Hybridization — problems, or solutions?

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Claytonia perfoliata species complex on the Tejon Ranch — this is only the beginning of your Montiaceae-related nightmares…

The taxonomy for the annual species of Claytonia (section Limnia) is VERY difficult to work with, mostly because diagnostic characters are not well preserved on herbarium specimens. Unfortunately, a molecular phylogeny that spells out the relationships among taxa in this group is still lacking, but I have added many samples as out-group taxa for my own dissertation studies on section Claytonia (i.e., the tuberous perennial Claytonia)… Is the cause for confusion in field identification due to phenotypic plasticity, hybridization, or both? Is it something else altogether, such as the rapid formation of localized ‘races’ due to poor dispersal capabilities? If the difficulty of accurate field identification is due to hybridization, is this a problem? For taxonomy, the morphological consequences of hybridization are an issue that must be addressed, but for the longevity of lineages, hybridization is probably not a ‘problem’ but rather a solution — it might just be the key to sustaining genetic diversity and promoting adaptation in a forever changing climate — evolutionary success! Before I get too deep into the hole I am digging, we’d better take a look at some nice plant images to really smell what I am stepping in đŸ˜‰

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Claytonia parviflora subsp. viridis — Tejon Ranch. Note the linear basal and cauline leaves of this mildly succulent annual. Were you to collect, you could rest easy with ID of this plant.

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Claytonia parviflora subsp. viridis X C. rubra ?!?!– Tejon Ranch. Note the non-linear basal and cauline leaves of this moderately succulent annual, and the floral morphology of C. rubra. Yet, this plant retains the fully separate leaf pair of C. parviflora subsp. viridis.

Claytonia parviflora subsp. viridis X C. perfoliata ?!?! -- Tejon Ranch. Note the non-linear basal and cauline leaves of this mildly succulent annual.

Claytonia parviflora subsp. viridis X C. perfoliata ?!?! — Tejon Ranch. Note the spatulate basal leaves. I certainly wouldn’t want to be doing a flora of this area, as I’m sure this isn’t the only group with these kinds of ‘problems’ with hybridization đŸ˜‰

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Claytonia exigua (left) and C. exigua X C. perfoliata (right) ?!?! — Tejon Ranch. Note the glaucus basal leaves of the plant on the right, which should otherwise look like the plant in the first picture of this post. Yikes!

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More fun with sympatry on Tejon Ranch!!! Left to right, Claytonia exigua, a diminutive C. perfoliata, and something that approaches C. rubra in morphology — section Limnia is tough!

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Could this possibly even be the same as any taxon we’ve seen elsewhere in this blog post? I’m really not sure, but I would lean toward calling it C. perfoliata-like. The C. perfoliata complex, including also C. rubra and C. parviflora, is probably the most difficult group in section Limnia.

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This is also Claytonia perfoliata! Its first leaves are narrow like these. Under drought conditions it can ‘bypass’ switching to the more mature spatulate leaf condition by going directly into flowering and therefore only producing the perfoliate cauline leaves.

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Contrast (or compare, in case of my suggested hybrids) the above pictures with this one of Claytonia rubra — this appears to be a good example of this species which at one point was treated as C. perfoliata but has been found to be a unique lineage and is treated as such.

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Now, compare the picture immediately above (of Claytonia rubra subsp. rubra) with this one — same or different?! Same! Well, sorta… This is ALSO C. rubra, presumably subsp. depressa, which apparently also occurs on the Tejon Ranch — how exciting!

Okay, so interestingly enough, I took all of these photos (and many, many, many more) in only one day on Tejon Ranch with Nick Jensen, a colleague at Rancho Santa Ana Botanic Garden doing a floristic study of the area. His website can be found here. This is a fascinating area because it serves (or, served) as a biogeographic traffic signal for the Sierra Nevada, the Transverse Ranges AND the San Joaquin Valley and the Mojave Desert. I suspect the evidence for hybridization exhibited by the numerous sympatric Claytonia here is mirrored in other plant groups on the Tejon Ranch where multiple taxa co-occur.

But that isn’t all, of course — the evidence of hybridization reappears in every mountain range I have explored in southern California! It seems to be a battle among divergent lineages to survive and compete for overlapping and limited niche space near the southern part of the geographic distribution of these plants, but maybe a little cooperation wouldn’t hurt for the ‘greater good’ of Claytonia if it increases genetic diversity… In the San Bernardino Mountains, you can find members of the C. perfoliata species complex in sympatry. The evidence for hybridization in this area mirrors what I observed at Tejon Ranch.

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From left to right, Claytonia parviflora, C. perfoliata and C. rubra, all members of the C. perfoliata species complex occurring together in Mill Creek Canyon, San Bernardino Mountains.

