The Distribution of Periodical Cicada Brood X in 2004 (original) (raw)
Independent divergence of 13- and 17-y life cycles among three periodical cicada lineages
Proceedings of the National Academy of Sciences, 2013
The evolution of 13- and 17-y periodical cicadas ( Magicicada ) is enigmatic because at any given location, up to three distinct species groups (Decim, Cassini, Decula) with synchronized life cycles are involved. Each species group is divided into one 13- and one 17-y species with the exception of the Decim group, which contains two 13-y species—13-y species are Magicicada tredecim , Magicicada neotredecim , Magicicada tredecassini , and Magicicada tredecula ; and 17-y species are Magicicada septendecim , Magicicada cassini , and Magicicada septendecula . Here we show that the divergence leading to the present 13- and 17-y populations differs considerably among the species groups despite the fact that each group exhibits strikingly similar phylogeographic patterning. The earliest divergence of extant lineages occurred ∼4 Mya with one branch forming the Decim species group and the other subsequently splitting 2.5 Mya to form the Cassini and Decula species groups. The earliest split o...
Temporal Separation and Speciation in Periodical Cicadas
BioScience, 2003
Speciation, the set of processes by which two populations of one species become distinct species, is an important topic in evolutionary biology. It is usually impractical to conduct experiments on how new species form, but occasionally the natural history of a species places it in a context that may be thought of as a "natural experiment" with regard to speciation. One such natural experiment involves the periodical cicadas of eastern North America, a group in which populations have become isolated in time and space. Some of these isolated populations appear to have evolved into distinct genetic lineages. A rare life-cycle switching event brought two such lineages into contact in the relatively recent past, and the two lineages are now behaving as distinct species. This natural experiment provides important insights into species differences and the processes that underlie species formation.
Evolution of Periodicity in Periodical Cicadas
Ecology, 2005
Periodical cicadas present numerous puzzles for biologists. First, their period is fixed, with individuals emerging as adults precisely after either 13 or 17 years (depending on species). Second, even when there are multiple species of either 13-or 17-year cicadas at the same location, only one or rarely two broods (cohorts) co-occur, so that periodical cicada adults appear episodically. Third, the 13-or 17-year periods of cicadas suggest there is something important about prime numbers. Finally, single broods can dominate large areas, with geographical boundaries of broods remaining generally stable through time. While previous mathematical models have been used to investigate some of these puzzles individually, here we investigate them all simultaneously. Unlike previous models, we take an explicitly evolutionary approach. Although not enough information is known about periodical cicadas to draw firm conclusions, the theoretical arguments favor a combination of predator satiation and nymph competition as being key to the evolution of strictly fixed periods and occurrence of only one brood at most geographical locations. Despite ecological mechanisms that can select for strictly fixed periods, there seem to be no plausible ecological mechanisms that select for periods being prime numbers. This suggests that the explanation for prime-numbered periods, rather than just fixed periods, may reside in physiological or genetic mechanisms or constraints.
Environmental Entomology, 2006
Periodical cicadas (Magicicada spp.) are insects with a 13-or 17-yr life cycle that spend most of this time underground feeding on xylem from plant roots. In the 13th or 17th year of the life cycle, typically millions of cicadas emerge from the soil within a given area in near perfect synchrony. Factors controlling emergence, whether exogenous or endogenous, remain a mystery. By removing 13-yr periodical cicadas [Magicicada cassini (Fisher 1851)] from their natural environment in northwest Arkansas and controlling most exogenous factors in the laboratory, this study examined deviations or similarities in life cycle patterns compared with those occurring in nature. In a series of replicated experiments starting 9 mo before natural emergence in environmental chambers with constant light and temperature, we found that 14 of 60 nymphs associated with soybean (Glycine max L.) plants or cedar trees (Juniperus virginiana L.) successfully emerged in May 1998 in synchrony with the natural population from which they were removed. Seven of 10 nymphs feeding on a control cedar tree for 9 mo at the Þeld study site also emerged in May 1998. It seemed that all nymphs surviving 9 mo under laboratory conditions emerged during the period of natural emergence. Whether this represents endogenous control of emergence remains to be critically tested, but from data collected in this study, the internal timing of emergence seems to be set at least 9 mo before emergence.
The 1999 Emergence of the Periodical Cicadas in Ohio (Homoptera: Cicadidae: Magicicada spp. Brood V)
1999
The periodical cicadas belonging to Brood V emerged in 1999 over most of eastern Ohio. The emergence was widespread and heavy in the southeastern portion of the state and in Summit, Medina, and southern Cuyahoga counties. The brood is experiencing a recession along its western boundary, which is as much as 10 miles eastward from its 1914 western boundary. The brood is also declining in parts of Wayne, Holmes, Stark, and Tuscarawas counties. Ohio Biological Survey Notes 2: 43-47, 1999. © Ohio Biological Survey