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PubMed2003

Silvicultural management in maintaining biodiversity and resistance of forests in Europe-temperate zone.

In Europe temperate forests play a prominent role in timber production, nature protection, water conservation, erosion control and recreation. For centuries temperate forests in Europe have been affected by forest devastation and soil degradation. Applying great efforts to eliminate the severe wood shortage of those days, countermeasures were taken during the last 150 years by regenerating and tending highly productive forests. High growth rates and an increasing growing stock of these forests indicate that formerly stated goals have been successfully achieved. Coniferous species were often favoured because they were easy to establish and manage, and gave reason for high volume growth expectations. Today coniferous forests expand far beyond the limits of their natural ranges. These changes have been accompanied by a loss of biodiversity, a shift to nonsite adapted tree species and reduce the resistance against storms, snow, ice, droughts, insects and fungi. Some of these hazards were further intensified by the increasing average stand age, as well as in some areas by severe air pollution. Climatic fluctuations, especially changes in the frequency and intensity of extreme warm and dry climatic conditions and of heavy storms, had considerable impact on forest ecosystems. The changing demands of today require a widened scope of forest management. Society is asking for sustainable forestry emphasizing biodiversity and naturalistic forest management. It is of great economic and ecological relevance to know on which sites today's forests are most susceptible to climatic and other environmental changes and hazards. In those areas adjustments of management through a conversion the prevailing forests towards more site adapted mixed forests needs to be considered with priority. The high diversity in site conditions, ownership, economic and socio-cultural conditions require strategies adapted to the local and regional needs. Higher resistance of forests will increase economic and social benefits of forests and reduce the risks by maintaining sustainable forestry.

Climate↗
PubMed2001

Mediterranean dairy sheep and goat products and their quality. A critical review.

Sheep and goat edible products (mainly meat and dairy products) have interesting characteristics in their levels of flavour, taste, aromas and leanness as well as the specific composition of fats, proteins, amino and fatty acids. Their quality is very much linked to historical and cultural uniqueness right through the production, marketing and consumption chains. This refers, at least in the Mediterranean region, to farming systems with dominant extensive grazing situations, specific technologies and conditions for slaughtering as well as for the transformation processes of cheese-making and its maturing; they are also characterised by traditional nutritional habits of the consumers. While the organoleptic properties of the dairy products are very important, the sanitary aspects become more and more influential and tend to modify the accepted definitions of these products and their quality (e.g. non-pasteurised milk, production chains, hygiene, transformation methodologies, etc.). Today there are major research efforts to ameliorate the production aspects but also the quality of the products; better cheese yield with the work undertaken on alpha-s1-casein, flavour and taste of cheeses is improved by the work on lipolysis and the study of the molecules responsible for the taste of the cheeses, studies on the fattening level of animals including genetic variability, and a better understanding of the fat distribution on carcasses. The future evolution of these products is difficult to foresee. Will quality be the criterion which will give the market direction in the developed countries (standardised products and top quality special products)? In the developing regions will we be able to maintain the actual production which is well adapted to the local demand or will this not be handicapped by the fragility and marginalisation of the existing livestock farming systems and untenable rises in costs?

Journal Article↗
PubMed2000

Cervical cancer screening in Luxembourg.

In 1962, a programme for early detection of cervical cancer was established at the national level. The programme is based on the collaboration of different groups of doctors and not on a system of sending out invitations to every woman. This programme was re-adapted twice according to the needs for assuring quality in a system of mainly liberal medicine. At present the programme is 'institutionalised' and is carried out according to the criteria defined in 1990. This includes a centralisation of the smear readings and handing out the material needed to take the smears. The contribution of the doctors is regulated by a system of bonuses given by the government and a reimbursement by the Health Fund. The annual cervical smear is free of charge for every woman. The participation of the women targeted by the programme (>15 years old) has increased by approximately 50% every decade from the early 1970s increasing from 10950 in 1972 to 70441 in 1999. Between 1980 and 1999, the number of women at risk taking part in the programme increased from 10.80 to 38.92%. The number of all the doctors taking smear samples increased from 68 to 105 and the number of gynaecologists increased from 19 (ratio Gyn/GP (gynaecologists/General Practitioners) of 28%) to 52 (ratio Gyn/GP of 50%). The mortality rate has decreased continuously from 6. 1/100000 in 1990 to 0.9/100000 in 1997. In conclusion, to be successful, a cervical cancer screening programme should be flexible enough to allow short-term adaptations to unexpected local situations and needs a highly motivated team of the different participants involved in the regional and national health policy.

