Independent transitions to freshwater environments promote phenotypic divergence, not convergence, in stingrays.

Instances of convergent or parallel evolution provide a potent model system for exploring contingency and determinism in evolutionary biology. Likewise, the multiple, independent habitat transitions from saltwater to freshwater biomes offer opportunity for studying convergent evolution within and among different vertebrate lineages. For example, stingrays have invaded freshwater habitats multiple times across different continents, sometimes even several times within the same clade (e.g., Dasyatidae). We evaluated the frequency of saltwater-freshwater invasions in stingrays, compared ecological and phenotypic diversification among freshwater and saltwater lineages, and assessed the degree of convergence among freshwater species. Despite not being morphologically distinct from saltwater stingrays, freshwater stingrays do expand the margins of stingray morphological diversity. According to our data, trophic specialists occupied non-overlapping regions of morphospace, with piscivores and molluscivores being distinct from other diet guilds. Freshwater stingrays as a group did not strongly converge morphologically, neither did freshwater rays from different lineages which shared similar niches. These findings could be explained by there not being enough time for convergence to occur among more ancient and more recent freshwater lineages. Alternatively, the different ancestral bauplans of various freshwater ray lineages and weak selection on optimal phenotypes could promote contingency in the form of evolution along paths of least resistance.

Ecological and Phenotypic Diversification after a Continental Invasion in Neotropical Freshwater Stingrays.

Habitat transitions are key potential explanations for why some lineages have diversified and others have not-from Anolis lizards to Darwin's finches. The ecological ramifications of marine-to-freshwater transitions for fishes suggest evolutionary contingency: some lineages maintain their ancestral niches in novel habitats (niche conservatism), whereas others alter their ecological role. However, few studies have considered phenotypic, ecological, and lineage diversification concurrently to explore this issue. Here, we investigated the macroevolutionary history of the taxonomically and ecologically diverse Neotropical freshwater river rays (subfamily Potamotrygoninae), which invaded and diversified in the Amazon and other South American rivers during the late Oligocene to early Miocene. We generated a time-calibrated, multi-gene phylogeny for Potamotrygoninae and reconstructed evolutionary patterns of diet specialization. We measured functional morphological traits relevant for feeding and used comparative phylogenetic methods to examine how feeding morphology diversified over time. Potamotrygonine trophic and phenotypic diversity are evenly partitioned (non-overlapping) among internal clades for most of their history, until 20-16 mya, when more recent diversification suggests increasing overlap among phenotypes. Specialized piscivores (Heliotrygon and Paratrygon) evolved early in the history of freshwater stingrays, while later trophic specialization (molluscivory, insectivory, and crustacivory) evolved in the genus Potamotrygon. Potamotrygonins demonstrate ecological niche lability in diets and feeding apparatus; however, diversification has mostly been a gradual process through time. We suggest that competition is unlikely to have limited the potamotrygonine invasion and diversification in South America.

Proximate and ultimate causes of signal diversity in the electric fish Gymnotus.

A complete understanding of animal signal evolution necessitates analyses of both the proximate (e.g. anatomical and physiological) mechanisms of signal generation and reception, and the ultimate (i.e. evolutionary) mechanisms underlying adaptation and diversification. Here we summarize the results of a synthetic study of electric diversity in the species-rich neotropical electric fish genus Gymnotus. Our study integrates two research directions. The first examines the proximate causes of diversity in the electric organ discharge (EOD) - which is the carrier of both the communication and electrolocation signal of electric fishes - via descriptions of the intrinsic properties of electrocytes, electrocyte innervation, electric organ anatomy and the neural coordination of the discharge (among other parameters). The second seeks to understand the ultimate causes of signal diversity - via a continent-wide survey of species diversity, species-level phylogenetic reconstructions and field-recorded head-to-tail EOD (ht-EOD) waveforms (a common procedure for characterizing the communication component of electric fish EODs). At the proximate level, a comparative morpho-functional survey of electric organ anatomy and the electromotive force pattern of the EOD for 11 species (representing most major clades) revealed four distinct groups of species, each corresponding to a discrete area of the phylogeny of the genus and to a distinct type of ht-EOD waveform. At the ultimate level, our analyses (which emphasize the ht-EOD) allowed us to conclude that selective forces from the abiotic environment have had minimal impact on the communication component of the EOD. In contrast, selective forces of a biotic nature - imposed by electroreceptive predators, reproductive interference from heterospecific congeners, and sexual selection - may be important sources of diversifying selection on Gymnotus signals.

