North American Dryopteris pubs

I'm thrilled to announce that a final version of the third chapter of my PhD thesis, which was published in provisional proof version months ago, has finally been posted on the journal's website, BMC Evolutionary Biology. If you're interested in reading about the evolutionary history of the fern genus Dryopteris in North America, you can find the paper here (or here's a direct link to the PDF). BMC is a collection of open-access journals, so you can download the paper for free. If you're really interested in Dryopteris and either feel like paying for articles or are associated with a university and have library access, you can find the papers corresponding to my chapters 1 and 2 online as well. You can also email me at sessa DOT emily AT gmail DOT com and I'll be happy to send you reprints (are they called that anymore if they're not actually printed out?). Here are links to the full set of what's published thus far:

• Phylogeny, divergence times, and historical biogeography of New World Dryopteris (Dryopteridaceae) (= ch. 1). Sessa, Zimmer, Givnish 2012 AJB 99(4): 730.
• Reticulate evolution on a global scale: A nuclear phylogeny for New World Dryopteris (Dryopteridaceae) (= ch. 2). Sessa, Zimmer, Givnish 2012 MPE 64(3): 563.
• Unraveling reticulate evolution in North American Dryopteris (Dryopteridaceae) (= ch. 3). Sessa, Zimmer, Givnish 2012 BMC Evol Biol 12: 104.

I'm proud of each of these papers for different reasons, but this third one is probably my favorite, because it tells the story that got me interested in Dryopteris in the first place. This group in North America has been suspected of having undergone reticulate evolution via allopolyploidy ever since botanists started looking at them over a hundred years ago, and many hypotheses have been suggested to explain the relationships among the 13 species on this continent (see Figure 1). 

The most widely accepted of these theories involves a missing, putatively extinct diploid ancestor of several of the allopolyploids, but no one had ever tested this using DNA sequence data. Figure 6 from the paper summarizes the results of my analyses, which unequivocally supported this hypothesis, known as the "D. semicristata" hypothesis after the missing ancestor.

I also included a figure showing the range maps of these taxa up above, because the final pieces of my PhD puzzle focus on transgressive trait expression and physiological ecology of these ferns. Hopefully you can see in the maps that several of the allopolyploids have ranges that are transgressive relative to one or both parents - meaning their ranges extend beyond those of their parents. This suggests that the polyploids, which are hybrids between those parental species that then underwent whole genome duplication, likely possess some physiological or morphological features that are distinct from the parents and that have allowed them to expand their ranges and coexist at a regional level with their progenitor species. The two final papers resulting from my PhD explore these ferns' physiology using field and common garden experiments. The first is in review right now, and the second awaits publication of the first. Stay tuned for more news about that in the coming months.

Gender Gap in Science Publishing

My friend and fellow blogger Dr. Budke over at Moss Plants and More has a great post today about a study on gender in academic publishing. The research group conducting it, at the University of Washington, have access (via the archive JStor) to almost 8 million scholarly papers in a number of academic fields, from evolution to anthropology to law to classics. They decided to use this database to study gender differences in academic publishing, and have built two really excellent online viewers that allow you to peruse the data, broken up by time period and field, and showing the percentage of papers that include female authors. You can also see what percentage have women as first and last authors (the two most important author positions in academic publishing).

The data are really fascinating, and I'm happy to observe that the overall trend as you move through the three time periods (going from 1665-1970 to 1971-1990 to 1991-2010) is one of increasing female participation in publishing over all fields. The increase in the most recent two decades, compared to the 1971-1990 timeframe, is particularly impressive. What's most fun, though, is that they break things down quite finely into discipline and subdiscipline - so, for example, within the Ecology & Evolution category, there's a subcategory for Ferns! The "All years" percentages of female authors for the category and subcategory, respectively, are 18.5% and 19.7%, but within the last two decades they've risen to 22.8% and 25.9%. So fern biology publications have tended to have more female authors than the general evolution category, but we've pulled a bit further ahead in the last 20 years or so. Pretty cool! And since it was Jessica's post that alerted me to this dataset in the first place, I have to acknowledge that her field, Bryophytes, is even closer to gender parity in its publishing than we fern folks - they're at 34.1% female authors over the last two decades. Way to go Moss Plants and your people!

You can explore the data in a variety of ways at these two sites:
Women as Academic Authors, 1665-2010
Gender composition of scholarly publications (1665-2011)

Berry Go Round #56

I forgot to mention that my post on the new fern genus Gaga was included in the November issue of Berry Go Round over at Seeds Aside! Go check it out for more great plant-focused blogging content this month!

Ferns of the Central Amazon

A while back I posted about the Portuguese word samambaia, which means 'fern'. I thought about this lovely word again yesterday when a speaker in our weekly evolution seminar series mentioned a group of guides that have been published for various plant groups in the Amazon - including the ferns!

This fern key is fantastic. It covers 125 taxa found in the central Amazon of Brazil, in the Reserva Biológica do Uatumã, an almost one million hectare reserve that was built in response to the construction of a dam that had pervasive environmental impacts in the region. It is located in the northeastern corner of the state of Amazonas, not too far from Manaus. The reserve is now a resource for research and education.

