Seddon Nathalie, Amos William, Mulder Raoul A, Tobias Joseph A
Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK.
Proc Biol Sci. 2004 Sep 7;271(1550):1823-9. doi: 10.1098/rspb.2004.2805.
Recent studies of non-social animals have shown that sexually selected traits signal at least one measure of genetic quality: heterozygosity. To determine whether similar cues reveal group quality in more complex social systems, we examined the relationship between territory size, song structure and heterozygosity in the subdesert mesite (Monias benschi), a group-living bird endemic to Madagascar. Using nine polymorphic microsatellite loci, we found that heterozygosity predicted both the size of territories and the structure of songs used to defend them: more heterozygous groups had larger territories, and more heterozygous males used longer, lower-pitched trills in their songs. Heterozygosity was linked to territory size and song structure in males, but not in females, implying that these traits are sexually selected by female choice and/or male-male competition. To our knowledge, this study provides the first direct evidence in any animal that territory size is related to genetic diversity. We also found a positive association between seasonal reproductive success and heterozygosity, suggesting that this heritable characteristic is a reliable indicator of group quality and fitness. Given that heterozygosity predicts song structure in males, and can therefore be determined by listening to acoustic cues, we identify a mechanism by which social animals may assess rival groups, prospective partners and group mates, information of potential importance in guiding decisions related to conflict, breeding and dispersal.
近期对非社会性动物的研究表明，性选择特征至少能体现一种遗传质量指标：杂合性。为了确定在更复杂的社会系统中类似线索是否能揭示群体质量，我们研究了马达加斯加特有的群居鸟类——亚沙漠美西地鸠（Monias benschi）的领地大小、鸣声结构与杂合性之间的关系。通过使用9个多态微卫星位点，我们发现杂合性既能预测领地大小，也能预测用于保卫领地的鸣声结构：杂合性更高的群体拥有更大的领地，杂合性更高的雄性在鸣叫时会使用更长、音调更低的颤音。杂合性与雄性的领地大小和鸣声结构有关，但与雌性无关，这意味着这些特征是通过雌性选择和/或雄性间竞争进行性选择的。据我们所知，这项研究首次在任何动物中提供了直接证据，证明领地大小与遗传多样性有关。我们还发现季节性繁殖成功率与杂合性之间存在正相关，这表明这种可遗传特征是群体质量和适应性的可靠指标。鉴于杂合性能预测雄性的鸣声结构，因此可以通过声学线索来确定，我们确定了一种机制，群居动物可以通过这种机制评估竞争群体、潜在配偶和群体成员，这一信息对于指导与冲突、繁殖和扩散相关的决策可能具有重要意义。
