Data from: MHC-similarity and sexual selection: different doesn't always mean attractive

  • Clelia Gasparini (Creator)
  • L. Congiu (Creator)
  • Andrea Pilastro (Creator)



dataset: Please see paper for details on data collection, experimental design and data analysis.

aligned sequences: MHC aligned sequences.

MHC: Raw data (1st sheet) and band sharing-similarity (2nd sheet).

Microsatellites data: raw data (1st sheet) and genalex summary-similarity (2nd sheet).

Females that mate multiply have the possibility to exert postcopulatory choice and select more compatible sperm to fertilize eggs. Prior work suggests that dissimilarity in major histocompatibility complex (MHC) plays an important role in determining genetic compatibility between partners. Favouring a partner with dissimilar MHC alleles would result in offspring with high MHC diversity and therefore with enhanced survival thanks to increased resistance to pathogens and parasites. The high variability of MHC genes may further allow discrimination against the sperm from related males, reducing offspring homozygosity and inbreeding risk. Despite the large body of work conducted at precopulatory level, the role of MHC similarity between partners at postcopulatory level has been rarely investigated. We used an internal fertilizing fish with high level of multiple matings (Poecilia reticulata) to study whether MHC similarity plays a role in determining the outcome of fertilization when sperm from two males compete for the same set of eggs. We also controlled for genomewide similarity by determining similarity at 10 microsatellite loci. Contrary to prediction, we found that the more MHC-similar male sired more offspring while similarity at the microsatellite loci did not predict the outcome of sperm competition. Our results suggest that MHC discrimination may be involved in avoidance of hybridization or outbreeding rather than inbreeding avoidance. This, coupled with similar findings in salmon, suggests that the preference for MHC-dissimilar mates is far from being unanimous and that pre- and postcopulatory episodes of sexual selection can indeed act in opposite directions.
Date made available9 Apr 2015


  • Sexual Selection
  • Inbreeding
  • MHC similarity
  • sperm competition
  • Poecilia reticulata

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