Costs and benefits of female-biased natal philopatry in the common goldeneye

Sex-biased natal dispersal in long-lived species may resultin interactions between parents and mature young of the philopatricsex. To investigate the evolutionary basis of natal philopatryin a noncooperative species, the common goldeneye Bucephalaclangula, we studied possible costs and benefits of simultaneousbreeding of females and philopatric daughters. We did not find any fitness consequences of a daughter's breeding on their mother'sbreeding in terms of nest-site selection, body weight, clutchsize, hatching date, or hatching success. Our results, therefore,did not support the assumption of the local resource competitionhypothesis, that the natally philopatric sex should be morecostly to a breeding parent. As possible benefits for daughters returning to their natal area, we tested inheritance of nestsites from mothers and explored whether daughters utilize thepresence of their mother by parasitically sneaking into hermother's nest. Daughters' nest-site selection was not associatedwith the presence of their mothers. A comparison between daughtersand control females revealed that daughters chose their nestsite closer to their natal nest than expected by nest-siteavailability alone. Daughters could not expect to inherit anest site from their mother, and we did not find other indicationsof cooperation between relatives either. The mother's clutchsize did not increase in the year breeding with the daughter, indicating daughters do not parasitize their mother's nest.We suggest that benefits such as decreased nest predation riskassociated with nesting close to the natal nest site may beimportant in the natal philopatric behavior of the species.     

Brood rearing costs affect future reproduction in the precocial common goldeneye Bucephala clangula

Life-history theory assumes a trade-off between current reproductive effort and future reproductive success. There are a large number of studies demonstrating reproductive trade-offs in different animal taxa, particularly in birds. Most bird studies have focused on the costs of chick rearing in altricial species. These costs have been assumed to be low in precocial species, but this aspect has been little studied. We used long-term individual reproductive data from the common goldeneye Bucephala clangula , an iteroparous precocial duck with uniparental female care, to examine whether brood rearing carries costs that affect future reproductive performance. All females were experienced breeders, and possible differences in female quality were ruled out. We compared within-individual (between-year) changes in clutch size, hatching date and body mass between females that had reared a brood in the previous year and females that had not. It turned out that brood rearing involved a cost in terms of clutch size and hatching date the next year, but not in terms of body mass: females that had reared a brood in the previous year laid relatively smaller clutches and laid relatively later than females that had not reared a brood. Our results show that normal brood rearing in a precocial species involves costs that affect future reproduction.     

A mutation in the ProteosomalRegulatory Particle AAA-ATPase-3 in Arabidopsis impairs the light-specific hypocotyl elongation response elicited by a glutamate receptor agonist, BMAA

BMAA is a cycad-derived glutamate receptor agonist that causes a two- to three-fold increase in hypocotyl elongation on Arabidopsis seedlings grown in the light. To probe the role of plant glutamate receptors and their downstream mediators, we utilized a previously described genetic screen to identify a novel, BMAA insensitive morphology (bim) mutant, bim409. The normal BMAA-induced hypocotyl elongation response observed on wild-type seedlings grown in the light is impaired in the bim409 mutant. This BMAA-induced phenotype is light-specific, as the bim409 mutant exhibits normal hypocotyl elongation in etiolated (dark grown) plants (+ or − BMAA). The mutation in bim409 was identified to be in a gene encoding the Proteosomal Regulatory Particle AAA-ATPase-3 (RPT3). Possible roles of the proteosome in Glu-mediated signaling in plants is discussed. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Do parasitic common goldeneye Bucephala clangula females choose nests on the basis of host traits or nest site traits?

