Plumage Bacterial Assemblages in a Breeding Wild Passerine: Relationships with Ecological Factors and Body Condition

Microorganisms have been shown to play an important role in shaping the life histories of animals, and it has recently been suggested that feather-degrading bacteria influence the trade-off between parental effort and self-preening behavior in birds. We studied a wild breeding population of great tits (Parus major) to explore habitat-, seasonal-, and sex-related variation in feather-degrading and free-living bacteria inhabiting the birds' yellow ventral feathers and to investigate associations with body condition. The density and species richness of bacterial assemblages was studied using flow cytometry and ribosomal intergenic spacer analysis. The density of studied bacteria declined between the nest-building period and the first brood. The number of bacterial phylotypes per bird was higher in coniferous habitat, while bacterial densities were higher in deciduous habitat. Free-living bacterial density was positively correlated with female mass; conversely, there was a negative correlation between attached bacterial density and female mass during the period of peak reproductive effort. Bacterial species richness was sex dependent, with more diverse bacterial assemblages present on males than females. Thus, this study revealed that bacterial assemblages on the feathers of breeding birds are affected both by life history and ecological factors and are related to body condition.     

黄喉鹀的羽色与雄鸟质量相关性分析

在国内首次利用光纤光谱仪对鸟类的羽色进行量化和分析.对黄喉鹀Emberiza elegans雌、雄鸟羽色的差异以及雄鸟羽色与雄鸟质量的相关性分析结果表明,黄喉鹀雌、雄鸟在人眼看来相同的黄色羽和白色羽部分,在紫外光色度上却存在显著差异,雄鸟紫外光色度高于雌鸟;雄鸟的质量与脸部黑色羽的亮度、可见光色度和色调呈显著正相关,雌...     

Lifetime Number of Mates Interacts with Female Age to Determine Reproductive Success in Female Guppies

In many species, mating with multiple males confers benefits to females, but these benefits may be offset by the direct and indirect costs associated with elevated mating frequency. Although mating frequency (number of mating events) is often positively associated with the degree of multiple mating (actual number of males mated), most studies have experimentally separated these effects when exploring their implications for female fitness. In this paper I describe an alternative approach using the guppy Poecilia reticulata, a livebearing freshwater fish in which females benefit directly and indirectly from mating with multiple males via consensual matings but incur direct and indirect costs of mating as a consequence of male sexual harassment. In the present study, females were experimentally assigned different numbers of mates throughout their lives in order to explore how elevated mating frequency and multiple mating combine to influence lifetime reproductive success (LRS) and survival (i.e. direct components of female fitness). Under this mating design, survival and LRS were not significantly affected by mating treatment, but there was a significant interaction between brood size and reproductive cycle (a correlate of female age) because females assigned to the high mating treatment produced significantly fewer offspring later in life compared to their low-mating counterparts. This negative effect of mating treatment later in life may be important in these relatively long-lived fishes, and this effect may be further exacerbated by the known cross-generational fitness costs of sexual harassment in guppies.     

Communal Relationships in a Social Spider Mite, Stigmaeopsis longus (Acari: Tetranychidae): An Equal Share of Labor and Reproduction between Nest Mates

The social spider mite, Stigmaeopsis longus (Saito), builds web‐nests and shares resources with fellow nest members. It does not show any distinct morphological castes. In this study, we observed whether there is any division of labor in reproductive and non‐reproductive tasks. Under experimental conditions, female density per nest did not affect per capita fecundity, even though the nest area allocated to an individual female, in which it feeds and oviposits, decreased with increased female density. Video observations on the behavior of either one or two females showed that there were no differences between these situations in the time budgets of all behaviors, nor in the nest‐weaving behavior of females. Furthermore, detailed behavioral analyses between the two situations suggested that S. longus females share reproduction and labor evenly with their nest mates, probably mediated through physical or chemical communication. Therefore, we concluded that the sociality of this mite species should be categorized as communal.     

Relationships between Binding Quality of Meat and Myofibrillar Proteins

The viscosity change of myosin A concentrated solution with or without other components was measured as the incubation time elapsed at 30°C.

The viscosity of myosin A solution increased, but that of F-actin solution did not. The shear stress at 0.04 sec^?1 was not increased to 1.0 dyne/cm² in the former, but in the latter was below 0.5 dyne/cm².

The viscosity of myosin B solution increased slightly, but that of native tropomyosin-free myosin B solution decreased remarkably. In both the shear stress at 0.04 sec^?1 was greater than or equal to 15 dynes/cm².

The speed of the viscosity increase in the presence of 3 mm pyrophosphate and 3 mm MgCl₂ was higher in concentrated solution of myosin B than in that of native tropomysin-free myosin B. The shear stress at 0.04 sec^?1 after 6 hr at 30°C was 11.5 and 8.2 dynes/cm², respectively.

