一只雌军舰鸟在一群雄军舰鸟的上空盘旋，后者会立即膨胀起它们像红气球一样的喉囊，借以展示自己的“男子气”，而这只雌军舰鸟最终也会在一只最大、最红的“喉囊”边落下脚来，并且陪伴在它的身边。
白腹军舰鸟
但是这种大小与鸡相仿的海鸟却可能会突然甩了自己未来的伴侣，前提是雄鸟闻起来与自己太过相似。
通过分析夏威夷种群的军舰鸟的基因，研究人员发现，雌军舰鸟更喜欢与那些携带了一组名为主要组织相容性复合（MHC）标记物的蛋白质的雄军舰鸟交配，后者从遗传学角度来说与前者差异很大，而不论这两只“爱情鸟”是否是亲戚。
鱼类和哺乳动物似乎都能够通过嗅觉区分不同的MHC蛋白质，因此鸟类可能也会这样做，研究人员在5月24日出版的英国《皇家学会学报B》报告了这一研究成果。
研究人员推测，由于MHC蛋白质与免疫响应有关，因此来自父母双方的不同排列的蛋白质将有助于后代避免更多类型的病原体的侵袭，这可比一个漂亮的大喉囊重要得多。
军舰鸟是一种大型热带海鸟，全世界目前已知的有5种，主要生活在太平洋、印度洋的热带地区。其捕食时的飞行时速可达400公里左右，是世界上飞得最快的鸟之一。军舰鸟还会通过骚扰其他带着猎物归来的海鸟获得食物。通过对其他正在飞行的鸟儿进行干扰，它们经常会得到从其他海鸟嘴里掉落下来的食物。（生物谷Bioon.com）
生物谷推荐原文：
Proceedings of the Royal Society B: Biological Sciences DOI： 10.1098/rspb.2011.0562
Sequence-based evidence for major histocompatibility complex-disassortative mating in a colonial seabird
Juola, Frans A.; Dearborn, Donald C.
The major histocompatibility complex (MHC) is a polymorphic gene family associated with immune defence, and it can play arole in mate choice. Under the genetic compatibility hypothesis, females choose mates that differ genetically from their ownMHC genotypes, avoiding inbreeding and/or enhancing the immunocompetence of their offspring. We tested this hypothesis ofdisassortative mating based on MHC genotypes in a population of great frigatebirds (Fregata minor) by sequencing the second exon of MHC class II B. Extensive haploid cloning yielded two to four alleles per individual, suggestingthe amplification of two genes. MHC similarity between mates was not significantly different between pairs that did (n = 4) or did not (n = 42) exhibit extra-pair paternity. Comparing all 46 mated pairs to a distribution based on randomized re-pairings, we observedthe following (i): no evidence for mate choice based on maximal or intermediate levels of MHC allele sharing (ii), significantlydisassortative mating based on similarity of MHC amino acid sequences, and (iii) no evidence for mate choice based on microsatellitealleles, as measured by either allele sharing or similarity in allele size. This suggests that females choose mates that differgenetically from themselves at MHC loci, but not as an inbreeding-avoidance mechanism.
