Neurotoxicidade perinatal por cádmio em ratos wistar e interação com clorpirifós

Pós-graduação em Medicina Veterinária - FMVZ

Ecologia e comportamento do bicudinho-do-brejo (Stymphalornis acutirostris Bornschein, Reinert & Teixeira, 1995 - aves, Thamnophilidae)

Pós-graduação em Ciências Biológicas (Zoologia) - IBRC

Predation of Caiman yacare (Spix, 1825) (Crocodilia, Alligatoridae) by Busarellus nigricollis (Latham, 1790) (Accipitriformes, Accipitridae) in the Taiama Ecological Station, Alto Pantanal, State of Mato Grosso

Predation of Caiman yacare (Spix, 1825) (Crocodilia, Alligatoridae) by Busarellus nigricollis (Latham, 1790) (Accipitriformes, Accipitridae) in the Taiama Ecological Station, Alto Pantanal, State of Mato Grosso. The Black-collared Hawk Busarellus nigricollis is an Accipitridae commonly seen on river banks, lagoon shores, and marshy areas. It feeds mainly on fishes and aquatic insects. It hunts from dead tree branches at forest edges or emergent trunks in flooded areas. Detailed information about the Black-collared Hawk food habits is scarce. In this study, we describe the predation of Caiman yacare (Pantanal alligator) by an individual of B. nigricollis. The event was observed on 20 August 2010 at 10: 14 am, in the Taiama Ecological Station, municipality of Caceres, Alto Pantanal, state of Mato Grosso. The B. nigricollis individual was seen leaving the Paraguay River carrying a juvenile C. yacare around 40 cm long. The prey was torn apart and given to a Black-collared Hawk nestling sitting atop a nest in flooded forest, ca. 15 m way from the river bank. This is the first published record of Pantanal alligator predation by the Black-collared Hawk.

The life histories of the two tropical warblers Sylvia boehmi and Sylvia lugens

Ziel der Arbeit war die Quantifizierung einer Reihe von Lebenszyklusmerkmalen der beiden tropischen Grasmückenarten Sylvia boehmi und S. lugens (Aves: Sylviidae; frühere Gattung Parisoma). 13 Brutpaare beider Arten wurden von 2000 bis 2002 in Kenia beobachtet. Die Daten wurden mit multivariater Statistik und multistate mark-recapture Modellen ausgewertet. Die Lebenszyklusmerkmale der beiden untersuchten Sylvia Arten sind im Vergleich zu den temperaten Sylvia-Arten gekennzeichnet durch kleine Gelege von zwei Eiern, lange Inkubationsperioden (S. boehmi (b.) 15.0 Tage, S. lugens (l.) 14.5 Tage), lange Nestlingsperioden (b. 12.9 Tage, l. 16.0 Tage), und niedrige Nesterfolgsraten (b. 19.4%, l. 33.2%). Der Zeitraum vom Ausfliegen der Jungen bis zu ihrer Unabhängigkeit war mit 58.5 Tagen bei S. boehmi und 37.5 Tagen bei S. lugens vergleichsweise lang und die Überlebensrate der flüggen Jungen in dieser Zeit war relativ hoch (b. 69.2%, l. 55.4%). Die jährliche Überlebensrate der brütenden adulten Tiere betrug bei S. boehmi 71.2% und bei S. lugens 57.2%. Die Saisonalität des Habitats, bedingt durch Regen- und Trockenzeiten, hatte keinen Einfluss auf die monatliche Überlebensrate im Laufe eines Jahres. Trotz hoher Nestprädationsraten gab es keinen klaren Zusammenhang zwischen Prädation und Fütterungsrate, Nestbewachung oder Neststandort.

Dissecting Carotenoid from Structural Components of Carotenoid-Based Coloration: A Field Experiment with Great Tits (Parus major)

Carotenoid-based yellowish to red plumage colors are widespread visual signals used in sexual and social communication. To understand their ultimate signaling functions, it is important to identify the proximate mechanism promoting variation in coloration. Carotenoid-based colors combine structural and pigmentary components, but the importance of the contribution of structural components to variation in pigment-based colors (i.e., carotenoid-based colors) has been undervalued. In a field experiment with great tits (Parus major), we combined a brood size manipulation with a simultaneous carotenoid supplementation in order to disentangle the effects of carotenoid availability and early growth condition on different components of the yellow breast feathers. By defining independent measures of feather carotenoid content (absolute carotenoid chroma) and background structure (background reflectance), we demonstrate that environmental factors experienced during the nestling period, namely, early growth conditions and carotenoid availability, contribute independently to variation in yellow plumage coloration. While early growth conditions affected the background reflectance of the plumage, the availability of carotenoids affected the absolute carotenoid chroma, the peak of maximum ultraviolet reflectance, and the overall shape, that is, chromatic information of the reflectance curves. These findings demonstrate that environment-induced variation in background structure contributes significantly to intraspecific variation in yellow carotenoid-based plumage coloration.

