Biodiversity modulates the cross-community scaling relationship in changing environments

Area of Science:

• Ecology
• Theoretical Ecology
• Microbiology

Background:

• Organismal abundance generally declines with increasing body size.
• Metabolic theory predicts a universal size-abundance slope of -0.75, linking body size to energy use and productivity.
• The invariance of this relationship across diverse environments remains largely untested.

Purpose of the Study:

• To empirically investigate the robustness of the size-abundance relationship under varying ecological conditions.
• To test how temperature and protist species richness jointly influence the cross-community size scaling relationship (CCSR).
• To determine if the size-abundance relationship is invariant or context-dependent.

Main Methods:

• Utilized replicated protist microcosms to simulate different ecological scenarios.
• Manipulated species richness (1-6 species) and temperature (15°C-25°C) to assess their effects on size-abundance scaling.
• Monitored changes in organismal abundance and body size over time.

Main Results:

• Confirmed the general size-abundance slope of -0.75 across communities.
• Demonstrated that the size-abundance relationship is not invariant, showing significant interactive effects between temperature and species richness.
• Observed that warming favored smaller protists in high-richness communities, leading to a steeper CCSR slope.

Conclusions:

• The cross-community size scaling relationship (CCSR) is dynamically shaped by ecological context, including temperature and biodiversity.
• Environmental changes, particularly warming, can alter size-abundance scaling in a richness-dependent manner.
• Size-dependent species interactions likely play a crucial role in mediating responses to environmental change over time.