SGER: Collection of Co-emergence of 13- & 17-year Periodical Cicadas

SGER：13-共同出现的集合

• 批准号: 9812779
• 负责人: Chris Simon
• 金额: $ 4.61万
• 依托单位: University of Connecticut
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-05-01 至 1999-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9812779&HistoricalAwards=false
• 关键词: SGER; Collection; Co; emergence; 13

9812779 Simon Collection of the co-emergence of 13- and 17-year periodical cicadas In 1998 there will be a joint emergence of the only two broods of 13- and 17-year cicadas whose ranges currently overlap. This happens only once every 221 years, and will provide a unique opportunity to study interactions between the two life-cycle-types in natural populations. Previous research by the principal investigator and co-workers has demonstrated that 13- and 17-year cicadas, Magicicada tredecim and M. septendecim, have evolved as distinct evolutionary units or species but that in an area of the midwestern United States termed "the anomalous zone" 17-year cicadas have permanently switched their life cycle to 13-years. This life-cycle-switching has allowed genetic mixing between formerly isolated species and could lead to significant genetic changes in the 13-year cicadas. The 17-year cicadas will not be affected because the movement of genes goes only in one direction--from 17- to 13-year cicadas via a four-year shortening of the 17-year life cycle. In this project we will collect and observe 13- and 17-year cicadas in their zones of overlap. In addition, past studies have concentrated on the largest pair of 13- and 17-year cicadas, Magicicada tredecim and M. septendecim. There are two smaller species pairs-- Magicicada tredecassini/M. cassini and M. tredecula/M. septendecula--that have not been studied in detail and will provide replicates for comparison. Periodical cicadas occur only in the eastern U.S. east of the great plains. Earlier studies have identified three strong genetic boundaries where gene exchange may be occurring between life cycles and species. We will collect specimens and study species interactions in the field. The most interesting areas are those where 13- and 17-year cicadas are sympatric (Oklahoma) or parapatric (North Carolina, Eastern Tennessee and North Georgia). One team will focus in the S W and the other in the SE; each will then work toward the Midwest. The Midwest is extremely important because the "anomalous zone" had not been discovered the last time that Brood XIX emerged, and sampling did not focus on the most important areas. Similarly, when Brood IV was sampled in 1981, it was not known that in 1985 13-year Brood XIX would emerge in the same trees in McCurtain County, Oklahoma. McCurtain County, Oklahoma, is the only area of the country where true 13- and 17-year cicadas overlap. By a stroke of good luck, the exact locality where Brood IV and XIX were observed in the same trees in 1981 and 1985--where the Little River crosses Hwy 259-lies in the heart of a US Fish and Wildlife Service (USFWS) refuge that was created 11 years ago. "The Little River National Wildlife Refuge" comprises 12,000 acres of mixed hardwood and pine forests and should ensure the future of the periodical cicadas in this area. Another focus for collecting will be the area where 13-year Brood XIX overlaps 17-year Brood III in southeastern Iowa. Last year 17-year Brood III was collected in areas in which eggs scars of both Brood III (from 1980) and Brood XIX (from 1985) had been found in the same trees. In the spring of 1998, collections will be made of Brood XIX in this same area for comparison. Finally, in North Carolina, eastern Tennessee and North Georgia, 13-year Brood XIX emerges in close proximity to three 17-year Broods (II, VI, and/or XIV). It is possible that formation of these four broods was interrelated and specimens collected this year in this area may shed light on this process. In preparation for the joint emergence, five diverse genetic markers were developed that can be used to explore hypotheses generated by previous research in our lab. If successful, this research will contribute to the growing body of evidence that hybridization between species is more common than previously recognized and can significantly influence the genetics of evolving species.

9812779 Simon 13年和17年周期蝉同时出现的合集1998年将会同时出现两窝13年和17年的蝉，它们的活动范围目前是重叠的。这种情况每221年才发生一次，这将为研究自然种群中两种生命周期类型之间的相互作用提供一个独特的机会。首席研究员和同事先前的研究表明，13年和17年的蝉，Magicicada tredecim和M. septendecim，已经进化成不同的进化单位或物种，但在美国中西部一个被称为“异常区”的地区，17年的蝉已经永久地将它们的生命周期转换为13年。这种生命周期的转换使得以前孤立的物种之间的基因混合，并可能导致13年蝉的重大遗传变化。17岁的蝉不会受到影响，因为基因只会向一个方向移动——通过将17年的生命周期缩短4年，从17岁的蝉变成13岁的蝉。在这个项目中，我们将在它们的重叠区域收集和观察13岁和17岁的蝉。此外，过去的研究主要集中在最大的一对13岁和17岁的蝉，Magicicada tredecim和M. septendecim。有两个较小的物种对——Magicicada tredecassini/M。卡西尼和M. tredecula/M。Septendecula，尚未被详细研究，将提供重复的比较。周期性的蝉只出现在美国东部大平原以东。早期的研究已经确定了生命周期和物种之间可能发生基因交换的三个强大的遗传边界。我们将在野外采集标本并研究物种间的相互作用。最有趣的地区是那些13岁和17岁的蝉是同栖的（俄克拉荷马州）或异栖的（北卡罗来纳州，田纳西州东部和佐治亚州北部）。一个团队将专注于西南，另一个团队专注于东南；然后各自向中西部进发。中西部地区是极其重要的，因为“异常地带”并没有被发现，最后一次产卵十九出现，采样没有集中在最重要的地区。同样，当1981年对第4代幼虫进行采样时，不知道1985年13年的第19代幼虫会在俄克拉何马州麦克库尔县的同一棵树上出现。俄克拉何马州的麦克科恩县是美国唯一一个真正的13年和17年蝉重合的地区。幸运的是，1981年和1985年在同一棵树上观察到四号和十九号幼虫的确切位置——小河穿过259号高速公路的地方——位于11年前创建的美国鱼类和野生动物管理局（USFWS）保护区的中心。“小河流国家野生动物保护区”由12,000英亩的硬木和松林混合组成，应该确保该地区周期性蝉的未来。另一个收集的重点将是爱荷华州东南部13年的第19群和17年的第3群重叠的地区。去年，在同一棵树上发现了1980年的第三和1985年的第十九种幼虫的卵痕的地区，收集了17年的第三种幼虫。在1998年春季，将在同一地区收集第19代幼虫进行比较。最后，在北卡罗莱纳、田纳西州东部和北乔治亚州，13年的第19代幼虫出现在3个17年的第2、第6和/或第14代幼虫附近。这四窝的形成可能是相互关联的，今年在该地区收集的标本可能会揭示这一过程。为了准备联合出现，开发了五种不同的遗传标记，可用于探索我们实验室先前研究产生的假设。如果成功，这项研究将有助于提供越来越多的证据，证明物种之间的杂交比以前认识到的更为普遍，并且可以显著影响进化物种的遗传学。