Juvenile coloration of Florida Scrub-Jays ( Aphelocoma coerulescens ) is sexually dichromatic and correlated with condition

The Florida Scrub-Jay is a monogamous cooperative breeder in which both males and females display extensive structurally based blue plumage. Juveniles of this species exhibit blue tail and wing feathers that they begin growing as nestlings, and some of these feathers are retained throughout their first year. Although the birds appear to be sexually monochromatic, we assessed whether cryptic dichromatism exists in both the magnitude and pattern of coloration in tail feathers of juvenile Florida Scrub-Jays. We then determined whether variation in plumage coloration is associated with nutritional condition during molt. Tails of juvenile male Florida Scrub-Jays exhibit a greater proportion of UV reflectance than those of females. Mass at age 11 days and ptilochronology of the juvenile tail feathers were used as measures of individual nutritional condition during feather growth, and the latter was found to be positively associated with UV chroma. These data demonstrate that Florida Scrub-Jays are sexually dichromatic and suggest that variation in plumage color may be condition dependent, although we cannot rule out alternative explanations. Juvenile plumage coloration, therefore, has the potential to function as a signal of individual quality in both males and females.     

Speciation rates are correlated with changes in plumage color complexity in the largest family of songbirds

Although evolutionary theory predicts an association between the evolution of elaborate ornamentation and speciation, empirical evidence for links between speciation and ornament evolution has been mixed. In birds, the evolution of increasingly complex and colorful plumage may promote speciation by introducing prezygotic mating barriers. However, overall changes in color complexity, including both increases and decreases, may also promote speciation by altering the sexual signals that mediate reproductive choices. Here, we examine the relationship between complex plumage and speciation rates in the largest family of songbirds, the tanagers (Thraupidae). First, we test whether species with more complex plumage coloration are associated with higher speciation rates and find no correlation. We then test whether rates of male or female plumage color complexity evolution are correlated with speciation rates. We find that elevated rates of plumage complexity evolution are associated with higher speciation rates, regardless of sex and whether species are evolving more complex or less complex ornamentation. These results extend to whole-plumage color complexity and regions important in signaling (crown and throat) but not nonsignaling regions (back and wingtip). Our results suggest that the extent of change in plumage traits, rather than overall values of plumage complexity, may play a role in speciation.     

Molecular phylogenetics of the hummingbird genus Coeligena

Advances in the understanding of biological radiations along tropical mountains depend on the knowledge of phylogenetic relationships among species. Here we present a species-level molecular phylogeny based on a multilocus dataset for the Andean hummingbird genus Coeligena. We compare this phylogeny to previous hypotheses of evolutionary relationships and use it as a framework to understand patterns in the evolution of sexual dichromatism and in the biogeography of speciation within the Andes. Previous phylogenetic hypotheses based mostly on similarities in coloration conflicted with our molecular phylogeny, emphasizing the unreliability of color characters for phylogenetic inference. Two major clades, one monochromatic and the other dichromatic, were found in Coeligena. Closely related species were either allopatric or parapatric on opposite mountain slopes. No sister lineages replaced each other along an elevational gradient. Our results indicate the importance of geographic isolation for speciation in this group and the potential interaction between isolation and sexual selection to promote diversification.     

Achromatic plumage reflectance predicts reproductive success in male black-capped chickadees

The size of achromatic (black, white, gray) plumage patchesserves as a male status signal in many species of birds, butvariation in the colors of these patches has received littleattention. We assessed the relation between achromatic plumagereflectance, dominance rank, body condition, and reproductivesuccess in male black-capped chickadees, Poecile atricapillus.We measured plumage reflectance for five body regions of 40male chickadees in late winter and monitored these males throughoutthe following breeding season to determine whether they survivedto breed, whether they successfully paired, whether their partnerlaid eggs, and both their apparent and realized reproductivesuccess. As expected from past studies, a male's dominance ranksignificantly predicted whether his partner laid eggs. However,only achromatic plumage reflectance significantly predictedother measures of male reproductive performance. Among maleswho fledged at least one offspring, both the brightness of whiteplumage regions and the UV-chroma of melanin-based plumage regionswere significant predictors of the proportion of within-pairyoung in their nests. When we consider all males we measured,assigning zero values to males who failed to sire any offspring,the UV-chroma of melanin-based plumage regions was a significantpredictor of realized reproductive success. Bib size was alsorelated to male realized reproductive success. Our findingssuggest that individual variation in achromatic plumage mayplay an important role in sexual signaling in chickadees.     