The effect of native tropomyosin and actin on the viscosity change was discussed.     

Relationships between Blood Parasites, Mating Success and Phenotypic Cues in Male Sage Grouse Centrocercus urophasianus

In lek breeding Sage Grouse Centrocercus urophasianus in easternCalifornia, male mating success is strongly correlated withindividual differences in lek attendance, and in the rate andacoustic quality of courtship display, suggesting that theseprovide cues by which females choose mates. Increased lek attendanceand high display rates are also associated with elevated metabolicexpenditure. This paper examines the hypothesis that the abilityto commit energy to display is related to the incidence of bloodparasites. A single hematozoan genus, Haemoproteus, was foundin 37.5% of 184 Sage Grouse sampled over a five year period.Parasitism varied across years and increased through the breedingseason. However, no measure of display performance or matingsuccess was significantly correlated with decreased parasiteload among adult males. Several additional lines of evidence,including numerically low infection intensities, the absenceof detectable effects of parasites on hematocrit and erythrocyteproduction, and the seasonal distribution of parasite incidenceallsuggested that infections were unlikely to impact male courtshipdisplay. Alternative factors maintaining individual variationin male display performance in this population are also evaluated.     

Costs and Benefits of Subadult Plumage in Mute Swans: Testing Hypotheses for the Evolution of Delayed Plumage Maturation

In some avian species, young birds capable of reproducing diminish their prospects of doing so by molting into a subadult plumage that accurately signals their subadult status. Several hypotheses have been proposed to explain the evolution of delayed plumage maturation, but testing them usually has involved interspecific comparisons that are hard to interpret. Mute swans (Cygnus olor) exhibit two phenotypes that differ in whether the birds have a gray subadult plumage (SAP phenotype) or molt immediately into an all white adult plumage (AP phenotype). The AP phenotype results from a recessive allele on the X chromosome; both phenotypes occur in the same population and even in the same brood. We compared costs and benefits of both phenotypes in mute swans on the Chesapeake Bay in 1972-1980 and on Long Island Sound in 1982-1989. Swans with the SAP phenotype had higher survival rates from hatching to fledging than AP swans. In the fall, when AP cygnets began to molt into their white plumage, their parents often attacked and drove them off while allowing SAP cygnets from the same brood to remain on their territories for several more months. SAP males had higher survival rates during their first 2 yr of life than AP males, but AP swans bred at a younger age than SAP swans. The only proposed hypothesis for the evolution of delayed plumage maturation that can explain its occurrence in mute swans is the status-signaling hypothesis. This hypothesis argues that males with subadult plumage honestly advertise their age and subordinate status while AP swans are cheaters and engaging in dishonest communication. SAP males acquire a longer period of parental care, suffer less aggression from older birds, and increase their survival but forgo the opportunity to breed at an early age. This is a unique example of how a single gene resulted in either honest or dishonest communication, changed a bird's relationship with its parents and potential mates, and altered the bird's chances to survive and to reproduce.     

Territory Quality and Plumage Morph Predict Offspring Sex Ratio Variation in a Raptor

Parents may adapt their offspring sex ratio in response to their own phenotype and environmental conditions. The most significant causes for adaptive sex-ratio variation might express themselves as different distributions of fitness components between sexes along a given variable. Several causes for differential sex allocation in raptors with reversed sexual size dimorphism have been suggested. We search for correlates of fledgling sex in an extensive dataset on common buzzards Buteo buteo, a long-lived bird of prey. Larger female offspring could be more resource-demanding and starvation-prone and thus the costly sex. Prominent factors such as brood size and laying date did not predict nestling sex. Nonetheless, lifetime sex ratio (LSR, potentially indicative of individual sex allocation constraints) and overall nestling sex were explained by territory quality with more females being produced in better territories. Additionally, parental plumage morphs and the interaction of morph and prey abundance tended to explain LSR and nestling sex, indicating local adaptation of sex allocation However, in a limited census of nestling mortality, not females but males tended to die more frequently in prey-rich years. Also, although females could have potentially longer reproductive careers, a subset of our data encompassing full individual life histories showed that longevity and lifetime reproductive success were similarly distributed between the sexes. Thus, a basis for adaptive sex allocation in this population remains elusive. Overall, in common buzzards most major determinants of reproductive success appeared to have no effect on sex ratio but sex allocation may be adapted to local conditions in morph-specific patterns.     

