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

9812779 1998年同时出现13年和17年期蝉的西蒙收藏1998年将出现仅有的两只13年和17年期蝉，它们的活动范围目前重叠。这每221年才发生一次，这将为研究这两种生命周期类型在自然种群中的相互作用提供一个独特的机会。首席调查员和同事以前的研究表明，13年和17年的蝉，Magicicada Tredecm和M.Septendecim，作为不同的进化单位或物种进化，但在美国中西部被称为“异常地带”的地区，17年的蝉永久地将其生命周期转变为13年。这种生命周期的转换允许了以前孤立的物种之间的基因混合，并可能导致13年蝉的重大基因变化。17年的蝉不会受到影响，因为基因的移动只有一个方向--通过缩短17年的生命周期，从17年到13年的蝉。在这个项目中，我们将收集和观察13年和17年的蝉在它们的重叠区。此外，过去的研究主要集中在最大的一对13年和17年的蝉上，它们是毛蝉和隔叶蝉。有两个较小的种对周期蝉只出现在大平原以东的美国东部。早期的研究已经确定了三个强大的遗传边界，在这些边界上，生命周期和物种之间可能发生基因交换。我们将收集标本，并在野外研究物种之间的相互作用。最有趣的地区是那些13年和17年蝉共处(俄克拉荷马州)或副地域性(北卡罗来纳州、田纳西州东部和佐治亚州北部)的地区。一支球队将专注于S W赛区，另一支球队将专注于东南区；然后每个球队都将向中西部进发。中西部地区极其重要，因为上一次Brood XIX出现时还没有发现“异常区”，采样也没有集中在最重要的区域。同样，当1981年对雏鸟四号进行采样时，并不知道在1985年，俄克拉荷马州麦克柯丁县的同一棵树上会出现13年的雏鸟十九号。俄克拉何马州的麦克柯丁县是美国唯一一个真正的13年和17年蝉重叠的地区。幸运的是，1981年和1985年在同一棵树上观察到第四代和第十九代的确切地点--小河穿过259号高速公路--位于11年前创建的美国鱼类和野生动物服务(USFWS)保护区的中心。“小河国家野生动物保护区”由12,000英亩的阔叶林和松林组成，应该可以保证这一地区的周期蝉的未来。另一个收集重点将是爱荷华州东南部13年Brood XIX与17年Brood III重叠的区域。去年，在同一棵树上发现了雏鸟三窝(1980年)和十九窝(1985年)卵痕的地区，采集了17年的雏鸟。1998年春，将在同一地区制作布鲁德十九世的收藏品，以供比较。最后，在北卡罗来纳州、田纳西州东部和佐治亚州北部，13年布鲁德XIX出现在三个17年布鲁德(II、VI和/或XIV)附近。这四个幼虫的形成可能是相互关联的，今年在该地区收集的标本可能有助于揭示这一过程。为了准备联合出现，我们开发了五个不同的遗传标记，可以用来探索我们实验室以前的研究产生的假说。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之前认识到的更常见，并可以显著影响进化物种的遗传学。

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.