Cypress Trees Saw Rupturing of Earth’s Supercontinents
by Wynne Parry  /  04 May 2012

“More than 200 million years ago, Pangaea contained all the modern continents, squished up against one another. The separation of these continents isolated populations of living things, putting them on different evolutionary paths.  Scientists have already found evidence of the separation of the continents in the family histories of reptiles, amphibians and mammals. “Until now, there has been no equivalent evidence for any plant family,” writes an international team of researchers in a study published May 1 in the journal Proceedings of the National Academy of Sciences.

The cypress familyCupressaceae, a group of conifers with scalelike leaves, is believed to have originated more than 200 million years ago, when Pangaea was still intact, according to the researchers. By looking at changes in the DNA (deoxyribonucleic acid, the code that makes up genes) of 122 species of cypress, the researchers were able to reconstruct a timeline for their evolution. They also included fossil evidence in the analysis.

The most recently evolved subfamilies of cypress, Cupressoideae and Callitroideae, split from each other about 153 million years ago, as the two remnants of Pangaea pulled away from each other. The northern half, Laurasia, contained what would become North America, Greenland, Europe and much of Asia, while the southern half, Gondwana, would later become South America, Africa, India, Antarctica and Australia. The legacy remains. Living members of Cupressoideae occur mainly in former Laurasian continents, while Callitroideae are found on the fragments of what was Gondwana, write the researchers led by Kangshan Mao of Lanzhou University, China. Cypress are now found on all continents except Antarcticathey note.”

Cypress Tree Distribution Reflects the Breakup of Pangaea / May 3, 2012

“In classical mythology, the cypress tree is associated with death, the underworld and eternity. Indeed, the family to which cypresses belong, is an ancient lineage of conifers, and a new study of their evolution affords a unique insight into a turbulent era in Earth’s history. During the geological era known as the Mesozoic, the continental crust was concentrated in a single huge landmass, the supercontinent Pangea. Pangea began to break up about 150 million years ago, and the fragments drifted apart, eventually giving rise to the disposition of continents we know today. The progressive break-up of such a large landmass meant that existing groups of plant and animal species were split apart, and the descendant lineages then evolved in isolation from each other.

Dating divergence with the molecular clock
“Fossils show that the cypress family is a very ancient group of plants,” says LMU biologist Professor Susanne Renner, who is also Director of the Munich Botanic Garden. “We therefore suspected that it might be possible to follow their evolutionary history back to the period before the break-up of Pangea, as long as the many episodes of climate change and associated extinctions had not obscured things too much.” Renner and her research group therefore set out to reconstruct the cypress family tree, based on the comparison of specific gene sequences from 122 species belonging to 32 genera reflecting the family’s worldwide distribution. In order to date divergence events, they applied the concept of the molecular clock. The idea is based on a simple principle. When two lineages diverge from a common ancestor, each accumulates genetic substitutions independent from the other. To a first approximation, the number of unique substitutions provides a measure of the time that has elapsed since a species diverged from its sister species. By comparing the spectra of genetic changes found in different lineages and calibrating the amount of change with fossils, one can therefore reconstruct a group’s history.

Evolutionary dead ends
“Over the past 15 years, these molecular methods, in combination with new fossil finds, have revolutionized the study of biogeography, the branch of biology concerned with understanding the distribution patterns of animal and plant species,” says Renner. Some groups have turned out to be surprisingly young in evolutionary terms, others much older than people had assumed. The new study confirms that cypresses represent a very old plant family. Their origins can be traced back to Pangea, and the evolutionary divergence of the northern and southern subfamilies of cypresses actually reflects the break-up of Pangea about 153 million years ago. As fragmentation progressed and ancestral lineages were separated from each other, new lineages were established and followed separate evolutionary trajectories. The Cupressaceae is the first plant family whose evolutionary history gives us such a detailed picture of the break-up of a supercontinent.”

Susanne Renner

Burnt 3,500 Year Old Tree in Florida Is a Candidate for Cloning

“The January 16 burning of The Senator, an enormous cypress tree in Longwood, Florida, was much mourned, and rightfully so. At 3,500 years of age, it was one of the oldest trees in the world and the largest east of the Mississippi River. But the loss of the great tree does not have to be permanent, says a group dedicated to forestation. The Archangel Ancient Tree Archivewants to clone the Senator’s DNA to preserve and propagate the genetics of a one of nature’s greatest success stories.

When the tree burnt on January 16 of this year, arson was originally suspected, but investigators determined that it had actually burned from the inside out after being struck by lightning earlier in the month (updated: see below). Firefighters’ efforts to save the historic tree were unsuccessful. The Senator is survived by a neighboring cypress tree- Lady Liberty is a sprightly 2,000 years old. The non-profit Archangel Ancient Tree Archive mainly focuses on archiving the genetics of ancient redwoods. The oldest trees, they say, are the hardiest and most likely to survive- thus they are the best candidates for cloning.

Anthony Scotti/CC BY 3.0

In an August, 2011 TED talk, co-founder David Milarch summarized the group’s goals:

Our mission is to propagate, archive and help reforest the planet using clones of the world’s oldest, largest trees of each species that will have the greatest positive environmental benefit for the world, We’re collecting samples of the best of the best.

These ancient trees have an unbroken chain of natural selection for tens of thousands of years with a complete memory of how they were able to do what they are doing today…SURVIVE.

In a letter to the editor of the Orlando SentinelUS Lawns President Ken Hutcheson explained that a sample of the Senator was taken in the 1990s, but failed to yield a usable genetic replica. He called for a renewed effort to procure a sample from the burnt remains, in order to replicate the great tree, which was 125′ feet high (165′ until a 1925 hurricane chopped off its upper reaches) and had a circumference of 47′. A US Lawns press release quoted Milarch as agreeing: “There is a golden opportunity in this tragedy.”

If the tree were successfully cloned, it would only be another three millennia until Florida would be home to the fully mature Senator, 2.0. And if scientists are already working on reviving extinct woolly mammoths, why not trees as well?

Updated March 1: It turns out the Senator was not set on fire by a lighting strike, but by a woman smoking methamphetamine at its base. 26-year-old Sarah Barnes admitted to starting the fire and was arrested on February 28, reported WFTV.”

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