Costly major histocompatibility complex signals produced only by reproductively active males, but not females, must be validated by a 'maleness signal' in three-spined sticklebacks.
Olfactory information about individual major histocompatibility complex (MHC) immune genotypes is important for mate choice in several species. For example, during the mate choice decisions of three-spined sticklebacks, females assess males on the basis of odour cues that convey information about their MHC diversity. Here, we show that an additional 'maleness' signal is needed to validate the MHC signal. Furthermore, using interaction between natural odour of sticklebacks and synthetic MHC-ligand peptides, we show that MHC signals are conditional on the reproductive state in males. By contrast, we find that gravid females do not produce such signals. Since MHC olfactory signals relevant to mate choice decisions are conditional upon gender and reproductive state, we suggest that their manufacture is likely to be costly to senders, and therefore, potentially conditional on the health/parasitization status of the sender. We hypothesize that shedding of peptide-MHC complexes compromises immune function, selecting against unconditional use of these signals.
Department of Evolutionary Ecology, Max Planck Institute for Evolutionary Biology, , August-Thienemann-Strasse 2, 24306 Ploen, Germany. milinski@evolbio.mpg.de
Manfred
M
Milinski
Siân W
SW
Griffiths
Thorsten B H
TB
Reusch
Thomas
T
Boehm
D000819:Animal Communication; D000818:Animals; D005260:Female; D014644:Genetic Variation; D008285:Major Histocompatibility Complex / Q000235:genetics / Q000502:physiology; D008297:Male; D052586:Mating Preference, Animal; D009812:Odorants; D010455:Peptides / Q000235:genetics; D012098:Reproduction; D012727:Sex Characteristics; D012726:Sexual Behavior, Animal; D015398:Signal Transduction; D023701:Smegmamorpha / Q000235:genetics / Q000378:metabolism; D012903:Smell
D010455:Peptides