than subtypes 1a (d = 0.060) and 3a (d = 0.062). Brazilian isolates of subtype 1b were distributed in the phylogenetic tree among sequences from other countries, whereas most subtype 1a and 3a sequences clustered into a single branch. Additional characterisation of subtype 1a in clades 1 and 2 revealed that all but two Brazilian subtype 1a sequences formed a distinct and strongly supported (approximate likelihood-ratio test = 93) group of sequences inside clade 1. Moreover, this subcluster inside clade 1 presented an unusual phenotypic characteristic in relation to the presence of resistance mutations for macrocyclic inhibitors. In particular, the mutation Q80K was found in the majority of clade 1 sequences, but not in the Brazilian isolates. These data demonstrate that Brazilian HCV subtypes display a distinct pattern of genetic diversity and reinforce the importance of sequence information in future therapeutic approaches.

Genetic diversity of EBV-encoded LMP1 in the Swiss HIV Cohort Study and implication for NF-Κb activation.

Epstein-Barr virus (EBV) is associated with several types of cancers including Hodgkin's lymphoma (HL) and nasopharyngeal carcinoma (NPC). EBV-encoded latent membrane protein 1 (LMP1), a multifunctional oncoprotein, is a powerful activator of the transcription factor NF-κB, a property that is essential for EBV-transformed lymphoblastoid cell survival. Previous studies reported LMP1 sequence variations and induction of higher NF-κB activation levels compared to the prototype B95-8 LMP1 by some variants. Here we used biopsies of EBV-associated cancers and blood of individuals included in the Swiss HIV Cohort Study (SHCS) to analyze LMP1 genetic diversity and impact of sequence variations on LMP1-mediated NF-κB activation potential. We found that a number of variants mediate higher NF-κB activation levels when compared to B95-8 LMP1 and mapped three single polymorphisms responsible for this phenotype: F106Y, I124V and F144I. F106Y was present in all LMP1 isolated in this study and its effect was variant dependent, suggesting that it was modulated by other polymorphisms. The two polymorphisms I124V and F144I were present in distinct phylogenetic groups and were linked with other specific polymorphisms nearby, I152L and D150A/L151I, respectively. The two sets of polymorphisms, I124V/I152L and F144I/D150A/L151I, which were markers of increased NF-κB activation in vitro, were not associated with EBV-associated HL in the SHCS. Taken together these results highlighted the importance of single polymorphisms for the modulation of LMP1 signaling activity and demonstrated that several groups of LMP1 variants, through distinct mutational paths, mediated enhanced NF-κB activation levels compared to B95-8 LMP1.

Cryptic diversity among Western Palearctic tree frogs: postglacial range expansion, range limits, and secondary contacts of three European tree frog lineages (Hyla arborea group).

We characterize divergence times, intraspecific diversity and distributions for recently recognized lineages within the Hyla arborea species group, based on mitochondrial and nuclear sequences from 160 localities spanning its whole distribution. Lineages of H. arborea, H. orientalis, H. molleri have at least Pliocene age, supporting species level divergence. The genetically uniform Iberian H. molleri, although largely isolated by the Pyrenees, is parapatric to H. arborea, with evidence for successful hybridization in a small Aquitanian corridor (southwestern France), where the distribution also overlaps with H. meridionalis. The genetically uniform H. arborea, spread from Crete to Brittany, exhibits molecular signatures of a postglacial range expansion. It meets different mtDNA clades of H. orientalis in NE-Greece, along the Carpathians, and in Poland along the Vistula River (there including hybridization). The East-European H. orientalis is strongly structured genetically. Five geographic mitochondrial clades are recognized, with a molecular signature of postglacial range expansions for the clade that reached the most northern latitudes. Hybridization with H. savignyi is suggested in southwestern Turkey. Thus, cryptic diversity in these Pliocene Hyla lineages covers three extremes: a genetically poor, quasi-Iberian endemic (H. molleri), a more uniform species distributed from the Balkans to Western Europe (H. arborea), and a well-structured Asia Minor-Eastern European species (H. orientalis).