Delayed plumage maturation in green‐backed flycatchers (Ficedula elisae): An evidence of female mimicry

Delayed plumage maturation (DPM) is the delayed acquisition of an adult color and pattern of plumage until after the first potential breeding period. Among the hypotheses proposed to explain DPM, the female mimicry hypothesis (FMH) has received considerable attention. FMH predicts that after‐second‐calendar‐year (ASY) males should attack ASY males more than second‐calendar‐year (SY) males and females, while no difference between the two latter. Few studies have been thought as support for FMH, while in fact most of them give no conclusive evidence to the assumption of FMH that ASY males are unable to distinguish SY males from females. Thus, other support besides behavioral experiments, such as it is physiologically impossible to discriminate SY males and females from avian perspective, is important in testing FMH. We studied color differences in six plumage patches between ASY male, SY male and female by analyzing reflectance spectra in the avian visual system, and tested the prediction of FMH by conducting intrusion experiments on territorial males with three kinds of conspecifics (i.e., ASY males, SY males and females) as territory “intruders” in the green‐backed flycatcher (Ficedula elisae). It is physiologically impossible for ASY males to distinguish SY males and females through the plumage color of crown, mantle, rump, and throat patches, moreover difficult to distinguish through breast and belly patches even under reasonable viewing conditions. ASY males were more aggressive toward ASY males than SY males and females with no differences between the two latter. SY males showed a slightly but not significantly higher attack intensity on ASY males than SY males and females. Our results suggest that female mimicry is more likely to be the explanation for DPM in the green‐backed flycatcher. To our knowledge, this is the first study combining avian visual system and behavioral experiments in testing hypotheses of DPM.     

Breeding in the monsoon: semi-annual reproduction in the Seychelles warbler ( Acrocephalus sechellensis )

Despite the absence of pronounced changes in day length, there is considerable climatological seasonality in the tropics. Its expression can be complex like in the monsoon climate of the Indian Ocean Islands. The land mass distribution on both sides of the equator leads to seasonal changes in prevailing wind direction and seasonal patterns in food supply, which are distinct between different coasts. Here we assess that territory quality of the Seychelles warbler, endemic to the small island of Cousin peaks during the South East monsoon (April to September) in most of the island. The Southeastern wind-exposed side is exceptional by being generally poor and having slightly increased food supply in the opposite season (NW monsoon; October to March). In response, the warblers in most territories breed primarily during the SE season, while on the SE shores they tend to breed in both seasons. The result is a semi-annual periodicity in breeding. Individual pairs can breed in 6 months intervals. In the poorer territories on the SE shore most of them indeed do this, while in the richer central habitats most pairs restrict themselves to the best (SE) season. The frequency of breeding thereby increases with territory quality in the SE season, and decreases with quality in the NW season. Withholding from breeding in the NW season despite the high food supply may have long-term advantages for the birds occupying the richer habitat. Such flexible adjustment of seasonality to local circumstances requires not only an immediate response mechanism but also access to accurate information about time of year. The subtle sensitivity of tropical songbirds to photoperiod, demonstrated so convincingly by Eberhard Gwinner (Biological rhythms, Hokkaido University Press, Sapporo, pp19–40, 2005), may well have profound adaptive meaning in taking temporally optimized reproductive decisions in response to both food and time of year.

