Dorylaimida

​By Cliff Bueno de Mesquita
 
Hello everyone, we hope you all are doing well in these pandemic times. The lab is closed, and we are working from home, but there is plenty of data analysis and writing to do!
 
Our collaborator Kelsey Reider, who has worked with us on projects in Perú, has recently been in touch and we are advancing manuscript preparation on our project looking at the effects of vicuña latrines on plant communities, microbial communities, soil nutrient concentrations, and soil temperatures. The idea is that these latrines are hotspots of nutrients in an otherwise severely nutrient-limited landscape (Darcy et al. 2018), and this could help plants establish on soils exposed by retreating glaciers (Figure 1). While glacier retreat is bad, it does open up some new habitat for plants, which is important because they may be losing habitat at lower elevations as they become too warm.

Figure 1. Photos of the field site and sampling locations. a) aerial photography of the rapidly retreating Puca Glacier and the locations of the six latrines sampled in this study. Inset shows the location in southeastern Peru. b) Photo of a latrine featuring dense plant growth, with the Puca Glacier in the background. c) A herd of vicuñas at the field site. d) Photo of SK Schmidt and CP Bueno de Mesquita in a latrine for scale. Photos by K. Reider.

​Vicuñas are abundant ungulates in the Andes Puna grasslands, and are traditionally herded for wool by native peoples of the region. An interesting feature of these animals is that groups of them defecate in the same place (Vilá 1994), leading to the creation of large piles of poop! In 2018 and 2019, we collected soils from such latrines and paired controls outside of the latrines.
 
A nematode from the order Dorylaimida (Phylum = Nematoda, class = Enoplea), was found to be significantly more abundant in control soils compared to latrines, which suggests that they are able to tolerate nutrient poor conditions. Interestingly, they have also been noted as being able to eat cyanobacteria (Darby and Neher 2016), and there are higher relative abundances of cyanobacteria in the control soils. Unfortunately, with our 18S sequencing we could not resolve the taxonomy at a finer resolution. The order Dorylaimida contains free-living predaceous, plant-parasitic, ectoparasitic nematodes, and have been found in soils and freshwater habitats, where they can make up a significant part of the nematode biomass in these systems (Jairajpuri and Ahmad 1992). As predators, dorylaims attack and devour a range of small invertebrates (Poinjar Jr. 2015)!

Figure 2. Picture of a Dorylaimida female tail. From Michigan State University https://www.canr.msu.edu/nemasoil/nematology/img_list/dorylaimida.

References:
Darby, B.J., & Neher, A. (2016). Microfauna within biological soil crusts. In Biological Soil Crusts: An Organizing Principle in Drylands. Weber, B., Büdel, B., and Belnap, J. (eds). Springer International Publishing Switzerland.
 
Darcy, J. L., Schmidt, S. K., Knelman, J. E., Cleveland, C. C., Castle, S. C., & Nemergut, D. R. (2018). Phosphorus, not nitrogen, limits plants and microbial primary producers following glacial retreat. Science advances, 4(5), eaaq0942.
 
Jairajpuri, M.S., & Ahmad, W. (1992). Dorylaimida: Free-living, Predaceous and Plant-parasitic nematodes. E.J. Brill, Leiden, The Netherlands.
 
Poinjar Jr., G.O. (2015). Phylum Nemata. In Thorp and Covich’s Freshwater Invertebrates (4th Edition). https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/dorylaimida/pdf
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