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Wednesday, 30 April 2014

Ecology and Evolution : Bird-related papers with abstracts from April 2014 Issue (Volume 4; Issue 8)

Ecology and Evolution

Cover image for Vol. 4 Issue 8

April 2014

Volume 4Issue 8
Pages i–iii, 1199–1503

Selected bird-related papers with abstracts.

Color expression in experimentally regrown feathers of an overwintering migratory bird: implications for signaling and seasonal interactions (pages 1222–1232)
Christopher M. Tonra, Kristen L. D. Marini, Peter P. Marra, Ryan R. Germain, Rebecca L. Holberton and Matthew W. Reudink
Article first published online: 11 MAR 2014 | DOI: 10.1002/ece3.994
Thumbnail image of graphical abstract
We examined the production of colorful feathers known to play a role in sexual selection in a migratory bird while on its tropical wintering grounds. Regardless of habitat and physiological condition, adult males experienced a reduction in the color quality in replaced feathers. Our findings illustrate how visual signals can be limited by the ability of individuals to maintain their quality throughout the year, and for migratory animals, across multiple locations.

Plumage coloration in birds plays a critical role in communication and can be under selection throughout the annual cycle as a sexual and social signal. However, for migratory birds, little is known about the acquisition and maintenance of colorful plumage during the nonbreeding period. Winter habitat could influence the quality of colorful plumage, ultimately carrying over to influence sexual selection and social interactions during the breeding period. In addition to the annual growth of colorful feathers, feather loss from agonistic interactions or predator avoidance could require birds to replace colorful feathers in winter or experience plumage degradation. We hypothesized that conditions on the wintering grounds of migratory birds influence the quality of colorful plumage. We predicted that the quality of American redstart (Setophaga ruticilla) tail feathers regrown after experimental removal in Jamaica, West Indies, would be positively associated with habitat quality, body condition, and testosterone. Both yearling (SY) and adult (ASY) males regrew feathers with lower red chroma, suggesting reduced carotenoid content. While we did not observe a change in hue in ASY males, SY males shifted from yellow to orange plumage resembling experimentally regrown ASY feathers. We did not observe any effects of habitat, testosterone, or mass change. Our results demonstrate that redstarts are limited in their ability to adequately replace colorful plumage, regardless of habitat, in winter. Thus, feather loss on the nonbreeding grounds can affect social signals, potentially negatively carrying over to the breeding period.

Ján Krištofík, Alžbeta Darolová, Juraj Majtan, Monika Okuliarová, Michal Zeman and Herbert Hoi
Article first published online: 18 MAR 2014 | DOI: 10.1002/ece3.1034
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Males mate faster when they sing more complex. Female egg investment is related to male song performance in several aspects.

Maternal investment can play an important role for offspring fitness, especially in birds, as females have to provide their eggs with all the necessary nutrients for the development of the embryo. It is known that this type of maternal investment can be influenced by the quality of the male partner. In this study, we first verify that male song is important in the mate choice of female Eurasian reed warblers, as males mate faster when their singing is more complex. Furthermore, female egg investment varies in relation to male song characteristics. Interestingly, clutch size, egg weight, or size, which can be considered as an high-cost investment, is not influenced by male song characteristics, whereas comparably low-cost investment types like investment into diverse egg components are adjusted to male song characteristics. In line with this, our results suggest that female allocation rules depend on investment type as well as song characteristics. For example, egg white lysozyme is positively correlated with male song complexity. In contrast, a negative correlation exists between-song speed and syllable repetitiveness and egg yolk weight as well as egg yolk testosterone concentration. Thus, our results suggest that female egg investment is related to male song performance in several aspects, but female investment patterns regarding various egg compounds are not simply correlated.

László Z. Garamszegi, Jakob C. Mueller, Gábor Markó, Eszter Szász, Sándor Zsebők, Gábor Herczeg, Marcel Eens and János Török
Article first published online: 24 MAR 2014 | DOI: 10.1002/ece3.1041
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Understanding the genetic architecture of behaviors is crucial for making evolutionary implications especially in wild animals. Here, in a Hungarian population of the collared flycatcher, we investigate how males with distinct DRD4genotypes differ in the consistent elements of their courtship behavior. We found that “AC” heterozygote individuals at the SNP764 take lower risk than the most common “AA” homozygotes (the “CC” homozygotes were not represented in this subsample of males).

There is increasing evidence that the genetic architecture of exploration behavior includes the dopamine receptor D4 gene (DRD4). Such a link implies that the within-individual consistency in the same behavior has a genetic basis. Behavioral consistency is also prevalent in the form of between-individual correlation of functionally different behaviors; thus, the relationship between DRD4 polymorphism and exploration may also be manifested for other behaviors. Here, in a Hungarian population of the collared flycatcher, Ficedula albicollis, we investigate how males with distinct DRD4 genotypes differ in the consistent elements of their behavioral displays during the courtship period. In completely natural conditions, we assayed novelty avoidance, aggression and risk-taking, traits that were previously shown repeatable over time and correlate with each other, suggesting that they could have a common mechanistic basis. We identified two single-nucleotide polymorphisms (SNP554 and SNP764) in the exon 3 of the DRD4 gene by sequencing a subsample, then we screened 202 individuals of both sexes for these SNPs. Focusing on the genotypic variation in courting males, we found that “AC” heterozygote individuals at the SNP764 take lower risk than the most common “AA” homozygotes (the “CC” homozygotes were not represented in our subsample of males). We also found a considerable effect size for the relationship between SNP554 polymorphism and novelty avoidance. Therefore, in addition to exploration, DRD4 polymorphisms may also be associated with the regulation of behaviors that may incur fear or stress. Moreover, polymorphisms at the two SNPs were not independent indicating a potential role for genetic constraints or another functional link, which may partially explain behavioral correlations.

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