The evolution of male nuptial colour in a sexually dimorphic group of fishes (Percidae: Etheostomatinae).

To test hypotheses explaining variation in elaborate male colouration across closely related species groups, ancestral-state reconstructions and tests of phylogenetic signal and correlated evolution were used to examine the evolution of male body and fin colouration in a group of sexually dichromatic stream fishes known as darters (Percidae: Etheostomatinae). The presence or absence of red-orange and blue-green male colour traits were scored across six body regions in 99 darter species using a recently estimated amplified fragment length polymorphism (AFLP) phylogeny for comparative analyses. Ancestral-state reconstructions infer the most recent common ancestor of darters to lack red-orange colour and possess blue-green colour on different body regions, suggesting variation between species is due to independent gains of red-orange and losses of blue-green. Colour traits exhibit substantial phylogenetic signal and are highly correlated across body regions. Comparative analyses were repeated using an alternative phylogenetic hypothesis based on one mitochondrial and two nuclear genes, yielding similar results to analyses based on the AFLP phylogeny. Red-orange colouration in darters appears to be derived; whereas, blue-green appears to be ancestral, which suggests that different selection mechanisms may be acting on these two colour classes in darters.

The accumulation of reproductive isolation in early stages of divergence supports a role for sexual selection.

Models of speciation by sexual selection propose that male-female coevolution leads to the rapid evolution of behavioural reproductive isolation. Here, we compare the strength of behavioural isolation to ecological isolation, gametic incompatibility and hybrid inviability in a group of dichromatic stream fishes. In addition, we examine whether any of these individual barriers, or a combined measure of total isolation, is predicted by body shape differences, male colour differences, environmental differences or genetic distance. Behavioural isolation reaches the highest values of any barrier and is significantly greater than ecological isolation. No individual reproductive barrier is associated with any of the predictor variables. However, marginally significant relationships between male colour and body shape differences with ecological and behavioural isolation are discussed. Differences in male colour and body shape predict total reproductive isolation between species; hierarchical partitioning of these two variables' effects suggests a stronger role for male colour differences. Together, these results suggest an important role for divergent sexual selection in darter speciation but raise new questions about the mechanisms of sexual selection at play and the role of male nuptial ornaments.

Evolution of the premaxillary fraenum and substratum in snubnose darters and allies (Percidae: Etheostoma).

Darters (Percidae: Etheostomatinae), a species-rich group of North American freshwater fishes, vary in the presence of a premaxillary fraenum, a strip of skin that connects the premaxillary bones to the snout, and it is hypothesized that this trait is a trophic adaptation to particular substrata. Ancestral state reconstructions and analyses of phylogenetic associations between presence of the premaxillary fraenum and preferred stream substratum were conducted in a clade of closely related darters (snubnose darters and allies) that vary in morphology and habitat preferences. The most recent common ancestor of this clade was inferred to possess a fraenum and to inhabit rocky substrata, consistent with previous hypotheses, but a significant correlation between fraenum presence and substratum type across the phylogeny was not found.

Association between parasite load and orange, but not blue, male nuptial colouration in Etheostoma caeruleum.

The hypothesis that males possessing more vivid nuptial colouration are of better quality with regard to individual measures of health such as parasite infection was investigated by taking spectral measurements of orange and blue bars in the nuptial males of a sexually dichromatic stream fish rainbow darter Etheostoma caeruleum to determine if male colouration in this species varied with parasite load in the form of black spot disease. The yellow chroma of orange bars, i.e. the relative contribution of wavelengths in the range of 550-625 nm to total brightness, was the only spectral measurement significantly associated with parasite counts. These results are discussed in the context of sexual selection and the potential of orange bars in E. caeruleum to serve as honest indicators of quality to potential mates.

Incomplete behavioural isolation and asymmetric female preference in darter sister species (Percidae: Etheostoma).

In this study, female preferences and behavioural isolation were estimated in a pair of allopatric sister species, Etheostoma duryi and Etheostoma flavum. Dichotomous mate preference trials were conducted to determine whether females prefer to associate with conspecific over heterospecific males and free-spawning assays were conducted to determine whether those preferences translated into behavioural isolation. Dichotomous mate choice trials revealed asymmetric female preference, as female E. flavum preferred conspecific males, whereas female E. duryi showed no preference. Free-spawning assays indicated that behavioural isolation remains incomplete between E. duryi and E. flavum (IB = 0·19). In addition to female mating preferences, male behaviour also appeared to influence mating outcomes as male E. flavum consistently courted conspecific females more often in free-spawning assays whereas male E. duryi did not. The data therefore suggest that despite marked divergence in male nuptial colour, divergence in female preferences between these species may not be sufficient to maintain species boundaries upon secondary contact. These results contrast with similar work in a sympatric darter species pair and may be explained by considering the contributions of reinforcement and differences in colour pattern as well as colour value.

AFLPs support deep relationships among darters (Percidae: Etheostomatinae) consistent with morphological hypotheses.