Data Collection↗
PubMed2000

Implementing evidence-based recommendations for health care: a roundtable comparing European and American experiences.

BACKGROUND: A roundtable held October 5-6 1999, in Maidstone, Kent, United Kingdom, was convened to identify current strategies and ongoing challenges in implementing evidence-based practice guidelines in health care. Despite numerous new medical research findings for improving health care and despite the dissemination of many practice guidelines, the recommendations from these efforts are not being uniformly adopted. Overuse, underuse, and misuse plague the practice of medicine today. IMPLEMENTING GUIDELINES: Multiple implementation strategies are more likely to succeed that a single implementation method; local selection and adaptation of guidelines are critical; and reminders, educational outreach (for prescribing), and interactive educational workshops are generally effective. EXPERIENCE IN EUROPE: In most countries, guideline development has progressed from consensus conference, to evidence-based statements, and finally to evidence-based guidelines that also consider cost-effectiveness. Guideline development is the most advanced in The Netherlands, where physicians have coordinated their efforts with the government to achieve more uniformity than is found elsewhere. EXPERIENCE IN THE UNITED STATES: Designing systems that will facilitate change--not changing physician behavior--should be the focus. The concern for effecting improvement in health care is now more acute because of the increased attention being given to medical errors and patient safety. SUMMARY STATEMENT: Multifaceted approaches are clearly the most important method for improving care. Such approaches may include many improvement methods, none of which work well alone most of the time or any of the time.

Accreditation↗
PubMed1995

Red cell membrane polypeptides under normal conditions and in genetic disorders.

Broadly speaking, the red cell membrane is comprised of --a cholesterol-rich phospholipid bilayer that is studded by a large number of trans-bilayer proteins, --of glycosylphosphatidylinositol-anchored proteins (GPI-proteins) standing outside, and --an important protein assembly, the erythrocyte or membrane skeleton, that laminates the inner surface of the bilayer. Among the trans-bilayer proteins, one finds the anion exchanger, the glycophorins, the glucose transporter, a variety of cation transporters and pumps, and of course proteins carrying the epitopes of many blood groups. Among the GPI-proteins, one encounters the acetylcholinesterase and the decay-accelerating factor (CD 55). Among the skeletal proteins, finally, one recognises spectrin, actin (and a number of actin-binding proteins other than spectrin: dematin, tropomyosin, tropomodulin, etc.), protein 4.1 and protein p55. Spectrin heterotetramer organizes into a bidimensional network with a hexagonal mesh on the average. This network is linked to trans-bilayer proteins, through the complex beta-spectrin-ankyrin-anion exchanger (+ protein 4.2) on the one hand and, on the other hand, through the triangular interaction between protein 4.1, glycophorin C and protein p55. The sequence of the above proteins and the exon-intron organisation of their genes are known in most cases. Many proteins have a widespread tissue distribution in the form of variants adapted to their local functions. Such variants may be the products of multigene families (anion exchanger, ankyrin, spectrin), or derive from a single gene (protein 4.1, protein 4.2), the transcripts of which undergo cell-specific alternative splicing. It has been established that many congenital haemolytic anaemias result from mutations altering the above-mentioned genes. We will provide two examples. Hereditary elliptocytosis stems from an array of mutations located at, or near the head-to-head self-association region of two spectrin alpha beta dimers, or from mutations which, most often, yield a reduction (heterozygous state) or the lack (homozygous state) of protein 4.1. The aggravation of elliptocytosis associated with alpha-spectrin mutations frequently yields poikilocytosis and usually stems from the occurrence, in trans, of a low expression allele, allele alpha LELY. Hereditary spherocytosis derives from mutations in the ankyrin gene (80% of the cases), the anion exchanger gene (10-15% of the cases), the protein 4.2 gene (rare cases) and the alpha- and beta-spectrin genes (rare cases). Anion exchanger mutations usually cause the decrease in this protein (heterozygous state).(ABSTRACT TRUNCATED AT 250 WORDS)

Anion Exchange Protein 1, Erythrocyte↗
PubMed2003

The dual role of IL-10.

