Novel insights on aquatic mammal MHC evolution: Evidence from manatee DQB diversity.
Dev Comp Immunol
; 132: 104398, 2022 07.
Article
em En
| MEDLINE
| ID: mdl-35307479
ABSTRACT
The low diversity in marine mammal major histocompatibility complex (MHC) appears to support the hypothesis of reduced pathogen selective pressure in aquatic systems compared to terrestrial environments. However, the lack of characterization of the aquatic and evolutionarily distant Sirenia precludes drawing more generalized conclusions. Therefore, we aimed to characterize the MHC DQB diversity of two manatee species and compare it with those reported for marine mammals. Our results identified 12 and 6 alleles in T. inunguis and T. manatus, respectively. Alleles show high rates of nonsynonymous substitutions, suggesting loci are evolving under positive selection. Among aquatic mammals, Pinnipeda DQB had smaller numbers of alleles, higher synonymous substitution rate, and a dN/dS ratio closer to 1, suggesting it may be evolving under more relaxed selection compared to fully aquatic mammals. This contradicts one of the predictions of the hypothesis that aquatic environments impose reduced pathogen pressure to mammalian immune system. These results suggest that the unique evolutionary trajectories of mammalian MHC may impose challenges in drawing ecoevolutionary conclusions from comparisons across distant vertebrate lineages.
Palavras-chave
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Trichechus
/
Complexo Principal de Histocompatibilidade
Limite:
Animals
Idioma:
En
Revista:
Dev Comp Immunol
Ano de publicação:
2022
Tipo de documento:
Article