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PubMed2001

Morphometric correlates of host specificity in Dactylogyrus species (Monogenea) parasites of European Cyprinid fish.

We test the hypothesis that living on larger fish may impose constraints, i.e. the need to develop large attachment organs, related to the necessity to remain attached on large gills. For this, we compiled data on body size and morphometric measurements of attachment organs of 44 Dactylogyrus species (ectoparasites with direct life-cycle) from 19 cyprinid species. Nineteen dactylogyrid species were considered as specialists (infecting only 1 host species) and 25 as generalists (infecting more than 1 species). The lack of phylogenetic information lead us to perform comparative analyses using raw values and independent contrasts obtained by random phylogenies. Our results show that rich parasite communities are formed by specialists and generalists whereas poor communities are composed mainly of generalist parasites. Moreover, specialists are found on larger hosts, which may reflect a specialization on a predictable resource, as larger fish live longer and offer large gills for parasite colonization. Parasite specialization is shown to be linked with adaptation of attachment organs to their fish hosts. Two morphometric variables of the attachment organ, the total length of anchor and length of base of anchor, were positively correlated with host length for specialists.

Animals↗
PubMed1998

Comparison of richness and diversity of macroparasite communities among eels from Nova Scotia, the United Kingdom and Australia.

Species richness and diversity of macroparasite assemblages were compared among American eels (Anguilla rostrata) from Nova Scotia, European eels (A. anguilla) from the United Kingdom (Kennedy, Bush & Aho, 1986; Esch et al. 1988; Kennedy, 1990, 1993), and Australian eels (A. reinhardtii) from Queensland (Kennedy, 1995). Community richness and diversity of the macroparasite fauna of American and European eels did not differ significantly for total parasite component communities, intestinal parasite component communities, and intestinal parasite infracommunities. The similarities in richness and diversity between the parasite communities of American and European eels are not surprising given the common, recent origin of these sister species. However, differences in species composition were noted between Nova Scotia and the UK. Both species of eels were infected by a nearly identical suite of specialists, but differences occurred in the species number and composition of generalist parasites. In addition, generalist species were rarely dominant in Nova Scotia, but commonly so in the UK. These differences can be attributed to the differences in the freshwater fish fauna and their parasites that occur between Nova Scotia and the UK. American and European eels are derived from a common ancestor and, whereas they have carried with them a common suite of specialist parasites during their brief period of independence, they acquired different suites of generalists apparently from their respective continental faunas after they diverged. In contrast, parasite communities of American and European eels were significantly less diverse and speciose than those of Australian eels regardless of scale (total component community, intestinal component community, intestinal infracommunity). These results support the notion that parasite communities have had more time to evolve and/or that tropical conditions have promoted parasite speciation in Australian eels.

Anguilla↗
PubMed2001

Population dynamics of interacting predatory mites, Phytoseiulus persimilis and Neoseiulus californicus, held on detached bean leaves.

The success of combined release of the predatory mites Phytoseiulus persimilis and Neoseiulus californicus in suppression of spider mites may be related to the effects of the interactions between the two predators on their population dynamics. We studied population growth and persistence of the specialist P persimilis and the generalist N. californicus reared singly versus reared in combination after simultaneous and successive predator introductions on detached bean leaf arenas with abundant prey, Tetranychus urticae. and with diminishing prey. When reared singly with abundant prey, either predator population persisted at high densities to the end of the experiment. In every predator combination system with abundant prey and various initial predator:predator ratios N. californicus displaced P persimilis. When held singly with diminishing prey, the population of P. persimilis grew initially faster than the population of N. californicus but both species reached similar population peaks. Irrespective whether reared singly or in combination. N. californicus persisted three to five times longer after prey depletion than did P. persimilis. Regarding the crucial interactions in the predator combination systems, we conclude that intraguild predation was a stronger force than food competition and finally resulted in the displacement of P. persimilis. Previous studies showed that intraguild predation between the specialist P. persimilis and the generalist N. californicus is strongly asymmetric favoring the generalist. We discuss the implications of potential interactions between P. persimilis and N. californicus to biological control of spider mites.

Animals↗
PubMed2001

Rapid responses of British butterflies to opposing forces of climate and habitat change.