Classification of cytokines as pro-versus anti-inflammatory might not apply to the pleiotropic effects of interleukin-10 (IL-10). Several reports suggest that IL-10 enhances the function of natural killer cells, which leads, through pathogen destruction, to increased antigen availability. In addition, by inhibiting the maturation of antigen-presenting cells (APCs), IL-10 preserves their ability for antigen uptake while simultaneously hampering their migration to draining lymph nodes. This review suggests that this "antigen-loading" phase might constitute an important component of the innate immune reaction to a pathogen. Additional proinflammatory stimuli might subsequently lead to maturation of "loaded" APCs that could migrate to draining lymph nodes or recruit and activate adaptive immune effectors locally.

Animals↗
PubMed2003

The epidemiology of malaria in Papua New Guinea.

Papua New Guinea (PNG) is a patchwork of different ecological zones, inhabited by human populations of exceptional cultural and linguistic diversity. This results in complex variations in vector ecology and malaria epidemiology. Malaria is the main cause of morbidity in many health facilities in lowland areas, but it is absent in much of the highlands. All four human malaria species occur, but endemicity varies widely, with Plasmodium falciparum locally reaching holo-endemic levels that are rarely found outside sub-Saharan Africa. The high frequency of Plasmodium vivax is an important difference to most African situations. PNG is therefore a prime location for studies of interactions between different parasite species, and of the biology of local human genetic adaptation and its implications for malaria morbidity and mortality.

Animals↗
PubMed2002

Evidence-based careflow management systems: the case of post-stroke rehabilitation.

The activities of a care providers' team need to be coordinated within a process properly designed on the basis of available best practice medical knowledge. It requires a rethinking of the management of care processes within health care organizations. The current workflow technology seems to offer the most convenient solution to build such cooperative systems. However, some of its present weaknesses still require an intense research effort to find solutions allowing its exploitation in real medical practice. This paper presents an approach to design and build evidence-based careflow management systems, which can be viewed as components of a knowledge management infrastructure each health care organization should be provided with to increase its performance in delivering high quality care by efficiently exploiting the available knowledge resources. The post-stroke rehabilitation process has been taken as a challenging care problem to assess our methodology for designing and developing careflow management systems. Then a system was co-developed with a team of rehabilitation professionals who will be committed to use it in their daily work. The system's main goal is to deliver a full array of rehabilitation services provided by an interdisciplinary team. They are related to identify which patients are most likely to benefit from rehabilitation, manage a rehabilitation treatment plan, and monitor progress both during rehabilitation and after return to a community residence. A model of the rehabilitation process was derived from an international guideline and adapted to the local organization of work. It involves different organizational units, such as wards, rehabilitation units, clinical laboratories, and imaging services. Several organizational agents work within them and play one or more roles. Each role is defined by the goals' set that she/he must fulfill. Special effort has been given to the design and development of a knowledge-based system for managing exceptions, which may occur in daily medical work as any deviation from the normal flow of activities. It allows either avoiding or recovering automatically from expected exceptions. When they are not expected, organizational agents, with enough power to do that, are allowed to modify the scheduled flow of activities for an individual patient under the only constraint of justifying their decision. After an intensive testing in a research laboratory, the system is now in the process of being transferred in a real working setting with the full support of its future users.

Delivery of Health Care↗
PubMed2002

Mechanical strain, induced noninvasively in the high-frequency domain, is anabolic to cancellous bone, but not cortical bone.

Departing from the premise that it is the large-amplitude signals inherent to intense functional activity that define bone morphology, we propose that it is the far lower magnitude, high-frequency mechanical signals that continually barrage the skeleton during longer term activities such as standing, which regulate skeletal architecture. To examine this hypothesis, we proposed that brief exposure to slight elevations in these endogenous mechanical signals would suffice to increase bone mass in those bones subject to the stimulus. This was tested by exposing the hind limbs of adult female sheep (n = 9) to 20 min/day of low-level (0.3g), high-frequency (30 Hz) mechanical signals, sufficient to induce a peak of approximately 5 microstrain (micro epsilon) in the tibia. Following euthanasia, peripheral quantitative computed tomography (pQCT) was used to segregate the cortical shell from the trabecular envelope of the proximal femur, revealing a 34.2% increase in bone density in the experimental animals as compared with controls (p = 0.01). Histomorphometric examination of the femur supported these density measurements, with bone volume per total volume increasing by 32% (p = 0.04). This density increase was achieved by two separate strategies: trabecular spacing decreased by 36.1% (p = 0.02), whereas trabecular number increased by 45.6% (p = 0.01), indicating the formation of cancellous bone de novo. There were no significant differences in the radii of animals subject to the stimulus, indicating that the adaptive response was local rather than systemic. The anabolic potential of the signal was evident only in trabecular bone, and there were no differences, as measured by any assay, in the cortical bone. These data suggest that subtle mechanical signals generated during predominant activities such as posture may be potent determinants of skeletal morphology. Given that these strain levels are three orders of magnitude below strains that can damage bone tissue, we believe that a noninvasive stimulus based on this sensitivity has potential for treating skeletal complications such as osteoporosis.

