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.     

The (mis)concept of species recognition

To many, the concept of 'species recognition' is integral to the origin and maintenance of species. However, the heuristic value of species recognition is hampered by its reliance on the problematic concept of species. In this paper, we first discuss assumptions associated with prevailing use of the term, including the typological implications of the concept, the false dichotomy of compatibility and mate quality, and the commonly held model of species recognition in which animals determine taxonomic status before mate status. Subsequently, we propose research directions aimed to improve our understanding of the role of courtship behavior in speciation. We propose two complementary research approaches, one addressing the processes that drive the evolution of mate recognition systems and the other addressing the phenotypic architecture of behavioral isolation. Our approach emphasizes the fitness consequences and multidimensional nature of mate choice.     

Characterization of the hypnotic effects of triazolam microinjections into the medial preoptic area.

We have previously reported that microinjections of the benzodiazepine hypnotic triazolam into the medial preoptic area (MPA) of the hypothalamus enhance sleep in rats. The present study further characterizes this effect, by examining its anatomical specificity, determining whether it is mediated by interaction with central benzodiazepine receptors, and assessing whether sleep induction is associated with changes in core temperature. It was found that microinjections of 0.25 and 0.5 micrograms triazolam into two nearby structures, the lateral preoptic area and diagonal band of Broca, failed to alter sleep. Total sleep time was enhanced by microinjection of triazolam into the MPA, and this effect was blocked by co-administration of the benzodiazepine receptor blocker RO 15-1788. Sleep enhancement by triazolam was not associated with significant alterations in core body temperature. These observations continue to suggest that the MPA may be a site which mediates the hypnotic effect of triazolam, and add to the growing body of data emphasizing the importance of hypothalamic function in the regulation of sleep and waking.     

Issues in using whole slide imaging for diagnostic pathology: “routine” stains,immunohistochemistry and predictive markers

The traditional microscope, together with the “routine” hematoxylin and eosin (H & E) stain, remains the “gold standard” for diagnosis of cancer and other diseases; remarkably, it and the majority of associated biological stains are more than 150 years old. Immunohistochemistry has added to the repertoire of “stains” available. Because of the need for specific identification and even measurement of “biomarkers,” immunohistochemistry has increased the demand for consistency of performance and interpretation of staining results. Rapid advances in the capabilities of digital imaging hardware and software now offer a realistic route to improved reproducibility, accuracy and quantification by utilizing whole slide digital images for diagnosis, education and research. There also are potential efficiencies in work flow and the promise of powerful new analytical methods; however, there also are challenges with respect to validation of the quality and fidelity of digital images, including the standard H & E stain, so that diagnostic performance by pathologists is not compromised when they rely on whole slide images instead of traditional stained tissues on glass slides.     

Experience with the deltopectoral flap.

The deltopectoral flap is a most versatile source of skin coverage or mucosal lining (or both). There is remarkable safety in the use of this flap in relation to its size, and there is only limited need for delay--because it pedicle is an axial flap. Nonetheless, the terminal part requires the attention to detail which any random flap requires--such as the avoidance of hematoma and infection and the prevention of tension, kinking, and angulation. This not only will ensure the safety of the flap, but also will prevent the rather common and annoying minor complications that delay the patient's convalescence.     

Preference for conspecifics evolves earlier in males than females in a sexually dimorphic radiation of fishes

Speciation by sexual selection is generally modeled as the coevolution of female preferences and elaborate male ornaments leading to behavioral (sexual) reproductive isolation. One prediction of these models is that female preference for conspecific males should evolve earlier than male preference for conspecific females in sexually dimorphic species with male ornaments. We tested that prediction in darters, a diverse group of freshwater fishes with sexually dimorphic ornamentation. Focusing on the earliest stages of divergence, we tested preference for conspecific mates in males and females of seven closely related species pairs. Contrary to expectation, male preference for conspecific females was significantly greater than female preference for conspecific males. Males in four of the 14 species significantly preferred conspecific females; whereas, females in no species significantly preferred conspecific males. Relationships between the strength of preference for conspecifics and genetic distance revealed no difference in slope between males and females, but a significant difference in intercept, also suggesting that male preference evolves earlier than females’. Our results are consistent with other recent studies in darters and suggest that the coevolution of female preferences and male ornaments may not best explain the earliest stages of behavioral isolation in this lineage.     

Amphibian Declines in Latin America: Widespread Population Declines,Extinctions, and Impacts1

Amphibian populations are in decline throughout Latin America; all families of frogs have experienced declines, but the species associated with aquatic habitats in upland areas have been most affected. Declines in Latin America were most common during the 1980s, but new declines continue to be reported. The causes of declines are varied, but they have most often been associated with habitat loss, a pathogenic fungus, and climate change. Scientists are just beginning to grasp the ethical and biological implications of losses of this magnitude. In this Special Section, we provide a general summary of the phenomenon and introduce five contributed papers that provide new data and new insights into Latin American declines.