Habitat degradation and climate change are thought to be altering the distributions and abundances of animals and plants throughout the world, but their combined impacts have not been assessed for any species assemblage. Here we evaluated changes in the distribution sizes and abundances of 46 species of butterflies that approach their northern climatic range margins in Britain-where changes in climate and habitat are opposing forces. These insects might be expected to have responded positively to climate warming over the past 30 years, yet three-quarters of them declined: negative responses to habitat loss have outweighed positive responses to climate warming. Half of the species that were mobile and habitat generalists increased their distribution sites over this period (consistent with a climate explanation), whereas the other generalists and 89% of the habitat specialists declined in distribution size (consistent with habitat limitation). Changes in population abundances closely matched changes in distributions. The dual forces of habitat modification and climate change are likely to cause specialists to decline, leaving biological communities with reduced numbers of species and dominated by mobile and widespread habitat generalists.

Adaptation, Physiological↗
PubMed2004

The combined effects of pathogens and predators on insect outbreaks.

The economic damage caused by episodic outbreaks of forest-defoliating insects has spurred much research, yet why such outbreaks occur remains unclear. Theoretical biologists argue that outbreaks are driven by specialist pathogens or parasitoids, because host-pathogen and host-parasitoid models show large-amplitude, long-period cycles resembling time series of outbreaks. Field biologists counter that outbreaks occur when generalist predators fail, because predation in low-density defoliator populations is usually high enough to prevent outbreaks. Neither explanation is sufficient, however, because the time between outbreaks in the data is far more variable than in host-pathogen and host-parasitoid models, and far shorter than in generalist-predator models. Here we show that insect outbreaks can be explained by a model that includes both a generalist predator and a specialist pathogen. In this host-pathogen-predator model, stochasticity causes defoliator densities to fluctuate erratically between an equilibrium maintained by the predator, and cycles driven by the pathogen. Outbreaks in this model occur at long but irregular intervals, matching the data. Our results suggest that explanations of insect outbreaks must go beyond classical models to consider interactions among multiple species.

Animals↗
PubMed2003

Classifying general and specialist children's nursing competencies.

BACKGROUND: Whilst there is evidence in the literature to support the continuation of a children's nursing qualification, the distinction between generalist and specialist nursing is insufficiently comprehensive to distinguish children's nursing from other branches of nursing. AIM: To develop a definition of children's nursing and specialist children's nursing in terms of competencies as the basis for differentiating them from other forms of nursing. DESIGN: A multi-method comparative design incorporating a case study approach was used. This included a nominal group technique, focus groups, Delphi survey and semi-structured interviews. Two arms of data collection were undertaken concurrently (during 1998-2000) with children's nurses (n = 146) and specialist children's nurses (children's cancer nurses, n = 37) from a number of centres in the United Kingdom (UK). FINDINGS: The holistic competencies developed from the data exposed characteristics of knowledge, skills, abilities, values and qualities displayed in the context of professional work for both groups of nurses. A classification of competencies was developed inductively from the data by two independent researchers through the labelling, defining and ordering of competencies. The resulting hierarchy of competencies and sub-competencies illustrates relationships between children's nurses and specialist children's nurses and provides a detailed definition of children's nursing and specialist children's nursing. CONCLUSION: There is a significant common element in these two areas of nursing practice, and generalist preparation in children's nursing is the foundation of specialist children's nursing practice. Generalist knowledge and skills are expanded in specialist practice and there is also evidence of specialist practice that is beyond the scope of general nursing practice.

Clinical Competence↗
PubMed2003

American internal medicine in the 21st century: can an Oslerian generalism survive?

American internal medicine suffers a confusion of identity as we enter the 21st century. The subspecialties prosper, although unevenly, and retain varying degrees of connection to their internal medicine roots. General internal medicine, identified with primary care since the 1970s, retains an affinity for its traditional consultant-generalist ideal even as primary care further displaces that ideal. We discuss the origins and importance of the consultant-generalist ideal of internal medicine as exemplified by Osler, and its continued appeal in spite of the predominant role played by clinical science and accompanying subspecialism in determining the academic leadership of American internal medicine since the 1920s. Organizing departmental clinical work along subspecialty lines diminished the importance of the consultant-generalist ideal in academic departments of medicine after 1950. General internists, when they joined the divisions of general internal medicine that appeared in departments of medicine in the 1970s, could sometimes emulate Osler in practicing a general medicine of complexity, but often found themselves in a more limited role doing primary care. As we enter the 21st century, managed care threatens what remains of the Oslerian ideal, both in departments of medicine and in clinical practice. Twenty-first century American internists will have to adjust their conditions of work should they continue to aspire to practice Oslerian internal medicine.

