Article

Retracted: MHC diversity and differential exposure to pathogens in kestrels (Aves: Falconidae )

Estación Biológica de Doñana (CSIC), Pabellón de Perú, Avda. Maria Luisa s/n, 41013, Sevilla, Spain.
Molecular Ecology (Impact Factor: 6.49). 02/2010; 19(4):691-705. DOI: 10.1111/j.1365-294X.2009.04507.x
Source: PubMed

ABSTRACT Pathogen diversity is thought to drive major histocompatibility complex (MHC) polymorphism given that host's immune repertories are dependent on antigen recognition capabilities. Here, we surveyed an extensive community of pathogens (n = 35 taxa) and MHC diversity in mainland versus island subspecies of the Eurasian kestrel Falco tinnunculus and in a sympatric mainland population of the phylogenetically related lesser kestrel Falco naumanni. Insular subspecies are commonly exposed to impoverished pathogen communities whilst different species' ecologies and contrasting life-history traits may lead to different levels of pathogen exposure. Although specific host traits may explain differential particular infections, overall pathogen diversity, richness and prevalence were higher in the truly cosmopolitan, euriphagous and long-distance disperser Eurasian kestrel than in the estenophagous, steppe-specialist, philopatric but long-distance migratory lesser kestrel. Accordingly, the continental population of Eurasian kestrels displayed a higher number (64 vs. 49) as well as more divergent alleles at both MHC class I and class II loci. Detailed analyses of amino acid diversity revealed that significant differences between both species were exclusive to those functionally important codons comprising the antigen binding sites. The lowest pathogen burdens and the smallest but still quite divergent set of MHC alleles (n = 16) were found in island Eurasian kestrels, where the rates of allele fixation at MHC loci seem to have occurred faster than at neutral markers. The results presented in this study would therefore support the role of pathogen diversity and abundance in shaping patterns of genetic variation at evolutionary relevant MHC genes.

