Local climate modulates the development of soil nematode communities after glacier retreat

Abstract

The worldwide retreat of glaciers is causing a faster than ever increase in ice‐free areas that are leading to the emergence of new ecosystems. Understanding the dynamics of these environments is critical to predicting the consequences of climate change on mountains and at high latitudes. Climatic differences between regions of the world could modulate the emergence of biodiversity and functionality after glacier retreat, yet global tests of this hypothesis are lacking. Nematodes are the most abundant soil animals, with keystone roles in ecosystem functioning, but the lack of global‐scale studies limits our understanding of how the taxonomic and functional diversity of nematodes changes during the colonization of proglacial landscapes. We used environmental DNA metabarcoding to characterize nematode communities of 48 glacier forelands from five continents. We assessed how different facets of biodiversity change with the age of deglaciated terrains and tested the hypothesis that colonization patterns are different across forelands with different climatic conditions. Nematodes colonized ice‐free areas almost immediately. Both taxonomic and functional richness quickly increased over time, but the increase in nematode diversity was modulated by climate, so that colonization started earlier in forelands with mild summer temperatures. Colder forelands initially hosted poor communities, but the colonization rate then accelerated, eventually leveling biodiversity differences between climatic regimes in the long term. Immediately after glacier retreat, communities were dominated by colonizer taxa with short generation time and r‐ecological strategy but community composition shifted through time, with increased frequency of more persister taxa with K‐ecological strategy. These changes mostly occurred through the addition of new traits instead of their replacement during succession. The effects of local climate on nematode colonization led to heterogeneous but predictable patterns around the world that likely affect soil communities and overall ecosystem development.

In silico assessment of 18S rDNA metabarcoding markers for the characterization of nematode communities

“…Among these primers, 13 were selected because they have been identified by a previous review as the primers more commonly used in nematode metabarcoding [10]. One additional primer, Euka02 [31] is often used for metabarcoding of eukaryotic eDNA and it has been suggested to provide a good estimate of nematode diversity [8,12,[31][32][33]. Furthermore, we developed a new primer pair (Nema02; see Table 1) by optimizing primer pair F548_A / R1912 from ref.…”

“…Ongoing development of DNA metabarcoding are opening new avenues to the study of biodiversity, and to the identification of management priorities [12,[69][70][71]. Nematodes are increasingly recognized as key components of soil communities, and advances in molecular approaches to assess and monitor their biodiversity are extremely important for the growing knowledge on this highly diverse phylum [11,56].…”

“…The biodiversity of nematodes is estimated to be 1-10 million species, but less than 30,000 species have been described using morphology [6]. Recent advances in DNA metabarcoding have fostered the study of nematode biodiversity from a range of environments, highlighting their impressive diversity and the multiple key roles they play [2,3,[7][8][9][10][11][12].…”