{"id":24643,"date":"2023-10-13T13:40:35","date_gmt":"2023-10-13T07:55:35","guid":{"rendered":"https:\/\/www.revoscience.com\/en\/?p=24643"},"modified":"2023-10-13T13:41:24","modified_gmt":"2023-10-13T07:56:24","slug":"200-year-old-dna-helps-map-tiny-flys-genetic-course-to-new-lands-modern-times","status":"publish","type":"post","link":"https:\/\/www.revoscience.com\/en\/200-year-old-dna-helps-map-tiny-flys-genetic-course-to-new-lands-modern-times\/","title":{"rendered":"200-year-old DNA helps map tiny fly\u2019s genetic course to new lands, modern times"},"content":{"rendered":"

By Chris Barncard<\/p><\/div><\/div>\n\n\n

MADISON \u2014 Back when the biggest fly enthusiasts of 19th century Sweden \u2014 Carl Fredrik Fall\u00e9n, for one, and later Johan Wilhelm Zetterstedt \u2014 were collecting insects for what would become Lund University\u2019s entomological collections, they wondered exactly what was that buzzing coming from their can of raisins.<\/p>\n\n\n\n

Skip forward 200 years, and the humble fruit fly, known better to geneticists as Drosophila melanogaster, is one of the most thoroughly studied animals on the planet. And DNA from Fall\u00e9n and Zetterstedt\u2019s centuries-old curiosities are still revealing new insights into the fly\u2019s evolution as it spread alongside people to new parts of the world.<\/p>\n\n\n\n

\"\"
This fruit fly, or Drosophila melanogaster, was collected in Europe around 1933 and added to the entomological collection at Lund University. UW\u2013Madison researchers are using its DNA \u2014 with more from ancestors collected in Europe as far back as the first decades of the 1800s \u2014 to round out the genetic history of one of the planet\u2019s most thoroughly studied animals. Image by Marcus Stensmyr, Lund University.<\/em><\/figcaption><\/figure>\n\n\n\n

Researchers from the University of Wisconsin\u2013Madison and Lund University extracted and analyzed DNA from fruit flies housed in museum collections in Lund, Stockholm and Copenhagen. The flies are museum specimens collected by naturalists in Europe as early as the first decade of the 19th century and as recently as the 1930s.<\/p>\n\n\n\n

The early fly-finders considered any insects they could get their hands on worth keeping \u2014 Fall\u00e9n\u2019s specimens indeed include some that appear to have been enjoying his raisins \u2014 but they probably couldn\u2019t have conceived of Drosophila\u2019s importance to science.<\/p>\n\n\n\n

\u201cThis species has been a key player in basic biological science for well over a century now,\u201d says John Pool, UW\u2013Madison professor of genetics. \u201cWe’ve turned to it to learn things about the basic rules of life, what genetic variation looks like in natural populations, how different evolutionary forces shape diversity. And that\u2019s just in my field.\u201d<\/p>\n\n\n\n

That means the genes of fruit flies may have been sequenced, catalogued and described more often than any other animal. But those samples came from modern specimens. Because a fruit fly lives about 50 days, the new DNA samples \u2014 described in a study published today in the journal PLOS Biology \u2014 come from some very ancient relatives of the flies buzzing around our fruit bowls these days.<\/p>\n\n\n\n

\u201cIt\u2019s not so unusual to get useful DNA from very old specimens of our hominid ancestors or other animals,\u201d Pool says. \u201cBut the number of generations \u2014 about 3,000 \u2014 that have elapsed in fly populations since some of these we\u2019ve sequenced were alive is about the same number of our generations since humans emerged from Africa.\u201d<\/p>\n\n\n\n

Lund zoologist Marcus Stensmyr recovered genetic material from the museum flies by soaking them in a solution that breaks open cell membranes to free up large molecules inside. The flies were washed and dried and returned to the museum collection. Their DNA was extracted from the solution and analyzed at UW\u2013Madison.<\/p>\n\n\n\n

Surprisingly, the researchers found the fruit flies collected in Sweden in the early 1800s were more genetically similar to 21st century flies than the Swedish samples from the 1930s. That\u2019s likely due to the older flies\u2019 place in Drosophila history as some of the first arrivals so far north of their original range in Southern Africa. For some time, they were a small outpost, in which random mutations would make larger differences in the population \u2014 more of what\u2019s called \u201cgenetic drift\u201d \u2014 as the 1800s became the 1900s. Swedish flies would get less unique, though, when their numbers were reinforced from the broader European gene pool.<\/p>\n\n\n\n

\u201cThere would have been a vast increase in fruit shipping between the 1930s and the present and, generally, more human transport that probably increased opportunities for longer distance Drosophila migration,\u201d Pool says. \u201cSo, what we think we are seeing between the 1930s and the present is the effect of that migration basically homogenizing genetic variation.\u201d<\/p>\n\n\n\n

