Haemosporidian parasites of a European passerine wintering in South Asia: diversity, mixed infections and effect on host condition.

We studied haemosporidian parasites in the scarlet rosefinch Carpodacus erythrinus in a small isolated semicolony during an eight-year period using molecular methods of parasite detection. The scarlet rosefinch is an interesting model of parasite host species. It winters in South Asia which represents a rare exception among European passerines. Males express yellow to red carotenoid-based plumage ornament which is a good predictor of male reproductive success. In 240 blood samples originating from 199 adult individuals, the total parasite prevalence reached 60%. Prevalence varied among years from 36 to 81% in Haemoproteus, 8 to 22% in Plasmodium, and 0 to 14% in Leucocytozoon. Twenty parasite lineages were detected (Haemoproteus: 5 lineages, Plasmodium: 10 lineages, and Leucocytozoon: 5 lineages). Among them, the Haemoproteus ROFI2 lineage, which is a host-specific parasite lineage of the scarlet rosefinch, was the most frequently found. Parasite lineages showed varying degree of lineage specificity. While Haemoproteus lineages detected in the scarlet rosefinch have relatively narrow host breadth restricted mainly to Fringillidae family, Leucocytozoon and Plasmodium lineages generally showed wider host range. The presence of some parasite lineages hitherto detected in sedentary European passerines (SISKIN1, CCF3, BT2) or in Culicoides biting midges at the same locality (ROFI1) suggest local transmission. On the contrary, lineages LK05 and FANTAIL1 that were previously reported exclusively from Asian hosts imply parasite transmission at the scarlet rosefinch wintering sites in South Asia. Mixed infections were found in 17% of infected samples and comprised mainly the most frequent lineages. The pattern of concomitant infections seemed to be rather random and matched expected levels based on lineage frequencies. Between-year comparisons revealed that in a majority of the repeatedly captured individual hosts the infection status remained unchanged (individuals stayed uninfected or possessed the same parasite lineages). However, 16 gains and 8 losses of lineages were also reported. We have not found any effect of haemosporidians on male carotenoid ornament expression or host body mass.

Extra-pair fertilizations contribute to selection on secondary male ornamentation in a socially monogamous passerine.

Despite considerable research effort, it remains unclear whether extra-pair fertilizations (EPF) drive the evolution of male secondary ornamentation in socially monogamous systems. In this study, we test the hypothesis that EPF contribute to the evolution or maintenance of male feather ornamentation in a sexually dichromatic passerine, the Scarlet Rosefinch, Carpodacus erythrinus. We show that the colouration of ornamental breast feathers is a good predictor of basic sources of variation in male annual reproductive output in rosefinches and that the annual realized reproductive success of males is positively associated with measures of ornamental colouration only when gains and losses because of EPF are considered. The results indicate that EPF in rosefinches may rely on absolute (good genes) rather than self referential (genetic complementarity) criteria of mate choice. Our study corroborates the potentially important role of EPF in the evolution and/or maintenance of elaborate male ornaments in socially monogamous taxa.

Identification of the first Toll-like receptor gene in passerine birds: TLR4 orthologue in zebra finch (Taeniopygia guttata).

Toll-like receptors (TLRs) are the basic components of the vertebrate pathogen recognition system. Despite uniform general structure, remarkable variability in domain composition can be found in individual TLRs among species. Knowledge of interspecific differences is of particular importance to our understanding of selective pressures on TLRs. Currently, most TLRs are characterized only in a limited number of model species, including domestic chicken as a universal avian model. Here, we describe structure and expression pattern of TLR4 in zebra finch, a widely used passerine model species. The tgTlr4 gene consists of three exons (204, 167 and 3033-3043 bp) that are transcribed into messenger RNA with a relatively long 3'-untranslated region (788 bp). Predicted protein is composed of 842 amino acids (aas) forming extracellular domain with nine leucine-rich repeat (LRR) motives flanked at the carboxy-terminal end by leucine-rich repeat carboxy-terminal domain, transmembrane domain and cytoplasmic toll/interleukin-1 receptor domain. The overall structure is similar to other known TLR4 molecules with 32%-49% aa identity to various mammals and 74% to chicken. Although the position of most of the domains in zebra finch TLR4 resembles their position in chicken, there is one extra LRR at the aa position 207-229 in tgTLR4 and one LRR known in chTLR4 is missing. The gene is highly expressed in the bone marrow and in the spleen, intermediately in the gut and low expression was found in the liver and lungs. For the first time in birds, expression of tgTLR4 in peritoneal macrophages was found to be enhanced by the Escherichia coli lipopolysaccharide treatment.