Animals↗
PubMed2001

Trematode infection and the distribution and dynamics of parthenogenetic snail populations.

According to the Red Queen hypothesis for sex, cross-fertilization should be positively associated with the probability of exposure (risk) to virulent parasites. Unfortunately, risk is difficult to measure in the wild, and prevalence of infection is often substituted for risk. Here I suggest that prevalence of infection may not generally suffice as a surrogate for risk, since the Red Queen model can make opposite predictions depending on the distribution of risk in the wild. Specifically, the results of a matching-alleles model suggest that asexual populations should be more infected than sexual populations, when (1) the variance in risk among populations is small, and (2) the mean risk of exposure to parasites is near the point where selection switches to favouring sex over asex. If, however, the variance in risk among populations is large, sexual reproduction should be positively associated with the prevalence of infection. In addition, the coefficient of variation for reproductive mode should increase sharply at the switch point. In light of these results, I re-evaluated data from two studies on the distribution of males in 95 populations of a freshwater snail (Potamopyrgus antipodarum). Populations of these snails are often mixtures of sexual and asexual individuals, and the frequency of males is correlated with the frequency of sexual females in the population. The results show a large, highly skewed variance among populations for prevalence of infection by larval trematodes. The results also show a positive, significant relationship between prevalence of infection and the frequency of males, with a sharp increase in the coefficient of variation at intermediate prevalence. In addition, experimental studies suggest that some of the necessary conditions of the Red Queen hypothesis are also met in this system. Specifically, the most common trematode infecting these snails is (1) adapted to infecting local host populations of the snail, and is (2) more infective to clones that were common in the recent past. It is too early to knoxv if the parasite theory is sufficient to explain the widespread distribution of sex. I suggest that the theory is not sufficient, but that parasites in combination with mutation accumulation in clonal lines may explain the maintenance of sex in species that occasionally produce apomictic mutants.

Animals↗
PubMed1997

In search of common foundations for cortical computation.

It is worthwhile to search for forms of coding, processing, and learning common to various cortical regions and cognitive functions. Local cortical processors may coordinate their activity by maximizing the transmission of information coherently related to the context in which it occurs, thus forming synchronized population codes. This coordination involves contextual field (CF) connections that link processors within and between cortical regions. The effects of CF connections are distinguished from those mediating receptive field (RF) input; it is shown how CFs can guide both learning and processing without becoming confused with the transmission of RF information. Simulations explore the capabilities of networks built from local processors with both RF and CF connections. Physiological evidence for synchronization, CFs, and plasticity of the RF and CF connections is described. Coordination via CFs is related to perceptual grouping, the effects of context on contrast sensitivity, amblyopia, implicit influences of color in achromotopsia, object and word perception, and the discovery of distal environmental variables and their interactions through self-organization. Cortical computation could thus involve the flexible evaluation of relations between input signals by locally specialized but adaptive processors whose activity is dynamically associated and coordinated within and between regions through specialized contextual connections.

Cerebral Cortex↗
PubMed2006

Evaluation of the Food and Agriculture Organization's global school-based nutrition education initiative, Feeding Minds, Fighting Hunger (FMFH), in schools of Hyderabad, India.

