Fecundity and survival in relation to resistance to oxidative stress in a free-living bird.

Major life history traits, such as fecundity and survival, have been consistently demonstrated to covary positively in nature, some individuals having more resources than others to allocate to all aspects of their life history. Yet, little is known about which resources (or state variables) may account for such covariation. Reactive oxygen species (ROS) are natural by-products of metabolism and, when ROS production exceeds antioxidant defenses, organisms are exposed to oxidative stress that can have deleterious effects on their fecundity and survival. Using a wild, long-lived bird, the Alpine Swift (Apus melba), we examined whether individual red cell resistance to oxidative stress covaried with fecundity and survival. We found that males that survived to the next breeding season tended to be more resistant to oxidative stress, and females with higher resistance to oxidative stress laid larger clutches. Furthermore, the eggs of females with low resistance to oxidative stress were less likely to hatch than those of females with high resistance to oxidative stress. By swapping entire clutches at clutch completion, we then demonstrated that hatching failure was related to the production of low-quality eggs by females with low resistance to oxidative stress, rather than to inadequate parental care during incubation. Although male and female resistance to oxidative stress covaried with age, the relationships among oxidative stress, survival, and fecundity occurred independently of chronological age. Overall, our study suggests that oxidative stress may play a significant role in shaping fecundity and survival in the wild. It further suggests that the nature of the covariation between resistance to oxidative stress and life history traits is sex specific, high resistance to oxidative stress covarying primarily with fecundity in females and with survival in males.

Additive effects of ectoparasites over reproductive attempts in the long-lived Alpine swift

1. Parasitism is a non-negligible cost of reproduction in wild organisms, and hosts are selected to partition resources optimally between current and future reproduction. While parents can compensate for the cost of parasitism by increasing their current reproductive investment, such change in resource allocation is expected to carry-over costs on future reproduction. 2. Life history theory predicts that because long-lived organisms have a high residual reproductive value, they should be more reluctant to increase parental effort in response to parasites. Also, when rearing successive infested broods, the cost of parasitism can cumulate over the years and hence be exacerbated by past infestations. 3. We tested these two predictions in the alpine swift Apus melba, a long-lived colonial bird that is infested intensely by the nest-based blood sucking louse-fly Crataerina melbae. For this purpose, we manipulated ectoparasite load over 3 consecutive years and measured reproductive parameters in successive breeding attempts of adults assigned randomly to 'parasitized' and 'deparasitized' treatments. 4. In current reproduction, fathers of experimentally parasitized broods produced a similar number of offspring as fathers from the deparasitized treatment, but the rearing period was prolonged by 4 days. Fathers that were assigned to the parasitized treatment in year x produced significantly fewer fledglings the following year x + 1 than those of the deparasitized treatment. The number of young produced by fathers in year x + 1 was correlated negatively with the number of days they cared for their brood in the previous year x. We also found a significant interaction between treatments performed over 2 successive years, with fathers of parasitized broods suffering a larger fitness loss if in the past they had already cared for a parasitized brood rather than for a deparasitized one. Similar effects of parasitism, although partly non-significant (0.05 < P-values > 0.10), were found in mothers. 5. Altogether, our results show that parasites can modify resource allocation between current and future reproduction in long-lived hosts, and that the cost of parasitism can cumulate over the years. It emphasizes the fact that effects of parasites can depend on past infestations and become apparent in future reproduction only.

Catch-up growth strategies differ between body structures: interactions between age and structure-specific growth in wild nestling Alpine swifts

1. Little is known on the occurrence and magnitude of faster than normal (catch-up) growth in response to periods of undernutrition in the wild, and the extent to which different body structures compensate and over what timescales is poorly understood. 2. We investigated catch-up growth in nestling Alpine Swifts, Apus melba, by comparing nestling growth trajectories in response to a naturally occurring 1-week period of inclement weather and undernutrition with growth of nestlings reared in a good year. 3. In response to undernutrition, nestlings exhibited a hierarchy of tissues preservation and compensation, with body mass being restored quickly after the end of the period of undernutrition, acceleration of skeletal growth occurring later in development, and compensation in wing length occurring mostly due to a prolongation of growth and delayed fledging. 4. The effect of undernutrition and subsequent catch-up growth was age-dependent, with older nestlings being more resilient to undernutrition, and in turn having less need to compensate later in the development. 5. This shows that young in a free-living bird population can compensate in body mass and body size for a naturally occurring period of undernutrition, and that the timing and extent of compensation varies with age and between body structures.

Melanin-based colorations signal strategies to cope with poor and rich environments

One hypothesis for the maintenance of genetic variation states that alternative genotypes are adapted to different environmental conditions (i.e., genotype-by-environment interaction GxE) that vary in space and time. Although GxE has been demonstrated for morphological traits, little evidence has been given whether these GxE are associated with traits used as signal in mate choice. In three wild bird species, we investigated whether the degree of melanin-based coloration, a heritable trait, covaries with nestling growth rate in rich and poor environments. Variation in the degree of reddish-brown phaeomelanism is pronounced in the barn owl (Tyto alba) and tawny owl (Strix aluco), and variation in black eumelanism in the barn owl and Alpine swift (Apus melba). Melanin-based coloration has been shown to be a criterion in mate choice in the barn owl. We cross-fostered hatchlings to test whether nestlings sired by parents displaying melanin-based colorations to different extent exhibit alternative growth trajectories when raised by foster parents in poor (experimentally enlarged broods) and rich (experimentally reduced broods) environments. With respect to phaeomelanism, barn owl and tawny owl offspring sired by redder parents grew more rapidly in body mass only in experimentally reduced broods. With respect to eumelanism, Alpine swift offspring of darker fathers grew their wings more rapidly only in experimentally enlarged broods, a difference that was not detected in reduced broods. These interactions between parental melanism and offspring growth rate indicate that individuals display substantial plasticity in response to the rearing environment which is associated with the degree of melanism: at least with respect to nestling growth, phaeomelanic and eumelanic individuals are best adapted to rich and poor environments, respectively. It now remains to be investigated why eumelanism and phaeomelanism have a different signaling function and what the lifelong consequences of these melanism-dependent allocation strategies are. This is important to fully appraise the role played by environmental heterogeneity in maintaining variation in the degree of melanin-based coloration.