Map from the Institute for Conservation and Sustainable Development of Amazonas

The fern guide is very comprehensive, and has a built in key that will allow you to use almost any feature of the plant that might be available to you, including habit, various features of the sori, and a number of characteristics of either the sterile or fertile fronds (which happily are separate categories - these folks really know ferns!).

Identification key to the ferns of Uatumã

In addition to this interactive key (which is a Java app), there are also two beautiful PDF guides that you could print out for your next Amazonian adventure. One is a PDF version of a gorgeous book, which I happened to pick up a hardcopy of at a conference a few years ago, called Guide to the Ferns and Lycophytes of Rebio Uatumã (below left). The other is a grid of photos of common ferns in the Reserve (below right). The latter would be more amenable to printing and laminating for a visit to the rainforest.

  

If you're interested in guides to other plant groups in Brazil, check out the website of the Brazilian branch of PPBio. PPBio is the Program for Planned Biodiversity and Ecosystem Research, which operates in Brazil and elsewhere. The site is in Portuguese, but the guide page has cover photos for each group that you can use to find what you're looking for. In addition to ferns they have guides for Zingiberales, Fabaceae, and also lizards.

Selaginella

I often post about non-ferns here, especially if I have particularly nice flowering plant photos I'd like to share, but today we shift to another lineage entirely: the often overlooked lycophytes! Lycophytes used to be called "fern allies" because the relationships between these two and the other groups of land plants weren't well understood. Now we know that lycophytes are the sister group to ferns plus angiosperms and gymnosperms, meaning that ferns are more closely related to conifers and flowering plants than they are to lycophytes. Lycophytes are equally related to all three, because they share a common ancestor with all of those three groups, before their three lineages diverged. Here's a family tree of the major land plant lineages that might clarify things:

(UPDATE, 8/6/13: Since posting this phylogeny figure over a year and a half ago, I've seen several colleagues use it in talks. I'm tickled by this, but it has also made me uneasy about the lack of attribution here for the images I used in the figure. I scavenged all seven of the images from the internet, and at this distance I've been unable to relocate the liverwort, hornwort, and lycophyte drawings; I think I recall that they are old enough to be in the public domain. Here is all the information I have about each of the other drawings and where I found them, and I am grateful to all of these artists for their wonderful work. Mosses: Moss, Watercolor, by Maria Alice De Rezende, Brazil. Ferns: Polypodium vulgare, Illustration from Scandinavian Ferns by Benjamin Øllgaard and Kirsten Tind, Rhodos, 1993. Gymnosperms: Pseudotsuga menziesi, by Brigid Edwards, Shirley Sherwood Collection. Angiosperms: Clematis 'Cezanne', watercolor, Karla Beatty.)

On our field trip to Organ Pipe a few weeks ago, we were after lycophytes, particularly members of the genus Selaginella. These are often called "resurrection plants" because of their ability to dry down when water becomes scarce and then rapidly rehydrate when the rains return. Here's a great video, made by a fern colleague, Fernando Matos, showing a Selaginella "coming back to life":

The ones that we found haven't quite gotten to resurrecting yet... it's pretty dry out there right now. You might not notice them at first, because they're quite diminutive and rather crinkly and dried up, but once you know what to look for, you'll find that you're surrounded by a carpet of Selaginella in many of the rocky, desert-y areas around here. The lower photos here demonstrate that:

This is the type of habitat we found these guys in, rocky upslope and surrounded by various grasses, cacti, cholla, and other typical desert plants:

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Desert ferns

Finally, some fern sightings here in the desert! These come to you courtesy of Organ Pipe National Monument, located in the far southwestern corner of Arizona. I took a field trip there with my lab last week, in search of Selaginella (which will be the focus of my next post), and we also came across two ferns growing cheek-by-jowl with those little lycophytes. My desert fern ID skills are not (yet!) great, so these might be off. If anyone recognizes either of these, please leave a note in the comments. 

First up we have an Astrolepis species, possibly A. cochisensis:

 And next we have, I'm pretty sure, Notholaena standleyi:

These guys may not look like much, but they are doing exactly what ferns (or any plants, for that matter) in the desert should be doing: trying to conserve water. They are xerophytes, plants that are adapted to places where there is very little moisture. And they are nicely demonstrating several of the adaptations that ferns around here have for dealing with this. For example, the Astrolepis is quite furry, and those little hairs serve two purposes: they shade the leaf a bit, and they help trap any moisture that becomes available, from rain, dew, or a particularly humid day. The Notholaena is employing a different strategy. It has curled up, reducing surface area, and is probably dormant and waiting for the next rains to arrive. Other desert ferns have farina, a waxy or grainy covering on one or both leaf surfaces that reflects light and prevents evaporation. 

There are some nice resources available online if you're interested in cultivating or identifying desert ferns, or learning more about their xerophytic adaptations. There's a nice list of southern Arizona ferns, complete with illustrations, and from the same source, a page about desert fern adaptations.

Finally, here are some views of the lovely Organ Pipe terrain around where we found these ferns... and of course the eponymous cactus itself: