Heritability of dispersal in the great reed warbler

Dispersal is commonly considered to be a condition‐dependent behaviour with no or low heritability. Here, we show that dispersal in the great reed warbler (Acrocephalus arundinaceus) has a high heritability. Analyses of capture–recapture data of male great reed warblers gathered from the species’ whole Swedish breeding range revealed a remarkable offspring–parent resemblance in dispersal behaviour (philopatry vs. inter‐population dispersal). Also, the degree of dispersal differed between cohorts, which shows that dispersal was partly conditionally dependent. The offspring to mid‐parent estimate of heritability was 0.50. In a previous study of the same data set of male offspring, we did not detect associations between dispersal and several relevant environmental, parental and offspring condition factors. Thus, our results indicate that variation in dispersal partly has a genetic basis in great reed warblers.     

Male‐biased gene flow across an avian hybrid zone: evidence from mitochondrial and microsatellite DNA

Mating pattern and gene flow were studied in the contact zone between two morphologically very similar Chiffchaff taxa (Phylloscopus collybita, P. brehmii) in SW France and northern Spain. Mating was assortative in brehmii, but not in collybita. Mixed matings were strongly asymmetric (excess of collybita male × brehmii female pairs), but did produce viable offspring in some cases. Sequence divergence of the mitochondrial cytochrome b gene was 4.6%. Haplotypes segregated significantly with phenotype (only five ‘mismatches’ among 94 individuals), demonstrating that mitochondrial gene flow was very restricted. The estimated proportion of F₁ hybrids in the reproductive population was significantly lower than expected under a closed population model, indicating strong selection against hybrids. Genetic typing of 101 individuals at four microsatellite loci also showed significant population differentiation, but nuclear gene flow was estimated to be 75 times higher than mitochondrial gene flow. This strong discrepancy is probably due to unisexual hybrid sterility (Haldane’s rule). Thus, there is a strong, but incomplete, reproductive barrier between these taxa.     

The Large-billed Reed Warbler Acrocephalus orinus revisited

The Large-billed Reed Warbler Acrocephalus orinus is known only from the type specimen, collected in Himachal Pradesh, India, in 1867. The specimen is poorly prepared, and it has been suggested that it could represent an isolated form of the Clamorous Reed Warbler A. stentoreus or an aberrant Blyth's Reed Warbler A. dumetorum . We tested the affinity of A. orinus by (1) re-examining the morphology of the type specimen and (2) amplifying and sequencing a portion of its mitochondrial cytochrome b gene. Both the morphological and the mitochondrial analyses showed the specimen to be similar to dumetorum , but distinct enough to qualify as a species of its own. Relative to dumetorum , it has a more rounded wing, longer bill, longer and more graduated tail with more pointed tail feathers, and larger claws. The divergence in mitochondrial DNA between orinus and dumetorum was 7.8%, well above the value expected between subspecies. A. orinus is smaller than any of the forms of A. stentoreus or the related Australian Reed Warbler A. australis . It has a somewhat longer first primary, more pointed tail feathers and paler, less robust feet and claws. DNA comparison places it in the clade of small unstreaked Acrocephalus warblers, and apart from the clade of large unstreaked warblers that contains stentoreus and australis .     

Stereoisomeric flavour compounds XLV: Structure analysis of 2-alkoxy-5-alkyl-tetrahydrofurans

The synthesis of several 2-alkoxy-5-alkyl-tetrahydrofurans is of interest in our investigations of structure–function relationships of chiral flavour compounds. For the preparation of the enantiomeric acetals the unambiguous configurational assignment of the cis and trans series of these compounds is indispensable. By means of crystalline acetal derivatives the absolute structure of a model compound in the cis and the trans configuration is revealed by X-ray measurement and correlated with the corresponding cis and trans configurated aroma compounds. The first complete structure elucidation of the class of 2-alkoxy-5-alkyltetrahydrofurans has been carried out.     

A peroxisome proliferator-activated receptor alpha/gamma dual agonist with a unique in vitro profile and potent glucose and lipid effects in rodent models of type 2 diabetes and dyslipidemia

LSN862 is a novel peroxisome proliferator-activated receptor (PPAR)alpha/gamma dual agonist with a unique in vitro profile that shows improvements on glucose and lipid levels in rodent models of type 2 diabetes and dyslipidemia. Data from in vitro binding, cotransfection, and cofactor recruitment assays characterize LSN862 as a high-affinity PPARgamma partial agonist with relatively less but significant PPARalpha agonist activity. Using these same assays, rosiglitazone was characterized as a high-affinity PPARgamma full agonist with no PPARalpha activity. When administered to Zucker diabetic fatty rats, LSN862 displayed significant glucose and triglyceride lowering and a significantly greater increase in adiponectin levels compared with rosiglitazone. Expression of genes involved in metabolic pathways in the liver and in two fat depots from compound-treated Zucker diabetic fatty rats was evaluated. Only LSN862 significantly elevated mRNA levels of pyruvate dehydrogenase kinase isozyme 4 and bifunctional enzyme in the liver and lipoprotein lipase in both fat depots. In contrast, both LSN862 and rosiglitazone decreased phosphoenol pyruvate carboxykinase in the liver and increased malic enzyme mRNA levels in the fat. In addition, LSN862 was examined in a second rodent model of type 2 diabetes, db/db mice. In this study, LSN862 demonstrated statistically better antidiabetic efficacy compared with rosiglitazone with an equivalent side effect profile. LSN862, rosiglitazone, and fenofibrate were each evaluated in the humanized apoA1 transgenic mouse. At the highest dose administered, LSN862 and fenofibrate reduced very low-density lipoprotein cholesterol, whereas, rosiglitazone increased very low-density lipoprotein cholesterol. LSN862, fenofibrate, and rosiglitazone produced maximal increases in high-density lipoprotein cholesterol of 65, 54, and 30%, respectively. These findings show that PPARgamma full agonist activity is not necessary to achieve potent and efficacious insulin-sensitizing benefits and demonstrate the therapeutic advantages of a PPARalpha/gamma dual agonist.     

Genetic differentiation and hybridization between greater and lesser spotted eagles (Accipitriformes:Aquila clanga, A. pomarina)

Greater and lesser spotted eagles (Aquila clanga, A. pomarina) are two closely related forest eagles overlapping in breeding range in east-central Europe. In recent years a number of mixed pairs have been observed, some of which fledged hybrid young. Here we use mitochondrial (control region) DNA sequences and AFLP markers to estimate genetic differentiation and possible gene flow between these species. In a sample of 83 individuals (61 pomarina, 20 clanga, 2 F1-hybrids) we found 30 mitochondrial haplotypes which, in a phylogenetic network, formed two distinct clusters differing on average by 3.0% sequence divergence. The two species were significantly differentiated both at the mitochondrial and nuclear (AFLP) genetic level. However, five individuals with pomarina phenotype possessed clanga-type mtDNA, suggesting occasional gene flow. Surprisingly, AFLP markers indicated that these mismatched birds (originating from Germany, E Poland and Latvia) were genetically intermediate between the samples of individuals in which mtDNA haplotype and phenotype agreed. This indicates that mismatched birds were either F1 or recent back-cross hybrids. Mitochondrial introgression was asymmetrical (no pomarina haplotype found in clanga so far), which may be due to assortative mating by size. Gene flow of nuclear markers was estimated to be about ten times stronger than for mtDNA, indicating a sex-bias in hybrid fertility in accordance with Haldanes rule. Hybridization between the two species may be more frequent and may occur much further west than hitherto assumed. This is supported by the recent discovery of a mixed pair producing at least one fledgling in NE Germany.     

A new PCR assay for simultaneous studies of Leucocytozoon, Plasmodium, and Haemoproteus from avian blood

Many bird species host several lineages of apicomplexan blood parasites (Protista spp., Haemosporida spp.), some of which are shared across different host species. To understand such complex systems, it is essential to consider the fact that different lineages, species, and families of parasites can occur in the same population, as well as in the same individual bird, and that these parasites may compete or interact with each other. In this study, we present a new polymerase chain reaction (PCR) protocol that, for the first time, enables simultaneous typing of species from the 3 most common avian blood parasite genera (Haemoproteus, Plasmodium, and Leucocytozoon). By combining the high detection rate of a nested PCR with another PCR step to separate species of Plasmodium and Haemoproteus from Leucocytozoon, this procedure provides an easy, rapid, and accurate method to separate and investigate these parasites within a blood sample. We have applied this method to bird species with known infections of Leucocytozoon spp., Plasmodium spp., and Haemoproteus spp. To obtain a higher number of parasite lineages and to test the repeatability of the method, we also applied it to blood samples from bluethroats (Luscinia svecica), for which we had no prior knowledge regarding the blood parasite infections. Although only a small number of different bird species were investigated (6 passerine species), we found 22 different parasite species lineages (4 Haemoproteus, 8 Plasmodium, and 10 Leucocytozoon).     

LINKAGE BETWEEN NUCLEAR AND MITOCHONDRIAL DNA SEQUENCES IN AVIAN MALARIA PARASITES: MULTIPLE CASES OF CRYPTIC SPECIATION?

Analyses of mitochondrial cytochrome b diversity among avian blood parasites of the genera Haemoproteus and Plasmodium suggest that there might be as many lineages of parasites as there are species of birds. This is in sharp contrast to the approximately 175 parasite species described by traditional methods based on morphology using light microscopy. Until now it has not been clear to what extent parasite mitochondrial DNA lineage diversity reflects intra- or interspecific variation. We have sequenced part of a fast-evolving nuclear gene, dihydrofolate reductase-thymidylate synthase (DHFR-TS), and demonstrate that most of the parasite mitochondrial DNA lineages are associated with unique gene copies at this locus. Although these parasite lineages sometimes coexist in the same host individual, they apparently do not recombine and could therefore be considered as functionally distinct evolutionary entities, with independent evolutionary potential. Studies examining parasite virulence and host immune systems must consider this remarkable diversity of avian malaria parasites.