The Paradox of Cryptic Species

A cryptic species is quite the paradox. If it is cryptic, how do you identify it as a species?

Well with cryptic species there is usually a hint. A tickle at the back of your brain. Maybe it is a species with wide morphological variation or a complex distribution that makes you wonder whether there are additional species hiding within. 

Many cryptic species are uncovered when molecular data is used to examine the relationships between species. Members of a cryptic species may seemingly look the same, but not be each other's closest relatives. And thus the real adventure begins.

Medina, R; Lara, F; Goffinet, B; Garilleti, R; Mazimpaka, V. 2012. Integrative taxonomy successfully resolves the pseudo-cryptic complex of the disjunct epiphytic moss Orthotrichum consimile s.l. (Orthotrichaceae) Taxon 61:1180-1198.

The star of the show Orthotrichum consimile.  Figure 2B from Medina et al. 2012

In this paper Dr. Rafael Medina and coauthors undertook an exploration of the moss species Orthotrichum consimile and uncovered four cryptic species hiding within. They carried out this research using the process of reciprocal illumination. They first made a detailed morphological examination of many specimens from across the range of O. consimile and detected three different morphotypes (A, B, C). Basically they were able to group the specimens into three piles based on their appearance. These observations set the stage for their molecular analyses. They then extracted DNA from representatives of each morphotype and used portions of their genetic code to build a phylogenetic tree to test the relationships between the samples. They found that the morphotypes were placed into four distinct clades (monophyletic groups). The members of A and B were each in their own clade, whereas the members of C came out in two separate clades (C1, C2). They then re-examined the specimens of group C to see if there were any features that could be used to tell them apart. After closer inspection, they found that there were a few small, but detectable differences between the specimens in C1 and C2. Thus, the morphology and molecular data were reciprocally illuminating.Based on the molecular phylogeny and the morphological differences they describe four Orthotrichum species. A more restricted Orthotrichum consimile, O. columbicum, O. confusum (this is my favorite specific epithet of the bunch!), and O persimile. 

I think that this study is a great example of morphological and molecular research complementing each other to address a question of species relationships. With morphologically austere lineages (Bickford et al. 2007), such as bryophytes, the challenge of teasing apart cryptic species may seem daunting. However, this study of Orthotrichum shows that when a systematic and detailed approach is used, uncovering cryptic species is possible even in the morphologically austere mosses.

If you are interested in reading more about Dr. Medina's research or downloading a pdf of this paper check out his page on Academia.edu. 

Medina, R, Lara, F, Goffinet, B, Garilleti, R, & Mazimpaka, V (2012). Integrative taxonomy successfully resolves the pseudo-cryptic complex of the disjunct epiphytic moss Orthotrichum consimile s.l. (Orthotrichaceae) Taxon, 61 (6), 1180-1198

February 2013 Desktop Calendar

My California moss explorations have started close to home. This is an Orthotrichum growing on the tree in my back yard. Some of the other tufts had small sporophytes topped by plicate calyptrae (calyptrae with folds). Unfortunately they resisted my photography efforts, but this little patch without sporophytes came out well.  

1 - Single click on the image to open it up in a new window. (If you use the image directly from the blog post you will lose a lot of resolution.)

2 - Right-click (or ctrl-click) on the image, and chose the option that says, "Set as Desktop Background" or "Use as Desktop Picture". The wording may vary.

3 - If the image does not fit your desktop neatly, you may have to adjust the image (Mac: System Preferences - Desktop and Screen Saver - Desktop; Windows: Control Panel - Display - Desktop) and choose "Fill screen" as the display mode of your background image.

Mosses at the Aspetuck Land Trust

Here are some photos from the Moss Workshop that I led at the Aspetuck Land Trust at Trout Brook Valley, CT in May. It was a fun group and we got to see quite a few great plants. 

Thanks to Heather Williams for helping to organize the workshop. Also thanks to the gal who took and sent me these photos. I can't recall her name at the moment. 

Passing out hand lenses and ID sheets before the walk.

 Scraping a moss off a rock. Probably an Orthotirchaceae. And now let me tell you about it. 

(At least my mouth wasn't gaping open mid-sentence.)

 Using a hand lens.

Winter Mosses

A friend of mine recently moved to Virginia and on a hike in the Shenandoah National Park she spotted some mosses growing on boulders in the winter snow. Since I still have not taken any moss photos this winter, I decided to share hers on the blog.

This rock looks to have some type of Orthotrichaceae with brown sporophytes left over from last season. There also appears to be some Dicranum sp. in the lower left of the photo. These are just my best guess given what I can make out from the photo.

For this photo I am not sure what type of moss is in the lower center of the photo. Would anyone like to hazard a guess? As for the large patch of lighter green moss, I would bet money that is a species of Thuidium.

Thanks for sending the photos Em!

Some More Mosses from Japan

While in Japan I traveled to the small town of Nozawa Onsen. It is about an hour north of Nagano, via train and then bus. Nozawa is nestled in the mountains and is famous for the many onsen (hot springs) that dot the village. I hear that it is also a great place to ski and we saw many ski lifts heading up into the surrounding mountains. While walking around town we visited a shrine that was surrounded by moss.

However, I did not collect any mosses. I am not sure what the karma impact might be from collecting moss from the grounds of a shrine. So I just took some pictures instead.

The photo to the right is a member of the Orthotricaceae. All of the little tan/brown structures are the sporophytes. The Orthotricaceae are recognized by their short sporophytes with upright capsules. Typically they grow on tree bark or rocks and have dark green gametophytes that can sometimes appear black when dry.

Sculptures on the grounds of the shrine were covered in mosses!

These a a couple of shots of some Fissidens sp. Members of this genus have a really gorgeous morphology! The leaves do not spiral around the stem as in most mosses. In Fissidens they have a distichous leaf arrangement, meaning that they are positioned 180 degrees opposite each other on the stem. It is the same leaf arrangement that you see in Iris plants. This distintictive pattern of leaves makes mosses in the genus Fissidens stand out from other species in the field.

Mosses with Moving Teeth

We had a couple classes in the Evolution of Green Plants laboratory that I am teaching which focused on mosses. During lab we looked at some mosses that have arthrodontous peristome teeth. (arthro- meaning joint & -dontous referring to teeth) The joints and thickenings of the cell walls enable the teeth in many mosses to move in response to changes in humidity. In the species shown here, the teeth are closed when wet and open when dry. This allows the spores to be dispersed from the capsule when the conditions are optimal for them to fly on the wind to distant locations.

In this moss, we added water to the peristome. Then with the tip of a paper towel we removed the water and watched the magic happen. This specimen is under a dissecting scope, hence the funny circular view, and I used the video function on my digital camera to record it. I cannot recall the species name of this moss. I am pretty sure it is either in the genus Ulota or Orthotrichum, both in the Orthotrichaceae.

Thanks to Dr. Goffinet for bringing in this moss and helping to make this video.