Structurally based plumage coloration is an honest signal of quality in male blue grosbeaks

We investigated the signaling function of blue plumage in maleblue grosbeaks (Guiraca caerulea) to determine if structurallybased coloration may act as a reliable signal of quality toconspecifics. Blue plumage results from the microstructureof feather barbules rather than from pigment granules, andthus it is possible that structurally based plumage ornamentsmay function differently from sexually selected ornamental coloration that is pigment based. The plumage of male blue grosbeaksreflects maximally in the blue-ultraviolet range, so most variationin plumage coloration among males is invisible to human observers.In previous research, we showed that increased area of blueplumage on the body is associated with a shift in the wavelengthof maximum feather reflectance toward the ultraviolet and withhigh intensity of light reflected at that maximum, and thatextreme expression of the male ornament is condition dependent.These observations suggest that blue plumage may be an honestadvertisement of male quality. We tested this hypothesis ina wild population of blue grosbeaks. We quantified male qualityin three broad categories. (1) Physical condition was assessed from subcutaneous fat deposits, ectoparasite load, and bodysize. (2) Territory quality was assessed from territory area,prey abundance, and predation risk. (3) Paternal investmentwas assessed from male feeding rate. We found that the bluestmales have the largest body size, maintain the largest territorieswith the greatest prey abundance, and feed nestlings in thefirst nest of the season at the highest rates. We conclude that structurally based plumage coloration functions as an honest,intraspecific signal of quality.     

Plumage maintenance affects ultraviolet colour and female preference in the budgerigar

Elaborate or colourful feathers are important traits in female-mate choice in birds but little attention has been given to the potential costs of maintaining these traits in good condition via preening behaviour. While preening is known to be an important component of plumage maintenance, it has received little attention with respect to colouration. We investigated whether preening can influence plumage reflectance and whether females show a preference for plumage cleanliness in captive-bred, wild-type budgerigars, Melopsittacus undulatus. To do this, we compared the spectral colour of birds that were allowed to preen their plumage and individuals that were prevented from preening. The plumage of birds that were prevented from preening showed a significant lower reflectance in the UV range (300-400 nm). Subsequently, we measured females’ preferences for preened and unpreened males using a two-choice test. In a second experiment we allowed females to choose between an unpreened male and a male smeared with UV-absorbing chemicals (UV-blocked male). The proportion of time that females stayed near preened males was statistically higher than for unpreened males, but females spent similar amounts of time with unpreened males and UV-blocked males. These results are consistent with the idea that female budgerigars are able to discriminate between preened and unpreened males, and that UV colours, mediated by preening, can convey information about a bird's current condition.     

Delayed maturation of plumage coloration and plumage spottedness in the Barn Owl (Tyto alba)

Summary The Barn Owl (Tyto alba) varies in plumage from dark reddish-brown to white, and from heavily marked with black spots to immaculate. Males are commonly lighter coloured and less spotted than females. I assessed whether male and female Barn Owls delay the full expression of plumage coloration and spottedness to the second year of life. In Switzerland, I quantified the two traits of birds captured at the nestling stage, first, second and third year of life. Males and females became lighter coloured only from the first to the second year. Males became less spotted only from the first to the second year, and females less spotted from the nestling stage to the first year but more spotted from the first to the second year. Females were also similarly spotted at the second and third year of age. By cutting off small pieces of feathers of females I could recognize which feathers had later been renewed. After a complete moult old females did not change in plumage characteristics.

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Verzögerter Wechsel vom Juvenil- zum Adultgefieder bei der Schleiereule(Tyto alba)

Zusammenfassung Das Gefieder der Schleiereule (Tyto alba) variiert von rostbraun bis weiss und von dicht gefleckt bis fleckenlos. Die Männchen sind eher hell und weniger gefleckt als die Weibchen. Es wurde untersucht, ob männliche und weibliche Schleiereulen die volle Entfaltung ihrer Gefiederfarbe und -struktur auf das zweite Lebensjahr verlegen. In der Schweiz habe ich beide Gefiederpolymorphismen bei Jungvögeln, ein-, zwei- und dreijährigen Vögeln quantifiziert. Bei Männchen und Weibchen wurde das Auslichten der Gefiederfarbe nur zwischen dem 1. und 2. Lebensjahr beobachtet. Männchen wurden weniger dicht gefleckt nur zwischen dem 1. und 2. Lebensjahr, während Weibchen zwischen dem Nestlingstadium und dem 1. Lebensjahr weniger gefleckt wurden und zwischen dem 1. und 2. Lebensjahr wieder mehr Flecken hatten. Weibchen wurden also gleich gefleckt im 2. und 3. Lebensjahr. Um die erneuerten Federn zu erkennen, wurden bei Weibchen kleine Federstücke herausgeschnitten. Nach einer vollständigen Erneuerung der Brustfedern hatte sich die Farbe und die Anzahl Punkte bei alten Weibchen nicht geändert.

