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PubMed2006

The evolution of resource adaptation: how generalist and specialist consumers evolve.

Why and how specialist and generalist strategies evolve are important questions in evolutionary ecology. In this paper, with the method of adaptive dynamics and evolutionary branching, we identify conditions that select for specialist and generalist strategies. Generally, generalist strategies evolve if there is a switching benefit; specialists evolve if there is a switching cost. If the switching cost is large, specialists always evolve. If the switching cost is small, even though the consumer will first evolve toward a generalist strategy, it will eventually branch into two specialists.

Biological Evolution↗
PubMed2005

Changes in the proportion and volume of care provided to children by generalists and subspecialists.

OBJECTIVE: To assess whether primary care physicians, via referrals or other mechanisms, are now providing proportionally less care for children with specific common diagnoses, thus driving greater demand for specialist services. STUDY DESIGN: Secondary data analysis (1993-2001) from one of the largest commercial healthcare organizations in the United States. Evaluation and management (E/M) common procedural terminology (CPT) visit codes and International Classification of Diseases (ICD) codes pertaining to asthma, constipation, headache, and heart murmurs were selected. Visits were then assigned to the specialty of physician providing care. Significant differences between and among categories of physicians were tested using logistic regression. RESULTS: Overall, pediatrician generalists and specialists provided a greater proportion of E/M visits to children in 2001 than in 1993, compared with nonpediatrician providers. However, although the absolute increase in the proportion of all E/M visits by children <18 years of age to pediatrician generalists was greater than that of pediatrician subspecialists (4.77% vs 0.69%; P <.0001), the relative increase was much smaller for the generalists (8.9% vs 19.7%; P <.0001). Findings were consistent for most of the specific diagnoses examined. CONCLUSIONS: The increases in both the proportion and number of visits made to specialists has not been accompanied by a decrease in visits to generalists.

Asthma↗
PubMed2005

Coevolution of generalist feeding ecologies and gyrencephalic mushroom bodies in insects.

Here we demonstrate the independent acquisition of strikingly similar brain architectures across divergent insect taxa and even across phyla under similar adaptive pressures. Convoluted cortical gyri-like structures characterize the mushroom body calyces in the brains of certain species of insects; we have investigated in detail the cellular and ecological correlates of this morphology in the Scarabaeidae (scarab beetles). "Gyrencephalic" mushroom bodies with increased surface area and volume of calycal synaptic neuropils and increased intrinsic neuron number characterize only those species belonging to generalist plant-feeding subfamilies, whereas significantly smaller "lissencephalic" mushroom bodies are found in more specialist dung-feeding scarab beetles. Such changes are not unique to scarabs or herbivores, because the mushroom bodies of predatory beetles display similar morphological disparities in generalists vs. specialists. We also show that gyrencephalic mushroom bodies in generalist scarabs are not associated with an increase in the size of their primary input neuropil, the antennal lobe, or in the number of antennal lobe glomeruli but rather with an apparent increase in the density of calycal microglomeruli and the acquisition of calycal subpartitions. These differences suggest changes in calyx circuitry facilitating the increased demands on processing capability and flexibility imposed by the evolution of a generalist feeding ecology.

Adaptation, Biological↗
PubMed2024

UDP-glycosyltransferases act as key determinants of host plant range in generalist and specialist Spodoptera species.

Phytophagous insects have evolved sophisticated detoxification systems to overcome the antiherbivore chemical defenses produced by many plants. However, how these biotransformation systems differ in generalist and specialist insect species and their role in determining insect host plant range remains an open question. Here, we show that UDP-glucosyltransferases (UGTs) play a key role in determining the host range of insect species within the Spodoptera genus. Comparative genomic analyses of Spodoptera species that differ in host plant breadth identified a relatively conserved number of UGT genes in generalist species but high levels of UGT gene pseudogenization in the specialist Spodoptera picta. CRISPR-Cas9 knockouts of the three main UGT gene clusters of Spodoptera frugiperda revealed that UGT33 genes play an important role in allowing this species to utilize the poaceous plants maize, wheat, and rice, while UGT40 genes facilitate utilization of cotton. Further functional analyses in vivo and in vitro identified the UGT SfUGT33F32 as the key mechanism that allows generalist S. frugiperda to detoxify the benzoxazinoid DIMBOA (2,4-dihydroxy-7-methoxy-2H-1,4-benzoxazin-3(4H)-one), a potent insecticidal phytotoxin produced by poaceous plants. However, while this detoxification capacity is conserved in several generalist Spodoptera species, Spodoptera picta, which specializes on Crinum plants, is unable to detoxify DIMBOA due to a nonfunctionalizing mutation in SpUGT33F34. Collectively, these findings provide insight into the role of insect UGTs in host plant adaptation, the mechanistic basis of evolutionary transitions between generalism and specialism and offer molecular targets for controlling a group of notorious insect pests.