Real-time quantitative PCR assay for measurement of bird telomeres

We present the application of a real-time quantitative PCR assay, previously developed to measure relative telomere length in humans and mice, to two bird species, the zebra finch Taeniopygia guttata and the Alpine swift Apus melba. This technique is based on the PCR amplification of telomeric (TTAGGG)(n) sequences using specific oligonucleotide primers. Relative telomere length is expressed as the ratio (T/S) of telomere repeat copy number (T) to control single gene copy number (S). This method is particularly useful for comparisons of individuals within species, or where the same individuals are followed longitudinally. We used glyceraldehyde-3-phosphate dehydrogenase (GAPDH) as a single control gene. In both species, we validated our PCR measurements of relative telomere length against absolute measurements of telomere length determined by the conventional method of quantifying telomere terminal restriction fragment (TRF) lengths using both the traditional Southern blot analysis (Alpine swifts) and in gel hybridization (zebra finches). As found in humans and mice, telomere lengths in the same sample measured by TRF and PCR were well correlated in both the Alpine swift and the zebra finch.. Hence, this PCR assay for measurement of bird telomeres, which is fast and requires only small amounts of genomic DNA, should open new avenues in the study of environmental factors influencing variation in telomere length, and how this variation translates into variation in cellular and whole organism senescence.

A distribuição funcional da renda no Brasil: 1959-2009

Inúmeros trabalhos têm sido escritos sobre a distribuição pessoal da renda na economia brasileira, suas origens, as mudanças ocorridas nos últimos anos e suas causas. A distribuição funcional da renda, com todas suas implicações para a distribuição pessoal da renda, por sua vez, tem sido pouco avaliada, principalmente, devido à falta de informações. Este trabalho busca, inicialmente, descrever a evolução dessa distribuição funcional da renda, sob o ponto de vista das remunerações dos assalariados, para o período em que se têm informações das contas nacionais, que vai de 1959 a 2009. Em seguida procura-se analisar essa evolução sob o ponto de vista da participação da remuneração do capital, utilizando-se uma função de produção CES. Aplicando-se os três procedimentos, descritos no corpo do trabalho, para auferir o que seria a remuneração do trabalho verifica-se que a participação da remuneração do trabalho é de, em média: 47,3, 57,1 ou, 52,6 %, de acordo com o procedimento adotado. Esta participação é inferior, na melhor situação, a de países mais desenvolvidos ou menos desenvolvidos do que o Brasil. Introduz-se neste trabalho uma novidade que se mostra relevante. É fato sabido que o mercado de trabalho no Brasil funciona de forma bastante diferente quando se trata do setor público ou do setor privado. Levando-se isto em consideração foram abordados os resultados para o total da economia que é comumente abordado neste tipo de comparação e para o setor público e o privado em separado. Pelos 3 procedimentos acima referidos, a participação das remunerações de assalariados do setor privado no PIB do setor privado é acentuadamente inferior (em média 8,4 pontos de percentagem) a esta participação quando se compara com o total da economia, embora se observe que as tendências são semelhantes. Isso se deve à notável diferença entre o salário médio do setor público que, em 2009, era quase o dobro do salário médio setor privado. Em seguida, vai-se além da descrição da evolução da distribuição funcional da renda. Para testar isso se introduz outra novidade neste tipo de trabalho: imputa-se como excedente das administrações públicas (APUs), o valor dos impostos sobre a produção e a importação, líquidos de subsídios, já que esta renda não pertence ao trabalho -- é um excedente, primariamente apropriado pelas APUs. Utilizando-se uma função de produção agregada com coeficiente de elasticidade de substituição constante (CES), procura-se explicar a evolução da participação dos rendimentos de propriedade na renda interna bruta, para o total da economia com os impostos sobre a produção imputados como excedente das administrações públicas; procede-se da mesma forma para o setor privado em separado. A teoria sugere que a relação entre participação do capital na renda e a quantidade de capital é negativa – isto é, a participação do capital na renda reduz-se quando a quantidade de capital sobe – se as possibilidades de substituição de capital por trabalho forem relativamente baixas. A experiência brasileira, até 2005, parece comprovar isto: a queda da participação do capital na renda ocorreu simultaneamente a uma elevação da relação capital-produto. O resultado da simulação da participação do rendimento de propriedade em função da relação capital-produto se mostrou bastante robusto, tanto para o total da economia com imputação de excedente para as administrações públicas, como para o setor privado em separado.

In cosuetudines Ducatus Burgundiae feréque totius Galliae commentarii amplissimi Bartlolomaeo Chassenaeo...

Marca tipográfica en la portada.

L. Annaei Flori Epitome rerum romanarum : cum integris Salmasii, Freinshemii, Graevii et selectis aliorum animadversionibus /

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Iosephi Aurelii De Januario ... Respublica iurisconsultorum ... /

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Tiḳune ha-Zohar : ʻal ha-Torah ... ṿe-hitsavnu tsiyunim ... mi-yom me-ʻerev ḥodesh Elul ʻad Yom ha-Kipurim ...

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