     

Variation in the magnitude of sexual size dimorphism in nestling Coal Tits (Periparus ater)

The magnitude of sexual size dimorphism can be affected by sex differences in environmental sensitivity early in ontogeny that result in differential growth rates of male and female nestlings. Here, the larger sex might either be more sensitive because of higher food demands or less sensitive due to greater competitive ability. When environmental conditions deteriorate during the breeding season, this “environmental stress” hypothesis predicts differential seasonal declines in the performance of male and female offspring. Based on a sample of molecularly sexed Coal Tit (Periparus ater) nestlings from 2 years, we investigated sexual size dimorphism in body mass, condition (i.e. size-corrected mass), tarsus and wing length and whether its magnitude changed from early to late broods. Male offspring were heavier, larger (in terms of tarsus and wing length) and had higher size-corrected mass than their female nest mates (the same was evident in adult breeders). In 2002 (the year with the longer effective breeding season), body mass and condition declined with progressing hatching date and this effect was significantly more pronounced in male than in female nestlings. There was also a seasonal decline in male wing length, while female wing length remained relatively constant, which resulted in males having shorter wings than females in late broods. Tarsus length was unaffected by time of breeding, except that the difference between males and females was relatively smaller in late (i.e. second) broods in 2002. While these results are in accordance with the idea of an increased environmental sensitivity of the larger males, confounding effects of sex-differential hatching order cannot be ruled out. Dedicated to Doris Winkel.     

Allofeeding in Arabian Babblers (Turdoides squamiceps)

Allofeeding is a common social display among adult Arabian babblers (Turdoides squamiceps). The sociology and rates of allofeeding were studied with a tame population of babblers at the Shezaf Nature Reserve in the Rift Valley, Israel. Allofeeding rate varies with the season and food availability. Experimental supplementation to the whole group or to certain individuals greatly increased the rate of allofeeding, but it did not change the social order of the interactions. The interactions were almost always unidirectional: the donor allofed an individual lower in rank. Most of the few exceptions were reciprocal allofeeding among pairs of low-ranking individuals, correlated with a change in dominance between a young male and a young female. Higher-ranking individuals sometimes interfered with allofeedings by lower-ranking ones, and receivers frequently refused to accept the food offered. Allofeeding may therefore be considered as a display of dominance. However, as dominance rank rarely changes, except in very young birds, we suggest that allofeeding interactions display the prestige of the donors, that is, the degree of dominance of one individual over the other.Electronic Supplementary Material Supplementary material is available for this article at .     

Alloparenting experience affects future parental behavior and reproductive success in prairie voles (Microtus ochrogaster)

Various hypotheses have been proposed to explain the function of alloparental behavior in cooperatively breeding species. We examined whether alloparental experience as juveniles enhanced later parental care and reproductive success in the prairie vole (Microtus ochrogaster), a cooperatively breeding rodent. Juveniles cared for one litter of siblings (1EX), two litters of siblings (2EX) or no siblings (0EX). As adults, these individuals were mated to other 0EX, 1EX or 2EX voles, yielding seven different pair combinations, and we recorded measures of parental behaviors, reproductive success, and pup development. As juveniles, individuals caring for siblings for the first time were more alloparental; and as adults, 0EX females paired with 0EX males spent more time in the nest with their pups. Taken together, these results suggest that inexperienced animals spend more time in infant care. As parents, 1EX males spent more time licking their pups than 2EX and 0EX males. Pups with either a 1EX or 2EX parent gained weight faster than pups with 0EX parents during certain developmental periods. While inexperienced animals may spend more time in pup care, long-term benefits of alloparenting may become apparent in the display of certain, particularly important parental behaviors such as licking pups, and in faster weight gain of offspring.     

