Deciphering the Patterns and Drivers of Tardigrade Diversity Along Altitudinal Gradients

Area of Science:

• Ecology
• Biodiversity research
• Microinvertebrate ecology

Background:

• Altitudinal gradients are key for understanding species richness drivers in mountains.
• Microhabitats introduce fine-scale heterogeneity often overlooked in macroenvironmental studies.
• This heterogeneity is crucial for microscopic animals like tardigrades.

Purpose of the Study:

• Investigate altitudinal patterns of microscopic invertebrates (Tardigrada).
• Test if microhabitat characteristics modulate macroenvironmental effects on tardigrade diversity and community structure.
• Analyze the interplay between macroenvironmental and microhabitat factors.

Main Methods:

• Compiled tardigrade inventory from bryophytes in the Western Alps.
• DNA metabarcoding analyzed 546 bryophyte samples for tardigrade communities.
• Spatially explicit statistical modeling assessed macroenvironmental and microhabitat variables.

Main Results:

• Species richness decreased with altitude; standardized phylogenetic and functional diversity increased.
• Tardigrade communities in bryophyte microhabitats showed high heterogeneity, species turnover, and underdispersion.
• Macroenvironmental variables (altitude, location) drove turnover; microhabitat traits governed trait structure.

Conclusions:

• Microhabitats act as fine-scale filters, modulating altitude's broader effects on diversity.
• Stochastic processes influence tardigrade distributions, but macroenvironmental factors drive turnover.
• Incorporating microhabitat heterogeneity is vital for understanding altitudinal diversity patterns.