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Female house sparrows "count on" male genes: experimental evidence for MHC-dependent mate preference in birds.

Griggio M, Biard C, Penn DJ, Hoi H - BMC Evol. Biol. (2011)

Bottom Line: Another potential indirect benefit from mating preferences is genetic compatibility, which does not require extravagant or viability indicator traits.Overall, we found no evidence that females preferred males with high individual MHC diversity.Yet, when we considered individual MHC allelic diversity of the females, we found that females with a low number of alleles were most attracted to males carrying a high number of MHC alleles, which might reflect a mating-up preference by allele counting.

View Article: PubMed Central - HTML - PubMed

Affiliation: Konrad Lorenz Institute for Ethology, Austrian Academy of Sciences, Austria. m.griggio@klivv.oeaw.ac.at

ABSTRACT

Background: Females can potentially assess the quality of potential mates using their secondary sexual traits, and obtain "good genes" that increase offspring fitness. Another potential indirect benefit from mating preferences is genetic compatibility, which does not require extravagant or viability indicator traits. Several studies with mammals and fish indicate that the genes of the major histocompatibility complex (MHC) influence olfactory cues and mating preferences, and such preferences confer genetic benefits to offspring. We investigated whether individual MHC diversity (class I) influences mating preferences in house sparrows (Passer domesticus).

Results: Overall, we found no evidence that females preferred males with high individual MHC diversity. Yet, when we considered individual MHC allelic diversity of the females, we found that females with a low number of alleles were most attracted to males carrying a high number of MHC alleles, which might reflect a mating-up preference by allele counting.

Conclusions: This is the first experimental evidence for MHC-dependent mating preferences in an avian species to our knowledge. Our findings raise questions about the underlying mechanisms through which birds discriminate individual MHC diversity among conspecifics, and they suggest a novel mechanism through which mating preferences might promote the evolution of MHC polymorphisms and generate positive selection for duplicated MHC loci.

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Frequency distribution of the number of MHC class I alleles in the 249 house sparrows captured from an Austrian population and used in the experiment.
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Figure 1: Frequency distribution of the number of MHC class I alleles in the 249 house sparrows captured from an Austrian population and used in the experiment.

Mentions: We specifically tested whether female house sparrows are attracted to males carrying a high allelic diversity at MHC loci (good genes) [29], or whether their preferences maximize or optimize MHC allelic diversity of offspring (genetic compatibility) [16,18]. If females seek the "best" mating partner, one would predict that most females will prefer one or few males, but if they are searching for a genetically compatible partner, females will differ in their preferences of males based on their own MHC diversity. We conducted a female mate preference test using a four-choice apparatus, in which the females had a choice between three males, each having either with low (1-2 alleles), medium (3 alleles) or high (4-6 alleles) number of MHC class I alleles (LM, MM and HM groups respectively), or a female control (CF) in a fourth chamber (for MHC alleles distribution in the population see Figure 1). To estimate proximity preference, we measured the time spent by each female on the part of the perch in front of a male's compartment (choice time). Stimulus individuals were tested to three experimental groups of focal females: females with low (LF), medium (MF) and high (HF) diversity (number) of MHC class I alleles.


Female house sparrows "count on" male genes: experimental evidence for MHC-dependent mate preference in birds.

Griggio M, Biard C, Penn DJ, Hoi H - BMC Evol. Biol. (2011)

Frequency distribution of the number of MHC class I alleles in the 249 house sparrows captured from an Austrian population and used in the experiment.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3044665&req=5

Figure 1: Frequency distribution of the number of MHC class I alleles in the 249 house sparrows captured from an Austrian population and used in the experiment.
Mentions: We specifically tested whether female house sparrows are attracted to males carrying a high allelic diversity at MHC loci (good genes) [29], or whether their preferences maximize or optimize MHC allelic diversity of offspring (genetic compatibility) [16,18]. If females seek the "best" mating partner, one would predict that most females will prefer one or few males, but if they are searching for a genetically compatible partner, females will differ in their preferences of males based on their own MHC diversity. We conducted a female mate preference test using a four-choice apparatus, in which the females had a choice between three males, each having either with low (1-2 alleles), medium (3 alleles) or high (4-6 alleles) number of MHC class I alleles (LM, MM and HM groups respectively), or a female control (CF) in a fourth chamber (for MHC alleles distribution in the population see Figure 1). To estimate proximity preference, we measured the time spent by each female on the part of the perch in front of a male's compartment (choice time). Stimulus individuals were tested to three experimental groups of focal females: females with low (LF), medium (MF) and high (HF) diversity (number) of MHC class I alleles.

Bottom Line: Another potential indirect benefit from mating preferences is genetic compatibility, which does not require extravagant or viability indicator traits.Overall, we found no evidence that females preferred males with high individual MHC diversity.Yet, when we considered individual MHC allelic diversity of the females, we found that females with a low number of alleles were most attracted to males carrying a high number of MHC alleles, which might reflect a mating-up preference by allele counting.

View Article: PubMed Central - HTML - PubMed

Affiliation: Konrad Lorenz Institute for Ethology, Austrian Academy of Sciences, Austria. m.griggio@klivv.oeaw.ac.at

ABSTRACT

Background: Females can potentially assess the quality of potential mates using their secondary sexual traits, and obtain "good genes" that increase offspring fitness. Another potential indirect benefit from mating preferences is genetic compatibility, which does not require extravagant or viability indicator traits. Several studies with mammals and fish indicate that the genes of the major histocompatibility complex (MHC) influence olfactory cues and mating preferences, and such preferences confer genetic benefits to offspring. We investigated whether individual MHC diversity (class I) influences mating preferences in house sparrows (Passer domesticus).

Results: Overall, we found no evidence that females preferred males with high individual MHC diversity. Yet, when we considered individual MHC allelic diversity of the females, we found that females with a low number of alleles were most attracted to males carrying a high number of MHC alleles, which might reflect a mating-up preference by allele counting.

Conclusions: This is the first experimental evidence for MHC-dependent mating preferences in an avian species to our knowledge. Our findings raise questions about the underlying mechanisms through which birds discriminate individual MHC diversity among conspecifics, and they suggest a novel mechanism through which mating preferences might promote the evolution of MHC polymorphisms and generate positive selection for duplicated MHC loci.

Show MeSH