![\"\"](\"..\/..\/attention\/Daphnia_retrocurva.jpg\")
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An email from a friend caused a chain of events that led me to a wonderful paper by Charles Kerfoot<\/a>, about resurrecting fossil eggs<\/a> from progressively deeper and older layers of sediment in a lake, and hatching the eggs from different layers to compare the creatures (Daphnia retrocurva<\/em>) as they evolve over time.<\/p>\n As these eggs are covered in sediment, they remain dormant (in facultative diapause<\/a>) for as long as 300 years or more (the paper only shows data going back to 1825).<\/p>\n In lakes that freeze over, sediments arrange in annual layers called varves<\/em>. They can be counted like tree rings. In addition to counting the annual layers, the sediments were also dated by Cesium, Potassium, Radium, and Lead radio-dating, which confirmed the dates done by counting.<\/p>\n The eggs from different layers were hatched, and the Daphnia (water fleas) that grew from them show differences in the body armor<\/a> over time as they adapted to evolving predators<\/a>. Genetic analysis also shows evolution, both in mitochondrial DNA, and in allozyme<\/em> analysis, where enzymes that differ only in their amino acid sequence show where specific mutations in a gene have ocurred.<\/p>\n By tracking the mutations as they accumulate in successive generations, further confirmation of the date sequences and evolutionary change<\/a> becomes visible.<\/p>\n Other eggs and fossil remains show how the predators of Daphnia evolve to keep up with defensive adaptations<\/a> by their prey.<\/p>\n By hatching dormant eggs from sediments laid down over hundreds of years, we can watch evolution progress right in front of our eyes<\/a>, in a complex crustacean, not just in bacteria<\/a> and viruses.<\/p>\n","protected":false},"excerpt":{"rendered":" An email from a friend caused a chain of events that led me to a wonderful paper by Charles Kerfoot, about resurrecting fossil eggs from progressively deeper and older layers of sediment in a lake, and hatching the eggs from different layers to compare the creatures (Daphnia retrocurva) as they evolve over time. As these […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[63,10],"tags":[64,66,67,65],"_links":{"self":[{"href":"https:\/\/scitoys.com\/sciblog\/wp-json\/wp\/v2\/posts\/54"}],"collection":[{"href":"https:\/\/scitoys.com\/sciblog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/scitoys.com\/sciblog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/scitoys.com\/sciblog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/scitoys.com\/sciblog\/wp-json\/wp\/v2\/comments?post=54"}],"version-history":[{"count":5,"href":"https:\/\/scitoys.com\/sciblog\/wp-json\/wp\/v2\/posts\/54\/revisions"}],"predecessor-version":[{"id":58,"href":"https:\/\/scitoys.com\/sciblog\/wp-json\/wp\/v2\/posts\/54\/revisions\/58"}],"wp:attachment":[{"href":"https:\/\/scitoys.com\/sciblog\/wp-json\/wp\/v2\/media?parent=54"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/scitoys.com\/sciblog\/wp-json\/wp\/v2\/categories?post=54"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/scitoys.com\/sciblog\/wp-json\/wp\/v2\/tags?post=54"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}