OBJECTIVE: To assess the efficacy of the Food and Agriculture Organization's global school-based nutrition education initiative, Feeding Minds, Fighting Hunger (FMFH), in improving nutrition-related knowledge levels of schoolchildren. DESIGN: Adopting the cluster randomisation technique, five schools each in experimental and control groups were randomly chosen from the member schools of a voluntary organisation. Repeated measures of knowledge levels were carried out at three points in time to assess pre-, post-intervention and retention of knowledge gained during the intervention. Children from experimental schools were given nutrition education by teachers in the classroom setting using FMFH material. SUBJECTS/SETTINGS: Schoolchildren (n=358 in the control group and n=312 in the experimental group) of grades VIII and IX from schools in Hyderabad, India. RESULTS: The classroom-based intervention resulted in a significant improvement (P<0.01) in nutrition knowledge levels of schoolchildren in the experimental group. Significant improvement in knowledge was also observed in the control group. The effect size indicated that the improvement in knowledge levels of schoolchildren in experimental schools over control schools was medium (d=0.40), indicating the efficacy of the FMFH programme in improving nutrition-related knowledge. No significant decrease (P>0.05) in knowledge levels was observed after 2 months, indicating retention of the knowledge acquired through the intervention. CONCLUSION: The FMFH programme provides an opportunity for schoolchildren to learn more about nutrition through their teachers in a classroom setting if the lesson plans are adapted to the local circumstances. Furthermore, it has the potential to make nutrition education interactive, effective and sustainable.

Agriculture↗
PubMed2000

Synthesis and wettability characteristics of model adhesive protein sequences inspired by a marine mussel.

Three adhesive polyoctapeptides (X/Y-Gly-Tyr-Ser-Ala-Gly-Tyr-Lys)n (X, Thr and Ala: Y, Thr:Ala = 3:2), which are the C-terminal octapeptide sequences shared by all those consensus motifs of a ribbed mussel Geukensia demissa adhesive protein (RMAP), have been synthesized by the polycondensation of the active esters. The correlation between wettability and adhesion with the alternative substitution by hydrophobic Ala and hydrophilic Thr in the synthetic RMAPs in aqueous solution and as films on high and low surface free energy (sfe) surfaces has been investigated by surface chemical approaches. The side chain moieties of RMAPs arrange their local conformation to adapt to the inherent surface character, and they orientate on high and low sfe surfaces. On a high sfe glass the hydrophilic side chains of the RMAP molecules face toward the surface, and on a low sfe polyethylene (HDPE) the hydrophobic side chains face toward the surface. The bonding strengths of synthetic RMAPs on glass and HDPE with and without enzymatic oxidation have been examined. Increased starting concentration exhibited the strongest adhesive capability (7.5 kgf/cm2) on alumina due to the increased cohesion among RMAP molecules. As another factor to increase adhesive ability, the intermolecular cross-linking among RMAP molecules by tyrosinase increases their adhesive capability by about 20% on HDPE, glass, and alumina except iron.

Adhesives↗
PubMed2006

Perchlorate reduction by autotrophic bacteria in the presence of zero-valent iron.

A series of batch experiments were performed to study the combination of zero-valent iron (ZVI) with perchlorate-reducing microorganisms (PRMs) to remove perchlorate from groundwater. In this method, H2 produced during the process of iron corrosion by water is used by PRMs as an electron donor to reduce perchlorate to chloride. Perchlorate degradation rates followed Monod kinetics, with a normalized maximum utilization rate (rmax) of 9200 microg g(-1) (dry wt) h(-1) and a half-velocity constant (Ks) of 8900 microg L(-1). The overall rate of perchlorate reduction was affected by the biomass density within the system. An increase in the OD600 from 0.025 to 0.08 led to a corresponding 4-fold increase of perchlorate reduction rate. PRM adaptation to the local environment and initiation of perchlorate reduction was rapid under neutral pH conditions. At the initial OD600 of 0.015, perchlorate reduction followed pseudo-first-order reaction rates with constants of 0.059 and 0.033 h(-1) at initial pH 7 and 8, respectively. Once perchlorate reduction was established, the bioreductive process was insensitive to the increases of pH from near neutral to 9.0. In the presence of nitrate, perchlorate reduction rate was reduced, but not inhibited completely.

Hydrogen↗
PubMed2002

Cycloheptatrienyl oxyallyl. An observable oxyallyl?

Density functional calculations have been carried out for cycloproylidene-, cyclopentylidene-, and tropyllideneallene oxides (7-9) and the reaction pathway for their conversion to the corresponding oxyallyls (10-12) and cyclopropanones (13-15) in order to probe the electronic structure of the intermediate oxyallyls. All three oxyallyls were found to be stabilized with respect to their allene oxides in comparison to the unsubstituted allene oxide and oxyallyl. For 7 and 9 the stabilization can be attributed to the zwitterionic character of the oxyallyls, while for 8 the stabilization can be attributed to its diradical character. This suggests that oxyallyl is capable of "adapting" to its local environment. Calculations predict that oxyallyl 12 should be an observable intermediate in the absence of nucleophiles, since it is calculated to be of lower energy than either the allene oxide 9 or the cyclopropanone 15.