Multifunctionality and Diversity in Bacterial Biofilms

Bacteria are highly diverse and drive a bulk of ecosystem processes. Analysis of relationships between diversity and single specific ecosystem processes neglects the possibility that different species perform multiple functions at the same time. The degradation of dissolved organic carbon (DOC) followed by respiration is a key bacterial function that is modulated by the availability of DOC and the capability to produce extracellular enzymes. In freshwater ecosystems, biofilms are metabolic hotspots and major sites of DOC degradation. We manipulated the diversity of biofilm forming communities which were fed with DOC differing in availability. We characterized community composition using molecular fingerprinting (T-RFLP) and measured functioning as oxygen consumption rates, the conversion of DOC in the medium, bacterial abundance and the activities of five specific enzymes. Based on assays of the extracellular enzyme activity, we calculated how the likelihood of sustaining multiple functions was affected by reduced diversity. Carbon source and biofilm age were strong drivers of community functioning, and we demonstrate how the likelihood of sustaining multifunctionality decreases with decreasing diversity

Teaching ethnic diversity in journalism school

It has been found that the symbolic elites have a prominent role in the discursive reproduction of racism in society, because they control the public discourse through which many ethnic prejudices are spread and shared. This special position of the mass media requires that the professional education of journalists, also featuring such topics as ethnic studies, diversity and racism, is optimally adapted to the multicultural societies in Europe, North America and Australia. This paper reports about an extensive research project examining ethnic education of journalists in these white-dominated countries, by examining the websites of many journalism and communication departments. Consistent with the general finding that white symbolic elites primarily deny or ignore (their) racism in society, none of the academic programs, anywhere in the world, mentions special classes on racism in the mass media. Finally, a practical proposal is made for a course on ethnic reporting in multicultural societies.

Introducing diversity in public organisations : diminishing theoretical ambiguity and controversy by empirical research

Many theoretical dissertations have an unclear definition of diversity and when interpreting strategies of organizational diversity policies, theories often contradict each other. It is argued that this ambiguity and controversy can be diminished by basing theory on diversity and diversity policy more on qualitative structured descriptive empirical comparisons.This argument is elaborated in two steps. First, diversity is shown to be a social construction: dynamic and plural in nature, dependent on the social-historical context. Second, the common theoretical dichotomy between diversity policy as equal opportunities or as diversity management in shown to be possibly misleading; empirical studies indicate more practical differentiation in types of diversity policy, manifested in public and private organizations. As qualitative comparisons are rare, especially in the European context and especially among public organizations, this article calls for more contributions of this kind and provides an analytical framework to assist scholars in the field of diversity studies.

Global Genomic Diversity of Human Papillomavirus 6 Based on 724 Isolates and 190 Complete Genome Sequences.

Human papillomavirus type 6 (HPV6) is the major etiological agent of anogenital warts and laryngeal papillomas and has been included in both the quadrivalent and nonavalent prophylactic HPV vaccines. This study investigated the global genomic diversity of HPV6, using 724 isolates and 190 complete genomes from six continents, and the association of HPV6 genomic variants with geographical location, anatomical site of infection/disease, and gender. Initially, a 2,800-bp E5a-E5b-L1-LCR fragment was sequenced from 492/530 (92.8%) HPV6-positive samples collected for this study. Among them, 130 exhibited at least one single nucleotide polymorphism (SNP), indel, or amino acid change in the E5a-E5b-L1-LCR fragment and were sequenced in full. A global alignment and maximum likelihood tree of 190 complete HPV6 genomes (130 fully sequenced in this study and 60 obtained from sequence repositories) revealed two variant lineages, A and B, and five B sublineages: B1, B2, B3, B4, and B5. HPV6 (sub)lineage-specific SNPs and a 960-bp representative region for whole-genome-based phylogenetic clustering within the L2 open reading frame were identified. Multivariate logistic regression analysis revealed that lineage B predominated globally. Sublineage B3 was more common in Africa and North and South America, and lineage A was more common in Asia. Sublineages B1 and B3 were associated with anogenital infections, indicating a potential lesion-specific predilection of some HPV6 sublineages. Females had higher odds for infection with sublineage B3 than males. In conclusion, a global HPV6 phylogenetic analysis revealed the existence of two variant lineages and five sublineages, showing some degree of ethnogeographic, gender, and/or disease predilection in their distribution. IMPORTANCE: This study established the largest database of globally circulating HPV6 genomic variants and contributed a total of 130 new, complete HPV6 genome sequences to available sequence repositories. Two HPV6 variant lineages and five sublineages were identified and showed some degree of association with geographical location, anatomical site of infection/disease, and/or gender. We additionally identified several HPV6 lineage- and sublineage-specific SNPs to facilitate the identification of HPV6 variants and determined a representative region within the L2 gene that is suitable for HPV6 whole-genome-based phylogenetic analysis. This study complements and significantly expands the current knowledge of HPV6 genetic diversity and forms a comprehensive basis for future epidemiological, evolutionary, functional, pathogenicity, vaccination, and molecular assay development studies.

