A joint team of researchers from Kyoto University and other institutions has partially uncovered why periodical cicadas simultaneously burst out of the ground every 13 or 17 years.<\/p>\n
Also known as \u201cprime-number cicadas\u201d in Japan, the various species that inhabit the eastern region of the United States were found to have growth cycles regulated by four-year intervals.<\/p>\n
The scientists said once a cicada exceeds a certain weight threshold in the year prior to molting and emerging\u00a0from underground as an adult, its vision-related genes kick in to prepare it for a fleeting life on the surface.<\/p>\n
Those species in the eastern United States spend exactly 13 or 17 years in the nymph state, and their mass appearance comprises\u00a0more than one species across each geographical area.<\/p>\n
Scientists speculate that they molt en masse partly to facilitate breeding and to defend themselves against birds and other predators.<\/p>\n
However, how exactly these bugs are able to measure time, synchronize when they molt and other specifics remain unknown.<\/p>\n
\u201cIt appears a certain mechanism of genetic control is at work to allow the cicadas to measure the four-year cycle accurately,\u201d said Teiji Sota, a Kyoto University professor emeritus of evolutionary ecology, who led the team. \u201cWe hope to do more gene analysis to find out more.\u201d<\/p>\n
The researchers hypothesized that certain changes take place in cicada nymphs after multiples of four years, or in the 12th year for 13-year cicada species and in the 16th year for 17-year cicada species.<\/p>\n
All go topside the following year, making both cycles multiples of four years plus one.<\/p>\n
To corroborate their hypothesis, the scientists began extracting\u00a0nymphs from the ground in 2019 for four years. They chose nymphs from four 17-year cicada broods that would molt in different years.<\/p>\n
Those collected were bred in a lab environment to study growth states and when gene expression took place.<\/p>\n
One notable instance of this\u00a0was a shift in eye color from white to red as the cicada nymphs developed sight before making their way aboveground.<\/p>\n
Among the nymphs collected, most of the 15-year-olds were white-eyed, but 97 percent of the 16-year-olds had turned red-eyed and had a mean body weight likely above the set threshold.<\/p>\n
The scientists also observed that gene expression tied to a nymph\u2019s ability to register light occurred at age 16, indicating it was developing sight.<\/p>\n
Twelve percent of the 12-year-old nymphs had exceeded the threshold weight level and their eyes turned red in preparation for molting, even though they belonged to 17-year cicada species.<\/p>\n
By contrast, only one 11-year-old, one 13-year-old, two 15-year-olds and none of the 14-year-olds exhibited red eyes.<\/p>\n
The team\u2019s research results were published on Aug. 27 in the British science journal Proceedings of the Royal Society B: Biological Sciences.<\/p>\n","protected":false},"excerpt":{"rendered":"A joint team of researchers from Kyoto University and other institutions has partially uncovered why periodical cicadas simultaneously…\n","protected":false},"author":3,"featured_media":232679,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[26],"tags":[125361,815,170,125360,50,159,67,132,68],"class_list":{"0":"post-232678","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-genetics","8":"tag-asahi-shimbun","9":"tag-genetics","10":"tag-japan","11":"tag-national-report","12":"tag-news","13":"tag-science","14":"tag-united-states","15":"tag-unitedstates","16":"tag-us"},"share_on_mastodon":{"url":"https:\/\/pubeurope.com\/@us\/115217077907706519","error":""},"_links":{"self":[{"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/posts\/232678","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/comments?post=232678"}],"version-history":[{"count":0,"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/posts\/232678\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/media\/232679"}],"wp:attachment":[{"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/media?parent=232678"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/categories?post=232678"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/tags?post=232678"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}