1 Lindgren A.R.

Buckley B.A.

Eppley S.M.

Reysenbach A.-L.

Stedman K.M.

Wagner J.T. Life on the edge-the biology of organisms inhabiting extreme environments: an Introduction to the symposium.

2 Rampelotto P.H. Extremophiles and extreme environments.

3 Wharton D.A. Life at the Limits: Organisms in Extreme Environments.

4 Borgonie G.

García-Moyano A.

Litthauer D.

Bert W.

Bester A.

van Heerden E.

Möller C.

Erasmus M.

Onstott T.C. Nematoda from the terrestrial deep subsurface of South Africa.

5 Sapir A.

Dillman A.R.

Connon S.A.

Grupe B.M.

Ingels J.

Mundo-Ocampo M.

Levin L.A.

Baldwin J.G.

Orphan V.J.

Sternberg P.W. Microsporidia-nematode associations in methane seeps reveal basal fungal parasitism in the deep sea.

6 Wharton D.

Ferns D. Survival of intracellular freezing by the Antarctic nematode Panagrolaimus davidi.

7 Cloud P.

Lajoie K.R. Calcite-impregnated defluidization structures in littoral sands of mono lake, california.

8 Oremland R.S.

Stolz J.F.

Hollibaugh J.T. The microbial arsenic cycle in Mono Lake, California.

9 Smedley P.L.

Kinniburgh D. A review of the source, behaviour and distribution of arsenic in natural waters.

10 Wiens J.A.

Patten D.T.

Botkin D.B. Assessing ecological impact assessment: lessons from Mono Lake, California.

7 Cloud P.

Lajoie K.R. Calcite-impregnated defluidization structures in littoral sands of mono lake, california.

11 Waiser M.J.

Robarts R.D. Saline inland waters.

12 Kanzaki N.

Kiontke K.

Tanaka R.

Hirooka Y.

Schwarz A.

Müller-Reichert T.

Chaudhuri J.

Pires-daSilva A. Description of two three-gendered nematode species in the new genus Auanema (Rhabditina) that are models for reproductive mode evolution.

13 Zdraljevic S.

Fox B.W.

Strand C.

Panda O.

Tenjo F.J.

Brady S.C.

Crombie T.A.

Doench J.G.

Schroeder F.C.

Andersen E.C. Natural variation in C. elegans arsenic toxicity is explained by differences in branched chain amino acid metabolism.

Extremophiles have much to reveal about the biology of resilience, yet their study is limited by sampling and culturing difficulties []. The broad success and small size of nematodes make them advantageous for tackling these problems []. We investigated the arsenic-rich, alkaline, and hypersaline Mono Lake (CA, US) [] for extremophile nematodes. Though Mono Lake has previously been described to contain only two animal species (brine shrimp and alkali flies) in its water and sediments [], we report the discovery of eight nematode species from the lake, including microbe grazers, parasites, and predators. Thus, nematodes are the dominant animals of Mono Lake in species richness. Phylogenetic analysis suggests that the nematodes originated from multiple colonization events, which is striking, given the young history of extreme conditions at Mono Lake []. One species, Auanema sp., is new, culturable, and survives 500 times the human lethal dose of arsenic. Comparisons to two non-extremophile sister species [] reveal that arsenic resistance is a common feature of the genus and a preadaptive trait that likely allowed Auanema to inhabit Mono Lake. This preadaptation may be partly explained by a variant in the gene dbt-1 shared with some Caenorhabditis elegans natural populations and known to confer arsenic resistance []. Our findings expand Mono Lake’s ecosystem from two known animal species to ten, and they provide a new system for studying arsenic resistance. The dominance of nematodes in Mono Lake and other extreme environments and our findings of preadaptation to arsenic raise the intriguing possibility that nematodes are widely pre-adapted to be extremophiles.