Bessert Michael L, Brozek Jeremy, Ortí Guillermo
School of Biological Sciences, University of Nebraska, Lincoln, NE 68588-0118, USA.
J Hered. 2007 Nov-Dec;98(7):716-22. doi: 10.1093/jhered/esm092. Epub 2007 Nov 5.
The fathead minnow (Pimephales promelas) is a nest-building North American cyprinid that spawns multiply and exhibits exclusive male parental care. Here, we examined the effects of nest substrate availability on the genetic mating system in 2 natural populations from the glacial pothole region of eastern South Dakota. The sites differed dramatically with respect to the type and density of available nest substrate. Substrate effects were examined by comparing the percentage and distribution of illegitimate offspring between the 2 sites. A total of 1338 embryos from 42 nests (21 from each site) were genotyped at 4 or 5 microsatellite loci. Bimodally distributed frequencies of illegitimate offspring occurred in the nests of guardian males from both sites and indicate the presence of nest takeovers as well as previously undocumented alternative reproductive tactics. As predicted, the rate of usurped nests, a previously documented behavior, was higher in the nest substrate-limited population; furthermore, males were significantly larger here and acquired more mates, suggesting a difference in sexual selection regime. Although these results are based on a single comparison between 2 sites, the results are intriguing and provide a foundation for future studies.
黑头呆鱼（Pimephales promelas）是一种在北美筑巢的鲤科鱼类，会多次产卵，并表现出雄性独有的亲代抚育行为。在此，我们研究了巢基质可用性对南达科他州东部冰川壶穴地区两个自然种群遗传交配系统的影响。这两个地点在可用巢基质的类型和密度方面存在显著差异。通过比较两个地点非婚生子代的百分比和分布来研究基质效应。对来自42个巢穴（每个地点21个）的总共1338个胚胎在4或5个微卫星位点进行了基因分型。两个地点的守护者雄性巢穴中都出现了非婚生子代频率的双峰分布，这表明存在巢穴接管以及之前未记录的替代生殖策略。正如预测的那样，在巢基质有限的种群中，巢穴被篡夺的比率（一种之前记录过的行为）更高；此外，这里的雄性明显更大，获得的配偶更多，这表明性选择机制存在差异。尽管这些结果基于两个地点之间的单一比较，但结果很有趣，并为未来的研究奠定了基础。