Recent attention has focused on the efficacy of amplified fragment length polymorphisms (AFLPs) for resolving deep evolutionary relationships. Here we show that AFLPs provide resolution of deep relationships within the family Percidae that are more consistent with previous morphological hypotheses than are relationships proposed by previous molecular analyses. Despite in silico predictions, we were able to resolve relatively ancient divergences, estimated at >25 MA. We show that the most distantly related species share the fewest fragments, but suggest that large data sets and extensive taxon sampling are sufficient to overcome this obstacle of the AFLP technique for deep divergences. We compare genetic distances estimated from mitochondrial DNA with those from AFLPs and contrast traditional PAUP(*) Nei-Li AFLP genetic distances with a recently proposed method utilizing the Dice equation with constraining nucleotides.

Correlates of suicidal ideation among an elderly depressed sample.

BACKGROUND: Suicidal ideation has been shown to be strongly associated with suicide completion and elders take their own lives more than any other age group. METHODS: The present study examined clinical and phenomenological correlates of suicidal ideation among an elderly sample (n = 167) derived from subjects enrolled in the Duke Clinical Research Center for the Study of Depression in Late Life. RESULTS: Bivariate results indicated that clinical variables associated with psychomotor retardation, a history of dysthymia, a previous psychiatric in-patient stay, and being a 'younger' elder were related to greater suicidal ideation. Multivariate analyses indicated that feeling guilty, sinful, or worthless was associated with over six times greater odds of having suicidal thoughts. LIMITATIONS: Findings are based on correlational analyses, and thus, the direction of causality cannot be inferred. CONCLUSIONS: This study provides evidence for clinicians of some of the 'red flags' associated with the presence of suicidal ideation among depressed older adults.

New onset and remission of suicidal ideation among a depressed adult sample.

BACKGROUND: Previous research has demonstrated that suicidal ideation often predicts suicide completion. METHODS: The present study examined clinical and phenomenological variables associated with the presence, development and remission of suicidal ideation among depressed adults. The sample (n = 81) was derived from subjects enrolled in the Duke Clinical Research Center for the Study of Depression in Late Life. RESULTS: Greater pessimistic thinking at baseline predicted the development of suicidal ideation one year later and the older a person was when he or she first experienced depression, the more likely he or she was to report remission from suicidal ideation one year following onset. LIMITATIONS: Longitudinal analyses were based on relatively small samples. Variables that were not significant in these analyses might be in a larger sample. CONCLUSIONS: The longitudinal design of this study mitigates limitations associated with cross-sectional or retrospective designs and advances our understanding of a clinical profile associated with the development and remission of suicidal thoughts.

Perceived social support among depressed elderly, middle-aged, and young-adult samples: cross-sectional and longitudinal analyses.

BACKGROUND: A number of studies have concluded that the perceived quality of support is more strongly associated with mental health than with the actual structure of personal networks. This study examined clinical, historical, and phenomenological variables associated cross-sectionally and longitudinally with perceived social support. METHODS: Participants included elderly, middle-aged, and young-adult depressed samples derived from the Duke Clinical Research Center for the Study of Depression in Late Life. RESULTS: Cross-sectional multivariate analyses revealed that perceived social support was: (1) for the elderly associated with pessimistic thinking, being divorced, having strange ideas, the degree of social interaction, and instrumental support; (2) for middle-age associated with dysthymia, divorce, pessimistic thoughts, social interaction, and instrumental support; and (3) among young adults with instrumental support only. Longitudinal multivariate analyses indicated that only perceived social support at Time 1 predicted perceived social support 1 year later among elderly and middle-aged subjects, whereas only instrumental support predicted perceived social support 1 year later among the young-adult sample. LIMITATIONS: The small number of subjects among the young-adult sample limit conclusions regarding this group. In addition, only patients provided data. Future studies should consider using multiple informants to enhance the accuracy of reported social support. CONCLUSIONS: Our findings indicate that in addition to whatever else they do for depressed patients, clinicians must endeavor to address relationship or social support difficulties, especially in the elderly.

Preventive health services and access to care for male veterans compared with their spouses.

The Veterans Health Administration is exploring ways to reform the current Veterans Affairs (VA) system in accordance with the changing health care environment of managed care. One proposal is for the VA to enlarge its patient base by expanding eligibility to include spouses of veterans. To compare reported preventive health care services received by male veterans and their spouses and to measure whether spouses would choose to receive their medical care through a VA medical center, we randomly selected 230 married male veterans and mailed self-administered questionnaires to be completed by them and their spouses; 170 (74%) eligible subjects completed the questionnaire. The mean age of the veterans and spouses was 73.6 and 67.4 years, respectively. Veterans reported significantly higher rates of receipt of recommended preventive services than their spouses in all 5 areas assessed, including blood pressure measurement; influenza, pneumococcal, and tetanus vaccinations; and serum cholesterol measurement. Veterans were significantly more satisfied than their spouses with their current health care. Finally, 83% (95% confidence interval, 77% to 89%) of spouses reported that they would choose to receive their medical care at the VA medical center is allowed to do so. These findings suggest that spouses of male veterans represent a sizable group that could be incorporated in the VA system, especially given their strong desire to do so.