Animals↗
PubMed2005

Host selection by the generalist aphid Myzus persicae (Hemiptera: Aphididae) and its subspecies specialized on tobacco, after being reared on the same host.

Decision-making during host selection by phytophagous insects has proved to be related to host range, with specialists taking faster decisions than generalists; however, this pattern fails to materialize in some host selection studies performed with aphids. Differences found in testing designs point to rearing effects on aphid host selection. To test whether specialization patterns derive from the nature of the aphid or as a consequence of rearing environment, host selection behaviours were compared between the generalist Myzus persicae (Sulzer) s.s. and its subspecies specialized on tobacco when reared on a common host and offered the choice of an alternative host and a non-host plant. Pre-alighting (host finding and attraction towards host volatiles) and post-alighting (leaf surface exploration and probing) behaviours did not differ between the generalist and the tobacco-specialist, except in the allocation of time to probing behaviour; furthermore, all specialists chose the host on which they performed best. Thus, although the specialist was not faster than the generalist, it showed a higher level of commitment to its preferred host plant.

Adaptation, Physiological↗
PubMed2004

Evolution restricts the coexistence of specialists and generalists: the role of trade-off structure.

Environmental variability and adaptive foraging behavior have been shown to favor coexistence of specialists and generalists on an ecological timescale. This leaves unaddressed the question of whether such coexistence can also be expected on an evolutionary timescale. In this article, we study the attainability, through gradual evolution, of specialist-generalist coexistence, as well as the evolutionary stability of such communities when allowing for immigration. Our analysis shows that the potential for specialist-generalist coexistence is much more restricted than originally thought and strongly depends on the trade-off structure assumed. We establish that ecological coexistence is less likely for species facing a trade-off between per capita reproduction in different habitats than when the trade-off acts on carrying capacities alone. We also demonstrate that coexistence is evolutionarily stable whenever it is ecologically stable but that in most cases, such coexistence cannot be reached through gradual evolution. We conclude that an evolutionarily stable community of specialists and generalists may be created only through immigration from elsewhere or through mutations of large effect. Our results highlight that trade-offs in fitness-determining traits can have counterintuitive effects on the evolution of specialization.

Adaptation, Physiological↗
PubMed1995

Health system reform and the generalist physician.

The quality of primary care services is central to reforming the health care system of the United States. The well-trained generalist is essential in a delivery system that emphasizes high-quality, cost-effective care. Several analyses estimate that within a few years the United States will have 100,000-150,000 too many specialists, and some estimates show a shortage of perhaps 35,000 generalists. Residents and residency programs in nongeneralist areas continue to increase, and two-thirds of graduates enter careers as specialists. Academic medical centers must assume major responsibility for changing their programs to produce the types of practitioners that U.S. society needs. Among the changes recommended or directed by advisory bodies and professional organizations are establishing a workforce commission to set long-term goals, limiting the number of first-year residency positions and allocating them to generalist and nongeneralist specialties, establishing a national payment system to support residency training, setting up transition payments to teaching hospitals that reduce their number of residency positions, and initiatives to graduate more minority and generalist physicians, improve geographic distribution, and expand the capacity for primary-care teaching.

Education, Medical↗
PubMed1995

A model for improving generalist physician output: the osteopathic experience.