Academic Medical Centers↗
PubMed1998

Dialysis patient ratings of the quality of medical care.

Dialysis patients receive medical care from a variety of physicians. Little is known about how dialysis patients assess the quality of this care. We sought to determine (1) who dialysis patients receive medical care from, (2) how they rate the quality of such care, and (3) how ratings differ for care provided by generalists, nephrologists, and other specialists. We performed a cross-sectional interview study of 148 patients from four chronic hemodialysis units. Using a structured questionnaire, we asked subjects about each condition for which they received care in the preceding 12 months. For each condition, subjects mentioned the type of physician who provided care and then rated their overall satisfaction with care as well as six components of quality of care (availability of doctor, technical skill, personal manner, explanations provided, amount of time spent, and how much patient was helped). We found that generalists, nephrologists, and other specialists provided care for 14%, 48%, and 38% of conditions for which patients received care. Sixty-nine percent of overall satisfaction ratings were very good or better. Of the six components of quality of care, explanations and amount of time received the lowest ratings. On multivariate analysis, increased patient age, black race, and care for acute illnesses were associated with lower ratings of quality of care. There was no difference in ratings of care provided by generalists, nephrologists, and other specialists. In conclusion, dialysis patients receive most of their medical care from nephrologists and other specialists. Although they generally rate this care highly, we recommend that providers pay special attention to explanations provided, time spent with patients, and care for acute illness.

Adult↗
PubMed1979

The contribution of specialists to the delivery of primary care.

Despite increased numbers of medical-school graduates and opportunities for "primary-care" specialty training since the mid-1960's, many believe that the shortage of physicians delivering generalist care will continue through the 1980's. Missing, however, is solid information on the role of physician specialists in providing such care. Two national studies have shown that one of every five Americans now receives continuing general medical care from a specialist physician. Our study suggests that, despite the current shortage of generalist-physician services, continuing specialist participation in primary care will lead to sufficient generalist medical services by the mid-1980's. Whether specialist participation is the most appropriate or cost-effective way to improve access to such care is unclear. However, until this question is resolved, more governmental regulation of graduate medical education may be unwise. Offering all physicains, regardless of specialty, more primary-care experience during residency training might better deal with this aspect of American medical practice.

California↗
PubMed2005

Re-evaluating the role of the MFM specialist: lead, follow, or get out of the way.

OBJECTIVE: To assess the effect of sub-specialty prenatal care provided to high-risk obstetrical patients in a community perinatal center as a function of whether consultation and referral to a Maternal-Fetal Medicine (MFM) sub-specialist was at the discretion of the generalist, required by the insurance carrier, or by patient choice. METHODS: Demographics, management, and perinatal outcomes for high-risk patients managed exclusively by MFM were compared with those managed by generalists who were later referred to MFM after problems arose. RESULTS: Despite similar demographics, high-risk patients managed exclusively by a single MFM had less prematurity, lower cesarean section rates, fewer low 5-minute Apgar scores (1.3% vs. 5.5%, p < 0.001), and lower perinatal mortality rates (8.0/1000 vs. 47.6/1000, p < 0.001) than those referred at a later date. CONCLUSIONS: In this setting, earlier MFM care resulted in better outcomes. These data suggest that the 'gatekeeper' model of generalist to MFM might be better the other way around.

Adult↗
PubMed2005

Predator diet breadth influences the relative importance of bottom-up and top-down control of prey biomass and diversity.

We investigated the effects of predator diet breadth on the relative importance of bottom-up and top-down control of prey assemblages, using microbial food webs containing bacteria, bacterivorous protists and rotifers, and two different top predators. The experiment used a factorial design that independently manipulated productivity and the presence or absence of two top predators with different diet breadths. Predators included a "specialist" predatory ciliate Euplotes aediculatus, which was restricted to feeding on small prey, and a "generalist" predatory ciliate Stentor coeruleus, which could feed on the entire range of prey sizes. Both total prey biomass and prey diversity increased with productivity in the predator-free control and specialist predator treatments, a pattern consistent with bottom-up control, but both remained unchanged by productivity in the generalist predator treatment, a pattern consistent with top-down control. Linear food chain models adequately described responses in the generalist predator treatment, whereas food web models incorporating edible and inedible prey (which can coexist in the absence of predators) adequately described responses in the specialist predator treatment. These results suggest that predator diet breadth can play an important role in modulating the relative strength of bottom-up and top-down forces in ecological communities.