Bateman's Principle in Cooperatively Breeding Vertebrates: The Effects of Non-breeding Alloparents on Variability in Female and Male Reproductive Success

The sex-specific slopes of Bateman's gradients have importantimplications for understanding animal mating systems, includingpatterns of sexual selection and reproductive competition. Intersexualdifferences in the fitness benefits derived from mating withmultiple partners are expected to yield distinct patterns ofreproductive success for males and females, with variance indirect fitness predicted to be greater among males. These analysesassume that typically all adults are reproductive and that failureto produce offspring is non-adaptive. Among some species ofcooperatively breeding birds and mammals, however, non-breedingadult alloparents are common and may comprise the majority ofindividuals in social groups. The presence of a large numberof non-breeding adults, particularly when coupled with greatersocial suppression of reproduction among females, may alterthe relative variance in direct fitness between the sexes, therebygenerating an apparent contradiction to Bateman's Paradigm.To explore quantitatively the effects of non-breeding alloparentson variance in reproductive success, we used genetic estimatesof parentage and reproductive success drawn from the literatureto calculate the relative variability in direct fitness forfemales and males in alloparental and "other" societies of birdsand mammals. Our analyses indicate that in mammals and, to alesser extent, in birds, variability in direct fitness is greateramong females in species characterized by the presence of non-breedingalloparents. These data suggest that social interactions, includingsocial suppression of reproduction, are powerful determinantsof individual direct fitness that may modify sex-specific patternsof reproductive variance from those described by Bateman.     

Relationships between iron and vanadium metabolism: The exchange of vanadium between transferrin and ferritin

The study of possible relationships between iron and vanadium metabolism (E. Sabbioni and E. Marafante, Proc. XIth Int. Conf. Biochem., 13-5-R122, Toronto, Canada) was extended to the vanadium in the biochemical mechanisms which involve the exchange of iron between transferrin and ferritin. The transfer of vanadium between transferrin and ferritin was investigated using ⁴⁸V radiotracer and gel filtration technique. ⁴⁸V labelled human transferrin and horse spleen ferritin, ⁴⁸V plasma from rats injected with ⁴⁸VO²⁺, unlabelled rat liver cytosol, and plasma were used as sources of the two proteins for their incubation under different conditions. The results show that the equilibrium:

occurs in vitro at physiological pH under the conditions of this experiment. No transfer of vanadium between the two proteins, however, occurs when they are incubated simply in a buffer at pH = 7.4. The maximum transfer was observed when transferrin and ferritin were mixed in their natural environments such as plasma and liver cytosol. This suggests that the exchange of the vanadium between the two proteins is affected by biochemical factors which are present in the body. A brief evaluation of the significance on the very low amounts of the element exchanged between the two proteins is also presented     

Winter Plumage Coloration in Male American Goldfinches: Do Reduced Ornaments Serve Signaling Functions in the Non‐Breeding Season?

The signaling role of sexual ornaments that are displayed during the mating season is well known for many species, but dimorphisms that occur in the non‐breeding season have received much less attention, particularly when individuals only partially express their breeding condition during reproductively inactive periods. I assessed variation in the expression of colorful breeding and non‐breeding plumages in male American goldfinches (Carduelis tristis), a species in which males molt out of their colorful breeding ornaments in the fall but still display reduced carotenoid‐ and melanin‐based sexual dichromatism during the winter. I found that variability in the saturation of carotenoid‐based plumage pigmentation did not differ significantly between the breeding and non‐breeding seasons. Moreover, the area of melanin coloration in the cap was more variable in winter than when it is fully displayed during breeding. I also detected a significant positive correlation between the extent of melanin coloration during the winter and the saturation of non‐breeding carotenoid‐based plumage. Because of such variation in and correlated expression of these two color ornaments in winter, it is conceivable that male goldfinches display these hints of non‐breeding coloration for use as conspecific social or sexual signals. Natural selection pressures like predation and energetic demands are traditionally thought of as factors that restrict sex ornaments to breeding times alone, but this should not preclude animals from simply reducing their exaggerated features during winter and finding an expression optimum that balances signal costs and value. Such ‘remnant’ winter ornaments might be expected to evolve not only in animals that live in large non‐breeding groups (e.g. status‐signaling systems) but also in those where mates begin associating before breeding onset.     

Interspecific Social Interactions and Breeding Success of the Frog Rana latastei: A Field Study

Interspecific reproductive interference can affect fitness‐related breeding performance, thus influencing fitness and distribution of populations. Laboratory studies demonstrated the social interference of Rana dalmatina males on R. latastei breeding females: the presence of heterospecific males reduced the percentage of viable embryos in R. latastei eggs. Here, we tested if the negative effects of R. dalmatina males on R. latastei reproductive success occur in field conditions. We compared the percentage of viable embryos of eggs laid in field conditions from populations where R. latastei breeds alone with the percentage of viable embryos of populations where R. latastei cohabits with R. dalmatina. We did not find any significant difference in percentage of viable embryos between R. latastei populations syntopic and allotopic with R. dalmatina, nor a relationship between the relative abundance of heterospecifics and reproductive success. In natural conditions, the presence of heterospecific males does not seem to interfere with the reproductive success of R. latastei. The experimental procedure may influence the interaction among individuals. Therefore, we suggest to validate on natural populations the results of experiments dealing with complex interactions.     