Osteopathic medicine is identified closely with primary care. Approximately one-half of all doctors of osteopathy (DOs) are family practitioners. The educational model responsible for producing such a high percentage of generalist physicians should be better understood for its achievements. Colleges of osteopathic medicine are unique in sharing a common mission of producing primary care physicians, and their methodologies reflect a similarly shared educational emphasis. Compared to allopathic medical schools, colleges of osteopathic medicine are the highest producers of generalist physicians because of several common features. This article evaluates colleges of osteopathic medicine by profiling each institution according to characteristics that have a potential impact on the output of generalist physicians: (1) institutional ownership; (2) age; (3) class size; (4) leadership; (5) educational focus; (6) whole-time as opposed to adjunct clinical faculty; (7) clinical educational settings; (8) clinical training sites; and (9) reliance on MD rather than DO clinical faculty. Comparisons between colleges of osteopathic medicine according to these characteristics yield mixed results but also highlight many differences from allopathic educational models. Factors separating the highest from lowest producers of generalist physicians vary at colleges of osteopathic medicine, and other characteristics or circumstances beyond their control may affect the number of graduates pursuing careers in primary care.

Career Choice↗
PubMed1995

Defining a generalist education: an idea whose time is still coming.

Generalist education is different from the traditional medical curriculum as it has developed over the past 40 years. For example, in their training doctors must develop the appropriate skills, knowledge, and attitudes to understand patients' specific expectations, address wellness rather than illness only, be familiar with concepts of clinical epidemiology, concentrate on interpersonal communication, and strive to control costs. The University of Illinois College of Medicine at Rockford was established to provide community-based medical education. Beginning in their second year, all Rockford students have extensive clinical training in one of three community health centers operated by the Department of Family and Community Medicine. Several kinds of evaluation have been conducted to assess the reaction to and impact of this clinical training on the students and faculty, and follow-up studies have tracked the students after graduation. The Rockford experience has shown that the entire curriculum must give uncompromising support for generalist education, all primary care faculty must have a common knowledge base in the theory and practice of generalist medicine, and the shift to generalist education will require shifts in attitude and behavior throughout the academic medicine community at the institution.

Ambulatory Care↗
PubMed1995

Continuous quality improvement and the education of the generalist physician.

The new health care environment--centered on patients, focused on health, and managed by generalists--requires new competencies for the generalist physician. Among these are knowledge and skills for the continuous improvement of health care. In many areas, generalist physicians already use quality improvement methods and principles to improve the health and health care of their communities. Efforts to teach medical students and residents to improve quality continuously in health care are beginning. Early lessons are: (1) quality improvement is most effectively learned in the context of real work; (2) initial emphasis must be on the basics; (3) the focus is on the needs of those we serve; (4) interdisciplinary skills are essential and best learned during clinical training; and (5) the best learning environment for future generalist physicians, one which results in optimism about the future and the ability to make things better, is an environment that is continuously improving.

Arizona↗
PubMed1998

Emerging lessons of the Interdisciplinary Generalist Curriculum (IGC) Project.

The Interdisciplinary Generalist Curriculum Project (IGC) was funded in 1993 by the Health Resources and Services Administration with the goal of developing innovative preclinical generalist curricula in ten of the nation's medical and osteopathic schools. The IGC successfully completed two competitive cycles in which ten schools were awarded three-year contracts. Although the long-term goal of the project is to increase the proportion of medical students choosing generalist careers, much has been learned thus far about the processes of curricular change and interdisciplinary cooperation. Drawing on information from school reports, site visits, external evaluations, academic presentations, and annual project meetings, this report presents the emerging lessons learned in the key areas of interdisciplinary collaboration, recruitment and retention of community preceptors, faculty development, and integration of generalist-related components into the four-year medical school curriculum. These lessons should prove useful for other schools embarking upon significant curricular innovations.

Career Choice↗
PubMed1999

The Virginia generalist initiative: lessons learned in a statewide consortium.

