Male genital size reflects a tradeoff between attracting mates and avoiding predators in two live-bearing fish species
Male genital size reflects a tradeoff between attracting mates and avoiding predators in two live-bearing fish species
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DOI：
10.1073/pnas.0500935102
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发表时间：
2005-05-24
影响因子：
11.1
通讯作者：
DeWitt, TJ
中科院分区：
文献类型：
--
作者：
Langerhans, RB;Layman, CA;DeWitt, TJ
男性的生殖器可能比其他任何动物的特征经历了更快、更多样化的进化，但为什么呢？过去几十年的研究最终得出这样的观点，即生殖器多样化主要是交配后性选择的结果（例如，精子竞争或神秘的雌性选择）。然而，交配前性选择的潜在作用（例如，交配选择）和自然选择很少受到关注。我们研究了可能的重要性，这些机制的调查分歧，在男性生殖器种群之间的捕食者制度不同的两个物种的活轴承鱼（食蚊鱼在得克萨斯州和食蚊鱼在巴哈马）。当控制的身体大小，男性表现出更大的生殖器（精子转移器官）在无捕食者的环境比在捕食环境中，持续跨空间（多个种群），时间（多年）和物种的趋势。通过对G. affinis，我们发现，交配前的性选择似乎有利于更大的男性生殖器（女性表现出交配偏好的男性具有较大的生殖器），但在捕食性鱼类的存在下，自然选择似乎有利于减少生殖器的大小（较大的生殖器大小与减少爆发游泳性能，一个重要的反捕食行为）。虽然交配后的性选择被广泛认为是最重要的机制驱动生殖器多样化，这些研究结果表明，替代机制，特别是生物体不能收回他们的生殖器，也可能证明是重要的。
Male genitalia may experience more rapid, divergent evolution than any other animal character, but why? Research during the past several decades has culminated in the view that genital diversification primarily results from postmating sexual selection (e.g., sperm competition or cryptic female choice). However, the potential roles of premating sexual selection (e.g., mate choice) and natural selection have received little attention. We examined the possible importance of these mechanisms by investigating divergence in male genitalia among populations differing in predator regime for two species of live-bearing fish (Gambusia affinis in Texas and Gambusia hubbsi in The Bahamas). When controlled for body size, males exhibited a larger gonopodium (sperm-transfer organ) in predator-free environments than in predatory environments, a trend that persisted across space (multiple populations), time (multiple years), and species. By conducting laboratory experiments with G. affinis, we found that premating sexual selection seems to favor larger male genitalia (females exhibited mating preference for males having larger gonopodia), but natural selection in the presence of predatory fishes seems to favor reduced genital size (larger gonopodium size was associated with reduced burst-swimming performance, an important antipredator behavior). Although postmating sexual selection is widely presumed to be the most important mechanism driving genital diversification, these findings suggest that alternative mechanisms, particularly for organisms that cannot retract their genitalia, may also prove important.