UNIDIRECTIONAL INTROGRESSION OF A SEXUALLY SELECTED TRAIT ACROSS AN AVIAN HYBRID ZONE: A ROLE FOR FEMALE CHOICE?
UNIDIRECTIONAL INTROGRESSION OF A SEXUALLY SELECTED TRAIT ACROSS AN AVIAN HYBRID ZONE: A ROLE FOR FEMALE CHOICE?
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性选择特征在鸟类杂交区的单向渗入：女性选择的作用？
DOI：
10.1554/05-575.1
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发表时间：
2006
期刊：
影响因子：
--
通讯作者：
C. Uy
中科院分区：
文献类型：
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作者：
Adam C Stein;And J Albert;C. Uy
摘要 杂交可以成为一种进化创造力，通过形成新的多倍体物种、创造新的遗传变异或充当杂交形式之间潜在有利性状的渠道。后者的证据通常很难找到，因为正选择下的等位基因可以在混合区域中快速传播并扫过固定。在巴拿马西部，存在马纳库斯属两种侏儒鸟之间的鸟类杂交区，明亮的黄色羽毛单向渗入到白色种群中，这证明了杂交区作为有利性状的渠道的重要性。一些间接证据表明，有利于黄色羽毛的性选择推动了这种不对称的传播，但缺乏更直接的证据。沿着杂交区的边缘，黄领和白领侏儒鸟都出现在相同的交配场所或leks中，并争夺相同的雌性（“混合leks”），这为我们提供了了解黄色羽毛渐渗动态的独特机会。我们研究了这些混合的leks，以确定黄色雄性是否比白人雄性具有交配优势，如果是的话，交配优势是否是由雄性与雄性相互作用、雌性选择或两者共同驱动的。我们发现黄色雄性比白色雄性交配更多，这表明有利于黄色雄性的性选择确实可以解释黄色羽毛的传播。然而，我们发现这种优势只出现在混合种族中，其中黄色雄性的频率高于白人雄性。这表明黄色雄性的优势可能取决于其他黄色雄性的存在，这可能会减慢黄色频率较低的 leks 的渗入速度，例如在黄色雄性开始殖民白人群体的地区。这与混合区主要河流构成的地理障碍一起，可能最初会限制或减缓黄色羽毛的传播。最后，我们发现黄色和白色雄性在攻击性和体型方面相似，并且在 leks 中占据相似的位置。由于这些特征或因素通常在攻击性雄性与雄性相互作用中很重要或由其决定，因此这些比较表明雄性与雄性相互作用并不是黄色羽毛传播的主要机制。然而，白人和黄种雄性收到的雌性求爱次数相似，但交配次数不同，这表明雌性积极拒绝白人，而青睐黄种雄性。我们的结果表明，雌性选择的性选择驱动了黄色羽毛单向渗入到白色种群中，为杂交区如何充当新颖和有利性状的渠道提供了一种机制。
Abstract Hybridization can be an evolutionary creative force by forming new polyploid species, creating novel genetic variation or acting as conduits of potentially advantageous traits between hybridizing forms. Evidence for the latter is often difficult to find because alleles under positive selection can spread rapidly across a hybrid zone and sweep to fixation. In Western Panama, an avian hybrid zone between two species of manakins in the genus Manacus exists where the unidirectional introgression of bright, yellow plumage into a white population provides evidence for the importance of hybrid zones as conduits of advantageous traits. Several lines of indirect evidence suggest that sexual selection favoring yellow plumage drives this asymmetrical spread, but more direct evidence is lacking. Along the edge of the hybrid zone, both yellow- and white-collared manakins are found in the same mating arenas or leks and compete for the same females (“mixed leks”), providing us with a unique opportunity to understand the dynamics of yellow plumage introgression. We studied these mixed leks to determine whether yellow males have a mating advantage over white males and, if so, whether the mating advantage is driven by male-male interactions, female choice, or both. We found that yellow males mated more than white males, suggesting that sexual selection favoring yellow males can, indeed, explain the spread of yellow plumage. However, we found that this advantage occurred only in mixed leks where the frequency of yellow males is greater than white males. This suggests that the advantage of yellow males may depend on the presence of other yellow males, which may slow the rate of introgression in leks where yellow frequency is low such as in areas where yellow males are beginning to colonize the white population. This, along with the geographic barrier posed by major rivers in the hybrid zone, may initially limit or slow the spread of yellow plumage. Finally, we found that yellow and white males were similar in aggression and body size, and held comparable positions within leks. Because these traits or factors are often important in or dictated by aggressive male-male interactions, these comparisons indicate that male-male interaction is not the primary mechanism for the spread of yellow plumage. However, white and yellow males received similar numbers of courtship visits from females but differed in the number of matings, suggesting that females actively rejected white in favor of yellow males. Our results indicate that sexual selection by female choice has driven the unidirectional introgression of yellow plumage into the white population, providing a mechanism for how hybrid zones act as conduits of novel and advantageous traits.