Extra-pair paternity and the opportunity for sexual selection in a socially monogamous bird (Dendroica petechia)

We used multi-locus DNA fingerprinting to characterise the genetic mating system of the socially monogamous yellow warbler (Dendroica petechia). Over 2 years there were no instances of brood parasitism, but 59% of families (n = 90) contained extrapair sired young and 37% of offspring (n = 355) were of extra-pair paternity. Most hypotheses for extra-pair mating in monogamous species assume a paternity benefit to extra-pair sires, and focus on the benefit(s) to females. However, the assumption of male benefit has been little tested. Among yellow warblers, known extra-pair sires were just as likely to be cuckolded as any male in the population, and there was at least one reciprocal exchange of extra-pair paternity. Nevertheless, among known extra-pair sires, the paternity gains from extra-pair paternity were, on average, greater than the losses in their own families. These results show there is a paternity benefit to certain males. However, the benefit is not absolute but relative and therefore more difficult to measure. The results also suggest that patterns of extra-pair fertilisation are not determined by female choice alone. Most confirmed extra-pair mates were territorial neighbours, but some resided as far as three territories apart, and greater spatial separation was implied in other cases. Thus, the opportunity for extra-pair mating is great. We estimate that as a result of extra-pair fertilisations, variance in male mating success is increased somewhere between 3-fold and 15-fold over that which would result from within-pair reproduction alone. These findings affirm the potential importance of extra-pair reproduction for sexual selection in monogamous species and they support earlier suggestions that extra-territorial forays by male yellow warblers are for the purpose of extra-pair mating.     

Effects of Selenium Supplementation on Arsenism: An Intervention Trial in Inner Mongolia

This paper reports the effects of a placebo-controlled Se-enriched yeast supplementation trial, conducted for 14 months, on arsenism in adult farmers living in a rural community in Inner Mongolia, China. The farmers had been naturally exposed to elevated concentrations of As in drinking water from tube-wells since 1983 but changed to arsenic-free drinking water when the trial began in June 1996. Blood and hair Se and As concentrations were analysed pre-intervention and at the end of the 3rd, 9th and 14th month, while skin lesions were assessed pre-intervention, as well as at the end of the 14th month, using the Arsenism Clinical Criteria established by the Ministry of Health, China. As the trial was a voluntary one, a number of farmers did not routinely have their blood and hair samples taken for analysis. Consequently, the data have been analysed in two categories. Fifty-four farmers from the Se-group and 29 from the placebo-group who were sampled on each occasion were considered as one group, which has been compared with the second group comprising up to a total of 100 farmers in the Se-group and 86 in the placebo-group. Results calculated for those farmers who were sampled on each occasion, showed that at the end of the trial, blood and hair Se concentrations of the Se-group increased from 0.130 to 0.186 µg ml^–1 and from 0.431 to 0.502 µg g^–1, respectively, while those of the placebo-groups remained constant. Blood and hair As concentrations of the Se-group decreased from 0.051 to 0.015 µg ml^–1 and from 2.57 to 0.680 µg g^–1, respectively, a greater reduction than those in the placebo-group that went from 0.064 to 0.024 µg ml^–1 and from 2.62 to 1.25 µg g^–1, respectively. When the data from all patients were examined, the analytical trends were similar. An evaluation of skin lesions in the category who were sampled for hair and blood on each occasion showed that 41.2% of hyperkeratosis, 50.0% of depigmentation and 44.7% of pigmentation in the Se-group improved one or more degrees, while those in the placebo-group improved by only 7.1, 12.0 and 6.7%, respectively. A total of 61.1% of the adults in Se-group improved in one or more type of skin lesion, but only 17.2% improved in the placebo-group. Comparable results were obtained when all the data from both categories of farmers were examined. Results from the trial showed that Se supplementation was more effective for the improvement of adults who were affected by double or triple skin lesions. In the placebo-group, most of the severely affected adults improved in only one kind of skin lesion, but in the Se-group, more adults improved in two or three kinds of skin lesions. Although the trial was limited by its relatively small size, the results have provided some evidence of the usefulness of Se supplementation for people affected by arsenism.     

Arsenism Clinical Stages and their Relation with Hair Arsenic Concentration of Residents of Bayinmaodao Rural District, Inner Mongolia, China

The clinical skin lesions of arsenism in men and women in Bayinmaodao rural district in Inner Mongolia, Peoples Republic of China, have been examined by doctors, and their hair and drinking water samples analysed for arsenic by hydride generation and ICP-AES. Altogether 311 arsenism patients with a 15.53% prevalence rate for the district were recorded. The disease prevalence rate was positively related to population, age, and their exposure to elevated arsenic concentrations in the drinking water from 1983 when new wells were dug and drinking of surface water was abandoned. Hyperkeratosis was the most serious skin lesion with the highest occurrence rate, then depigmentation and pigmentation in decreasing order. With increasing severity of the disease, ranging from skin lesion with single hyperkeratosis 1° to hyperkeratosis 3° with depigmentation 3° and pigmentation 3°, the results showed that arsenic concentrations in head hair had increased. Arsenic concentrations in hair were positively correlated with the arsenic concentrations in drinking water obtained from local wells.     