Animals↗
PubMed2025

Temporal Genomics Reveal a Century of Genomic Diversity Shifts Across a Biodiversity Hotspot Avian Assemblage.

Biodiversity has experienced tremendous shifts in community, species, and genetic diversity during the Anthropocene. Understanding temporal diversity shifts is especially critical in biodiversity hotspots, i.e., regions that are exceptionally biodiverse and threatened. Here, we use museomics and temporal genomics approaches to quantify temporal shifts in genomic diversity in an assemblage of eight generalist highland bird species from the Ethiopian Highlands (part of the Eastern Afromontane Biodiversity Hotspot). With genomic data from contemporary and historical samples, we demonstrate an assemblage-wide trend of increased genomic diversity through time, potentially due to improved habitat connectivity within highland regions. Genomic diversity shifts in these generalist species contrast with general trends of genomic diversity declines in specialist or imperiled species. In addition to genetic diversity shifts, we found an assemblage-wide trend of decreased realized mutational load, indicative of overall trends for potentially deleterious variation to be masked or selectively purged. Across this avian assemblage, we also show that shifts in population genomic structure are idiosyncratic, with species-specific trends. These results are in contrast with other charismatic and imperiled African taxa that have largely shown strong increases in population genetic structure over the recent past. This study highlights that not all taxa respond the same to environmental change, and generalists, in some cases, may even respond positively. Future comparative conservation genomics assessments on species groups or assemblages with varied natural history characteristics would help us better understand how diverse taxa respond to anthropogenic landscape changes.

Animals↗
PubMed2002

Comparative analysis of quantitative trait loci controlling glucosinolates, myrosinase and insect resistance in Arabidopsis thaliana.

Evolutionary interactions among insect herbivores and plant chemical defenses have generated systems where plant compounds have opposing fitness consequences for host plants, depending on attack by various insect herbivores. This interplay complicates understanding of fitness costs and benefits of plant chemical defenses. We are studying the role of the glucosinolate-myrosinase chemical defense system in protecting Arabidopsis thaliana from specialist and generalist insect herbivory. We used two Arabidopsis recombinant inbred populations in which we had previously mapped QTL controlling variation in the glucosinolate-myrosinase system. In this study we mapped QTL controlling resistance to specialist (Plutella xylostella) and generalist (Trichoplusia ni) herbivores. We identified a number of QTL that are specific to one herbivore or the other, as well as a single QTL that controls resistance to both insects. Comparison of QTL for herbivory, glucosinolates, and myrosinase showed that T. ni herbivory is strongly deterred by higher glucosinolate levels, faster breakdown rates, and specific chemical structures. In contrast, P. xylostella herbivory is uncorrelated with variation in the glucosinolate-myrosinase system. This agrees with evolutionary theory stating that specialist insects may overcome host plant chemical defenses, whereas generalists will be sensitive to these same defenses.

Animals↗
PubMed1998

Cost considerations with infertility therapy: outcome and cost comparison between health maintenance organization and preferred provider organization care based on physician and facility cost.

Of 98 retrospectively selected patient couples insured under one scheme (group I) who, based on performance of a hysterosalpingogram (HSG), were assumed to be under active infertility care, 96 were confirmed as infertile. These were matched by date, patient age and time of HSG to 96 patients under infertility care (group II). Both patient populations were then prospectively evaluated for outcome and cost of treatment. Total physician charges for groups I and II were similar. However, charges per achieved clinical pregnancy were higher in group I than group II since group I patients demonstrated a lower pregnancy rate (28/96, 29%) than group II patients (41/96, 43%) (P=0.05). Within group I, pregnancy rates were identical, whether treatment was provided by generalists or subspecialists. In group II, all care was provided by specialists. The number of days of treatment did not vary between groups I and H, though generalists in group I provided significantly fewer treatment days than specialists in either group I (P=0.003) or in group II (P=0.021). This was primarily due to a significantly higher patient drop-out rate in group I patients, and especially amongst those who received care from generalists (P < 0.0019). Group I patients also encountered significantly more surgical procedures than group H patients (P=0.0016). If physician charges are discounted and customary surgical facility costs are added, the actual cost structure for fertility care in group I patients was dramatically higher than in group II patients. The most cost-effective format to provide infertility care of high quality appears to be a managed care setting in which subspecialists provide a majority of care and in which patient choice is restricted to those subspecialists.

Female↗
PubMed1996

'Identities ascertained': British ophthalmology in the first half of the nineteenth century.