Molecular phylogenetics reveals a pattern of biome conservatism in New World anchovies (family Engraulidae).

Evolutionary transitions between marine and freshwater biomes are relatively rare events, yielding a widespread pattern of biome conservatism among aquatic organisms. We investigated biome transitions in anchovies (Engraulidae), a globally distributed clade of economically important fishes. Most anchovy species are near-shore marine fishes, but several exclusively freshwater species are known from tropical rivers of South America and were previously thought to be the product of six or more independent freshwater invasions. We generated a comprehensive molecular phylogeny for Engraulidae, including representatives from 15 of 17 currently recognized genera. Our data support previous hypotheses of higher-level relationships within Engraulidae, but show that most New World genera are not monophyletic and in need of revision. Ancestral character reconstruction reveals that New World freshwater anchovies are the product of a single marine to freshwater transition, supporting a pattern of biome conservatism. We argue that competition is the principal mechanism that regulates aquatic biome transitions on a continental scale.

The Casiquiare river acts as a corridor between the Amazonas and Orinoco river basins: biogeographic analysis of the genus Cichla.

The Casiquiare River is a unique biogeographic corridor between the Orinoco and Amazonas basins. We investigated the importance of this connection for Neotropical fishes using peacock cichlids (Cichla spp.) as a model system. We tested whether the Casiquiare provides a conduit for gene flow between contemporary populations, and investigated the origin of biogeographic distributions that span the Casiquiare. Using sequences from the mitochondrial control region of three focal species (C. temensis, C. monoculus, and C. orinocensis) whose distributions include the Amazonas, Orinoco, and Casiquiare, we constructed maximum likelihood phylograms of haplotypes and analyzed the populations under an isolation-with-migration coalescent model. Our analyses suggest that populations of all three species have experienced some degree of gene flow via the Casiquiare. We also generated a mitochondrial genealogy of all Cichla species using >2000 bp and performed a dispersal-vicariance analysis (DIVA) to reconstruct the historical biogeography of the genus. This analysis, when combined with the intraspecific results, supports two instances of dispersal from the Amazonas to the Orinoco. Thus, our results support the idea that the Casiquiare connection is important across temporal scales, facilitating both gene flow and the dispersal and range expansion of species.

Ancient trans-Atlantic flight explains locust biogeography: molecular phylogenetics of Schistocerca.

The desert locust (Schistocerca gregaria) has been an important agricultural pest at least since biblical times. Although the ecology, physiology and behaviour of this insect species have been well characterized, its biogeographical origins and evolutionary history are more obscure. Schistocerca gregaria occurs throughout Africa, the Middle East and Western Asia, but all other species in the genus Schistocerca are found in the New World. Because S. gregaria has the capacity for extreme long-distance movement associated with swarming behaviour, dispersal may have played an important role in determining current distribution patterns. Some authors have argued that S. gregaria is the product of an eastward trans-Atlantic dispersal from North America to Africa; others consider it more likely that the New World taxa are the product of westward dispersal from Africa. Here, we present a mitochondrial DNA phylogeny of Schistocerca species that supports the monophyly of New World species (including the Galapagos endemic Halmenus) relative to S. gregaria. In concert with observed patterns of molecular divergence, and in contrast to previous morphological studies, our analysis indicates a single trans-Atlantic flight from Africa to South America, followed by extensive speciation and ecological divergence in the New World.

Reinterpreting recapitulation: systematics of needlefishes and their allies (Teleostei: Beloniformes).

As needlefishes (Belonidae) grow, their jaws pass through a "halfbeak" stage that resembles the adult jaw condition of the closely related family of halfbeaks (Hemiramphidae). Based on this pattern, some authors have suggested that halfbeaks are "developmentally arrested" or paedomorphic needlefish derivatives, whereas others have supported the notion that needlefishes are descended from halfbeak-like ancestors and that needlefish ontogeny thereby recapitulates phylogeny. To test these ideas and to better understand evolutionary changes in jaw ontogeny, phylogenetic relationships among genera of needlefishes, sauries (Scomberesocidae), halfbeaks, and flyingfishes (Exocoetidae) were assessed using mitochondrial (cytochrome b and 16S), nuclear (Tmo-4C4), and morphological characters. The resultant tree provides several novel taxonomic findings: (1) flyingfishes appear to be nested within halfbeaks; (2) sauries appear to be nested within needlefishes; and (3) the Indo-West Pacific freshwater halfbeaks appear to be most closely related to the needlefish/saury clade. The structure of the tree falsifies the idea that halfbeaks are paedomorphic needlefishes. Instead, halfbeaks are basal relative to needlefishes, fitting the pattern predicted by the hypothesis of recapitulation. I discuss limitations to phylogenetic perspectives on recapitulation based on discrete character data by comparing aspects of von Baerian and Haeckelian views of the relation between ontogeny and phylogeny.

