Tuesday, April 15, 2014

Neochrome evolution in ferns

Photo by Fay-Wei Li, via phys.org
Some very exciting new research on fern evolution was just published in the Proceedings of the National Academy of Sciences! Researchers have known for years that ferns possess a chimeric photoreceptor, called neochrome, that allows them to use both red and blue light for photosynthesis. This is a significant advantage in forest understories where blue light has often been filtered out by overhanging leaves of taller plants. In the new paper published yesterday, a team of researchers led by Fay-Wei Li at Duke has discovered that neochrome in ferns is actually most closely related to neochromes in hornworts, and that it likely passed from hornworts to ferns via horizontal gene transfer about 179 million years ago. The timing of this event suggests that this transfer, and the low-light photosynthetic ability it conferred on ferns, allowed them to subsequently diversify "in the shadow" of angiosperms, as the latter exploded in diversity starting around 120 million years ago. This is a really cool finding, and expands our understanding of fern evolution and diversification tremendously!

Check out more coverage of this story in the Economist:
Time and change: The survival of ferns to the present depended on an ancient accident

And at Phys.org:
Ferns borrowed genes to flourish in low light

And read the abstract of the paper here (subscription to PNAS required for full article):
Horizontal transfer of an adaptive chimeric photoreceptor from bryophytes to ferns

Saturday, April 12, 2014

Splinter Hill Bog: Sarracenia leucophylla

One of the most impressive plants we saw on our field trip to Splinter Hill Bog (see part I) was the white-topped pitcher plant, Sarracenia leucophylla. We arrived a bit too early for the height of its display; in a few weeks the whole bog will be solid with these pitchers. Nonetheless, it's a beautiful plant, and quite a few were already leafed out and in flower. The flowers of Sarracenia are beautiful and somewhat complex, and have evolved to maximize the chances of outcrossing by ensuring that pollinators first brush against the stigma with any pollen they may be carrying, then pick up new pollen, and finally exit without touching the stigma again, thereby hopefully avoiding self-pollination.


The remains of last season's dining 

Tuesday, April 8, 2014

Splinter Hill Bog, part I

This past weekend I went on a field trip to Splinter Hill Bog, near Perdido, Alabama, with friends and colleagues to find carnivorous plants. There are many great places to find plant carnivores in the Florida Panhandle and boggy areas to its west, but Splinter Hill boasts a diversity that few others can match: 5 species of Sarracenia (pitcher plants), 3 Drosera (sundews), 1 Utricularia (bladderwort), and 2 Pinguicula (butterworts). We managed to see a fair number of these including most of the pitcher plants and sundews, and Utricularia. Photos of those will follow in subsequent posts; here are some shots of the bog and assorted other flowering plants we encountered.
Flowers of Sarracenia leucophylla, the white-topped pitcher plant
The group, hunting pitcher plants
Pinus palustris, longleaf pine
Hellenium sp.
Polygala lutea, orange milkwort
Vaccinium corymbosum, highbush blueberry
Linaria sp.
Lycopodium alopecuroides
Pinus palustris, longleaf pine, after a burn

Sunday, March 30, 2014

Talk at Botany 2014

I will be giving a talk at the Botany 2014 conference this summer, which be held from July 26-30 in Boise, Idaho. I'll be talking about the fern mating system survey I've been posting about here for the last few months, which is a collaborative project with Weston Testo at the University of Vermont, and Rehman Momin and Eddie Watkins at Colgate University. You can check out our abstract here, and come to the talk if you're attending the conference! As usual, it looks like the Pteridological Section talks will be the absolute highlight of the week.

Tuesday, March 25, 2014

A slew of fern gametophytes

Our spore growing efforts are really paying off! The species we're growing are from a variety of sources, including the Royal Botanic Garden Edinburgh, the greenhouses at Colgate University, and the Duke University herbarium. The latter have proven a little challenging – it's difficult to collect viable spores from herbarium sheets! But we're having success with a number of species in many different families, and it's very interesting to see their various morphologies and growth rates. Quite a few have produced eggs and sperm, found mates (not hard on the crowded petri plates) and made new sporophytes. For the actual experiments, we're moving them to separate plates long before they develop reproductive capacity, so that we can determine whether they're able to self or must have another gametophyte to mate with.

Have a look at some of what we've got growing:
Ceratopteris richardii
Davallia pentaphylla
Davallia pentaphylla
Notholaena californica, already producing farina in the gametophytes and young sporophytes
Notholaena californica 
Pellaea sp., hard to see the gametophytes because of the little sporophytes!
Pityrogramma calomelanos 
Thelypteris sp., with healthy young sporophytes

Sunday, March 23, 2014

180 million year old fern fossil discovered

Photo from the Science paper, credit: Benjamin Bomfleur
Several Swedish biologists (from Lund University and the Swedish Museum of Natural History) have published a paper in Science documenting an exquisitely preserved, 180 million year old fern fossil! The Jurassic-era fossil is a member of the family Osmundaceae, which includes modern taxa like cinnamon fern (Osmundastrm cinnamomea), royal fern (Osmunda regalis), and interrupted fern (Osmunda claytoniana), all of which are widespread in the temperate northern hemisphere (and are pictured below). The fossil's exquisite preservation is attributed to rapid burial during volcanic activity.

It has long been known that modern members of Osmundales don't vary much morphologically compared to ancient forms – fossilized members of the order dating to the early Mesozoic (ca. 220 million years ago) are remarkably similar in several aspects of their morphology to modern species. The new fossil goes a step further: it contains intact cells, and even individual chromosomes, that the researchers were able to visualize with various types of microscopy. The fossil species had the same number of chromosomes and roughly the same predicted DNA content in the nucleus as modern cinnamon fern. This suggests that the lineage has not experienced significant upheaval in DNA content, through whole-genome duplication (polyploidy) or extensive gene loss, in the last 180 million years. The authors note that to date, most of what we know about ancient fern genome size is due to extrapolation from living taxa; this new fossil has permitted the first direct observations of paleo-DNA content in a fern.

Coverage of the new fossil online:
From Lund University
From Phys.org

The paper (requires a subscription): Bomfleur, B., S. McLoughlin, and V. Vajda. 2014. Fossilized nuclei and chromosomes reveal 180 million years of genomic stasis in royal ferns. Science 343: 1376–1377.

If you want to read more about relationships of Osmundales (also requires a subscription): Metzgar, J.S., J.E. Skog, E.A. Zimmer, and K.M. Pryer. 2008. The paraphyly of Osmunda is confirmed by phylogenetic analyses of seven plastid loci. Systematic Botany 33: 31-36.

Osmundastrum cinnamomea 
Osmunda regalis
Osmunda claytoniana

Saturday, March 15, 2014

UF campus plants, part V

More photos from walks around the UF campus with Walt Judd (see part I for more information). This walk was on March 13, 2014 at UF's Natural Area Teaching Lab.
Acer negundo
Quercus nigra
Acer negundo
Thelypteris sp.
Rumex crispus
Rumex crispus
Prunus caroliniana
Pinus sp. 
Rubus trivialis
Stachys floridana
Tradescantia ohioensis