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A good example of Claytonia parviflora; note the erect, linear basal leaves that are almost terete in shape, and the cleft in the disc-like cauline leaf-pair resulting from incomplete fusion of two leaves.

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Compared with the picture immediately above, this one looks like a fusion of C. parviflora and presumably one (or both?) of the other two annual species in the area. I tend to think C. perfoliata may have played a role in the formation of this hybrid, but we can only be sure by DNA sequencing or by extensive cytological screening. Note the erect basal leaves that are no longer linear in shape but instead have rather distinct blades — this is NOT C. parviflora in the strictest sense of the name.

In the San Jacinto Mountains, you can find more of the same — members of the C. perfoliata species complex in sympatry and evidence for hybridization that may make you want to tear your hair out if you are working to identify plant specimens collected here. For instance, the pictures below from the San Jacinto Mountains are more or less taken from within ~1 contiguous square mile in Garner Valley.

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An excellent example of C. parviflora subsp. viridis is strutting its stuff roadside in the San Jacinto Mountains. Here, you have more action in the ring coming from the C. parviflora corner than from elsewhere in the C. perfoliata complex — I’m not sure the reason but think it is related to the locality I visited, a recently burned area in Garner Valley with little overstory cover.

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Compare the picture immediately above (of C. parviflora subsp. viridis) with this one of C. parviflora subsp. parviflora — similarly erect basal leaves that approach a terete-linear shape, but a contrastingly perfoliate cauline leaf-pair that is almost completely fused (as opposed to the free cauline leaves of C. parviflora subsp. viridis photographed above). The two appear to have different coloration under the same conditions here as well in both the flowers and foliage. — Garner Valley, San Jacinto Mountains.

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Now, compare the picture immediately above (of C. parviflora subsp. parviflora) with this one of some sort of C. parviflora hybrid — similarly erect basal leaves but these appear to be forming distinct blade and petiolar regions unlike the other two photos above from the same general location… tempting to call them the same, but I imagine this fishiness has both rhyme and reason to it. — Garner Valley, San Jacinto Mountains.

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This plant is OBVIOUSLY different from the rest, but what do you call it?! Under some Jeffrey pines that survived the fire, these plants approach the morphology of C. perfoliata subsp. mexicana but the smaller leaves in the center of the rosette are suggestive of certain races of C. rubra. — Garner Valley, San Jacinto Mountains.

What a wild and wacky world we live in! Claytonia will keep me busy (and happy) for many years to come…

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THANKS (Experimental Success!)… and a report on my Northern California and Southern Oregon trip to sympatric Claytonia sites

IMG_7744Above, two members of the genus Claytonia from different Sections — C. “serpenticola” (an undescribed species in Section Claytonia) on the left, and C. rubra (Section Limnia) on the right. The two occur in close sympatry in the Lassic Mountain Wilderness, practically high-fiving their cauline leaves. This was a highly productive trip to the north, but before I get to that…

 

I want to say THANKS to all who supported my recent fundraising endeavor with Dr. Ingrid Jordon-Thaden on Experiment.com — we are going to be able to do some much needed fieldwork and conduct fundamental biodiversity research with the money you have all helped us to raise! Thanks so very much, and stay tuned for updates (Lab Notes and Blog Posts) on this ‘open access’ alpine research.

 

OK, back to talking about my recent trip to Oregon and California — I was on the hunt to find locations where multiple Claytonia occur in close sympatry, particularly areas where species may be hybridizing. I am interested in knowing just how well species can maintain their identities in these situations…

IMG_6819I started the trip by meeting up with Larry Crawford for some botanizing in the Sierra Nevada — we found Claytonia sessilifolia (Torrey) Henshaw(pictured above) flowering profusely near Carson Pass in an area that Larry had previously scouted. This plant was featured in the recent Spring Beauty Pageant hosted on my website — it isn’t too late for you to cast a vote for your favorite(s)! In this population it seems like there is only one species present (C. sessilifolia), but this taxon occurs in an interesting habitat (pictured below, with Diana Jolles and Larry Crawford). It also occurs next to some other fantastic spring ephemerals, such as Dicentra uniflora (pictured below) — the hike was well worth it!