Cancer-related depression: Part I--Neurologic alterations and cognitive-behavioral therapy.

PURPOSE/OBJECTIVES: To describe neurologic and cognitive alterations underlying symptoms of depression and to explore cognitive-behavioral approaches to promoting recovery from cancer-related depression. DATA SOURCES: Published literature, unpublished raw data, and clinical observations. DATA SYNTHESIS: Depression is a progressive condition that is most responsive to treatment in its earliest stages because of the progressive nature of alterations in neurologic circuits and neurotransmitters. Aggressive screening and management using cognitive-behavioral therapy (CBT) techniques can promote recovery from cancer-related depression and improve patients' quality of life. Application of CBT techniques to patient environments also holds promise of relieving and preventing depression. IMPLICATIONS FOR NURSING PRACTICE: By placing more emphasis on screening for cancer-related depression among newly diagnosed and treated patients, oncology nurses can expedite treatment of cancer-related depression. Working within psychiatric liaison teams or guidelines for routine psychiatric care, oncology nurses can promote recovery and create therapeutic environments that are conducive to promoting patients' mental health along the cancer trajectory.

Cancer-related depression: Part II--Neurologic alterations and evolving approaches to psychopharmacology.

PURPOSE/OBJECTIVES: To describe evolving psychopharmacologic options for managing depression related to cancer. DATA SOURCES: Literature review and case study. DATA SYNTHESIS: Optimal recovery from depression requires early detection and selection of psychopharmacologic agents--singly or in combination--to address each depressive symptom. CONCLUSIONS: Adequate psychopharmacologic management of depression requires consistent, informed involvement of healthcare professionals, patients, and caregivers. Patients and caregivers need to be prepared to assess responses to therapy, recognize adverse effects, manage minor side effects and threats to adherence, and seek appropriate assistance for adverse events, including drug-drug interactions. IMPLICATIONS FOR NURSING PRACTICE: Oncology nurses need to take an active role in assessing, documenting, and monitoring patients' responses to antidepressants, particularly during key phases (e.g., induction, substitutions, augmentation, withdrawal). Nurses also need to take an active role in screening patients for depression, preparing patients and caregivers for psychopharmacologic management of depression, and reinforcing these competencies regularly. Oncology nurses also can be instrumental in recognizing signs and symptoms of treatment resistance and addressing these issues appropriately. Because of the rapid pace of psychopharmacologic research, oncology nurses need to update knowledge continuously to provide safe care to depressed patients with cancer.

Molecular systematics, biogeography and population structure of neotropical freshwater needlefishes of the genus Potamorrhaphis.

Phylogenetic relationships of populations and species within Potamorrhaphis, a genus of freshwater South American needlefishes, were assessed using mitochondrial cytochrome b sequences. Samples were obtained from eight widely distributed localities in the Amazon and Orinoco rivers, and represented all three currently recognized species of Potamorrhaphis. The phylogeny of haplotypes corresponded imperfectly to current morphological species identities: haplotypes from P. guianensis, the most widespread species, did not make up a monophyletic clade. Geography played a strong role in structuring genetic variation: no haplotypes were shared between any localities, indicating restricted gene flow. Possible causes of this pattern include limited dispersal and the effects of current and past geographical barriers. The haplotype phylogeny also showed a complex relationship between fishes from different river basins. Based on the geographical distribution of clades, we hypothesize a connection between the middle Orinoco and Amazon via rivers of the Guianas. More ancient divergence events may have resulted from Miocene alterations of river drainage patterns. We also present limited data for two other Neotropical freshwater needlefish genera: Belonion and Pseudotylosurus. Pseudotylosurus showed evidence of substantial gene flow between distant localities, indicating ecological differences from Potamorrhaphis.

Cognitive-behavioral interventions to manage depression in patients with cancer: research and theoretical initiatives.