Conspecific brood parasitism (CBP) is an important alternative breeding strategy for gaining reproductive output in birds. While interactions between hosts and parasites and consequences of CBP to breeding success of both parties have been studied a lot, the roles of host characteristics and nest site characteristics in CBP have received less attention. We studied the relative importance of host‐related traits, such as female condition and breeding experience, and nest‐site‐related factors, such as overall nest site preference and occupation rate, in explaining the occurrence of CBP in a common goldeneye Bucephala clangula population. We used spatially and temporally extensive data sets, analysed the data with generalized linear mixed models that allowed us to account for the non‐independency of individual nesting attempts across females and nesting sites, and used an information theoretic approach in model selection and inference. About half of the nests were parasitized annually during the seven year study period. The occurrence of CBP decreased with advancement of the breeding season but late nests were also frequently parasitized. We found that the occurrence of CBP was better explained by nest‐site characteristics than host traits, implying that parasitic females target a given nest based on factors related to the nest site itself rather than on the host. Our results suggest that more attention should be paid to factors associated with nest site attractiveness and quality when studying laying decisions of parasites and the occurrence of CBP in general.     

Sid4: A secreted vertebrate immunoglobulin protein with roles in zebrafish embryogenesis

The small members of the immunoglobulin superfamily (IGSF) are a molecularly diverse group of proteins composed solely of immunoglobulin domains. They may be secreted or tethered to the cell mebrane via GPI linkages and are proposed to have important functions in vivo. However, very few small IGSFs have been functionally characterized. During an ongoing in situ hybridization analysis of expressed sequence tags in zebrafish we identified secreted immunoglobulin domain 4 (sid4), a gene encoding a soluble vertebrate protein composed solely of four immunoglobulin domains. Throughout development, sid4 is expressed in regions of the embryo undergoing active cell division and migration. Functional analysis using morpholino antisense oligonucleotides demonstrates that timing of gene expression is normal in morphants, but these embryos are smaller and exhibit defects in epiboly and patterning of axial and prechordal mesoderm. Analyses of chordin, pax2, krox20, and dlx2 expression in morphants demonstrate that early brain patterning is normal but later organization of hindbrain neurons and development of cranial neural crest are perturbed. Levels of apoptosis in morphants were normal prior to 90% epiboly, but were elevated after 10 h post-fertilization (hpf). Apoptosis does not account for early patterning defects of axial mesoderm, but likely contributes to overall reduction in embryo size. Phylogenetic analysis demonstrates that Sid4 is strikingly similar to the fibronectin binding Ig domains of Perlecan/HSPG2. Overall, our data demonstrate a fundamental role for sid4, possibly as a co-factor in extracellular matrix (ECM) interactions, in processes underlying tissue patterning and organogenesis in a vertebrate.     

Overexpression of frataxin in the mitochondria increases resistance to oxidative stress and extends lifespan in Drosophila

In Friedreich's ataxia, reduction of the mitochondria protein frataxin results in the accumulation of iron and reactive oxygen species, which leads to oxidative damage, neurodegeneration and a diminished lifespan. Recent studies propose that frataxin might play a role in the antioxidative process. Here we show that overexpression of Drosophila frataxin in the mitochondria of female transgenic animals increases antioxidant capability, resistance to oxidative stress insults, and longevity. This suggests that Drosophila frataxin may function to protect the mitochondria from oxidative stresses and the ensuing cellular damage.     

Do environmental conditions experienced in early life affect recruitment age and performance at first breeding in common goldeneye females?

Environmental conditions experienced early in life may have long‐term impacts on life history traits and reproductive performance. We investigated whether ambient temperature experienced during the first two to four weeks of life and weather severity during the first two winters affected recruitment age and relative timing of breeding in the year of recruitment in female common goldeneyes Bucephala clangula. Our sample consisted of 141 female recruits hatched in a study population in central Finland between 1985 and 2013 and captured later as breeders. About 56% of the recruited females bred for the first time when two years old (range 2–6 yr). Individuals facing colder ambient temperatures during the first two to four weeks posthatch or more severe winter conditions during the first two winters did not recruit at an older age. Nor did maternal characteristics, relative hatch date or nest site availability affect recruitment age. For females that recruited at two years old, the date of first breeding was usually late relative to the population mean that year (mean difference 6.9 d, range –7 to 21 d). Our results suggest developmental buffering enables female goldeneye ducklings to mitigate the impacts of adverse environmental conditions experienced during the first weeks of life, at least in terms of first breeding.