In response to Virginia's need for an increased supply of generalist physicians, the state's three medical schools--Eastern Virginia Medical School, Virginia Commonwealth University School of Medicine, and the University of Virginia School of Medicine--have formed a partnership with key governmental stakeholders in the Virginia Generalist Initiative funded by The Robert Wood Johnson Foundation's Generalist Physician Initiative. These state-supported medical schools historically have functioned independently, with little cooperative effort. This paper describes the consortium, its activities, its successes, and its unmet objectives, and uses a series of cases in point to illustrate relevant lessons learned. Some of these lessons are that (1) stakeholders must be involved from the beginning of planning to identify mutual goals and establish consortium protocols; (2) all partners must share a philosophical commitment to the consortium's mission, as well as the time and resources needed; (3) an atmosphere that enables risk-taking behavior must be created; (4) stakeholders must be willing to revise goals and sustain an environment conductive to change; and (5) trust is essential and must be vigilantly maintained. The paper concludes that the Virginia Generalist Initiative has dramatically altered the goals, objectives and programs of the three schools and has succeeded in aligning the schools' strategic objectives with the state's priorities.

Databases as Topic↗
PubMed1999

Use of a mini-grant program to stimulate generalist training at the University of Massachusetts Medical Center.

The authors describe and evaluate an annual competitive "mini-grant" program, funded by The Robert Wood Johnson Foundation's Generalist Physician Initiative established at the University of Massachusetts Medical School as a strategy to stimulate greater faculty involvement in the development of innovative, generalist-oriented projects. The mini-grant program stimulated proposals from across the academic community. The average award was small (mean = $7,039) but at times the awards led to results exceeding the scope of the original funding. In several cases, mini-grant support provided seed funding for faculty to undertake pilot projects to test new initiatives that would otherwise not have been developed. Some projects led to further ideas or to collaborations between generalists and basic scientists or specialists. More than half of funded projects were eventually institutionalized, and nearly 20% led to formal presentations at national meetings. Two problems are identified: (1) there were fewer proposals generated by specialist faculty and fewer collaborative proposals from generalists and specialists than anticipated, and (2) no funded proposals were generated by community-based faculty who were predominantly clinicians, such as preceptors. Despite these problems, and in light of available solutions, the authors conclude that an institutional mini-grant program can provide an ongoing, flexible mechanism to support a shift in institutional culture toward an enhanced status for generalism.

Curriculum↗
PubMed1999

Recruiting and selecting generalist-oriented students at New York Medical College.

This paper describes the strategies developed for student recruitment and selection at New York Medical College (NYMC), a private medical school with a consortium of 22 teaching hospitals, to meet its goal of 50% of graduating medical students entering generalist careers. With funding from The Robert Wood Johnson Foundation Generalist Physician Initiative, NYMC developed strategies to attract applicants interested in primary care and to select primary care applicants for matriculation. These strategies included use of recruiting newsletters to describe the primary care curriculum, on-campus open houses for undergraduates, visits to regional undergraduate schools by generalist faculty, changes in the admission committee to include more generalists, and changes in the interview format to stress nonacademic qualities in applicants. The authors present data from the Association of American Medical Colleges (AAMC) Pre-Medical Student Questionnaire and from the AAMC Medical School Matriculation Questionnaire that indicate NYMC achieved its objectives. They warn, however, that it is unclear whether these changes occurred solely as a result of NYMC's strategies, as a result of market forces driving career choices, or as a result of some combination of these factors.

Career Choice↗
PubMed1999

Measuring and predicting academic generalists' work satisfaction: implications for retaining faculty.

PURPOSE: To develop a measure that could be used to identify interventions to improve the work satisfaction of academic generalists. METHODS: To field-test the measure, the authors surveyed the generalist faculty at the University of Texas Southwestern Medical Center at Dallas. Ninety-four (80%) of the faculty responded. The measure's reliability was established using Cronbach's alpha, and its validity was established with the Pearson correlation coefficient using a previously validated global work-satisfaction measure. Using ten work-satisfaction dimensions and selected faculty characteristics, the authors performed univariate and stepwise multiple regression analyses to predict the generalist faculty's global work satisfaction and intentions of leaving their positions. RESULTS: Work-satisfaction dimension predictors were autonomy in the workplace, professional status, teaching activities, clinical resources and activities, professional relationships, institutional governance, compensation, and professional advancement. Faculty characteristic predictors were gender, age, race or ethnicity, and living with children. CONCLUSION: The measure includes eight valid and reliable work-satisfaction dimensions that predict global work satisfaction or intentions to leave. Others may want to use this measure, along with the four faculty-characteristic predictors, as a management tool for improving academic generalists' work satisfaction and, ultimately, their performances and retention.