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Larry Crawford and Diana Jolles enjoying the habitat on Meiss Ridge

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Following some rest and recovery at Larry’s house (thanks, Larry and Suzanne!), my colleagues and I continued north to Lassen Volcanic National Park, catching a wonderful view of Mt. Lassen (pictured below) — this was my first time taking in such a beautiful sight. I also have never (knowingly) been this close to a stratovolcano. I can’t say that I was nervous that the mountain might erupt, but it actually hasn’t been long since something like that happened (click here to read more about the geologically recent eruption of Lassen Peak). Unfortunately we didn’t find any Claytonia in this area, but we might have also been a tad on the early side for the area we looked — several feet of snow in some drifts. It has been a bit of a whacky weather year…

IMG_6885Having been thwarted by a lack of Claytonia at Lassen Volcanic National Park and lower elevation sites in Lassen National Forest, I decided to book it northward to Crater Lake National Park in an attempt to catch up with a rapidly fading spring. Many of the areas in California where Claytonia have previously been reported as abundant are looking quite parched — the Spring Beauties are apparently less than pleased about it. At Crater Lake, though, we found C. sessilifolia plants blooming where else but in the parking lot (pictured below)!Snagging a few quick pictures of the cinder cone “Wizard Island” (pictured below) in the middle of Crater Lake was just a bonus of doing fieldwork in the area. đŸ˜‰IMG_6959

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We found some more plants a few miles north of Crater Lake NP on the Rogue River-Siskiyou National Forest, and I also happened to snap a quick picture of the BEAUTIFUL Mt. Thielsen (pictured below) on my way out of Crater Lake National Park — this is another place I’ve got my eye on visiting. I’ve heard the Claytonia on Mt. Thielsen are quite interesting… IMG_7019

Next was Abbott Butte (west of Crater Lake National Park) — I ABSOLUTELY had to visit that area this year, as it is the type locality for Claytonia obovata Rydberg. Ray Davis chose to sink this taxon into synonymy in the 1960’s — it has been treated as C. lanceolata since that time. Ray mentioned in his 1966 North American Perennial Species of Claytonia that he collected plants answering the original descriptions of C. obovata, C. multicaulis, and C. chrysantha, as well as C. lanceolata at Abbott Butte. Although he didn’t recognize C. obovata, tubers he collected of that taxon from around the type locality that he grew in a ‘common garden’ retained their rounded leaf shape. What did I find at Abbott Butte? Claytonia lanceolata (pictured below, lacking bifid petals), but not any C. obovata — did it not come up this year? I’ve certainly observed this happening before with C. “peirsonii” in southern California… at least Julian (pictured below) found some delicous black morels (Morchella elata-M. angusticeps-M. conica complex). = YUMMY.IMG_7177

Julian enjoys yummy morels...

Julian enjoys yummy morels…

What do you do when you can’t find a species at its type locality? You write a paper about it  — look for Stoughton et al. (in prep.) coming to a Madroño near you. Fortunately, I have seen C. obovata previously with Heath Bartosh at Hull Mountain — this area is also mentioned in the protologue for C. obovata Rydberg. I did find C. obovata with Diana Jolles and Julian Roberts later during our trip near Cory Peak and Mount Eddy on the Shasta-Trinity National Forest in the Klamath Region of California, but I want to tell you first about the next stop on our road trip at the Siskiyou Mountains of southern Oregon — Observation Peak (pictured below) is an area where C. “serpenticola” (pictured below, and at the beginning of this post) is known to occur.IMG_7263

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After seeing C. “serpenticola” (pictured above) more or less ‘alone’ in the Siskiyou Mountains of southern Oregon on serpentinite and peridotite, we next saw C. obovata (pictured below) similarly secluded in the Scott Mountains of California near Cory Peak — I now had my search images for a hike that was a major part of the trip. The two species occur in sympatry at Deadfall Lakes just below Mount Eddy, which is where we were headed next. I REALLY want to measure levels of hybridization in this population on Mount Eddy — obvious intermediates exist in the area in seemingly marginal habitats.

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What do hybrids between C. obovata and C. “serpenticola” look like? They probably look something like the pictures below — the two species occur in very close proximity in this area…IMG_7574

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SUCH A COOL SPOT — I will revisit this area next year when there is hopefully a bit better snow pack (which generally = many happy Claytonia). Who is coming with me?! I’m climbing up to the top again for sure. Claytonia “serpenticola” (pictured below) grows very near to the summit, and the view of Mount Shasta (pictured below) from atop Mount Eddy is SPECTACULAR.IMG_7698

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After poking around Mount Eddy with Dana York and Julie Nelson, and a much needed night of rest (Thanks, Dana and Eva!), Diana and Julian headed with me south to the Lassic Mountain Wilderness (Six Rivers National Forest) and Anthony Peak (Mendocino National Forest) to see C. “serpenticola” (pictured below) and C. obovata (pictured below) at additional areas where they occur in allopatry — plants were pretty crispy in northern California, but they were still identifiable!

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I am VERY excited to see how things shake out in the molecular phylogeny I am developing for this group… Stay Tuned!!!