Primary aortoduodenal fistula caused by severe atherosclerosis, not by aneurysm.

Primary aortoduodenal fistula is an uncommon cause of massive upper gastrointestinal hemorrhage usually due to pressure erosion of an abdominal aortic aneurysm into the third portion of the duodenum. This report describes a case of a 59-year-old man who died of massive gastrointestinal hemorrhage due to a primary aortoduodenal fistula. This case is unique in that the fistula formed as a result of complex atherosclerotic disease of the abdominal aorta, with adventitial chronic inflammation and foreign body reaction against atheromatous plaque, and not from an aneurysm. We were unable to identify any other reports of aortoduodenal fistulas developing spontaneously in the absence of aneurysmal disease of the aorta.

Herpes simplex virus type 2 encephalitis in two homosexual men with persistent lymphadenopathy.

Within a 5-month period, 2 homosexual men with persistent lymphadenopathy developed clinical findings consistent with herpes simplex virus (HSV) encephalitis. These signs included abrupt change in mental status, seizures, cerebrospinal fluid pleocytosis, and localized electroencephalographic abnormalities showing temporal lobe involvement. Initial computed tomographic scans were unremarkable. Treatment with adenine arabinoside was instituted and temporal lobe biopsies were performed. Although virus-specific antigens were detectable in only 1 patient, cultures of biopsy tissue from both patients yielded HSV type 2 organisms. Spiking fevers persisted and the patients failed to improve, prompting administration of acyclovir. Both patients recovered gradually after their second course of antiviral therapy and survived with severe neurological deficits. These patients should raise concerns about an increased incidence of type 2 encephalitic illness among homosexual men with persistent lymphadenopathy or acquired immune deficiency syndrome. In addition, the importance of using HSV type 2 antibody in the immunofluorescence test of brain biopsy tissue for rapid diagnosis of the disease is emphasized.

Developmental profiles for the brainstem auditory evoked potential.

Brainstem auditory evoked potentials (BAEP's) were recorded from 641 subjects in eleven age groups ranging from birth through adulthood, including three levels of prematurity, in order to establish an age-specific normative data base. The amplitude and latency values for waves 1-6, interwave differences for 3-1, 5-3, 5-1 and the amplitude ratios for 5/3 and 5/1 were then converted to percentile scores to permit construction of age-related BAEP profile report forms. Visual inspection of the printed output reveals the proportion of subjects falling above and below a given individual across all BAEP measures. This simple format is useful for general screening purposes as well as plotting maturational changes in healthy or high risk infants.

Maturational effects on the middle components of the averaged electroencephalic response.

Middle component AERs to brief click stimuli were recorded from 60 subjects in four age groups to assess age effects on waveform, latency, and amplitude. Replicable responses similar in waveform to those recorded in adults were observed in 3 - 4-year-old children, full-term newborns, and premature infants tested as early as the 31st postconceptional week. Latencies and amplitudes were compared across ages and significant age effects were evident for amplitude but not latency. Amplitudes of components Po, Pa and Pb were found to increase until 3 - 4 years of age and decline in adulthood. Response amplitudes for premature infants differed significantly from those of adults, but newborns' responses did not differ from either group. Only the responses of 3 - 4-year-old children were clearly differentiated from those of all other groups in this respect. Significant age effects on latency were found only for Po, which is postulated to be synonymous with Wave V of the brainstem response. The absence of a trend for decreasing latency as a function of age in the middle components is surprising in that both early (brainstem) and late (cortical) responses demonstrate this effect. This finding raises questions about the generator sources for middle components.

Binaural interactions in the short-latency evoked potentials of neonates.

Short-latency evoked potentials to monaural and binaural clicks were recorded from scalp electrodes on healthy full-term neonates and on normally hearing adults. Binaural interaction (BI) was measured by summing the average monaural responses obtained from each ear (L+R) and subtracting the binaural response (B) from the monaural sum (BI=L+R-B). Consistent BI was apparent following stimulation with moderate level clicks in all cooperative infants. As in the adult, BI occurred during waves IV, V and VI, where there were systematic amplitude differences between the L+R and B waveforms. Peak latencies of the waves were not significantly affected. However, peak latencies were longer in neonates than in adults, reflecting maturational changes in the response. Similarly, peak latencies in the BI waveforms were also prolonged for the neonates. These results indicate that: (1) BI is present at or soon after birth; (2) the gross response properties of BI are similar in infants and adults; (3) BI occurs during specific waves in the response, independent of age, and (4) the assessment of BI may prove useful in estimating the functional integrity of brain stem structures in infants.

Differential development of brainstem potentials in healty and high-risk infants.

Maturation along the brainstem acoustic pathway, as well as the integrity of these structures, has been shown to be reflected in brainstem evoked potential recordings. Trajectories formed from repeated sequential measurements of several brainstem response variables reveal distinct developmental curves for healthy and high-risk infants. Longitudinal analysis offers a means of determining temporary or permanent maturational effects on the central nervous system in early life.