Individual color variation and male quality in pied flycatchers (Ficedula hypoleuca): a role of ultraviolet reflectance

Bright coloration of males in many animal species has inspiredresearchers for more than a century. In this field study, weinvestigated whether color variation between individuals isrelated to individual quality in pied flycatcher (Ficedulahypoleuca) males in terms of arrival time at the breeding sites.In addition to traditional visual color scoring, plumage color was measured using spectroradiometric measurements between 320and 700 nm. This range includes the near-ultraviolet wavebandfrom 320 to 400 nm. Males that arrived earlier at breedingsites had higher proportional UV reflectance in the crown andmantle. The proportional UV reflectance in the crown and mantlewas not related to traditionally scored general brownness inmales. However, adult males had a higher proportion of ultravioletin the plumage than yearling males or females. These resultssuggest that in pied flycatcher males, the UV reflectance ofplumage may be positively correlated with individual quality.     

Abnormal embryo development in the seagrass Posidonia oceanica

In this study the occurrence of twin-like embryos and abnormal embryos in Posidonia oceanica, a rare phenomenon in seagrasses, was documented. The ability of additional embryos to develop seedlings was also demonstrated for the first time in seagrasses. Approximately 1750 fruits collected at three localities of the north-western Mediterranean on 2 years (1994 and 2004) were screened for abnormal embryo morphology. The frequency of embryo anomalies varied from 1.9 to 7.1% among localities, and no differences between years were detected within the same locality. Twin-like embryos were usually in contact and germinated to produce complete twin seedlings that could be separated. Abnormal embryos showed additional plumules but had a common hypocotyl and a single primary root; these embryos germinated and grew like “Siamese” seedlings.     

利用ISSR分子标记检测空间诱导罗汉果DNA突变

为探究太空环境对罗汉果造成的诱变效应,筛选罗汉果新品种培育优异种质,该研究运用ISSR分子标记技术,对28个航天诱变罗汉果及主栽品种进行了全基因组多态性检测和聚类分析。结果表明:从100个ISSR引物中筛选得到17个引物,共扩增出157个条带,其中83条具有多态性,多态条带百分率为52.87%,遗传相似系数范围为0.707~0.987。根据UPGMA聚类图,28个罗汉果样本可以分为3类:聚类Ⅰ为航天种质B6♂和B3♀;聚类Ⅱ为航天种质A1♀、A14、A18♂与主栽品种;聚类Ⅲ中都为航天罗汉果种质。上述结果暗示A1♀、A14、A18♂与其他航天种质已经产生了一定的遗传分化,具有与主栽品种相似的遗传背景,可能获得了有益突变。该研究结果为罗汉果新品种培育和杂交亲本选配提供了科学依据。     

拟南芥黄心突变体yh基因的图位克隆及分析

在研究光合作用相关基因的过程中,获得了一个叶片为黄心(yellow heart,yh)的突变株,与野生型拟南芥(Col 0)相比,其新生叶片发黄,突变表型由隐性单基因控制。采用图位克隆及其精细定位技术,将yh突变基因定位在1号染色体的INS1_55_342与INS1_56_34区间,物理距离约为676 kb。通过测序得知yh在At1g64790第44个内含子剪接处有4个碱基的缺失,导致内含子剪切位点的变化。RT PCR分析显示,该基因表达降低,是At1g64790基因的一个新等位突变。研究表明,yh突变体与叶绿体的发育相关,可为进一步探究植物叶绿体和叶片发育机制提供新的遗传材料。     

Song structure in the Hoopoe (Upupa epops) — Strophe length reflects male condition