Broad-band versus narrow-band irradiance for estimating latitude by archival tags

The relative effectiveness of different bands of irradiance to estimate the latitude of archival tags was evaluated. These tags are placed on fishes in order to describe their movements during long distance migrations. Measurements were recorded of broad-band irradiance with and without a cosine collector and narrow-band irradiance of seven narrow bands with 50% attenuation 30 nm on either side of their central wavelength of 400 (violet), 450 (blue), 500 (blue–green), 550 (green), 600 (yellow), 650 (orange), and 700 nm (red). A holographic, cosine collector was used to reduce the vertical transmission of irradiance to the sensor and to increase horizontal transmission of irradiance so the sensor detected more of the diffuse irradiance penetrating the water at dawn and dusk. Daily measurements were made during seven periods of 1–2 days each, beginning 28 June (after 21 June solstice) and ending on 6 October 1999 (after September 23 equinox) of submarine irradiance at 15-s intervals at a fixed depth (10 m) and location (38.31°N; 123.08°W) in Horseshoe Cove, California. Irradiance transmission at this site is intermediate between the clearest offshore waters, where blue irradiance (450 nm) penetrates farther with depth than green irradiance (550 nm) and most oceanic and coastal waters, where green penetrates farther than blue irradiance. Two algorithms were used to estimate latitude, the maximum slope method and the maximum logarithmic difference method. The broad-band, cosine-corrected light, excluding those deployments near the equinox when error is highest, produced an estimate of latitude of 38.30° for both methods and a latitudinal error of ±34.4 km for the former and ±27.2 km for the latter. The mean latitudinal error for non-cosine-collected, broad-band irradiance was ±190.9 km, using the slope algorithm and ±184.8 km using the difference algorithm. The blue band of irradiance, which attenuates least with increasing depth in clear, oceanic water, also produced a comparatively high-latitudinal error of ±163.8 km error for the former algorithm and ±170.4 km for the latter algorithm. Tag designers should consider using cosine-collectors over the irradiance sensors on their archival tags to increase the accuracy of position estimates.     

Light levels used during feeding by primate species with different color vision phenotypes

The intensity of available light is important in determining how well a diurnal animal can distinguish color. Primates with different types of color vision may exhibit behaviors that maximize visual contrast during critical activities such as feeding. We hypothesized that (1) trichromatic taxa will feed in a wide range of light conditions because color constancy permits stabilized color appearance across changes in illumination, and (2) that taxa with a high proportion of dichromatic individuals will tend to feed at higher light levels to increase color contrast. We recorded light levels during feeding bouts of seven primate taxa with varying degrees of color vision: the dichromatic Lemur catta, two polymorphic species, Propithecus v. verreauxi and Ateles geoffroyi, and the routine trichromats, Alouatta palliata, Colobus guereza, Piliocolobus badius, and Cercopithecus ascanius. Results were equivocal for our hypotheses. While routinely trichromatic taxa used varying light levels, the pattern of results did not differ from the dichromatic Lemur catta. However, polymorphic taxa not only sought the highest light, but females, which are the only individuals in polymorphic taxa that can be trichromatic, fed in higher light levels than males when eating non-green foods. This result is consistent with selection operating to maintain a balanced polymorphism in these taxa, though the connection between light levels and color vision type for the females is unclear. Our results further suggest that trichromatic vision may afford a selective advantage because it permits foraging under a greater range of light levels.     

Red bioluminescence in fishes: on the suborbital photophores of Malacosteus,Pachystomias and Aristostomias

Many deep-sea animals produce blue bioluminescence, but species of three genera of midwater dragonfishes also produce red light. In addition to numerous small body photophores, species of these genera (Malacosteus, Pachystomias and Aristostomias) have large suborbital photophores that emit red light and postorbital ones that emit blue light. Pachystomias microdon additionally has a red-emitting preorbital photophore. Fluorescence measurements from the intact suborbital photophores, and from their exposed cores, confirm the previous hypothesis that the red light emitted by Malacosteus is spectrally altered by a superficial shortwave cutoff brown filter. No such filter is present in the other two genera. Studies of the anatomy of the photophores show that the suborbital photophore of Malacosteus is similar in general organisation to other photophores, including the postorbital photophore. The red-emitting photophores of Pachystomias and Aristostomias, however, have a unique organisation, in which the bulk of the photophore comprises a gland that lies outside the thick reflector. Strands of tissue run from the gland into the photogenic core of the photophore through numerous pores in the reflector. The production and use of red light by these fishes is discussed in the context of these results.Electronic Supplementary Material Supplementary material is available for this article at