PARASITE BURDEN AND CONSTITUTION OF MAJOR HISTOCOMPATIBILITY COMPLEX IN THE MALAGASY MOUSE LEMUR, MICROCEBUS MURINUS
Article first published online: 9 MAY 2007
Volume 59, Issue 2, pages 439–450, February 2005
How to Cite
Schad, J., Ganzhorn, J. U. and Sommer, S. (2005), PARASITE BURDEN AND CONSTITUTION OF MAJOR HISTOCOMPATIBILITY COMPLEX IN THE MALAGASY MOUSE LEMUR, MICROCEBUS MURINUS. Evolution, 59: 439–450. doi: 10.1111/j.0014-3820.2005.tb01002.x
- Issue published online: 9 MAY 2007
- Article first published online: 9 MAY 2007
- Received May 18, 2004. Accepted November 10, 2004.
- major histocompatibility complex;
- Microcebus murinus;
- parasite load.
Abstract We investigated the importance of the major histocompatibility complex (MHC) constitution on the parasite burden of free-ranging mouse lemurs (Microcebus murinus) in four littoral forest fragments in southeastern Madagascar. Fourteen different MHC class II DRB-exon 2 alleles were found in 228 individuals with high levels of sequence divergence between alleles. More nonsynonymous than synonymous substitutions in the functional important antigen recognition and binding sites indicated selection processes maintaining MHC polymorphism. Animals from the four forest fragments differed in their infection status (being infected or not), in the number of different nematode morphotypes per individual (NNI) as well as in the fecal egg counts (FEC) values. Heterozygosity in general was uncorrelated with any of these measures of infection. However, a positive relationship was found between specific alleles and parasite load. Whereas the common allele Mimu-DRB*1 was more frequently found in infected individuals and in individuals with high NNI and FEC values (high parasite load), the rare alleles Mimu-DRB*6 and 10 were more prevalent in uninfected individuals and in individuals with low NNI and FEC values (low parasite load). These three alleles associated with parasite load had unique amino acid motifs in the antigen binding sites. This distinguished them from the remaining 11 Mimu-DRB alleles. Our results support the hypothesis that MHC polymorphism in M. murinus is maintained through pathogen-driven selection acting by frequency-dependent selection. This is the first study of the association of MHC variation and parasite burden in a free-ranging primate.