Effect of sibling competition and male carotenoid supply on offspring condition and oxidative stress

Early developmental conditions have major implications for an individual's fitness. In species where offspring are born simultaneously, the level of sibling competition for food access is intense. In birds, high sibling competition may subject nestlings to decreased growth rate as a result of limited food and increased levels of oxidative stress through high metabolic activity induced by begging behaviors. We manipulated the level of sibling competition in a natural population of great tits and assessed the consequences for nestling body condition and resistance to oxidative stress. In a full factorial design, we both augmented brood size to increase sibling competition and supplemented the male parents with physiological doses of carotenoids thereby doubling the natural carotenoid intake, aiming at increasing the males' investment in current reproduction and thereby decreasing sibling competition. Nestling body mass was reduced by the brood enlargement and enhanced by the carotenoid supplementation of fathers. Nestling resistance to oxidative stress, measured as total antioxidant defenses in whole blood, was not influenced by the treatments. Because nestlings experience high metabolic activities, an absence of an effect of sibling competition on free radicals production seems unlikely. Nestling body mass decreased and resistance to oxidative stress tended to increase with initial brood size, and hence these correlational effects suggest a trade-off between morphological growth and development of the antioxidant system. However, the result of the experimental treatment did not support this trade-off hypothesis. Alternatively, it suggests that nestling developed compensatory mechanisms that were not detected by our antioxidant capacity measure.

Barn owl (Tyto alba) siblings vocally negotiate resources

Current theory proposes that nestlings beg to signal hunger level to parents honestly, or that siblings compete by escalating begging to attract the attention of parents. Although begging is assumed to be directed at parents, barn owl (Tyto alba) nestlings vocalize in the presence but also in the absence of the parents. Applying the theory of asymmetrical contests we experimentally tested three predictions of the novel hypothesis that in the absence of the parents siblings vocally settle contests over prey items to be delivered next by a parent. This 'sibling negotiation hypothesis' proposes that offspring use each others begging vocalization as a source of information about their relative willingness to contest the next prey item delivered. In line with the hypothesis we found that (i) a nestling barn owl refrains from vocalization when a rival is more hungry, but (ii) escalates once the rival has been fed by a parent, and (iii) nestlings refrain from and escalate vocalization in experimentally enlarged and reduced broods, respectively. Thus, when parents are not at the nest a nestling vocally refrains when the value of the next delivered prey item will be higher for its nest-mates. These findings are the exact opposite of what current models predict for begging calls produced in the presence of the parents. [References: 20]

Carotenoid-based plumage colors and immune function: Is there a trade-off for rare carotenoids?

Theory suggests that carotenoid-based signals are used in animal communication because they contain specific information about parasite resistance or immunocompetence. This implies that honesty of carotenoid-based signals is maintained by a trade-off between pigmentation and immune function for carotenoids, assuming that the carotenoids used for coloration are also immunoenhancing. We tested this hypothesis by altering the diets of nestling great tits (Paris major) with supplementary beadlets containing the carotenoids that are naturally ingested with food or beadlets containing the carotenoids that are incorporated into the feathers; a control group received beadlets containing no carotenoids. We simultaneously immune challenged half of the nestlings of each supplementation group, using a two-factorial design. Activatior of the immune system led to reduced color expression. However, only nestlings fed with the naturally ingested carotenoids and not with the carotenoids deposited in the feathers showed an increased cellular immune response. This shows that the carotenoids used for ornamentation do not promote the immune function, which conflicts with the trade-off hypothesis. Our results indicate that honesty of carotenoid-based signals is maintained by an individual's physiological limitation to absorb and/or transport carotenoids and by access to carotenoids, indicating that preferences for carotenoid-based traits in sexual selection or parent-offspring interactions select for competitive individuals, rather than specifically for immune function.

