Unveiling global species abundance distributions

Area of Science:

• Ecology
• Biodiversity Science
• Statistical Ecology

Background:

• Understanding species abundance distributions is fundamental to ecology.
• The commonness versus rarity of species has been a long-standing debate.
• Global Species Abundance Distributions (gSADs) provide insights into biodiversity patterns.

Purpose of the Study:

• To assess global species abundance distributions (gSADs) for 39 eukaryotic taxonomic classes.
• To investigate how sampling effort influences the unveiling of gSAD shapes over time.
• To identify universal patterns in gSADs across diverse taxa.

Main Methods:

• Utilized over one billion species observations from the Global Biodiversity Information Facility (GBIF).
• Analyzed data spanning from 1900 to 2019.
• Applied statistical modeling to determine the best fit for observed gSADs, identifying the Poisson log-normal distribution.

Main Results:

• The shape of gSADs becomes increasingly unveiled with greater sampling effort over time.
• The proportion of unveiled species decreases with higher species richness within a class.
• Birds and other groups were found to be fully unveiled, indicating comprehensive sampling.
• The Poisson log-normal distribution provided the best statistical fit for most taxonomic classes.

Conclusions:

• A universal pattern exists in gSADs across diverse eukaryotic taxa.
• This suggests underlying general ecological or evolutionary mechanisms governing species commonness and rarity.
• The findings contribute to a broader understanding of biodiversity organization on Earth.