Summary The structure of Hoopoe (Upupa epops) song is analysed in a colour ringed population in southern Spain. The song of males in this species is very simple, with a repertoire size of one. The strophes of a male only differ in the number of elements that they include (strophe length), and strophe length is the main song feature differing between males. During the prelaying period each individual used mainly strophes of only two lengths, between 2 and 6 elements per strophe, and mean strophe length of males during this period was highly repeatable. However, some males changed the range of strophe types produced and decreased their mean strophe length after unsuccessful breeding or spending long periods of time singing (unpaired males). These changes show that strophe length is phenotypically plastic, and suggest that singing long strophes is energetically more costly than singing short ones. The significant relationship between strophe length and body condition, and the fact that long strophes were associated with longer previous pauses than short strophes, also suggest that increasing strophe length is costly. All these findings are in accordance with the hypothesis that strophe length reflects male condition in the Hoopoe, although it is not clear what the actual cost of singing long strophes is.

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Struktur des Gesangs des Wiedehopfs (Upupa epops) — Strophenlänge reflektiert Männchen-Qualität

Zusammenfassung Die Struktur des Gesangs des Wiedehopfs wurde in einer farbberingten südspanischen Population untersucht. Der Gesang des Männchens ist sehr einfach und umfaßt nur ein Repertoire. Die Strophen eines Männchens differieren nur in der Anzahl Elemente (Strophenlänge), und die Männchen unterscheiden sich vor allem in der Strophenlänge voneinander. In der Vorbrutphase verwendeten die Männchen meist nur zwei verschieden lange Strophen, bestehend aus 2 und 6 Elementen je Strophe, und die durchschnittliche Strophenlänge war in dieser Phase sehr konstant. Nach Brutverlust oder bei kontinuierlich singenden, ledigen Männchen kam es zu einer Verkürzung der mittleren Strophenlänge. Die Strophenlänge ist phänotypisch plastisch, und lange Strophen zu singen scheint energetisch aufwendiger als kurze Strophen. Der enge Zusammenhang zwischen Strophenlänge und männlicher Konstitution einerseits und die Beobachtung, daß lange Strophen mit langen Pausen korrelieren andererseits, zeigen ebenfalls, daß längere Strophen energetisch aufwendiger sind. Die wirklichen Kosten dafür sind jedoch noch nicht bekannt.

     

Hunting, healing, and hxaro exchange: A long-term perspective on !Kung (Ju/''hoansi) large-game hunting

The question of why hunters target large game knowing that most of the meat will end up far beyond their own hearths is an intriguing one. It raises the issue of whether foragers pursue nonnutritional goals in food procurement and which goals they pursue. Here, I will use data from studies that have been carried out over a 34-year period among the Ju/'hoansi (!Kung Bushmen) to evaluate four hypotheses concerning why foragers target large game: reciprocity, costly signaling, nepotism, and long-term political goals aimed at bringing about conditions conducive to cooperative breeding. I will propose on the basis of qualitative and quantitative data that (1) all four hypotheses identify benefits that are gained by Ju/'hoansi through producing and distributing a surplus of meat, (2) different benefits might be important at different stages of a man's life, and (3) the pursuit of broader political goals merits serious consideration in accounting for men's work effort.     

我国部分禽流感病毒H5N1之HA序列变异演化分析

从GenBank上获得我国人(Homo sapiens)、家禽和野鸟42株H5N1亚型禽流感病毒的HA基因核酸序列,利用DNAStar分析HA蛋白关键位点氨基酸残基的变化,比较HA基因核苷酸序列同源性,构建遗传进化树.探讨我国部分人、家禽和野鸟H5N1病毒基因的遗传进化关系.序列分析结果表明:禽流感病毒H5N1亚型的HA基因持续地发生着变异,但并非以均一速度进行,时间间隔愈长,核苷酸同源性愈低;我国同一地区或临近地区,当年或前后两年发生的人及家禽感染的禽流感病毒高度同源.推测我国部分人发生的禽流感可能是通过家禽感染的;候鸟的迁徙在传播病毒过程中所起的作用有待深入探讨.