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    ABSTRACT: Abstracts Background Rhesus macaques living in western Sichuan, China, have been separated into several isolated populations due to habitat fragmentation. Previous studies based on the neutral or nearly neutral markers (mitochondrial DNA or microsatellites) showed high levels of genetic diversity and moderate genetic differentiation in the Sichuan rhesus macaques. Variation at the major histocompatibility complex (MHC) loci is widely accepted as being maintained by balancing selection, even with a low level of neutral variability in some species. However, in small and isolated or bottlenecked populations, balancing selection may be overwhelmed by genetic drift. To estimate microevolutionary forces acting on the isolated rhesus macaque populations, we examined genetic variation at Mhc-DQB1 loci in 119 wild rhesus macaques from five geographically isolated populations in western Sichuan, China, and compared the levels of MHC variation and differentiation among populations with that previously observed at neutral microsatellite markers. Results 23 Mamu-DQB1 alleles were identified in 119 rhesus macaques in western Sichuan, China. These macaques exhibited relatively high levels of genetic diversity at Mamu-DQB1. The Hanyuan population presented the highest genetic variation, whereas the Heishui population was the lowest. Analysis of molecular variance (AMOVA) and pairwise FST values showed moderate genetic differentiation occurring among the five populations at the Mhc-DQB1 locus. Non-synonymous substitutions occurred at a higher frequency than synonymous substitutions in the peptide binding region. Levels of MHC variation within rhesus macaque populations are concordant with microsatellite variation. On the phylogenetic tree for the rhesus and crab-eating macaques, extensive allele or allelic lineage sharing is observed betweenthe two species. Conclusions Phylogenetic analyses confirm the apparent trans-species model of evolution of the Mhc-DQB1 genes in these macaques. Balancing selection plays an important role in sharing allelic lineages between species, but genetic drift may share balancing selection dominance to maintain MHC diversity. Great divergence at neutral or adaptive markers showed that moderate genetic differentiation had occurred in rhesus macaque populations in western Sichuan, China, due to the habitat fragmentation caused by long-term geographic barriers and human activity. The Heishui population should be paid more attention for its lowest level of genetic diversity and relatively great divergence from others.
    BMC Evolutionary Biology 06/2014; 14(1):130. DOI:10.1186/1471-2148-14-130 · 3.41 Impact Factor
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    • "Thus, island life apparently leads to an immunological reorganization ; however, little can be concluded regarding links between this reorganization and disease susceptibility or other aspects of avian biology (Matson 2006). Other studies focused on single island-continent pairs (e.g., Egyptian vulture, Neophron percnopterus [Gangoso et al. 2009] and Eurasian kestrel, Falco tinnunculus [Alcaide et al. 2010]) did reveal differences in terms of both immune and disease parameters. Thus, data support the notion that the evolutionary divergence associated with island life relates to the physiology of self-maintenance in birds. "
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    ABSTRACT: Abstract Island organisms face a range of extrinsic threats to their characteristically small populations. Certain biological differences between island and continental organisms have the potential to exacerbate these threats. Understanding how island birds differ from their continental relatives may provide insight into population viability and serve as a predictive tool for conservation efforts. We compared an eastern bluebird population in Ohio with a threatened population in Bermuda in terms of the birds' development, morphology, immunology, and reproduction. These comparisons revealed that island nestlings had shorter wings and island adults had longer wings than their continental analogs. Island nestlings also had shorter tarsi than continental nestlings at day 8 posthatch, but this difference was absent at day 15 and in adults. Adults weighed less in Bermuda than in Ohio, and both nestlings and adults in Bermuda exhibited higher levels of two immunological indexes (concentrations of an acute-phase protein and titers of nonspecific antibodies). Clutch sizes and hatch rates did not differ between the island and continental populations; however, as the breeding season progressed, brood sizes declined in Bermuda, whereas no such decline occurred in Ohio. Despite these differences and differences in nestling development, island and continental parents fed their nestlings at equal rates. Overall, our results suggest that the Bermuda phenotype may be adjusted to certain aspects of the island environment but not to others. Efforts to conserve the bluebirds of Bermuda may be improved by focusing on the intraseasonal patterns in nestling mortality and, more generally, the survival probabilities of different age classes.
    Physiological and Biochemical Zoology 01/2014; 87(1):172-82. DOI:10.1086/670811 · 2.05 Impact Factor
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    • "Until recently these islands had been largely ignored by evolutionary biologists in comparison to the attention given to other archipelagos such as Hawaii or Galapagos (Fernández-Palacios et al., 2011; Illera et al. 2012). Consequently, their avian haemosporidian communities still remain relatively poorly studied (Foronda et al., 2004; Hille et al., 2007; Illera et al., 2008; Alcaide et al., 2010; Hellgren et al., 2011; Spurgin et al., 2012). This paucity of research does not reflect the great interest shown to the Macaronesian avifauna which includes both locally evolved ancient endemics and recent colonizer species with broader geographical ranges outside the islands (Illera et al., 2012), and provides an excellent rage of different host models for the analysis of parasitism on oceanic islands. "
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    ABSTRACT: AimThe study of parasite biogeography on islands is important for our understanding of both the processes involved in the evolution of parasite assemblages worldwide and the ecology and conservation of insular communities. By studying the haemosporidian blood parasites of a bird that has recently colonized a number of oceanic islands, we were able to test hypotheses relating to the processes of parasite colonization and community assembly prior to the permanent isolation of host species on islands. LocationThe Atlantic Ocean archipelagos of Madeira and the Canary Islands. Methods We used cytochrome bDNA sequences to determine the prevalence and richness of parasites of the genera Haemoproteus, Plasmodium and Leucocytozoon in blackcaps, Sylvia atricapilla, a widespread passerine that colonized these archipelagos during the Last Glacial Maximum. We compared insular blackcap parasite assemblages with those observed in 37 blackcap populations sampled on mainland Europe. ResultsThe insular parasite assemblage was impoverished, containing c.10% of the parasites found on the continent. None of the parasites observed on the islands were blackcap specific. Some of the observed parasites appear to have switched from blackcaps to other Macaronesian host species, whereas others were of Afrotropical origin and were acquired after blackcaps colonized the islands. The prevalence of parasites in the island populations of blackcaps was lower than in mainland blackcap populations and parasite richness decreased with increasing island distance to the continent. Main conclusionsMacaronesian blackcaps do not face the strong parasite load encountered by their mainland counterparts despite the fact that blackcap migration from the continent may directly transport mainland blackcap parasites to the islands. This supports the idea that normal mainland host-parasite associations are compromised on islands and that parasite island syndromes (low richness, frequent host-switching and reduced specialization) evolve even before insular host populations become completely isolated from their mainland counterparts.
    Global Ecology and Biogeography 12/2013; 22(12):1272-1281. DOI:10.1111/geb.12084 · 7.24 Impact Factor
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