7/25/2023 0 Comments Cicada life cycle![]() Using a numerical model, we test the general feasibility of life cycle switching by the introduction of alleles for one cycle into populations of the other cycle. One explanation for the apparent polyphyly of 13- and 17-year life cycles is that populations switch between the two cycles. Each group contains at least one species with a 17-year life cycle and one with a 13-year cycle each species is most closely related to one with the other cycle. This pattern of reproductive character displacement suggests that the songs have evolved to reduce wasteful sexual interactions between the species.Periodical cicadas ( Magicicada spp.) in the USA are divided into three species groups (-decim, -cassini, -decula) of similar but distinct morphology and behavior. tredecim songs are slightly lower-pitched. ![]() In this overlap zone, Magicicada neotredecim songs are much higher-pitched, while M. tredecim overlap, male calling songs (and female song preferences) of these species have evolved to become more distinct. By comparison, the three 17-year species are found together from Connecticut to Kansas, and the remaining 13-year species together inhabit most 13-year populations. The two species overlap only along a narrow region in northern Arkansas, western Kentucky, and southern Missouri, Illinois, and Indiana. tredecim inhabits the southern and southeastern part. Magicicada neotredecim inhabits the midwestern part of the 13-year range, while M. The two 13-year -decim species have a special geographic relationship - they are not sympatric (living together) across the entire 13-year range. The -decim species differ in abdomen color. The four 13-year species are all found together in only a limited portion of the 13-year range (see below). Brood VI lacks Magicicada cassinii, Brood VII contains only Magicicada septendecim (which tends to be found alone along the northern edge of the 17-year range), and 13-year Brood XXII lacks Magicicada neotredecim. Most of the broods contain all of the 13- or 17-year species, with a few exceptions. For this reason and for practical purposes, most writers have adopted the taxonomy that recognizes the life cycle siblings as distinct species. ![]() More information on the nature of the boundary between 13- and 17-year populations and the extent of hybridization between them would help to resolve this question, but for now there is no evidence that the distinctiveness of the life-cycle-forms is decreasing. Some biologists have argued that the life cycle difference alone is not enough to justify species status. Some species pairs can be distinguished only by life cycle and geographic distribution. The closest relative of each Magicicada species appears to be a counterpart with the alternative life cycle. Magicicada tredecula Alexander and Moore 1962 Magicicada tredecassini Alexander and Moore 1962 Magicicada neotredecim Marshall and Cooley 2000 Magicicada tredecim (Walsh and Riley 1868) Magicicada septendecula Alexander and Moore 1962įor each 17-year species, there is at least one morphologically and behaviorally similar species with a 13-year life cycle: ![]() Three 17-year cicada species are described, each with distinctive morphology (shape and color), behavior, and calling signals: The songs and morphology of the seven periodical cicada species are described on pages linked below. Males and females join dense aggregations, or leks, where the males search for the stationary females using short flights and calls. These cicadas have striking black bodies, red eyes, and red wing veins. The genus Magicicada contains the periodical cicadas, known for their 17- or 13-year synchronized life cycles and dense choruses.
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