Dataset Information

Hidden MHC genetic diversity in the Iberian ibex (Capra pyrenaica).

ABSTRACT: BACKGROUND:Defining hidden genetic diversity within species is of great significance when attempting to maintain the evolutionary potential of natural populations and conduct appropriate management. Our hypothesis is that isolated (and eventually small) wild animal populations hide unexpected genetic diversity due to their maintenance of ancient polymorphisms or introgressions. RESULTS:We tested this hypothesis using the Iberian ibex (Capra pyrenaica) as an example. Previous studies based on large sample sizes taken from its principal populations have revealed that the Iberian ibex has a remarkably small MHC DRB1 diversity (only six remnant alleles) as a result of recent population bottlenecks and a marked demographic decline that has led to the extinction of two recognized subspecies. Extending on the geographic range to include non-studied isolated Iberian ibex populations, we sequenced a new MHC DRB1 in what seemed three small isolated populations in Southern Spain (n?=?132). The findings indicate a higher genetic diversity than previously reported in this important gene. The newly discovered allele, MHC DRB1*7, is identical to one reported in the domestic goat C. aegagrus hircus. Whether or not this is the result of ancient polymorphisms maintained by balancing selection or, alternatively, introgressions from domestic goats through hybridization needs to be clarified in future studies. However, hybridization between Iberian ibex and domestic goats has been reported in Spain and the fact that the newly discovered allele is only present in one of the small isolated populations and not in the others suggests introgression. The new discovered allele is not expected to increase fitness in C. pyrenaica since it generates the same protein as the existing MHC DRB1*6. Analysis of a microsatellite locus (OLADRB1) near the new MHC DRB1*7 gene reveals a linkage disequilibrium between these two loci. The allele OLADRB1, 187 bp in length, was unambiguously linked to the MHC DRB1*7 allele. This enabled us to perform a DRB-STR matching method for the recently discovered MHC allele. CONCLUSIONS:This finding is critical for the conservation of the Iberian ibex since it directly affects the identification of the units of this species that should be managed and conserved separately (Evolutionarily Significant Units).

SUBMITTER: Angelone S

PROVIDER: S-EPMC5941765 | biostudies-literature | 2018 May

REPOSITORIES: biostudies-literature

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Hidden MHC genetic diversity in the Iberian ibex (Capra pyrenaica).

Angelone Samer S Jowers Michael J MJ Molinar Min Anna Rita AR Fandos Paulino P Prieto Paloma P Pasquetti Mario M Cano-Manuel Francisco Javier FJ Mentaberre Gregorio G Olvera Jorge Ramón López JRL Ráez-Bravo Arián A Espinosa José J Pérez Jesús M JM Soriguer Ramón C RC Rossi Luca L Granados José Enrique JE

BMC genetics 20180508 1

<h4>Background</h4>Defining hidden genetic diversity within species is of great significance when attempting to maintain the evolutionary potential of natural populations and conduct appropriate management. Our hypothesis is that isolated (and eventually small) wild animal populations hide unexpected genetic diversity due to their maintenance of ancient polymorphisms or introgressions.<h4>Results</h4>We tested this hypothesis using the Iberian ibex (Capra pyrenaica) as an example. Previous studi ...[more]

PMID: 29739323

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Project description:BackgroundSarcoptic mange is one of the main parasitic diseases affecting the Iberian ibex Capra pyrenaica. Scabietic animals suffer a decline in body condition and reproductive fitness and in severe cases may die. Although several previous studies of the pathology of this disease and the physiological changes it produces in ibex have been carried out in recent years, our knowledge of the relationship between Sarcoptes scabiei and other ectoparasites of this host is still limited.MethodsWe analysed 430 Iberian ibex skin samples. Ectoparasites were removed, counted and identified. Mite (S. scabiei) numbers were obtained after digesting the skin samples in a 5% KOH solution. We modelled mite numbers in terms of host sex and age, site, year, season and the presence of other ectoparasites such as ticks and lice using generalized linear mixed models (GLMMs) and ectoparasite co-occurrence patterns using two different models: the probabilistic model species co-occurrence and the generalized linear latent variable model (GLLVM).ResultsThe ectoparasite community was mainly composed of S. scabiei, six ticks (Haemaphysalis sulcata, Haemaphysalis punctata, Rhipicephalus bursa, Rhipicephalus turanicus, Dermacentor marginatus and Ixodes ricinus) and two lice (Bovicola crassipes and Linognathus stenopsis). Adult male ibex harboured more mites than females. Mite numbers varied greatly spatially and seasonally and increased with the presence of other parasites. Some positive co-occurrence relationships between pairs of different ectoparasites were observed, particularly between ticks. The presence of S. scabiei negatively affected lice and H. sulcata numbers.ConclusionsSarcoptic mange has spread above all in ibex populations in and around the Mediterranean Basin, where it is now found in almost a third of its host's range. Mite numbers varied seasonally and spatially and were higher in male hosts. The presence of S. scabiei had a negative effect on lice numbers but favoured the presence of ticks.

Project description:Sarcoptic mange has been identified as the most significant infectious disease affecting the Iberian ibex (Capra pyrenaica). Despite several studies on the effects of mange on ibex, the pathological and clinical picture derived from sarcoptic mange infestation is still poorly understood. To further knowledge of sarcoptic mange pathology, samples from ibex were evaluated from histological, microbiological and serological perspectives.Samples of skin, non-dermal tissues and blood were collected from 54 ibex (25 experimentally infected, 15 naturally infected and 14 healthy). Skin biopsies were examined at different stages of the disease for quantitative cellular, structural and vascular changes. Sixteen different non-dermal tissues of each ibex were taken for histological study. Acetylcholinesterase and serum amyloid A protein levels were evaluated from blood samples from ibex with different lesional grade. Samples of mangy skin, suppurative lesions and internal organs were characterized microbiologically by culture. Bacterial colonies were identified by a desorption/ionization time-of-flight mass spectrometry system (MALDI TOF/TOF).The histological study of the skin lesions revealed serious acanthosis, hyperkeratosis, rete ridges, spongiotic oedema, serocellular and eosinophilic crusts, exocytosis foci, apoptotic cells and sebaceous gland hyperplasia. The cellular response in the dermis was consistent with type I and type IV hypersensitivity responses. The most prominent histological findings in non-dermal tissues were lymphoid hyperplasia, leukocytosis, congestion and the presence of amyloid deposits. The increase in serum concentrations of acetylcholinesterase and amyloid A protein correlated positively with the establishment of the inflammatory response in mangy skin and the presence of systemic amyloidosis. A wide variety of bacterial agents were isolated and the simultaneous presence of these in mangy skin, lymph nodes and internal organs such as lungs, liver, spleen and kidney was compatible with a septicaemic pattern of infection.The alteration of biomarkers of inflammation and its implication in the pathogenesis of the disease and development of lesions in non-dermal tissues and septicaemic processes are serious conditioners for the survival of the mangy ibex. This severe clinical picture could be an important factor when considering the decision to eliminate animals that exceed a certain disease threshold from a population.

Dataset Information

Hidden MHC genetic diversity in the Iberian ibex (Capra pyrenaica).

Publications

Hidden MHC genetic diversity in the Iberian ibex (Capra pyrenaica).

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