紫蓬山区三种鹭种群繁殖成效的研究

：作者１９９６年４～７月在紫蓬山区国家级森林公园,对白鹭、池鹭和夜鹭繁殖种群的数量和繁殖成效进行了研究。结果表明：三块样地中,夜鹭的种群平均密度最大,白鹭的种群平均密度最小;白鹭、池鹭和夜鹭的种群繁殖生产力分别为２３７４ｉｎｄ／ｈｍ２、１４４１ｉｎｄ／ｈｍ２和２０１２ｉｎｄ／ｈｍ２;繁殖成效分别为５２０％、５５１％和４５１％。繁殖成效与巢位高度有关,低位巢卵损失率高,高位巢雏丢失率高。     

The Relationships between Transpiration and Potassium Uptake in Ricinus communis

The water uptake by individual water-culture-grown castor-oilplants (Ricinus communis) was varied and corresponding ratesof potassium uptake measured. The water flux was varied by changingthe rate of transpiration or by detopping the transpiring plants.Transpiration was altered by changing the atmospheric humidityat constant temperature and light intensity in a climatologicalwind tunnel. It was found that the uptake of potassium was divisibleinto two components: (a) an accumulation by the cells of theroot and (b) a passage through the root to the shoot via thevessels. These components were found to be entirely independentof one another. Also while (a) was unaffected by the water flux(b) was linearly related to it. The concentration of potassiumin the vessels was between 15 and 26 times that of the mediumand this ratio which was found to be similar in both intactand detopped exuding plants remained constant in the face ofwide changes in water flux. This essential similarity betweenexuding and transpiring plants and the finding that there wasa lag between the change in water flux and the response in potassiumuptake indicated that there is no continuous mass-flow pathwaybetween medium and xylem in these plants. Instead, increasedtranspiration seems in some way to increase the rate of theexudation process. These conclusions are discussed in relationto the results of other workers.     

Relationships between oak decline and groundwater class in The Netherlands

In 1989, the mortality since 1983 and the health class distribution of pedunculate oak, (Quercus robur) on soils of different groundwater classes at 11 locations in The Netherlands were compared. It was found that dead and unhealthy oak trees are most prevalent on soils with strongly fluctuating groundwater levels in the rooted zone. On these soils oaks root less deeply and have more dead roots, especially in the deepest part of the root systems. These findings suggest that unusually dry and wet weather conditions in 1982–1983 led to, abnormally low and high groundwater levels in the growing seasons of those years. In addition to other factors such as defoliation by insects and frost damage, this phenomenon probably aggravated oak decline.     

The Subadult Plumage of Male Purple Martins: Variability,Female Mimicry and Recent Evolution

Like a number of other passerine birds year-old male purple martins, Progne subis, often breed in a ♀-like plumage. We have examined delayed plumage maturation in martins by testing assumptions and predictions derived from two hypotheses advanced to explain their appearance and behavior: the sexual selection hypothesis and the female mimicry hypothesis. First, we examine the success of subadults of different appearance 1) in dominance interactions with adults and with other subadults and 2) at entering colonies with different numbers of adults. Second, we compare the mating success of subadults of different appearance. Finally, we examine predictions from the female mimicry hypothesis concerning the appearance of subadults with regard to geographic variation in colony size and with regard to historical changes in colony size in Eastern North America.     

Immaculate tits: head plumage pattern as an indicator of quality in birds

Great tits, Parus major, display their white cheek patches to one another during intraspecific encounters. We measured the size of these patches and the regularity of their borders (immaculateness) as part of an investigation into their function as signals. Patch size was not significantly related to any of our measures of fitness, but male great tits with more immaculate cheek patches had significantly greater access to a safer feeding site in winter and produced heavier chicks in small woods. Females with more immaculate patches bred significantly earlier in 2 of the 3 years of the study in both large and small woods. We decreased the immaculateness of both sexes with dye and found that competition with other tits significantly increased their exposure to danger when feeding. Factors resulting in reduced immaculateness included ectoparasites, fighting with conspecifics, faster feather wear in young birds and the timing of the autumn moult. Selection for immaculateness by conspecifics may be one mechanism responsible for the evolution of regular head and body patterns in several species of birds and in other animals.