The incidence of depression is rising worldwide, possibly due to urban crowding and insufficient resources. This pandemic raises the possibility that disabling depression among patients with cancer will increase. Already, about one-third of patients with cancer present with depression. Although many progressive cancer centers are instituting psychooncology services, the projected decline in numbers of psychiatrists in the coming decade suggests that these programs may flounder unless nurses are able to provide adjuvant support. Consequently, this article describes the theoretical and emerging research data base regarding the treatment of cancer-related depression with cognitive-behavioral therapy. Implications drawn from this review suggest that nurses can take an active role in preventing and managing cancer-related depression in direct care environments by developing critical pathways for screening, prevention, treatment, and outcomes assessment using theory-based research.

Life stress and risk of precancerous cervical lesions: a pretest directed by the life stress model.

PURPOSE/OBJECTIVES: To present the results of a pilot study to pretest instruments designed to measure selected variables named in the Life Stress Model, a model of health outcomes. Additional aims were to determine the effect of completing personal risk assessments for precancerous squamous-cell intraepithelial lesions of the cervic (SIL) on receptivity to cervical cancer prevention information and to extend knowledge of stressful life events experienced by inner-city women attending high-risk health clinics. DESIGN: Cross-sectional. SAMPLE: 20 adult women attending high-risk prenatal or human immunodeficiency virus (HIV) outpatient clinics in one of two New York City hospitals. Most were recovering drugs abusers; half were diagnosed with HIV infections. METHODS: Data were collected by self-report using standard measures. Demographics, medical histories of immunosuppressive states, and investigator-developed screening inventories of behavioral and dietary risk factors associated with SIL also were administered. MAIN RESEARCH VARIABLES: Life event stressors, psychological state, social support, symptom distress, and SIL diagnosis. FINDINGS: Instruments met acceptable psychometric standards for internal consistency, but the standard measure of stressful life events did not capture the full range of stressors experienced by this group of patients: hovering relatives, abusive spouses, HIV diagnosis, changes in welfare benefits, the HIV status of the unborn, and mandatory foster care. Although unable to recall cancer histories of family members, about half of the women who completed study instruments were interested in receiving more information cervical cancer. Exploratory analyses suggest that women diagnosed with SIL experience more psychological distress and family disfunction than women without SIL. CONCLUSIONS: Completing personal SIL risk assessments may stimulate patients' receptivity to cancer risk factor information. Health outcomes studies guided by the Life Stress Model may prove fruitful. IMPLICATIONS FOR NURSING PRACTICE: Cancer risk factor assessments may be an important method for promoting receptivity to cancer prevention information.

A method for developing faculty leaders.

The authors explore peer review as a mechanism for developing faculty leaders who can meet the educational challenges posed by public demands for accountability in higher education and an increasingly diverse student body. How educational paradigms influence the design of peer review programs is described. Incentives and disincentives as well as options for counteracting disincentives also are considered. Recommendations include the need to study effects of peer review programs on productivity, professional relationships, and educational outcomes within situational contexts, resources, and constraints.

Pharmacokinetics and pharmacodynamics of mood-altering drugs in patients with cancer.

Undertreatment of depression in patients with cancer is a clinical problem requiring prompt action. Although responsive to cognitive and behavioral interventions, unipolar depression in patients with cancer often requires pharmacologic management. Because of pathologies associated with cancer and its treatment, pharmacologic outcomes are often unpredictable, necessitating careful assessment of risk factors for over- and undermedication. This article reviews important principles of pharmacokinetics and pharmacodynamics of mood-altering drugs administered by oral routes and ways therapeutic effects might be influenced by cancer. Contigent implications for advancing practice, research, and policy are also described.

Multinational approaches to cervical cancer screening: a review.

Worldwide, cervical cancer incidence is 75% higher than the projected ideal set by the World Health Organization. Despite an effective screen for in situ stage cancer, many women do not adhere to regular screening schedules. These delays raise mortality rates, since curative therapies are available only for the early stages of disease. Seeking to improve cancer control among women, investigators have developed a variety of methods to improve adherence rates. This article presents these methods as well as the cost-effectiveness of each when evaluative data are available. The article suggests that nurses may draw upon current knowledge to design and test the effectiveness of cancer control models in the catchment areas served by their institutions and agencies.

Squamous cell cervical lesions in women with and without AIDS. Biochemical risk factors, prevention, and policy.