Allyl Compounds↗
PubMed2002

Frequency of the high-molecular-weight glutenin allele in Asian hexaploid wheat (Triticum aestivum L.) and the transmission route through which the wheat may have reached Japan, the most geographically remote region of wheat production in the world.

The frequency of the Glu-D1f allele in Japanese, Chinese, and other Asian hexaploid wheat varieties was analyzed in order to investigate a possible transmission route for hexaploid wheat to the Far East, Japan. The 1380 published data sets were compared to the results for 1107 hexaploid Asian wheat varieties which were determined in this study. The frequency of the Glu-D1f allele was clearly different between areas; the allele was present from northern and southern Japan, from Xinjiang, Jiangsu, Zhejiang, and Beijing in China, and from Afghanistan. A high frequency of the high-molecular-weight glutenin Glu-D1f allele was found predominantly in southern Japan. This distribution of an adaptively neutral character suggests a specific route of transmission for hexaploid wheat to eastern China and the Far East, Japan. It was introduced from Afghanistan, carried to Xinjiang (in northwest China), Jiangsu, and Zhejiang (in southeast China), and then to southern Japan along the so-called Silk Road. It is believed that cultivated hexaploid wheat originated in the Middle East and the Near East and was carried along the Silk Road through China to the Far East, Japan. Japan is the most geographically remote region of wheat production in the world. During the course of its long journey and its adaptation to diverse local environments, Japanese hexaploid wheat has developed a unique composition of glutenin Glu-D1 alleles. The frequency of this allele in different wheat varieties allowed us to hypothesize a possible route for the transmission of hexaploid wheat into the Far East, Japan.

Agriculture↗
PubMed2004

[Central issues of prevention of nosocomial infections--status in 2004].

Despite significant progress in our understanding of their pathogenesis, nosocomial infections remain a major problem in hospitals. They may originate from the endogenous flora of the patient as a result of translocation of microorganisms from a physiologically colonized area to an area, where they act as pathogens. Transmission of microorganisms between patients results in exogenous infections. Healthcare workers may serve as transient carriers and vectors or even as reservoir of these infectious agents. Both, exogenous as well as endogenous nosocomial infections are preventable. Based on knowledge of the mode of transmission, the pathogenesis of and risk factors for infection, it is possible to design appropriate preventive strategies, which must be targeted to the type of infection to be prevented and should also be adapted to the local circumstances in a given hospital. Regardless of the type of infection to be prevented, hand disinfection is a standard measure and remains the most important preventive activity. The approach to the prevention of nosocomial infections has to be interdisciplinary and should involve all areas that are affected by any of the proposed measures. Hospital epidemiology plays a central role in coordinating preventive activities and often sets the priorities for prevention based on the available information. Given the growing complexity and the emergence of new nosocomial threats such as SARS, hospital administrators are well advised to invest sufficiently into their department of hospital hygiene and epidemiology in order to be ready for all the problems that will need to be tackled in the future.

Bacterial Infections↗
PubMed2003

Speciation along environmental gradients.

Traditional discussions of speciation are based on geographical patterns of species ranges. In allopatric speciation, long-term geographical isolation generates reproductively isolated and spatially segregated descendant species. In the absence of geographical barriers, diversification is hindered by gene flow. Yet a growing body of phylogenetic and experimental data suggests that closely related species often occur in sympatry or have adjacent ranges in regions over which environmental changes are gradual and do not prevent gene flow. Theory has identified a variety of evolutionary processes that can result in speciation under sympatric conditions, with some recent advances concentrating on the phenomenon of evolutionary branching. Here we establish a link between geographical patterns and ecological processes of speciation by studying evolutionary branching in spatially structured populations. We show that along an environmental gradient, evolutionary branching can occur much more easily than in non-spatial models. This facilitation is most pronounced for gradients of intermediate slope. Moreover, spatial evolutionary branching readily generates patterns of spatial segregation and abutment between the emerging species. Our results highlight the importance of local processes of adaptive divergence for geographical patterns of speciation, and caution against pitfalls of inferring past speciation processes from present biogeographical patterns.

Animals↗