Pyrroloquinoline quinone biosynthesis gene pqqC, a novel molecular marker for studying the phylogeny and diversity of phosphate-solubilizing pseudomonads.

Many root-colonizing pseudomonads are able to promote plant growth by increasing phosphate availability in soil through solubilization of poorly soluble rock phosphates. The major mechanism of phosphate solubilization by pseudomonads is the secretion of gluconic acid, which requires the enzyme glucose dehydrogenase and its cofactor pyrroloquinoline quinone (PQQ). The main aim of this study was to evaluate whether a PQQ biosynthetic gene is suitable to study the phylogeny of phosphate-solubilizing pseudomonads. To this end, two new primers, which specifically amplify the pqqC gene of the Pseudomonas genus, were designed. pqqC fragments were amplified and sequenced from a Pseudomonas strain collection and from a natural wheat rhizosphere population using cultivation-dependent and cultivation-independent approaches. Phylogenetic trees based on pqqC sequences were compared to trees obtained with the two concatenated housekeeping genes rpoD and gyrB. For both pqqC and rpoD-gyrB, similar main phylogenetic clusters were found. However, in the pqqC but not in the rpoD-gyrB tree, the group of fluorescent pseudomonads producing the antifungal compounds 2,4-diacetylphloroglucinol and pyoluteorin was located outside the Pseudomonas fluorescens group. pqqC sequences from isolated pseudomonads were differently distributed among the identified phylogenetic groups than pqqC sequences derived from the cultivation-independent approach. Comparing pqqC phylogeny and phosphate solubilization activity, we identified one phylogenetic group with high solubilization activity. In summary, we demonstrate that the gene pqqC is a novel molecular marker that can be used complementary to housekeeping genes for studying the diversity and evolution of plant-beneficial pseudomonads.

The influence of environmental spatial structure on the life history traits and diversity of species in a metacommunity

Several models have been proposed to understand how so many species can coexist in ecosystems. Despite evidence showing that natural habitats are often patchy and fragmented, these models rarely take into account environmental spatial structure. In this study we investigated the influence of spatial structure in habitat and disturbance regime upon species' traits and species' coexistence in a metacommunity. We used a population-based model to simulate competing species in spatially explicit landscapes. The species traits we focused on were dispersal ability, competitiveness, reproductive investment and survival rate. Communities were characterized by their species richness and by the four life-history traits averaged over all the surviving species. Our results show that spatial structure and disturbance have a strong influence on the equilibrium life-history traits within a metacommunity. In the absence of disturbance, spatially structured landscapes favour species investing more in reproduction, but less in dispersal and survival. However, this influence is strongly dependent on the disturbance rate, pointing to an important interaction between spatial structure and disturbance. This interaction also plays a role in species coexistence. While spatial structure tends to reduce diversity in the absence of disturbance, the tendency is reversed when disturbance occurs. In conclusion, the spatial structure of communities is an important determinant of their diversity and characteristic traits. These traits are likely to influence important ecological properties such as resistance to invasion or response to climate change, which in turn will determine the fate of ecosystems facing the current global ecological crisis.