By comparing changes across the centuries of fly samples now at their disposal, the researchers also identified a handful of genes showing signs of evolutionary pressure.<\/p>\n\n\n\n

\u201cThat was a key interest of our study, to try to figure out which genes may have been the most important in helping this fly population adapt to very novel climate and a novel environment,\u201d Pool says.<\/p>\n\n\n\n

Differences between DNA from 1930s specimens and their present-day kin revealed the emergence of a gene called Cyp6g1 that\u2019s known now to make the flies more resistant to the pesticide DDT.<\/p>\n\n\n\n

\u201cThat was our top result for the more recent time interval,\u201d Pool says. \u201cAnd that made perfect sense, in terms of when DDT was introduced.\u201d<\/p>\n\n\n\n

That would be in the 1940s, not long after the study\u2019s most recent museum sources of Drosophila were still airborne. Earlier than that, important genetic shifts show a gene called Ahcy aiding the 19th century flies\u2019 adaptation to cooler temperatures and shorter days \u2014 important factors in the fly\u2019s reproductive cycles \u2014 in Sweden (and other high-latitude homes).<\/p>\n\n\n\n

Another gene, ChKov1, was thought to be insecticide-related, but DNA from museum flies collected in the 1800s showed that the gene evolved before the relevant insecticides were even invented. Previous work by other researchers had suggested ChKov1 also conferred resistance to a virus, called sigmavirus, believed to have appeared in flies about 200 years ago.<\/p>\n\n\n\n

\u201cOur results strongly favor the viral resistance hypothesis over the insecticide resistance hypothesis,\u201d Pool says. \u201cSo, that\u2019s an example of a gene that was already suggested to be under natural selection, but we learned some new things about it by having these temporal samples.\u201d<\/p>\n\n\n\n

It\u2019s a testament to both the work done long ago by curious scientists breaking new ground in their field and present-day practitioners using modern technology to much the same effect.<\/p>\n\n\n\n

\u201cThis is an example of what millions of museum specimens all around the world could tell us about the changes that have taken place in many different species,\u201d says Pool<\/p>\n","protected":false},"excerpt":{"rendered":"

Researchers from the University of Wisconsin\u2013Madison and Lund University extracted and analyzed DNA from fruit flies housed in museum collections in Lund, Stockholm and Copenhagen.<\/p>\n","protected":false},"author":2,"featured_media":24645,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3,17],"tags":[],"class_list":["post-24643","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-news","category-research"],"featured_image_urls":{"full":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2023\/10\/Drosophila-melanogaster.jpg",1200,842,false],"thumbnail":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2023\/10\/Drosophila-melanogaster-200x200.jpg",200,200,true],"medium":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2023\/10\/Drosophila-melanogaster-570x400.jpg",570,400,true],"medium_large":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2023\/10\/Drosophila-melanogaster-768x539.jpg",750,526,true],"large":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2023\/10\/Drosophila-melanogaster-675x474.jpg",675,474,true],"1536x1536":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2023\/10\/Drosophila-melanogaster.jpg",1200,842,false],"2048x2048":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2023\/10\/Drosophila-melanogaster.jpg",1200,842,false],"ultp_layout_landscape_large":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2023\/10\/Drosophila-melanogaster-1200x800.jpg",1200,800,true],"ultp_layout_landscape":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2023\/10\/Drosophila-melanogaster-870x570.jpg",870,570,true],"ultp_layout_portrait":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2023\/10\/Drosophila-melanogaster-600x842.jpg",600,842,true],"ultp_layout_square":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2023\/10\/Drosophila-melanogaster-600x600.jpg",600,600,true],"newspaper-x-single-post":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2023\/10\/Drosophila-melanogaster-760x490.jpg",760,490,true],"newspaper-x-recent-post-big":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2023\/10\/Drosophila-melanogaster-550x360.jpg",550,360,true],"newspaper-x-recent-post-list-image":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2023\/10\/Drosophila-melanogaster-95x65.jpg",95,65,true],"web-stories-poster-portrait":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2023\/10\/Drosophila-melanogaster.jpg",640,449,false],"web-stories-publisher-logo":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2023\/10\/Drosophila-melanogaster.jpg",96,67,false],"web-stories-thumbnail":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2023\/10\/Drosophila-melanogaster.jpg",150,105,false]},"author_info":{"info":["By Chris Barncard"]},"category_info":"News<\/a> Research<\/a>","tag_info":"Research","comment_count":"0","_links":{"self":[{"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/posts\/24643","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/comments?post=24643"}],"version-history":[{"count":3,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/posts\/24643\/revisions"}],"predecessor-version":[{"id":24648,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/posts\/24643\/revisions\/24648"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/media\/24645"}],"wp:attachment":[{"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/media?parent=24643"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/categories?post=24643"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/tags?post=24643"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}