Worldwide, squamous cell cervical cancer and intraepithelial lesions (SIL) are a major source of morbidity and mortality. Compared to women in general, women with human immunodeficiency syndromes (HIV) are at higher risk of developing SIL. With the HIV epidemic escalating among women, prevalence, morbidity, and mortality related to SIL are likely to increase unless adequate prevention and detection programs are mounted. Consequently, this article provides background information for the design of such programs, focusing on selected biochemical risk factors and natural history of SIL in women infected with HIV (HIV+) and women in general (HIV-). Current screening policies are described, and implications for nursing research and policy are discussed.

Precancerous and cancerous cervical lesions: the multicultural "male" risk factor.

PURPOSE/OBJECTIVES: To review current knowledge regarding characteristics of males whose partners develop cervical cancer. DATA SOURCES: Classic and current descriptive, cohort, and case-control studies of "male factors" associated with risk of precancerous squamous cell intraepithelial lesions and invasive cervical cancer. DATA SYNTHESIS: Male hygiene sperm and seminal fluids, occupational exposure to carcinogens, smoking, promiscuity, and venereal infections have been linked to increased risks for developing cervical cancer in a number of studies. Results vary from culture to culture. CONCLUSIONS: Areas of strongest association that can be targeted for prevention programs include male history of genital warts, poor hygiene, smoking, high numbers of sexual partners, and infrequent practice of safe sexual behaviors. IMPLICATIONS FOR NURSING PRACTICE: Establishment of prevention programs predicated on reducing male factors known to increase risk, encouraging screening of high-risk populations, and using patient education to reduce the practice of high-risk sexual behaviors are called for.

AIDS epidemiology and pathology. Implications for intensive care units.

The acquired immunodeficiency syndrome (AIDS) evolves from infection with the human immunodeficiency virus (HIV). The HIV attacks the hosts' immune and neuroendocrine systems, rendering the host susceptible to a myriad of chronic and acute conditions requiring intensive care. This article reviews epidemiologic and pathologic trends associated with HIV infections that have the potential to increase demands for admission to intensive care units. Research describing potential predictors of survival among patients with HIV-related conditions is also described. In addition, possible implications for practice, education, and research are discussed.

Potential predictors of information-seeking behavior by homosexual/bisexual (gay) men with a human immunodeficiency virus seropositive health status.

Seeking ways to improve their health, gay men with human immunodeficiency virus (HIV) infections living in San Francisco are developing information networks and patterns of self-care behavior. Drawing from a set of explanatory theories, this cross-sectional survey with retrospective elements examined patterns and potential predictors of information-seeking activity in a cohort or 162 HIV seropositive (HIV+) men, 60 of whom provided complete data sets. The study suggests that 1 year after becoming aware of an HIV+ health status, most patients have developed multifaceted information networks. The amount of tangible aid acquired from these networks and frequency of consultation is positively related to patterns of HIV self-care behaviors and "feeling calm" (p less than 0.01), suggesting that these variables may be important markers for the need of supportive-educative nursing care. Suggestions for nursing practice and research are also described.

Potential correlates of self-care and symptom distress in homosexual/bisexual men who are HIV seropositive.

Although treatment of HIV infections is possible, anecdotal data and research suggest that infected homosexual and bisexual men are developing sets of HIV-specific self-care behaviors that they believe will maintain their health or delay progressive disease. However, little is known about frequent use of HIV self-care in relationship to symptom distress or other factors commonly assessed by nurses. These deficits limit the ability of healthcare providers to intervene appropriately. Consequently, the following repeated-measures study retrospectively examined correlates of HIV self-care in 162 outpatients who were attending a major healthcare facility in San Francisco, CA. Standard and HIV-specific instruments created for the study were used in data collection. Results suggest that the men increased their use of 35 of 81 HIV self-care behaviors once they became aware of being HIV seropositive (p less than 0.001). Frequent use of HIV self-care behaviors was related to several variables, including previous patterns of self-care (p less than 0.001), and AIDS diagnosis (p less than 0.01), and a locus of control (LOC) indicator (e.g., the statement "What happens to me is beyond my control") (p less than 0.001). Symptom distress also was related to several variables, including selected LOC and quality-of-life (QOL) indicators, mood states, and recent diagnosis of selected AIDS-related diseases (p less than 0.01). Collectively, these results suggest that taking self-care and selected psychosocial histories will allow nurses to identify ambulatory patients with HIV infections who need intensive care.