Parental influence on sibling rivalry in great tit, Parus major, nests

Sibling and parente-offspring conflicts arise mainly over the amount and distribution of parental care, especially food. In altricial bird species where the young depend on parents for obtaining food, parents may control sibling competition by the choice of their respective provisioning locations. In great tits, the parents use fixed provisioning positions on the nest rim that are determined early in the breeding cycle and maintained until. edging. The two parents may choose positions that are close to each other, or far apart, and thereby increase or relax the pressure for optimal feeding positioning among nestlings. As an inspiration to this study we previously found that the two parents provide food from closer positions if the nest is infested by ectoparasites. Here, we tested the hypothesis that the parental choice of relative provisioning locations could be strategically used to control nestling competition. We forced parents to feed from either one or two provisioning locations and assessed the induced change in nestling movement, weight gain, and food distribution among siblings. We show that the angular distance between male and female locations influences the level of behavioural competition and affects nestling weight gain and food distribution. It is the first evidence for hole-nesting birds, where it was assumed that the nestling closest to the entrance hole was fed first, that the apparent choice of feeding positions by parents could be a way of controlling sibling competition and thereby also taking partial control over the outcome of parente-offspring conflict. (c) 2007 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.

Parasite- and predator-induced maternal effects in the great tit (Parus major)

Both predators and parasites can elicit behavioral and physiological responses in prey and hosts, respectively. These responses may involve the reallocation of resources and may thus limit each other. We investigated the effects of concurrent pre-laying exposure of great tit females (Parus major) to both a simulated predation risk and a nest-based ectoparasite, the hen flea (Ceratophyllus gallinae), on nestling growth and development. We manipulated perceived predation risk using models and vocalizations of sparrowhawks (Accipiter nisus). At the start of incubation, we swapped whole clutches between treated and untreated nests to separate pre-laying maternal effects from posthatching effects. Since costs and benefits of maternal responses to parasites need to be assessed under parasite pressure, we infested half of the rearing nests with hen fleas. Parasites had negative effects on mass gain and wing growth, both via maternal effects and via direct exposure of nestlings, whereas maternal predation risk had no significant effect. The interaction between predator and parasite treatments was not significant and, thus, suggests the absence of a trade-off between the 2 stressors operating at the level of maternal effects. Alternatively, the complexity of the design, despite a relatively large sample size, may have limited the power for detection of this expected trade-off.

Parent – environmental interactions shape acoustic signatures in tree swallows: a cross-fostering experiment.

Acoustic signatures are common components of avian vocalizations and are important for the recognition of individuals and groups. The proximate mechanisms by which these signatures develop are poorly understood, however. The development of acoustic signatures in nestling birds is of particular interest, because high rates of extra-pair paternity or egg dumping can cause nestlings to be unrelated to at least one of the adults that are caring for them. In such cases, nestlings might conceal their genetic origins, by developing acoustic signatures through environmental rather than genetic mechanisms. In a cross-fostering experiment with tree swallows Tachycineta bicolor, we investigated whether brood signatures of nestlings that were about to fledge were attributable to their genetic/maternal origins or to their rearing environment. We found that the calls of cross-fostered nestlings did not vary based on their genetic/maternal origin, but did show some variation based on their rearing environment. Control nestlings that were not swapped, however, showed stronger brood signatures than either experimental group, suggesting that acoustic signatures develop through an interaction between rearing environment and genetic/maternal effects.

Sex ratio adjustment in relation to paternal attractiveness in a wild bird population.

When the relative fitness of sons and daughters differs, sex-allocation theory predicts that it would be adaptive for individuals to adjust their investment in different sexes of offspring. Sex ratio adjustment by females in response to the sexual attractiveness of their mate would be an example of this. In vertebrates the existence of this form of sex ratio adjustment is controversial and may be confounded with sex-biased mortality, particularly in sexually size-dimorphic species. Here we use PCR amplification of a conserved W-chromosome-linked gene to show that the sex ratio within broods of a natural population of sexually size-monomorphic collared flycatchers Ficedula albicollis is related to the size of their father's forehead patch, a heritable secondary sexual character implicated in female choice. Experimental manipulations of paternal investment, which influence the size of his character in future breeding attempts, result in corresponding changes in the sex ratio of offspring born to males in those breeding attempts. In contrast, manipulations of maternal investment have no effect on future sex ratios, and there is no relationship between variables predicting the reproductive value of the brood and nestling sex ratio. Analysis of recruitment of offspring reveals similar patterns of sex ratio bias. The results suggest that female collared flycatchers be able to adjust the sex ratio of eggs ovulated in response to the phenotype of their mate. This finding is most consistent with "genetic quality" models of sexual selection.