The paper takes its cue from the work on specialization and American ophthalmology by George Rosen (1944). Where Rosen's account was inspired by sociology, this paper gives a non-teleological account of medical specialization through a cultural history of ophthalmology. The cultural nature of the ophthalmic epidemics motivated practitioners to study the eye in earnest. These practitioners had to surmount obstacles intrinsic to the medical culture: the division between physicians and surgeons, hostility to specialisms, and the association with quackery. Practitioners justified their interests through the management of history, the association with philanthropy, and the construction of a father-figure. New interest in the eye was partly legitimated by the use of existing discourses, both philosophical and religious, that offered practitioners motivating languages to describe their practice. Specialization was effected through varying combinations of elements: emotional and intellectual investment in the eye, the advocacy of further research, and the explicit prosecution of specialties. The process depended upon generalist enthusiasm for the eye, and specialists' championing of generalist medicine. Specialization is a continual cultural process in a constant balancing act with the generalist tendency in medicine.

History, 19th Century↗
PubMed1995

Communication as an essential part of program and institutional development.

The Longitudinal Primary Care Program, an innovative curriculum in generalist medicine at the University of Illinois at Chicago College of Medicine, has been enhanced by a commitment to fostering good communication among all of its participants (who include more than 350 students and nearly 300 office-based generalist preceptors) and between participants and administrators. The diverse and widely scattered group of preceptors is brought together through orientation sessions and faculty development workshops that stress precepting skills and mentoring. Preceptors are regularly surveyed and the survey data are analyzed to help administrators learn how best to recruit and retain these faculty members. Students' input comes through surveys, small-group meetings, and their participation on committees. Program evaluation data and formal notes from committee meetings are promptly compiled and disseminated. Such efforts to promote good communication among preceptors, students, program administrators, and the medical college have both enhanced the generalist program and encouraged other curricular reforms in the college.

Chicago↗
PubMed1995

Medical students' career indecision and specialty rejection: roads not taken.

The authors used data from the AAMC Matriculating Student Questionnaire and Medical School Graduation Questionnaire to ascertain how closely the specialty or subspecialty choices of the 1991 and 1994 graduates of U.S. medical schools matched the preferences they had declared when they were matriculated; the extent to which these students strongly considered and then rejected choices that arose during medical school; and the graduation choices of the substantial number of students in both cohorts who were undecided about their careers when they entered medical school. Approximately 80% of the graduates in both classes rejected the specialty intentions they had declared when they began medical school. However, matriculation interests in the generalist specialties--family practice, general pediatrics, and general internal medicine--were more enduring for the 1994 cohort, while interests in the medical, surgical, and support specialties were less so. Large percentages of the 1991 and 1994 cohorts were undecided about their careers at matriculation (20.8% and 26.2%, respectively), and nearly the same proportions remained undecided at graduation. However, more of the graduates in the 1994 cohort who had initially been undecided reached decisions favoring one of the generalist specialties than was true for the 1991 cohort. Nearly half the 1994 graduates had strongly considered and then rejected an alternative to their matriculation interest that arose during medical school. Within the generalist specialties, both early and later interests in family practice were more durable than were those in general pediatrics and general internal medicine: for every student who retreated from tentative interest in family practice, another student's interest was reinforced or kindled.(ABSTRACT TRUNCATED AT 250 WORDS)

Career Choice↗
PubMed1995

Measuring the use of the population perspective on internal medicine attending rounds.

BACKGROUND: The population perspective (risk-factor assessment, prevention, epidemiology, and the social aspects of illness) is increasingly important in medical school and residency curricula. The authors designed an observational study to assess the population-perspective content of internal medicine teaching rounds led by attending physicians at the Columbia-Presbyterian Medical Center. METHOD: During eight months in 1992 a trained research assistant used a structured observation form in observing attending rounds. Population scores were calculated by totaling the number of times population-perspective topics were mentioned during each case presentation (one point was awarded per mention, with an additional point being added for discussions lasting 30 seconds or more). Chi-square tests and unpaired t-tests were used to compare scores between teams with one generalist and one subspecialist attending physician and teams with two subspecialists. RESULTS: Fifteen teams and 368 patient presentations were observed. The mean population scores were 24.5 for teams with generalist attending physicians and 17.9 for teams with subspecialists only (p < .0001). The population scores for individual case presentations ranged from 2 to 55. CONCLUSION: The population-perspective topics were raised more frequently on the internal medicine teaching rounds when a generalist attending physician was present than when there were only subspecialist attending physicians.

Clinical Medicine↗