Metabarcoding reveals seasonal and spatial patterns of arthropod community assemblages in two contrasting habitats: Desert and oasis of the Baja California Peninsula, Mexico

Aim: Desert springs or oases are the only permanent mesic environments in highly water-limited arid regions. Oases have immense cultural, evolutionary and ecological importance for people and a high number of endemic and relic species. Nevertheless, they are also highly vulnerable ecosystems, with invasive species, overexploitation and climate change being the primary threats. We used the arthropod communities' spatiotemporal diversity and distribution patterns as a proxy to understand biodi-versity dynamics in two geographically close but ecologically contrasting and highly threatened ecosystems: deserts and oases.Location: Baja California Peninsula, Mexico.Methods: Arthropod communities at five oases and surrounding desert scrub areas were sampled in two seasons. Using DNA metabarcoding and traditional taxonomic surveys, we tried to identify what biotic and abiotic characteristics of the habitat are important drivers of arthropod diversity and how these characteristics can change across spatial and temporal scales.Results: Over 6200 individuals representing 23 orders were collected. In oasis sam-ples, the community composition fluctuated more in space (i.e. among sites) than in time (i.e. seasons). Thus, seasonal changes did not affect oasis community diversity and composition, but the dissimilarity among sites increased with geographic dis-tance. Moreover, anthropic activities negatively correlated with arthropod diversity in oases. On the other hand, the season, geography (e.g. latitude) and biotic charac-teristics of the habitat (e.g. sampled scrub species) significantly affected the diversity and composition of the desert arthropod communities.Main Conclusions: Neutral dynamics (e.g. historical climatic events, dispersal limi-tation and spatial component) and human impact significantly influenced the biodi-versity patterns of each oasis. In contrast, the habitat's seasonal variation and biotic characteristics were the most important variables influencing the diversity of the desert communities. Baja California oases harbour distinct invertebrate communities; therefore, each oasis should be conserved individually to preserve these unique assemblages.

Automated summary

This study investigated the biodiversity dynamics in two contrasting and highly threatened ecosystems - deserts and oases - using arthropod community diversity and distribution patterns. The results showed that the community composition of arthropods in oases fluctuated more in space than in time, and anthropic activities negatively impacted arthropod diversity in oases. On the other hand, the season and biotic characteristics significantly affected the diversity of desert arthropod communities. Therefore, each oasis should be conserved individually to preserve the unique assemblages of invertebrates.