Coexistence of Three Tardigrade Species in Xeric Moss Microhabitats of Northeastern Iran

Articles in Press

Document Type : Original Article

Authors

farahnaz Molavi

Simin Nayebi Moghaddam

Department of Biology, Mashhad Branch, Islamic Azad University, Mashhad, Iran

10.22067/ijab.2026.96380.1112

Abstract

Tardigrades are renowned for their ability to withstand extreme environments, but the role of individual-level variability in enabling coexistence under resource-limited conditions is not well understood. We studied the seasonal dynamics of Echiniscus testudo, Macrobiotus sp, and Milnesium sp. in xeric moss patches of the Zoshk mountains, northeastern Iran, over two years (2022–2024). Across 54 moss samples, all three species were consistently present, yet their abundances and reproductive activity varied seasonally. E. testudo individuals showed enhanced reproductive effort in autumn, coinciding with transitional moisture availability, whereas Milnesium individuals increased in winter, suggesting physiological and behavioral adaptation to cold, dry extremes. Macrobiotus sp remained less abundant but persisted through flexible resource use. These individual-based differences in timing of reproduction, tolerance to stress, and trophic strategy collectively reduced competitive exclusion and promoted stable coexistence. Our findings demonstrate how individual variability and adaptive behavior contribute to community resilience, highlighting the importance of moss patches as microecosystems that support biodiversity in semi-arid montane landscapes.

Keywords

Coexistence

Cryptobiosis

Individual-based ecology

Iran

Moss microhabitats

Tardigrada

Subjects

• Ecology and Evolution

---