Adult↗
PubMed2001

The Interdisciplinary Generalist Curriculum Project at the University of California, San Francisco.

The Interdisciplinary Generalist Curriculum (IGC) Project came at a pivotal time in curriculum development at the University of California, San Francisco, School of MEDICINE: In the three years prior to the project, the curriculum committee had considered implementation of early longitudinal clinical experiences. This had not been proposed as a primary care experience. Introduction of generalist skills, with the goal of increasing numbers of students choosing generalist residencies, presented significant challenges at this tertiary care and research-oriented medical school. The new IGC course, Foundations of Patient Care, consists of on-campus lectures, small-group sessions, physical examination skills instruction, and a six-quarter preceptorship. As proposed, the school increased teaching of generalist skills and competencies and developed a large pool of primary care preceptors. There was no change in the number of graduates choosing primary care. The strong collaboration that resulted from the development of this new course served as a catalyst for major curricular reform now under way at this medical school.

Curriculum↗
PubMed1996

Specialist and generalist physicians' adoption of antibiotic therapy to eradicate Helicobacter pylori infection.

OBJECTIVES: The authors examine how specialist and generalist physicians adapted their practice patterns to emerging information on the role of Helicobacter pylori in peptic ulcer disease (PUD). METHODS: Data were collected via a mail survey sent to national random samples of gastroenterologists, family practitioners, and general internists in April 1994. A Cox proportional hazards regression was used to evaluate the determinants of the timing of adoption of antibiotic therapy for suspected or confirmed PUD. RESULTS: Most respondents (99.1% of specialists and 64.6% of generalists) had prescribed antibiotic therapy to eradicate Helicobacter pylori at least once. The median specialist adopted 21 months before the medical generalist. Timing of adoption also was related to gender, board certification, PUD case load, and practice setting. CONCLUSIONS: Gastroenterologists were more likely than primary care physicians to adopt antibiotic therapy for PUD, even before the evidence of this therapy's effectiveness was conclusive. Primary care physicians remained less likely to adopt after efficacy was established. The slower adoption by primary care physicians appeared to be related both to having less information than specialists about the new therapy and to more conservative practice styles. Measures to facilitate the flow of information about new technologies to primary care physicians may be warranted. Research on interspecialty differences in adoption of new therapies can contribute to understanding the consequences of the current shift from specialist- to generalist-driven care.

Adult↗
PubMed2003

Morphological shifts in island-dwelling birds: the roles of generalist foraging and niche expansion.

Passerine birds living on islands are usually larger than their mainland counterparts, in terms of both body size and bill size. One explanation for this island rule is that shifts in morphology are an adaptation to facilitate ecological niche expansion. In insular passerines, for instance, increased bill size may facilitate generalist foraging because it allows access to a broader range of feeding niches. Here we use morphologically and ecologically divergent races of white-eyes (Zosteropidae) to test three predictions of this explanation: (1) island populations show a wider feeding niche than mainland populations; (2) island-dwelling populations are made up of individual generalists; and (3) within insular populations there is a positive association between size and degree of foraging generalism. Our results provide only partial support for the traditional explanation. In agreement with the core prediction, island populations of white-eye do consistently display a wider feeding niche than comparative mainland populations. However, observations of individually marked birds reveal that island-dwelling individuals are actually more specialized than expected by chance. Additionally, neither large body size nor large bill size are associated with generalist foraging behavior per se. These latter results remained consistent whether we base our tests on natural foraging behavior or on observations at an experimental tree, and whether we use data from single or multiple cohorts. Taken together, our results suggest that generalist foraging and niche expansion are not the full explanation for morphological shifts in island-dwelling white-eyes. Hence, we review briefly five alternative explanations for morphological divergence in insular populations: environmental determination of morphology, reduced predation pressure, physiological optimization, limited dispersal, and intraspecific dominance.

Animals↗