Why Evolution is True is a blog written by Jerry Coyne, centered on evolution and biology but also dealing with diverse topics like politics, culture, and cats.
I have gone into the lab to find that my Paphiopedilum orchid has bloomed. I’m pretty sure this is not a hybrid, but a real, naturally-occurring species; sadly, I forgot the species name, but I’m sure Lou Jost or someone else will tell me, and perhaps give a bit of information about the flower:
Once a year I get this flower, which lasts for about ten days. Lovely, ain’t it?
I won’t go on about this cool new paper at length, for it’s already been described by Ed Yong at Not Exactly Rocket Science as well as in a piece at The New York Times. Still, it behooves us to know about it. The upshot is that a group of Russian scientists recovered from the Siberian permafrost a cache of seeds and fruits stashed by ancient squirrels, and managed to use tissue culture to regenerate plants from immature fruits. The estimated age of the seeds is 32,000-30,000 years old, so this is clearly the most ancient organism ever “revived.”
The plant, a species that still exists (at least the morphological similarities suggest conspecific status), is Silene stenophylla. Silene (of which there are several species) is also known as “catchfly” or “campion” (literate readers will recognize it as the flower with which Mellors the gamekeeper bedecked Lady Chatterly’s pubic hair in Lady Chatterly’s Lover). It’s often used in evolutionary studies because some species have separate sexes while others do not, and ditto for sex chromosomes. It could thus tell us something about the evolutionary origin of gender and gender-specific chromosomes. Some species are also gynodioecious (i.e. some plants are “female” [male parts sterile], while other plants are hemaphroditic), and this could also give us a clue to how “male” versus “female” plants arose.
But I digress. In a new paper published in the Proceedings of the National Academy of Sciencesby Svetlana Yashina et al., the authors describe finding a group of fossil burrows, 20-40 meters below the surface, in the permafrost of northeastern Siberia. Some of these burrows contained as many as 600,000 seeds/fruits! These were stashed by equally ancient ground squirrels of the species Urocitellus parryii:
Permafrost provides the dry and cold conditions needed to preserve seeds; that’s how they’re preserved in special seed banks. Attempts to germinate the seeds failed, but they managed to grow one species of Silene by dissecting out the “placental tissue” (special tissue in the fruit to which the seed is connected), culturing it in nutrient media and then adding hormones (auxins, etc.), to induce formation of roots and shoots. And they got the plant to grow, flower, and, after cross fertilization with other ancient plants, set seed. Here are two specimens of the plant grown from cultured ancient tissue:
The two articles cited above will give you more information. What interests me most about this is that the “species” still exists, and this allows us to see how much evolutionary change has transpired in 30,000 years. (This is similar to the way that bacterial evolutionists can freeze an ancestral culture and then, after reviving it, compare it to its descendants that have undergone many generations of evolution).
The plant appears to have actually changed during those 30,000-odd generations. (This is probably genetic rather than environmental change because the differences between ancient and modern plant are seen in the second generation of cultured ancient plants which have been produced by cross-mating them.) The authors note the differences:
Thirty-six ancient plants (12 from each fruit) and 29 extant plants were morphologically tested. All ancient plants were morphologically identical. During vegetative development, the ancient and extant plants were morphologically indistinguishable from one another. However, at the flowering stage they showed different corolla shape: petals of extant flowers were obviously wider and more dissected (Fig. 3). Moreover, all flowers of the extant plants were bisexual (b) (Fig. 3A), whereas the primary flowers (two to three in number) of each ancient plant were strictly female (f) (Fig. 3 B and C, f), and then bisexual flowers were formed on each ancient plant (Fig. 3C, b).
For those botany geeks among us, here’s Figure 3 showing the differences (click to enlarge):
The one thing I really wanted to know, and which the authors didn’t study, is whether the ancient plants are reproductively compatible with the modern ones. They crossed ancient plant with ancient plant, and showed that they cross readily, as of course do modern plants crossed with modern plants. But they didn’t cross ancient plants with modern ones! They need to do that.
If they found reproductive incompatibility in those crosses, that would suggest incipient (or full) speciation between ancestor and descendant, something that we rarely get to study because ancestor and descendants never get the chance to meet and mate (this would be like mating the 750,000 year old ancestors of Homo sapiens with modern H. sapiens, since a comparative number of generations have transpired). And even if reproductive isolation didn’t evolve, one can still study the genetic basis of differences in petal shape and appearance of different kinds of flowers. Ten to one the Russian team is doing this, and I look forward to the results.
h/t: Dr. John H. Willis III, esq.
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You’d think that Darwin’s Beagle collections had been pretty well worked over, but it turns out that we didn’t even know everything that Darwin collected. According to the Associated Press, Howard Falcon-Lang, a paleobotanist at the University of London, found a cache of 314 slides of specimens collected not only by Charles Darwin, but by his colleague Joseph Hooker and by John Henslow, Darwin’s college mentor. The specimens were apparently misplaced because Hooker forgot to catalog them before he took off on a field trip to Asia. They appear to all be thin sections of fossil plants.
Imagine opening a dusty old cabinet and finding something like this:
That’s one of the specimens, and yes, that’s CD’s signature. What is it?:
This image made available by the Royal Holloway, University of London on Tuesday Jan. 17, 2012 shows a polished section of a 40-million-year-old fossil wood collected by Charles Darwin in 1834 on Chiloe Island, South America in the course of his famous “Voyage of the Beagle.” British scientists have found scores of fossils the great evolutionary theorist Charles Darwin and his peers collected but that had been lost for more than 150 years. Dr. Howard Falcon-Lang, a paleontologist at Royal Holloway, University of London, said Tuesday that he stumbled upon the glass slides containing the fossils in an old wooden cabinet that had been shoved in a “gloomy corner” of the massive, drafty British Geological Survey. (AP Photo/Royal Holloway, University of London, Kevin D’Souza Ho)
“It took me a while just to convince myself that it was Darwin’s signature on the slide,” the paleontologist said, adding he soon realized it was a “quite important and overlooked” specimen.
He described the feeling of seeing that famous signature as “a heart in your mouth situation,” saying he wondering “Goodness, what have I discovered!” . .
(I wouldn’t have used the word “Goodness!”)
Falcon-Lang added:
“To find a treasure trove of lost Darwin specimens from the Beagle voyage is just extraordinary,” Falcon-Lang added. “We can see there’s more to learn. There are a lot of very, very significant fossils in there that we didn’t know existed.”
Falcon-Lang expects great scientific papers to emerge from the discovery.
“There are some real gems in this collection that are going to contribute to ongoing science.”
Well, maybe, though my guess would be that they’d contribute more to the history of science than to ongoing research. We shall see.
On the way to Biolley in the mountains of Costa Rica, my colleague, botanist Judy Stone, pointed out this magnificent specimen of Bursera simaruba, also known locally as indio desnudo, or the “nude Indian” tree. The name certainly derives from its reddish bark and the fact that it’s semi-deciduous, shedding its leaves completely before producing new ones.
The tree is found throughout tropical America, including the southeastern U.S., where it’s called the “gumbo-limbo tree”.
This specimen is nearly in the desnudo stage. Click to enlarge.
The tree has important medicinal uses for the locals, and is used to treat skin problems, digestive disorders, and infections.
I won’t often post single pictures from my trip to Costa Rica (I plan on doing posts with multiple photos), but this magnificent tree didn’t fit in anywhere.