Maternal effort mediates the prevalence of trypanosomes in the offspring of a passerine bird.

The relationships between parental effort, offspring growth, and offspring blood parasitemias are poorly known. We examined the effect of parental effort on offspring size and prevalence of trypanosomes in peripheral blood of nestling Pied Flycatchers Ficedula hypoleuca aged 13 days. Trypanosome infections were likely to be shared by siblings, indicating the role of a common environment and/or shared genes in the susceptibility to infection. Broods infected by trypanosomes had reduced growth, but this was due to decreased parental, especially maternal, energy expenditure in broods with nestlings infected by trypanosomes. There was no association between parental infection with trypanosomes and both their energy expenditure and the infection of their broods. Under stressful conditions caused by low maternal energy expenditure, the immune response of nestlings during growth was probably impaired, in a way analogous to the relapses of blood parasitemias with reproductive effort in breeding animals.

Biología reproductiva de Polioptila lembeyei (Aves: Polioptilidae) en la Reserva Ecológica Siboney-Juticí, Santiago de Cuba, Cuba

Se estudió la biología reproductiva de Polioptila lembeyei en la Reserva Ecológica Siboney-Juticí, Santiago de Cuba, Cuba durante los años 2006 y 2007 en seis formaciones vegetales. Se describieron aspectos de su reproducción en términos de cronología reproductiva, tamaño de puesta, duración del período de incubación, permanencia de los polluelos en el nido, morfometría de nidos y huevos, y caracterización del sitio de nidificación en cuanto a la altura de los nidos y especie y altura de las plantas utilizadas como sitio de nidificación. Se localizaron 89 nidos durante las dos temporadas reproductivas, 43 en el año 2006 y 46 en el 2007. El período reproductivo se extendió desde finales de marzo hasta julio, abarcando 129 días en el año 2006 y 122 días durante el año 2007. Las nidadas tuvieron una duración de 36–56 días (construcción 8,6 ± 2,8 días, puesta 8,6 ± 2,7 días, incubación de 14,0 ± 1,2 días y permanencia de los pichones en el nido 14,5 ± 1,0 días). De los 45 nidos examinados el tamaño de puesta modal fue de tres huevos (88,9 %), encontrándose también nidadas de dos (6,7 %) y cuatro huevos (4,4 %). De 38 nidos con huevos para ambas temporadas, 15 nidos produjeron pichones (32 pichones en el 2006 y 20 pichones en el 2007) y solo tres nidos durante el 2006 (37,5 %) lograron producir volantones, los cuales salieron con éxito del nido. La planta más utilizada como sitio de nidificación fue Acacia macracantha (80 % de los nidos detectados), aunque también se hallaron nidos en otras ocho especies de plantas. Las alturas de ubicación del nido fue de 2,7 ± 1,5 m (n = 82; rango 0,3–6,4 m) y la distancia del nido al dosel de la planta utilizada como sustrato fue de 1,1 ± 0,9 m (n = 80; rango 0,1–5,4 m).

Chic chicks: the evolution of chick ornamentation in rails

Competition over access to food has led to the evolution of a variety of exaggerated visual and vocal displays in altricial nestling birds. Precocial chicks that are fed by their parents also vary widely in appearance ranging from those with inconspicuous coloration to those with brightly colored bills, fleshy parts, and plumes. These ornaments are lost by the end of the period of parental dependence, suggesting they function in competition over parental care. We use a comparative approach to evaluate which ecological or life-history variables may have favored the evolution of conspicuous ornamentation in precocial chicks. We compiled data on chick morphology, ecology, and social organization of species in the Family Rallidae, a group with highly variable downy chicks. Chick ornamentation in the form of brightly colored bills, fleshy patches, or plumes is observed in 36 of 97 species for which downy chicks are described. Phylogenetic reconstructions suggest that nonornamentation is the ancestral state. Chick ornamentation has evolved multiple times within the Rallidae and is significantly associated with large clutch sizes and polygamous mating systems. Chick ornamentation was also weakly associated with adult ornamentation and adult dimorphism. We argue that these results support the hypothesis that lineages with higher levels of sibling competition are more likely to evolve ornamented chicks.